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基于Arcgis的污染空气扩散模拟软件设计 预览
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作者 左海龙 《电子测试》 2020年第4期87-88,68,共3页
本研究以高斯点源空气扩散模型为原型,研究多因子空气污染扩散复合模型,利用ArcGIS的空间地理数据可视化功能,以区域地形为基础显示空气质量的空间分布情况并对空气污染扩散路径进行模拟。结合风力、风向、温度、气压、地形等多因子对... 本研究以高斯点源空气扩散模型为原型,研究多因子空气污染扩散复合模型,利用ArcGIS的空间地理数据可视化功能,以区域地形为基础显示空气质量的空间分布情况并对空气污染扩散路径进行模拟。结合风力、风向、温度、气压、地形等多因子对空气进行扩散性评价,并采用三维表达技术模拟污染空气的扩散,最后基于ArcGIS Engine,实现空气污染扩散模拟的可视化目标。 展开更多
关键词 ARCGIS 污染空气 扩散 GIS
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Three-dimensional bioprinting collagen/silk fibroin scaffold combined with neural stem cells promotes nerve regeneration after spinal cord injury 预览
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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
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A model for knowledge transfer in a multi-agent organization based on lattice kinetic model 预览
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作者 WU Weiwei MA Qian +1 位作者 LIU Yexin KIM Yongjun 《系统工程与电子技术:英文版》 SCIE EI CSCD 2020年第1期156-167,共12页
A study on knowledge transfer in a mutli-agent organization is performed by applying the basic principle in physics such as the kinetic theory.Based on the theoretical analysis of the knowledge accumulation process an... A study on knowledge transfer in a mutli-agent organization is performed by applying the basic principle in physics such as the kinetic theory.Based on the theoretical analysis of the knowledge accumulation process and knowledge transfer attributes,a special type of knowledge field(KF)is introduced and the knowledge diffusion equation(KDE)is developed.The evolution of knowledge potential is modeled by lattice kinetic equation and verified by numerical experiments.The new equation-based modeling developed in this paper is meaningful to simulate and predict the knowledge transfer process in firms.The development of the lattice kinetic model(LKM)for knowledge transfer can contribute to the knowledge management theory,and the managers can also simulate the knowledge accumulation process by using the LKM. 展开更多
关键词 knowledge transfer multi-agent system knowledge field(KF) lattice kinetic model(LKM) knowledge diffusion equation(KDE)
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迁移型阻锈剂在既有混凝土结构中阻锈作用研究 预览
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作者 宋屹林 姚森元 +1 位作者 舒海斌 柳俊哲 《宁波大学学报:理工版》 CAS 2020年第1期95-100,共6页
通过内掺氯盐混凝土试件和既有混凝土结构中迁移型阻锈剂的修复试验,结合钢筋自然电位、腐蚀面积率和失重率,综合评价迁移型阻锈剂修复措施的阻锈效果.研究结果表明:涂刷、灌注、复合修复均能起到良好的阻锈效果,其中复合修复阻锈效果最... 通过内掺氯盐混凝土试件和既有混凝土结构中迁移型阻锈剂的修复试验,结合钢筋自然电位、腐蚀面积率和失重率,综合评价迁移型阻锈剂修复措施的阻锈效果.研究结果表明:涂刷、灌注、复合修复均能起到良好的阻锈效果,其中复合修复阻锈效果最佳;涂刷、灌注修复时,若达不到亚硝酸根离子与氯离子临界摩尔比,会引起宏电池腐蚀,加速钢筋锈蚀;磷酸氢二钠阻锈性能弱于亚硝酸钠,但不发生宏电池腐蚀. 展开更多
关键词 既有混凝土结构 阻锈剂 扩散 修复措施
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Diffusion of ions in an electrostatic stochastic field and a space-dependent unperturbed magnetic field
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作者 Marian NEGREA 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2020年第1期1-14,共14页
We calculate the diffusion coefficients for ions moving in a prescribed electromagnetic field.The field is considered to he a superposition of an electrostatic stochastic field and a space-dependent and sheared magnet... We calculate the diffusion coefficients for ions moving in a prescribed electromagnetic field.The field is considered to he a superposition of an electrostatic stochastic field and a space-dependent and sheared magnetic field.We have considered as parameters involved in the calculation of the diffusion coefficients the shear ion Kubo number the electrostatic Kubo number K.the parallel shear ion Kubo number and the parallel thermal ion Kubo number A geometrical parameter which is the measure of the product of the stochastic perpendicular correlation length and the gradient in the magnetic field strength(see definitions in the text)is found not to he important in our calculation.The results concerning the diffusion coefficients obtained in our model are in agreement with experimental data and with those corresponding to other models,and the neoclassical and anomalous values for the diffusion coefficients arc obtained. 展开更多
关键词 magnetic field TURBULENCE DIFFUSION
Al/Cr复合涂层对Ti2AlNb合金抗热腐蚀性能的影响 预览
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作者 李阳 缪强 +4 位作者 梁文萍 林浩 黄朝军 赵子龙 孙自旺 《表面技术》 EI CAS CSCD 北大核心 2020年第2期192-199,共8页
目的改善Ti2AlNb合金在高温腐蚀盐环境中的耐热腐蚀性能。方法在Ti2AlNb合金表面通过双层辉光等离子渗铬及磁控溅射镀铝技术制备Al/Cr复合涂层,分析涂层热腐蚀前后的微观形貌和物相组成,并探究涂覆Na2SO4盐膜的试样在不同温度下(750、85... 目的改善Ti2AlNb合金在高温腐蚀盐环境中的耐热腐蚀性能。方法在Ti2AlNb合金表面通过双层辉光等离子渗铬及磁控溅射镀铝技术制备Al/Cr复合涂层,分析涂层热腐蚀前后的微观形貌和物相组成,并探究涂覆Na2SO4盐膜的试样在不同温度下(750、850、950℃)的热腐蚀行为。结果Al/Cr复合涂层组织均匀致密,且与基体结合良好,厚度约73μm,由表及里依次由Al沉积层、Al/Cr合金层、Cr沉积层、Cr扩散层四部分组成。经不同温度Na2SO4盐热腐蚀后,Al/Cr复合涂层腐蚀程度均显著小于合金基体。涂层试样经750~850℃Na2SO4盐热腐蚀后质量变化较小,850℃腐蚀增重仅0.525 mg/cm^2,而经历950℃、40 h熔盐热腐蚀后失重达到73.571 mg/cm^2,且试样截面出现剥离、脱落现象,Al/Cr复合涂层抵抗热腐蚀能力减弱。结论具有涂层保护的试样抗热腐蚀性能明显优于合金基体。Al/Cr复合涂层在750~850℃Na2SO4盐环境中具有良好的热腐蚀抗力,而更高温度段(850~950℃)的热腐蚀抗力下降。Al/Cr复合涂层在Na2SO4盐环境中良好的抗热腐蚀性得益于涂层中Al、Cr元素氧化形成以Al2O3、Cr2O3为主的混合氧化膜,有效阻碍外界氧气及腐蚀性介质侵入基体。 展开更多
关键词 Al/Cr涂层 Ti2AlNb合金 NA2SO4 热腐蚀 扩散 碱性溶解
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Propagation History Ranking in Social Networks:A Causality-Based Approach
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作者 Zheng Wang Chaokun Wang +2 位作者 Xiaojun Ye Jisheng Pei Bin Li 《清华大学学报自然科学版(英文版)》 EI CAS CSCD 2020年第2期161-179,共19页
Information diffusion is one of the most important issues in social network analysis.Unlike most existing works,which either rely on network topology or node profiles,this study focuses on the diffusion itself,i.e.,th... Information diffusion is one of the most important issues in social network analysis.Unlike most existing works,which either rely on network topology or node profiles,this study focuses on the diffusion itself,i.e.,the recorded propagation histories.These histories are the evidence of diffusion and can be used to explain to users what happened in their networks.However,these histories can quickly grow in size and complexity,limiting their capacity to be intuitively understood.To reduce this information overload,in this paper we present the problem of propagation history ranking.The goal is to rank participant edges/nodes by their contribution to the diffusion.We first discuss and adapt a causal measure,Difference of Causal Effects(DCE),as the ranking criterion.Then,to avoid the complex calculation of DCE,we propose two integrated ranking strategies by adopting two indicators.One is responsibility,which captures the necessity aspect of causal effects.We further give an approximate algorithm,which could guarantee a feasible solution,for this indicator.The other is capability,which captures the sufficiency aspect of causal effects.Finally,promising experimental results are presented to verify the feasibility of the proposed ranking strategies. 展开更多
关键词 propagation history ranking CAUSALITY social networks information diffusion
Local discontinuous Galerkin methods with explicit-implicit-null time discretizations for solving nonlinear diffusion problems
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作者 Haijin Wang Qiang Zhang +1 位作者 Shiping Wang Chi-Wang Shu 《中国科学:数学英文版》 SCIE CSCD 2020年第1期183-204,共22页
In this paper,we discuss the local discontinuous Galerkin methods coupled with two specific explicitimplicit-null time discretizations for solving one-dimensional nonlinear diffusion problems Ut=(a(U)Ux)x.The basic id... In this paper,we discuss the local discontinuous Galerkin methods coupled with two specific explicitimplicit-null time discretizations for solving one-dimensional nonlinear diffusion problems Ut=(a(U)Ux)x.The basic idea is to add and subtract two equal terms a0 Uxx the right-hand side of the partial differential equation,then to treat the term a0 Uxx implicitly and the other terms(a(U)Ux)x-a0 Uxx explicitly.We give stability analysis for the method on a simplified model by the aid of energy analysis,which gives a guidance for the choice of a0,i.e.,a0≥max{a(u)}/2 to ensure the unconditional stability of the first order and second order schemes.The optimal error estimate is also derived for the simplified model,and numerical experiments are given to demonstrate the stability,accuracy and performance of the schemes for nonlinear diffusion equations. 展开更多
关键词 local discontinuous Galerkin explicit-implicit-null time discretization nonlinear diffusion stability error estimates
Hydrogen embrittlement of X80 pipeline steel in H2S environment:Effect of hydrogen charging time,hydrogen-trapped state and hydrogen charging–releasing–recharging cycles 预览
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作者 Peng-peng Bai Jie Zhou +3 位作者 Bing-wei Luo Shu-qi Zheng Peng-yan Wang Yu Tian 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2020年第1期63-73,共11页
This study investigated the susceptibility of X80 pipeline steel to hydrogen embrittlement given different hydrogen pre-charging times and hydrogen charging–releasing–recharging cycles in H2S environment.The fractur... This study investigated the susceptibility of X80 pipeline steel to hydrogen embrittlement given different hydrogen pre-charging times and hydrogen charging–releasing–recharging cycles in H2S environment.The fracture strain of the steel samples decreased with increasing hydrogen pre-charging time;this steel degradation could almost be recovered after diffusible hydrogen was removed when the hydrogen pre-charging time was<8 d.However,unrecoverable degeneration occurred when the hydrogen pre-charging time extended to 16–30 d.Moreover,nanovoid formation meant that the hydrogen damage to the steel under intermittent hydrogen pre-charging–releasing–recharging conditions was more serious than that under continuous hydrogen pre-charging conditions.This study illustrated that the mechanical degradation of steel is inevitable in an H2S environment even if diffusible hydrogen is removed or visible hydrogen-induced cracking is neglected.Furthermore,the steel samples showed premature fractures and exhibited a hydrogen fatigue effect because the repeated entry and release of diffusible hydrogen promoted the formation of vacancies that aggregated into nanovoids.Our results provide valuable information on the mechanical degradation of steel in an H2S environment,regarding the change rules of steel mechanical properties under different hydrogen pre-charging times and hydrogen charging–releasing–recharging cycles. 展开更多
关键词 high-strength steel hydrogen embrittlement corrosion hydrogen diffusion
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海水养殖生境中硫化物污染及控制技术研究进展 预览
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作者 赵阳国 汤海松 +3 位作者 周弋铃 高孟春 郭亮 王君鹏 《中国海洋大学学报:自然科学版》 CAS CSCD 北大核心 2020年第3期37-43,共7页
在近海集约化养殖过程中,水动力条件的改变、大量饵料的投放以及强烈的生物沉降导致底质生境有机污染严重,形成大面积缺氧区。在此环境中,含硫蛋白质降解和硫酸盐异化还原导致硫化物大量产生并扩散,成为海水养殖生态系统中危害程度仅次... 在近海集约化养殖过程中,水动力条件的改变、大量饵料的投放以及强烈的生物沉降导致底质生境有机污染严重,形成大面积缺氧区。在此环境中,含硫蛋白质降解和硫酸盐异化还原导致硫化物大量产生并扩散,成为海水养殖生态系统中危害程度仅次于氨氮的污染物,应该引起人们的足够重视。本文分析了近海养殖环境中硫化物产生的驱动力、硫化物在沉积物-水界面的扩散、硫化物污染控制技术及其优缺点,指出以铁氧化物为基础的化学控制技术和以硫氧化菌为基础的生物控制技术在硫化物污染控制持久性、可靠性等方面具有明显优势,在实际工程中具有应用潜力。 展开更多
关键词 海水养殖 硫酸盐还原 硫化物 扩散 控制
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锐钛矿型TiO2羟基化表面与H2O相互作用的分子动力学研究 预览
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作者 桑丽霞 雷蕾 +1 位作者 陈平方 王军 《北京工业大学学报》 CAS CSCD 北大核心 2020年第2期180-190,共11页
利用经典分子动力学对锐钛矿型TiO2(101)/(001)羟基化表面与水分子的相互作用进行模拟计算,分析得到表面羟基对TiO2鄄H2O界面性质的影响.首先,通过TiO2表面钛、氧原子与水中氧、氢原子间的径向分布函数及键长验证得到,所建羟基化TiO2(10... 利用经典分子动力学对锐钛矿型TiO2(101)/(001)羟基化表面与水分子的相互作用进行模拟计算,分析得到表面羟基对TiO2鄄H2O界面性质的影响.首先,通过TiO2表面钛、氧原子与水中氧、氢原子间的径向分布函数及键长验证得到,所建羟基化TiO2(101)/(001)模型和力场能够很好地模拟TiO2鄄水体系的结构和相关特性.由分子动力学快照图可知,TiO2表面的O2c吸附位在羟基化前后不发生改变,而完整表面原有的Ti5c吸附位被表面羟基中的氢原子取代.羟基化表面的水分子以氢键作用吸附于TiO2表面引起界面电荷转移,根据水分子密度分布可知TiO2鄄H2O界面形成内亥姆霍兹层、外亥姆霍兹层和体相3个分层结构.与完整表面比较,羟基使TiO2(101)表面内、外亥姆霍兹层均变窄,而TiO2(001)表面仅内亥姆霍兹层变窄.对水分子的扩散性质和平均速度分布进行分析,相对于TiO2(101)羟基表面,TiO2(001)羟基表面结构更有利于水分子沿表面法线方向移动.最后,由水的电荷密度分布函数得到,表面羟基使得TiO2(101)和(001)表面的电荷波动加剧,正、负电荷密度分布极值的绝对值明显增加. 展开更多
关键词 锐钛矿型TiO2 羟基化表面 吸附 扩散 界面性质
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Finding an Effective Distance Between T-Cell and B-Cell Using S/W ARQ in an Immune System Communication 预览
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作者 Sanjit Ningthoujam Tekcham Chingkheinganba Swarnendu K Chakraborty 《中国通信:英文版》 SCIE CSCD 2020年第1期174-185,共12页
In this paper,we present the effective distance between T-cell and B-cell in an immune system using Stop and Wait(S/W)Automatic Repeat Request(ARQ).The concentration of the molecules can be increased by increasing the... In this paper,we present the effective distance between T-cell and B-cell in an immune system using Stop and Wait(S/W)Automatic Repeat Request(ARQ).The concentration of the molecules can be increased by increasing the transmitting number of molecules but it may reduce the performance of communication due to higher collision or interference with other molecules.It is also reported in the literature that the concentration of the emitted molecules reduces if the distance from Transmitter(Tx)to Receiver(Rx)increases.Thus,this paper mainly focuses on enhancing the receiver’s capture probability and higher successful complete transmission of the desired molecules by obtaining the effective distance from T-cell to B-cell.In order to find the effective distance,T-cell transmits the molecules 1(Interleukins-2)to B-cell,upon successful reception of molecules 1,antibodies(molecules 2)transmit back to T-cell.Then,the effective distance of an immune system can be obtained after T-cell detects the concentration of the molecules 2 with respect to time.Different schemes of S/W ARQ protocols have implemented in Molecular Communication(MC)but it requires retransmission of duplicate copies due to the lack of addressing an effective distance.Thus,the simulations are performed in MATLAB and the results obtain higher capture probability and also successful complete transmission of the desired molecules. 展开更多
关键词 T-CELL B-CELL MC ANTIGENS antibodies diffusion coefficient(D) round trip time(RTT)
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Oxidation Kinetics of Aluminum Powders in a Gas Fluidized Bed Reactor in the Potential Application of Surge Arresting Materials 预览
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作者 Hong Shih 《材料科学与应用期刊(英文)》 2019年第3期253-292,共40页
In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arre... In this technical paper, the oxidation mechanism and kinetics of aluminum powders are discussed in great details. The potential applications of spherical aluminum powders after oxidation to be part of the surging arresting materials are discussed. Theoretical calculations of oxidation of spherical aluminum powders in a typical gas fluidization bed are demonstrated. Computer software written by the author is used to carry out the basic calculations of important parameters of a gas fluidization bed at different temperatures. A mathematical model of the dynamic system in a gas fluidization bed is developed and the analytical solution is obtained. The mathematical model can be used to estimate aluminum oxide thickness at a defined temperature. The mathematical model created in this study is evaluated and confirmed consistently with the experimental results on a gas fluidization bed. Detail technical discussion of the oxidation mechanism of aluminum is carried out. The mathematical deviations of the mathematical modeling have demonstrated in great details. This mathematical model developed in this study and validated with experimental results can bring a great value for the quantitative analysis of a gas fluidization bed in general from a theoretical point of view. It can be applied for the oxidation not only for aluminum spherical powders, but also for other spherical metal powders. The mathematical model developed can further enhance the applications of gas fluidization technology. In addition to the development of mathematical modeling of a gas fluidization bed reactor, the formation of oxide film through diffusion on both planar and spherical aluminum surfaces is analyzed through a thorough mathematical deviation using diffusion theory and Laplace transformation. The dominant defects and their impact to oxidation of aluminum are also discussed in detail. The well-controlled oxidation film on spherical metal powders such as aluminum and other metal spherical powders can potentially become an important part of switc 展开更多
关键词 Aluminum Spherical Power GAS FLUIDIZATION Bed Oxidation Mechanism Oxide Growth Rate Gibbs Free Energy Ellingham Diagram Mathematical Modeling Dynamic System Plasma DIFFUSION DIFFUSION Coefficient Crystallographic Defect Vacancy Pressure Temperature Flow Laplace Transform Equation Boundary Condition Fick’s Second Law Software Experimental Theoretical SURGE ARRESTING MATERIALS Analytical Solution
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Diffusion kurtosis imaging of microstructural changes in brain tissue affected by acute ischemic stroke in different locations 预览
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作者 Liu-Hong Zhu Zhong-Ping Zhang +2 位作者 Fu-Nan Wang Qi-Hua Cheng Gang Guo 《中国神经再生研究:英文版》 SCIE CAS CSCD 2019年第2期272-279,共8页
The location of an acute ischemic stroke is associated with its prognosis. The widely used Gaussian model-based parameter, apparent diffusion coefficient (ADC), cannot reveal microstructural changes in different locat... The location of an acute ischemic stroke is associated with its prognosis. The widely used Gaussian model-based parameter, apparent diffusion coefficient (ADC), cannot reveal microstructural changes in different locations or the degree of infarction. This prospective observational study was reviewed and approved by the Institutional Review Board of Xiamen Second Hospital, China (approval No. 2014002). Diffusion kurtosis imaging (DKI) was used to detect 199 lesions in 156 patients with acute ischemic stroke (61 males and 95 females), mean age 63.15 ± 12.34 years. A total of 199 lesions were located in the periventricular white matter (n = 52), corpus callosum (n = 14), cerebellum (n = 29), basal ganglia and thalamus (n = 21), brainstem (n = 21) and gray-white matter junctions (n = 62). Percentage changes of apparent diffusion coefficient (ΔADC) and DKI-derived indices (fractional anisotropy [ΔFA], mean diffusivity [ΔMD], axial diffusivity [ΔDa], radial diffusivity ΔDr, mean kurtosis [ΔMK], axial kurtosis [ΔKa], and radial kurtosis [ΔKr]) of each lesion were computed relative to the normal contralateral region. The results showed that (1) there was no significant difference in ΔADC, ΔMD, ΔDa or ΔDr among almost all locations. (2) There was significant difference in ΔMK among almost all locations (except basal ganglia and thalamus vs. brain stem; basal ganglia and thalamus vs. gray-white matter junctions; and brainstem vs. gray-white matter junctions. (3) The degree of change in diffusional kurtosis in descending order was as follows: corpus callosum > periventricular white matter > brainstem > gray-white matter junctions > basal ganglia and thalamus > cerebellum. In conclusion, DKI could reveal the differences in microstructure changes among various locations affected by acute ischemic stroke, and performed better than diffusivity among all groups. 展开更多
关键词 nerve REGENERATION APPARENT DIFFUSION coefficient DIFFUSION weighted IMAGING DIFFUSION KURTOSIS IMAGING acute ischemic stroke mean KURTOSIS microstructure changes white matter 1.5 TESLA magnetic resonance system neural REGENERATION
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Traumatic axonal injury of the cingulum in patients with mild traumatic brain injury:a diffusion tensor tractography study 预览
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作者 Sung Ho Jang Seong Ho Kim Han Do Lee 《中国神经再生研究:英文版》 SCIE CAS CSCD 2019年第9期1556-1561,共6页
The cingulum,connecting the orbitofrontal cortex to the medial temporal lobe,involves in diverse cognition functions including attention,memory,and motivation.To investigate the relationship between the cingulum injur... The cingulum,connecting the orbitofrontal cortex to the medial temporal lobe,involves in diverse cognition functions including attention,memory,and motivation.To investigate the relationship between the cingulum injury and cognitive impairment in patients with chronic mild traumatic brain injury,we evaluated the integrity between the anterior cingulum and the basal forebrain using diffusion tensor tractography in 73 patients with chronic mild traumatic brain injury(39 males,34 females,age 43.29±11.42 years)and 40 healthy controls(22 males,18 females,age 40.11±16.81 years).The patients were divided into three subgroups based on the integrity between the anterior cingulum and the basal forebrain on diffusion tensor tractography:subgroup A(n=19 patients)– both sides of the anterior cingulum were intact;subgroup B(n=36 patients)– either side of the anterior cingulum was intact;and subgroup C(18 patients)– both sides of the anterior cingulum were discontinued.There were significant differences in total Memory Assessment Scale score between subgroups A and B and between subgroups A and C.There were no significant differences in diffusion tensor tractography parameters(fractional anisotropy,apparent diffusion coefficient,and fiber volume)between patients and controls.These findings suggest that the integrity between the anterior cingulum and the basal forebrain,but not diffusion tensor tractography parameter,can be used to predict the cognitive function of patients with chronic mild traumatic brain injury.This study was approved by Yeungnam University Hospital Institutional Review Board(approval No.YUMC-2014-01-425-010)on August 16,2017. 展开更多
关键词 mild traumatic BRAIN injury BRAIN trauma DIFFUSION TENSOR TRACTOGRAPHY DIFFUSION TENSOR imaging cognitive impairment CINGULUM memory Glasgow COMA Scale neural regeneration
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Application of interface material and effects of oxygen gradient on the performance of single-chamber sediment microbial fuel cells (SSMFCs)
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作者 Chin-Tsan Wang Thangavel Sangeetha +5 位作者 Wei-Mon Yan Wen-Tong Chong Lip-Huat Saw Feng Zhao Chung-Ta Chan Chen-Hao Wang 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第1期163-168,共6页
Single-chamber sediment microbial fuel cells (SSMFCs) have received considerable attention nowadays because of their unique dual-functionality of power generation and enhancement of wastewater treatment performance.Th... Single-chamber sediment microbial fuel cells (SSMFCs) have received considerable attention nowadays because of their unique dual-functionality of power generation and enhancement of wastewater treatment performance.Thus,scaling up or upgrading SSMFCs for enhanced and efficient performance is a highly crucial task.Therefore,in order to achieve this goal,an innovative physical technique of using interface layers with four different pore sizes embedded in the middle of SSMFCs was utilized in this study. Experimental results showed that the performance of SSMFCs employing an interface layer was improved regardless of the pore size of the interface,material,compared to those without such layers.The use of an interface layer resulted in a positive and significant effect on the performance of SSMFCs because of the effective prevention of oxygen diffusion from the cathode to the anode.Nevertheless,when a smaller pore size interface was utilized,better power performance and COD degradation were observed.A maximum power density of 0.032mW/m^2 and COD degradation of 47.3% were obtained in the case of an interface pore size of 0.28μm.The findings in this study are of significance to promote the future practical application of SSMFCs in wastewater treatment plants. 展开更多
关键词 Single sediment MICROBIAL fuel cells INTERFACE layer Dissolved OXYGEN PORE size OXYGEN DIFFUSION DIFFUSION coefficient
扩散峰度成像在轻度认知功能障碍患者额叶前皮质微结构变化中的应用分析 预览
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作者 刘东涛 李坤 +3 位作者 卜乔 潘振宇 周立春 胡文立 《中国脑血管病杂志》 CAS CSCD 北大核心 2019年第3期123-128,共6页
目的 探讨MR扩散峰度成像(DKI)技术在轻度认知功能障碍(MCI)患者额叶前皮质微结构变化的应用价值。方法 回顾性连续纳入2018年1月至12月于首都医科大学附属北京朝阳医院神经内科脑小血管病住院患者79例,经头部MRI和MR血管成像证实,并采... 目的 探讨MR扩散峰度成像(DKI)技术在轻度认知功能障碍(MCI)患者额叶前皮质微结构变化的应用价值。方法 回顾性连续纳入2018年1月至12月于首都医科大学附属北京朝阳医院神经内科脑小血管病住院患者79例,经头部MRI和MR血管成像证实,并采用蒙特利尔认知评估(MoCA)量表对总体认知功能进行评估。根据是否存在MCI,将79例患者分为MCI组(46例)和无MCI组(33例)。记录并分析两组患者一般临床资料;神经心理学测评结果,包括MoCA量表、汉密尔顿抑郁量表(HAMD)、汉密尔顿焦虑量表(HAMA);常规MR形态学及DKI扫描结果。选择患者额叶前皮质为感兴趣区,即双侧背外侧额上回、内侧额上回、前扣带和旁扣带脑回;测量兴趣区的DKI相关参数,包括平均扩散率(MD)、扩散各向异性分数(FA)、轴向扩散峰度(AK)、平均扩散峰度(MK)和径向扩散峰度(RK)。对多个兴趣区的多次比较应用Bonferroni方法校正P值,校正P值以P <0. 008为差异有统计学意义。结果 (1) MCI组患者MoCA量表评分低于无MCI组,组间差异有统计学意义[20(19,22)分比27(25,28)分,Z=-6. 836,P <0. 01];年龄、性别、受教育年限、HAMD评分、HAMA评分的组间差异均无统计学意义(均P> 0. 05)。(2)在右侧前扣带和旁扣带脑回,MCI组患者FA、AK、MK值均低于无MCI组,组间差异均有统计学意义(0. 16±0. 03比0. 18±0. 03、0. 64±0. 08比0. 70±0. 06、0. 67±0. 09比0. 73±0. 06,均P <0. 008),MD、RK值的组间差异均无统计学意义(均P> 0. 008);在左侧前扣带和旁扣带脑回,MD、FA、AK、MK、RK值的组间差异均无统计学意义(均P> 0. 008)。(3) MD、FA、AK、MK及RK值在双侧背外侧额上回、双侧内侧额上回的组间差异均无统计学意义(均P> 0. 008)。结论 DKI技术可尝试用于MCI患者额叶前皮质微结构改变的观察,DKI相关参数在MCI患者临床影像学评估中具有一定的价值。 展开更多
关键词 认知障碍 磁共振成像 弥散 扩散峰度成像 额叶前皮质
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中尺度煤块中煤层气多尺度扩散系数随时间依赖的实验及模型
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作者 李志强 彭建松 成墙 《煤炭技术》 CAS 2019年第1期86-88,共3页
为探究煤层气含气量(和储量)测定过程中混有中尺度(厘米级)煤块的影响,开展了不同煤种的毫米-厘米级中等尺度煤块在不同压力下的煤层气扩散实验。实验发现,扩散前期实验扩散率大于经典模型的理论扩散率,扩散后期实验扩散率小于经典模型... 为探究煤层气含气量(和储量)测定过程中混有中尺度(厘米级)煤块的影响,开展了不同煤种的毫米-厘米级中等尺度煤块在不同压力下的煤层气扩散实验。实验发现,扩散前期实验扩散率大于经典模型的理论扩散率,扩散后期实验扩散率小于经典模型的理论值。全时扩散过程中扩散系数并非一个常数,而是随时间延长而衰减的函数。提出了能精确描述不同气压下不同煤种中尺度煤块的煤层气扩散全过程的动扩散系数新模型。与以往实验相比,中尺度煤块的初始扩散系数比粉煤大1~2个数量级,而扩散系数衰减系数比粉煤小1~2个数量级,原因是中尺度煤块包含了更大的孔裂隙,而其孔径级差较小。 展开更多
关键词 煤层气 扩散 扩散系数 模型
A comprehensive assessment on the durability of gas diffusion electrode materials in PEM fuel cell stack
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作者 Arunkumar JAYAKUMAR 《能源前沿:英文版》 CSCD 2019年第2期325-338,共14页
Polymer electrolyte membrane (PEM) fuel cell is the most promising among the various types of fuel cells. Though it has found its applications in numerous fields, the cost and durability are key barriers impeding the ... Polymer electrolyte membrane (PEM) fuel cell is the most promising among the various types of fuel cells. Though it has found its applications in numerous fields, the cost and durability are key barriers impeding the commercialization of PEM fuel cell stack. The crucial and expensive component involved in it is the gas diffusion electrode (GDE) and its degradation, which limits the performance and life of the fuel cell stack. A critical analysis and comprehensive understanding of the struc-tural and functional properties of various materials involved in the GDE can help us to address the related durability and cost issues. This paper reviews the key GDE components, and in specific, the root causes influencing the durability. It also envisages the role of novel materials and provides a critical recommendation to improve the GDE durability. 展开更多
关键词 PEM FUEL CELL GAS DIFFUSION electrode(GDE) GAS DIFFUSION layer(GDL) membrane ELECTRODE assembly DURABILITY FUEL CELL catalyst
An Empirical Model for Dinitrogen Gas Emission from Inland Waters 预览
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作者 Elizabeth Sikar Marco Aurelio dos Santos Ednaldo Oliveira dos Santos 《大气和气候科学(英文)》 2019年第1期1-25,共25页
The motivation to calculate this empirical model resulted from often observing—at the time disconcerting—excess dinitrogen gas (N2 concentration > background concentration) in bubble-gas emission samples, collect... The motivation to calculate this empirical model resulted from often observing—at the time disconcerting—excess dinitrogen gas (N2 concentration > background concentration) in bubble-gas emission samples, collected primarily for the purpose of carbon budget research, from Brazilian rivers and reservoirs sampled during roughly 100 field surveys lasting 4 days each on average and executed between years 2000 and 2012. We model the (serendipitously) measured dinitrogen gas above environmental concentration (N2aec) escaping in bubbles from Brazilian rivers as a function of dissolved nitrogen (N) in water. To this model, we mathematically add a pre-existing model of diffusively emitted denitrified dinitrogen (also as a function of dissolved N) from streams in the United States of America (USA). The resulting model predicts denitrified dinitrogen water-air emission from inland waters in the USA, China and Germany. 展开更多
关键词 DINITROGEN Gas Emission INLAND WATERS BUBBLES DIFFUSION Nitrogen Cycle DENITRIFICATION
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