期刊文献+
共找到121,780篇文章
< 1 2 250 >
每页显示 20 50 100
Relationship between MRI perfusion and clinical severity in multiple sclerosis 预览
1
作者 Maria Marcella Laganà Laura Pelizzari Francesca Baglio 《中国神经再生研究:英文版》 SCIE CAS CSCD 2020年第4期646-652,共7页
Perfusion alterations within several brain regions have been shown in multiple sclerosis patients using different magnetic resonance imaging(MRI)techniques.Furthermore,MRI-derived brain perfusion metrics have been inv... Perfusion alterations within several brain regions have been shown in multiple sclerosis patients using different magnetic resonance imaging(MRI)techniques.Furthermore,MRI-derived brain perfusion metrics have been investigated in association with multiple sclerosis phenotypes,physical disability,and cognitive impairment.However,a review focused on these aspects is still missing.Our aim was to review all the studies investigating the relationship between perfusion MRI and clinical severity during the last fifteen years to understand the clinical relevance of these findings.Perfusion differences among phenotypes were observed both with 1.5T and 3T scanners,with progressive multiple sclerosis presenting with lower perfusion values than relapsing-remitting multiple sclerosis patients.However,only 3T scanners showed a statistically significant distinction.Controversial results about the association between MRI-derived perfusion metrics and physical disability scores were found.However,the majority of the studies showed that lower brain perfusion and longer transit time are associated with more severe physical disability and worse cognitive performances. 展开更多
关键词 brain PERFUSION cerebral blood flow COGNITION DISABILITY magnetic resonance imaging MRI multiple SCLEROSIS PHENOTYPES progressive relapsing remitting
在线阅读 下载PDF
Three-dimensional bioprinting collagen/silk fibroin scaffold combined with neural stem cells promotes nerve regeneration after spinal cord injury 预览
2
作者 Ji-Peng Jiang Xiao-Yin Liu +9 位作者 Fei Zhao Xiang Zhu Xiao-Yin Li Xue-Gang Niu Zi-Tong Yao Chen Dai Hui-You Xu Ke Ma Xu-Yi Chen Sai Zhang 《中国神经再生研究:英文版》 SCIE CAS CSCD 2020年第5期959-968,共10页
Many studies have shown that bio-scaffolds have important value for promoting axonal regeneration of injured spinal cord.Indeed,cell transplantation and bio-scaffold implantation are considered to be effective methods... Many studies have shown that bio-scaffolds have important value for promoting axonal regeneration of injured spinal cord.Indeed,cell transplantation and bio-scaffold implantation are considered to be effective methods for neural regeneration.This study was designed to fabricate a type of three-dimensional collagen/silk fibroin scaffold (3D-CF) with cavities that simulate the anatomy of normal spinal cord.This scaffold allows cell growth in vitro and in vivo.To observe the effects of combined transplantation of neural stem cells (NSCs) and 3D-CF on the repair of spinal cord injury.Forty Sprague-Dawley rats were divided into four groups: sham (only laminectomy was performed),spinal cord injury (transection injury of T10 spinal cord without any transplantation),3D-CF (3D scaffold was transplanted into the local injured cavity),and 3D-CF + NSCs (3D scaffold co-cultured with NSCs was transplanted into the local injured cavity.Neuroelectrophysiology,imaging,hematoxylin-eosin staining,argentaffin staining,immunofluorescence staining,and western blot assay were performed.Apart from the sham group,neurological scores were significantly higher in the 3D-CF + NSCs group compared with other groups.Moreover,latency of the 3D-CF + NSCs group was significantly reduced,while the amplitude was significantly increased in motor evoked potential tests.The results of magnetic resonance imaging and diffusion tensor imaging showed that both spinal cord continuity and the filling of injury cavity were the best in the 3D-CF + NSCs group.Moreover,regenerative axons were abundant and glial scarring was reduced in the 3D-CF + NSCs group compared with other groups.These results confirm that implantation of 3D-CF combined with NSCs can promote the repair of injured spinal cord.This study was approved by the Institutional Animal Care and Use Committee of People’s Armed Police Force Medical Center in 2017 (approval No.2017-0007.2). 展开更多
关键词 3D BIOPRINTING COLLAGEN diffusion tensor IMAGING functional recovery magnetic resonance IMAGING nerve REGENERATION NEURAL REGENERATION NEURAL stem cell SCAFFOLD silk fibroin spinal cord injury
在线阅读 下载PDF
Alteration of functional connectivity in patients with Alzheimer’s disease revealed by resting-state functional magnetic resonance imaging 预览
3
作者 Jie Zhao Yu-Hang Du +2 位作者 Xue-Tong Ding Xue-Hu Wang Guo-Zun Men 《中国神经再生研究:英文版》 SCIE CAS CSCD 2020年第2期285-292,共8页
The main symptom of patients with Alzheimer’s disease is cognitive dysfunction. Alzheimer’s disease is mainly diagnosed based on changes in brain structure. Functional connectivity reflects the synchrony of function... The main symptom of patients with Alzheimer’s disease is cognitive dysfunction. Alzheimer’s disease is mainly diagnosed based on changes in brain structure. Functional connectivity reflects the synchrony of functional activities between non-adjacent brain regions, and changes in functional connectivity appear earlier than those in brain structure. In this study, we detected resting-state functional connectivity changes in patients with Alzheimer’s disease to provide reference evidence for disease prediction. Functional magnetic resonance imaging data from patients with Alzheimer’s disease were used to show whether particular white and gray matter areas had certain functional connectivity patterns and if these patterns changed with disease severity. In nine white and corresponding gray matter regions, correlations of normal cognition, early mild cognitive impairment, and late mild cognitive impairment with blood oxygen level-dependent signal time series were detected. Average correlation coefficient analysis indicated functional connectivity patterns between white and gray matter in the resting state of patients with Alzheimer’s disease. Functional connectivity pattern variation correlated with disease severity, with some regions having relatively strong or weak correlations. We found that the correlation coefficients of five regions were 0.3–0.5 in patients with normal cognition and 0–0.2 in those developing Alzheimer’s disease. Moreover, in the other four regions, the range increased to 0.45–0.7 with increasing cognitive impairment. In some white and gray matter areas, there were specific connectivity patterns. Changes in regional white and gray matter connectivity patterns may be used to predict Alzheimer’s disease;however, detailed information on specific connectivity patterns is needed. All study data were obtained from the Alzheimer’s Disease Neuroimaging Initiative Library of the Image and Data Archive Database. 展开更多
关键词 Alzheimer's disease blood oxygen level-dependent signal correlation coefficient FUNCTIONAL connectivity pattern FUNCTIONAL magnetic resonance imaging GRAY MATTER RESTING state white MATTER
在线阅读 下载PDF
Effect of the combination of high-frequency repetitive magnetic stimulation and neurotropin on injured sciatic nerve regeneration in rats 预览
4
作者 Jie Chen Xian-Ju Zhou Rong-Bin Sun 《中国神经再生研究:英文版》 SCIE CAS CSCD 2020年第1期145-151,共7页
Repetitive magnetic stimulation is effective for treating posttraumatic neuropathies following spinal or axonal injury.Neurotropin is a potential treatment for nerve injuries like demyelinating diseases.This study sou... Repetitive magnetic stimulation is effective for treating posttraumatic neuropathies following spinal or axonal injury.Neurotropin is a potential treatment for nerve injuries like demyelinating diseases.This study sought to observe the effects of high-frequency repetitive magnetic stimulation,neurotropin and their combined use in the treatment of peripheral nerve injury in 32 adult male Sprague-Dawley rats.To create a sciatic nerve injury model,a 10 mm-nerve segment of the left sciatic nerve was cut and rotated through 180°and each end restored continuously with interrupted sutures.The rats were randomly divided into four groups.The control group received only a reversed autograft in the left sciatic nerve with no treatment.In the high-frequency repetitive magnetic stimulation group,peripheral high-frequency repetitive magnetic stimulation treatment(20 Hz,20 min/d)was delivered for 10 consecutive days after auto-grafting.In the neurotropin group,neurotropin therapy(0.96 NU/kg per day)was administrated for 10 consecutive days after surgery.In the combined group,the combination of peripheral high-frequency repetitive magnetic stimulation(20 Hz,20 min/d)and neurotropin(0.96 NU/kg per day)was given for 10 consecutive days after the operation.The Basso-Beattie-Bresnahan locomotor rating scale was used to assess the behavioral recovery of the injured nerve.The sciatic functional index was used to evaluate the recovery of motor functions.Toluidine blue staining was performed to determine the number of myelinated fibers in the distal and proximal grafts.Immunohistochemistry staining was used to detect the length of axons marked by neurofilament 200.Our results reveal that the Basso-Beattie-Bresnahan locomotor rating scale scores,sciatic functional index,the number of myelinated fibers in distal and proximal grafts were higher and axon lengths were longer in the high-frequency repetitive magnetic stimulation,neurotropin and combined groups compared with the control group.These measures were not significantly different am 展开更多
关键词 AXON myelinated NERVE fibers NERVE REGENERATION neurological rehabilitation NEUROTROPIN peripheral NERVE injury REPETITIVE magnetic stimulation SCIATIC NERVE trauma
在线阅读 下载PDF
铟-镧系元素(La,Ce,Pr和Nd)金属间化合物磁学和热力学性质的第一性原理计算 预览
5
作者 徐允 张兆春 +1 位作者 郭海波 谢耀平 《材料导报》 EI CAS CSCD 北大核心 2020年第2期2093-2099,共7页
在高燃耗率时,作为裂变产物的镧系元素(主要为La,Ce,Pr,Nd,Pm,Sm)在合金燃料内部不断积累,并且逐渐迁移至包覆层-燃料界面,与包覆层主要化学元素(Fe,Cr,Ni)发生化学反应,生成低熔点金属间化合物。控制包覆层-燃料界面化学反应的有效措... 在高燃耗率时,作为裂变产物的镧系元素(主要为La,Ce,Pr,Nd,Pm,Sm)在合金燃料内部不断积累,并且逐渐迁移至包覆层-燃料界面,与包覆层主要化学元素(Fe,Cr,Ni)发生化学反应,生成低熔点金属间化合物。控制包覆层-燃料界面化学反应的有效措施之一是将特定化学元素掺入合金燃料中,与镧系元素发生化学反应,生成稳定的、难以迁移的化合物,从而显著减少或延迟包覆层-燃料界面化学反应的发生。铟(In)由于具有与合金燃料元素相容、对包覆层金属元素呈现化学惰性以及与镧系元素能够生成金属间化合物等特性,已作为合金燃料的化学掺杂剂而被研究。本工作通过第一性原理计算,研究了铟-镧系元素(In-La)金属间化合物(InLa,CeIn3,αInPr,In 3Nd)的基态性质以及在自旋-轨道耦合存在下的电子和磁性性质;此外,基于Debye-Slater模型,对InLa、CeIn3、αInPr、In3Nd在不同温度和压力下的热力学性质进行了计算。该研究可更好地表征铟结合和稳定镧系裂变产物的功能。 展开更多
关键词 镧系元素 磁学 热力学性质 第一性原理
在线阅读 免费下载
功能化磁性纳米材料在磷酸化肽富集中的应用 预览
6
作者 熊芳芳 江丹丹 贾琼 《色谱》 CAS CSCD 北大核心 2020年第1期60-65,共6页
蛋白质磷酸化是最重要和最普遍的翻译后修饰之一。基于质谱的技术已成为分析蛋白质磷酸化的重要手段。然而,磷酸化肽固有的低丰度和电离效率以及由非磷酸化肽共存引起的严重抑制使得直接质谱分析仍然是一个挑战。为解决此问题,需在质谱... 蛋白质磷酸化是最重要和最普遍的翻译后修饰之一。基于质谱的技术已成为分析蛋白质磷酸化的重要手段。然而,磷酸化肽固有的低丰度和电离效率以及由非磷酸化肽共存引起的严重抑制使得直接质谱分析仍然是一个挑战。为解决此问题,需在质谱分析前对磷酸化蛋白质进行选择性富集。磁性纳米材料具有良好的磁响应性,可以在外界磁铁的帮助下实现与溶液的迅速分离。功能化磁性纳米材料作为一种新型的分析技术已在蛋白质组学研究中得到广泛的应用。该文就近年来对磁性纳米粒子进行各种功能化修饰以提高其特异性吸附能力的吸附材料在磷酸化肽的富集方面的应用予以综述,并展望了功能化磁性纳米材料在磷酸化肽富集领域的应用前景。 展开更多
关键词 功能化 磁性 磷酸化肽 综述
在线阅读 下载PDF
Evolving role of magnetic resonance techniques in primary sclerosing cholangitis 预览
7
作者 Emmanuel A Selvaraj Emma L Culver +3 位作者 Helen Bungay Adam Bailey Roger W Chapman Michael Pavlides 《世界胃肠病学杂志:英文版》 SCIE CAS 2019年第6期644-658,共15页
Development of non-invasive methods to risk-stratify patients and predict clinical endpoints have been identified as one of the key research priorities in primary sclerosing cholangitis(PSC).In addition to serum and h... Development of non-invasive methods to risk-stratify patients and predict clinical endpoints have been identified as one of the key research priorities in primary sclerosing cholangitis(PSC).In addition to serum and histological biomarkers,there has been much recent interest in developing imaging biomarkers that can predict disease course and clinical outcomes in PSC.Magnetic resonance imaging/magnetic resonance cholangiopancreatography(MRI/MRCP)continue to play a central role in the diagnosis and follow-up of PSC patients.Magnetic resonance(MR)techniques have undergone significant advancement over the last three decades both in MR data acquisition and interpretation.The progression from a qualitative to quantitative approach in MR acquisition techniques and data interpretation,offers the opportunity for the development of objective and reproducible imaging biomarkers that can potentially be incorporated as an additional endpoint in clinical trials.This review article will discuss how the role of MR techniques have evolved over the last three decades from emerging as an alternative diagnostic tool to endoscopic retrograde cholangiopancreatography,to being instrumental in the ongoing search for imaging biomarker of disease stage,progression and prognosis in PSC. 展开更多
关键词 Primary SCLEROSING CHOLANGITIS MAGNETIC RESONANCE IMAGING MAGNETIC RESONANCE CHOLANGIOPANCREATOGRAPHY MAGNETIC RESONANCE elastography Diffusion MAGNETIC RESONANCE IMAGING Endoscopic retrograde CHOLANGIOPANCREATOGRAPHY
在线阅读 免费下载
Evaluation of tumor response to antiangiogenic therapy in patients with recurrent gliomas using contrast-enhanced perfusion-weighted magnetic resonance imaging techniques: A meta-analysis 预览
8
作者 Akanganyira Kasenene Aju Baidya +1 位作者 Salman Shams Hai-Bo Xu 《世界荟萃分析杂志》 2019年第2期51-65,共15页
BACKGROUND It is of vital importance to find radiologic biomarkers that can accurately predict treatment response. Usually, the initiation of antiangiogenic therapy causes a rapid decrease in the contrast enhancing tu... BACKGROUND It is of vital importance to find radiologic biomarkers that can accurately predict treatment response. Usually, the initiation of antiangiogenic therapy causes a rapid decrease in the contrast enhancing tumor. However, the treatment response is observed only in a fraction of patients due to the partial radiological response secondary to stabilization of abnormal vessels which does not essentially indicate a true antitumor effect. Perfusion-weighted magnetic resonance imaging (PWMRI) techniques have shown implicitness as a strong imaging biomarker for gliomas since they give hemodynamic information of blood vessels. Hence, there is a rapid expansion of PW-MRI related studies and clinical applications. AIM To determine the diagnostic performance of PW-MRI techniques including:(A) dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI);and (B) dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) for evaluating response to antiangiogenic therapy in patients with recurrent gliomas. METHODS Databases such as PubMed (MEDLINE included), EMBASE, and Google Scholar were searched for relevant original articles. The included studies were assessed for methodological quality with the Quality Assessment of Diagnostic Accuracy Studies 2 tool. Medical imaging follow-up or histopathological analysis was used as the reference standard. The data were extracted by two reviewers independently, and then the sensitivity, specificity, summary receiver operating characteristic curve, area under the curve (AUC), and heterogeneity were calculated using Meta-Disc 1.4 software.RESULTS This study analyzed a total of six articles. The overall sensitivity for DCE-MRI and DSC-MRI was 0.69 [95% confidence interval (CI): 0.53-0.82], and the specificity was 0.99 (95%CI: 0.93-1) by a random effects model (DerSimonianee- Laird model). The likelihood ratio (LR)+, LR-, and diagnostic odds ratio (DOR) were 12.84 (4.54-36.28), 0.35 (0.22-0.53), and 24.44 (7.19-83.06), respectively. The AUC (± SE) was 0.9921 (± 0.0120), 展开更多
关键词 Glioma Perfusion-weighted MAGNETIC RESONANCE IMAGING DYNAMIC contrastenhanced MAGNETIC RESONANCE IMAGING DYNAMIC susceptibility contrast MAGNETIC RESONANCE IMAGING Anti-vascular endothelial growth factor ANTIANGIOGENIC Metaanalysis
在线阅读 免费下载
Synthesis of PEI-Functionalized Magnetic Nanoparticles for Capturing Bacteria
9
作者 陈保利 谢浩 +4 位作者 ZHANG Ao LIU Nian LI Qichang GUO Junhui SU Baolian 《武汉理工大学学报:材料科学英文版》 SCIE EI CAS 2019年第1期236-242,共7页
Polyethyleneimine(PEI) functionalized Fe3O4 MNPs were synthesized by a modified hypothermal oxidative hydrolysis method. The magnetic nanoparticles showed positively charged surface, strong magnetic responsivity and u... Polyethyleneimine(PEI) functionalized Fe3O4 MNPs were synthesized by a modified hypothermal oxidative hydrolysis method. The magnetic nanoparticles showed positively charged surface, strong magnetic responsivity and uniform particle size distribution at 56.1±0.6 nm. Aggregation of these magnetic nanoparticles were observed on the surface of different type of bacteria. Magnetic capturing of bacteria were facilitated by these magnetic nanoparticles. The capturing efficiency could reach 90% after two rounds of interactions of 5 minutes. The mechanism and process of interactions between bacteria and polyethyleneimine functionalized Fe3O4 magnetic nanoparticles were explored and discussed. The present study not only provides insight into interactions between Fe3O4@PEI MNPs and bacterial cells, but also opens a new avenue for designing and applying Fe3O4@PEI MNPs as biosensors in microbiology, medicine, and environmental science. 展开更多
关键词 MAGNETIC nanoparticles(MNPs) polyethyleneimine(PEI) MAGNETIC separation BACTERIAL surface
Crystal-field levels of Nd^3+in a new langasite compound Nd3CrGe3Be2O14
10
作者 Sergei A.Klimin Boris V.Mill Marina N.Popova 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第11期1250-1254,共5页
We report on the crystal-field(CF)levels of Nd3+in Nd3CrGe3Be2O14,a representative of recently synthesized Be-containing langasites.They are the first in the family to contain two magnetic subsystems,1 D chromium and ... We report on the crystal-field(CF)levels of Nd3+in Nd3CrGe3Be2O14,a representative of recently synthesized Be-containing langasites.They are the first in the family to contain two magnetic subsystems,1 D chromium and Kagome-like rare-earth ones.High-resolution broad-band temperature-dependent spectra allow us to find all five CF Kramers doublets of the ground 4I9/2 CF multiplet and 38 levels of the excited 4I11/2,13/2,15/2,4F3/2,4F5/2+2H9/2,4F7/2+4S3/2 and 4F9/2 CF multiplets.These data form a basis for a future exploration of this interesting two-sublattice magnet with frustrated interactions.Optical transitions between Kramers doublets of Nd3+indicate magnetic activity of 1D-chromium chains at T<20 K. 展开更多
关键词 LANGASITE Two magnetic subsystems High-resolution spectroscopy Crystal-field levels Magnetic correlations Rare earths
Imaging plaque inflammation in asymptomatic cocaine addicted individuals with simultaneous positron emission tomography/magnetic resonance imaging 预览
11
作者 Keren Bachi Venkatesh Mani +4 位作者 Audrey E Kaufman Nadia Alie Rita Z Goldstein Zahi A Fayad Nelly Alia-Klein 《世界放射学杂志:英文版(电子版)》 2019年第5期62-73,共12页
BACKGROUND Chronic cocaine use is associated with stroke, coronary artery disease and myocardial infarction, resulting in severe impairments or sudden mortality. In the absence of clear cardiovascular symptoms, indivi... BACKGROUND Chronic cocaine use is associated with stroke, coronary artery disease and myocardial infarction, resulting in severe impairments or sudden mortality. In the absence of clear cardiovascular symptoms, individuals with cocaine use disorder (iCUD) seeking addiction treatment receive mostly psychotherapy and psychiatric pharmacotherapy, with no attention to vascular disease (i.e., atherosclerosis). Little is known about the pre-clinical signs of cardiovascular risk in iCUD and early signs of vascular disease are undetected in this underserved population. AIM To assess inflammation, plaque burden and plaque composition in iCUD aiming to detect markers of atherosclerosis and vascular disease. METHODS The bilateral carotid arteries were imaged with positron emission tomography/magnetic resonance imaging (PET/MRI) in iCUD asymptomatic for cardiovascular disease, healthy controls, and individuals with cardiovascular risk. PET with 18F-fluorodeoxyglucose (18F-FDG) evaluated vascular inflammation and 3-D dark-blood MRI assessed plaque burden including wall area and thickness. Drug use and severity of addiction were assessed with standardized instruments. RESULTS The majority of iCUD and controls had carotid FDG-PET signal greater than 1.6 but lower than 3, indicating the presence of mild to moderate inflammation. However, the MRI measure of wall structure was thicker in iCUD as compared to the controls and cardiovascular risk group, indicating greater carotid plaque burden. iCUD had larger wall area as compared to the healthy controls but not as compared to the cardiovascular risk group, indicating structural wall similarities between the non-control study groups. In iCUD, wall area correlated with greater cocaine withdrawal and craving. CONCLUSION These preliminary results show markers of carotid artery disease burden in cardiovascular disease-asymptomatic iCUD. Broader trials are warranted to develop protocols for early detection of cardiovascular risk and preventive intervention in iCUD. 展开更多
关键词 3-D dark-blood magnetic resonance imaging 18F-fluorodeoxyglucose POSITRON emission TOMOGRAPHY SIMULTANEOUS POSITRON emission TOMOGRAPHY Magnetic resonance Substance use disorder COCAINE addiction Atherosclerosis PLAQUE burden Vascular INFLAMMATION
在线阅读 免费下载
Chiral phase structure of the sixteen meson states in the SU(3) Polyakov linear-sigma model for finite temperature and chemical potential in a strong magnetic field
12
作者 Abdel Nasser Tawfik Abdel Magied Diab M.T.Hussein 《中国物理C:英文版》 SCIE CAS CSCD 2019年第3期56-71,共16页
In characterizing the chiral phase-structure of pseudoscalar(Jpc = 0-+), scalar(Jpc = 0++), vector(Jpc =1--) and axial-vector(Jpc = 1++t) meson states and their dependence on temperature, chemical potential, and magne... In characterizing the chiral phase-structure of pseudoscalar(Jpc = 0-+), scalar(Jpc = 0++), vector(Jpc =1--) and axial-vector(Jpc = 1++t) meson states and their dependence on temperature, chemical potential, and magnetic field,we utilize the SU(3) Polyakov linear-sigma model(PLSM) in the mean-field approximation. We first determine the chiral(non)strange quark condensates,σl and σs, and the corresponding deconfinement order parameters, φ and φ*, in thermal and dense(finite chemical potential) medium and finite magnetic field. The temperature and the chemical potential characteristics of nonet meson states normalized to the lowest bosonic Matsubara frequency are analyzed. We note that all normalized meson masses become temperature independent at different critical temperatures. We observe that the chiral and deconfinement phase transitions are shifted to lower quasicritical temperatures with increasing chemical potential and magnetic field. Thus, we conclude that the magnetic field seems to have almost the same effect as the chemical potential, especially on accelerating the phase transition, i.e. inverse magnetic catalysis. We also find that increasing the chemical potential enhances the mass degeneracy of the various meson masses, while increasing the magnetic field seems to reduce the critical chemical potential, at which the chiral phase transition takes place. Our mass spectrum calculations agree well with the recent PDG compilations and PNJL, lattice QCD calculations, and QMD/UrQMD simulations. 展开更多
关键词 CHIRAL transition MAGNETIC fields MAGNETIC catalysis critical temperature viscous properties of QGP
Large lattice mismatch induced perpendicular magnetic anisotropy and perpendicular exchange bias in CoPt/FeMn bilayer films
13
作者 PAN ChunJiao GAO TengHua +4 位作者 ITOGAWA Nobuhide HARUMOTO Takashi ZHANG ZhengJun NAKAMURA Yoshio SHI Ji 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2019年第11期2009-2013,共5页
Perpendicular magnetic anisotropy and perpendicular exchange bias of CoPt/FeMn bilayers fabricated by dc magnetron sputtering were investigated in this work.Magnetic anisotropy,showing strong dependence on thickness o... Perpendicular magnetic anisotropy and perpendicular exchange bias of CoPt/FeMn bilayers fabricated by dc magnetron sputtering were investigated in this work.Magnetic anisotropy,showing strong dependence on thickness of CoPt layer,changes from perpendicular magnetic anisotropy(PMA) into in-plane magnetic anisotropy when CoPt layer is thicker than 4.5 nm.The evolution of internal stress with thickness,from tensile to compressive,has been analyzed by sin^2 ψ method using an equal biaxial stress model.Distinctive perpendicular exchange bias(PEB) has been successfully established due to PMA of CoPt and out-ofplane spin component of 3 Q-spin-structured FeMn.FeMn thickness dependence of exchange bias field has been systematically investigated. 展开更多
关键词 PERPENDICULAR MAGNETIC ANISOTROPY PERPENDICULAR exchange BIAS X-ray technique MAGNETIC materials
Enhanced soft magnetic properties of iron powders through coating MnZn ferrite by one-step sol–gel synthesis
14
作者 刘冬 高善民 +4 位作者 金仁成 王峰 初晓晓 高太平 王玉宝 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第5期300-304,共5页
The MnZn ferrite coating formed on the surface of iron-based soft magnetic powders via facile and modified sol–gel process has been fabricated to obtain better magnetic performance due to its higher permeability comp... The MnZn ferrite coating formed on the surface of iron-based soft magnetic powders via facile and modified sol–gel process has been fabricated to obtain better magnetic performance due to its higher permeability compared with traditional nonmagnetic insulation coatings.The influence of the MnZn ferrite contents on the magnetic performance of the soft magnetic composites (SMCs) has been studied.As the MnZn insulation content increases,the core loss first experiences a decreasing trend that is followed by progressive increase,while the permeability follows an increasing trend and subsequently degrades.The optimized magnetic performance is achieved with 2.0 wt% MnZn ferrite,which results from the decrement of inter-particle eddy current losses based on loss separation.A uniform and compact coating layer composed of MnZn ferrite and oxides with an average thickness of 0.38±0.08 μm is obtained by utilizing ion beam technology,and the interface between the powders and the coating shows satisfied adhesiveness compared with the sample directly prepared by mechanical mixing.The evolution of the coating layers during the calcination process has been presented based on careful analysis of the composition and microstructure. 展开更多
关键词 soft MAGNETIC POWDERS MAGNETIC performance COATING layer ion beam technology
Field-variable magnetic domain characterization of individual 10 nm Fe3O4 nanoparticles
15
作者 李正华 李翔 陆伟 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第7期470-474,共5页
The local detection of magnetic domains of isolated 10 nm Fe3O4 magnetic nanoparticles(MNPs) has been achieved by field-variable magnetic force microscopy(MFM) with high spatial resolution.The domain configuration of ... The local detection of magnetic domains of isolated 10 nm Fe3O4 magnetic nanoparticles(MNPs) has been achieved by field-variable magnetic force microscopy(MFM) with high spatial resolution.The domain configuration of an individual MNP shows a typical dipolar response.The magnetization reversal of MNP domains is governed by a coherent rotation mechanism, which is consistent with the theoretical results given by micromagnetic calculations.Present results suggest that the field-variable MFM has great potential in providing nanoscale magnetic information on magnetic nanostructures,such as nanoparticles, nanodots, skyrmions, and vortices, with high spatial resolution.This is crucial for the development and application of magnetic nanostructures and devices. 展开更多
关键词 FE3O4 nanoparticles MAGNETIC force MICROSCOPY MAGNETIC DOMAIN
Magnetization Reversal in Magnetic Bilayer Systems
16
作者 金礼鹏 刘拥军 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第6期88-92,共5页
Magnetization reversal in magnetic soft/hard bilayer systems is studied analytically by means of a variational method for magnetic energies in a continuum model. The demagnetization curve is involved with nonlinear eq... Magnetization reversal in magnetic soft/hard bilayer systems is studied analytically by means of a variational method for magnetic energies in a continuum model. The demagnetization curve is involved with nonlinear equations,and the solution is given implicitly in the form of Jacobi functions,which is valid for the total reversal process. Based on the non-trivial solutions, hysteresis loops, as well as the maximum energy product(BH)max versus thicknesses of soft/hard layers are obtained. With regard to(BH)max, improvement of the remanence competes with loss of coercive force. As a result, an optimum condition exists. For a given thickness of the hard layer, the optimum condition at which the largest(BH)max could be achieved is discussed, which is slightly different from previous works. 展开更多
关键词 MAGNETIZATION REVERSAL MAGNETIC BILAYER SYSTEMS MAGNETIC ENERGIES
Magnetic properties and magnetic entropy change of perovskite manganites La0.9-xEuxSr0.1MnO3(x=0.000,0.075) by experimental method and numerical fitting
17
作者 Xiang Jin Jianjun Zhao +8 位作者 Hongye Wu Bao Xu Yunbin Sun Xiaodong Sun Fengze Cao Kai Wang Wenxing Wang Yutong Zhang Yi Lu 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第6期622-627,共6页
Polycrystalline samples La0.9-xEuxSr0.1MnO3(x = 0.000, 0.075) were prepared by the standard solid-state reaction method. The results show that the samples preform a characteristic of clusters spin-glass state at low t... Polycrystalline samples La0.9-xEuxSr0.1MnO3(x = 0.000, 0.075) were prepared by the standard solid-state reaction method. The results show that the samples preform a characteristic of clusters spin-glass state at low temperature. The samples show a characteristic of ferromagnetism(FM) characteristic in the temperature range of 15-125 K and 15-150 K respectively;the samples show preformed clusters in the temperature range of 125-343 K and 150-325 K, respectively, the samples show paramagnetism(PM)characteristic above 343 and 325 K, respectively. The second-order transitions are found at 118 and 135 K for undoped and doped sample, respectively. When the applied magnetic field is 7 T, the maximum magnetic entropy change |△SM| value of the samples is near the Curie temperature(Tc), and the value of|△SM| reaches 2.76 and 3.03 J/(K kg), respectively. In addition, the relative cooling power(RCP) is found to be 425.28 and 443.53 J/kg. The numerical fitting data fit well with experimental data. These results indicate that both the samples have the potential to realize magnetic refrigeration in the high temperature region(T > 77 K). 展开更多
关键词 PEROVSKITE MAGNETIC properties MAGNETIC ENTROPY change Preforming cluster phase Least SQUARE method Rare earths
The predicaments and expectations in development of magnetic semiconductors 预览
18
作者 Qiang Cao Shishen Yan 《半导体学报:英文版》 EI CAS CSCD 2019年第8期9-19,共11页
Over the past half a century, considerable research activities have been directing towards the development of magnetic semiconductors that can work at room temperature. These efforts were aimed at seeking room tempera... Over the past half a century, considerable research activities have been directing towards the development of magnetic semiconductors that can work at room temperature. These efforts were aimed at seeking room temperature magnetic semiconductors with strong and controllable s, p-d exchange interaction. With this s, p-d exchange interaction, one can utilize the spin degree of freedom to design applicable spintronics devices with very attractive functions that are not available in conventional semiconductors. Here, we first review the progress in understanding of this particular material and the dilemma to prepare a room temperature magnetic semiconductor. Then we discuss recent experimental progresses to pursue strong s, p-d interaction to realize room temperature magnetic semiconductors, which are achieved by introducing a very high concentration of magnetic atoms by means of low-temperature nonequilibrium growth. 展开更多
关键词 MAGNETIC SEMICONDUCTORS s p-d interaction high concentration of MAGNETIC ATOMS low temperature NONEQUILIBRIUM growth SEMICONDUCTOR SPINTRONICS
在线阅读 下载PDF
Highly efficient and flexible preparation of water-dispersed Fe3O4 nanoclusters using a micromixer
19
作者 Xiaojing Liu Yangcheng Lu 《颗粒学报:英文版》 SCIE EI CAS CSCD 2019年第4期42-48,共7页
Solvent exchange is widely used to synthesize magnetic nanoclusters (MNCs).However,it remains a challenge to increase the production and decrease the addition ofsurfactants,both of which are important for the applicat... Solvent exchange is widely used to synthesize magnetic nanoclusters (MNCs).However,it remains a challenge to increase the production and decrease the addition ofsurfactants,both of which are important for the application and functionalization of MNCs.Herein,we use a rapid and tunable mixing method to control the assembly of Fe3O4 nanoparticles.This method involves shear-mixing in a channel of a Tjunction micromixer.Smaller and more monodisperse MNCs were synthesized with less surfactant,when compared with conventional bulk synthesis.Varying the mixing rate and the formula of the magnetic suspension allowed for the flexible adjustment of the nanocluster size while maintaining a uniformly sized MNCs.The flow synthesis and ease of scale-up make this method potentially suitable for broad industrial application. 展开更多
关键词 FE3O4 MAGNETIC nanoparticle MAGNETIC NANOCLUSTER Micromixer-assisted continuous SYNTHESIS Bulk SYNTHESIS
Effect of cobalt substitution on structure and magnetic properties of Nd0.4Zr0.6Fe10-xCoxSi2(x =0-3) alloys and their ribbons
20
作者 M.Gjoka C.Sarafidis +5 位作者 G.Giannopoulos D.Niarchos G.Hadjipanayis J.A.Tabares G.A.Pérez Alcázar L.E.Zamora 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第10期1096-1101,共6页
This study reports the stabilization of the RFe12-type based compounds where part of R and Fe are substituted with Zr and Co and Si, respectively, in order to examine whether these rare-earth-lean materials are suitab... This study reports the stabilization of the RFe12-type based compounds where part of R and Fe are substituted with Zr and Co and Si, respectively, in order to examine whether these rare-earth-lean materials are suitable for applications as permanent magnets. Structural and magnetic characterization of the family of alloys with the general formula Nd0.4 Zr0.6 Fe10-xCoxSi2(x = 0 -3) and their melt-spun ribbons were carried out using X-ray diffraction and M€ossbauer spectroscopy. The ThMn12-type structure is obtained for all samples as the majority phase with a minority a-Fe(CoSi) phase(less than 5 wt%) as it was estimated by XRD for x = 1 and 2. The Curie temperature increases linearly with Co substitution from 561 K for x = 0 to 712 K for x = 3. The saturation magnetization decreases slightly from 130.5(x =1)to 129.1 A·m2/kg(x=3), while the anisotropy field is following the same trend. 展开更多
关键词 Permanent MAGNETS X-ray diffraction M€ossbauer spectroscopy Rare-earth-lean MAGNETIC materials MAGNETIC properties MELT-SPUN RIBBONS
上一页 1 2 250 下一页 到第
使用帮助 返回顶部 意见反馈