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锈胀开裂钢筋混凝土粘结疲劳性能试验研究 预览
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作者 林红威 赵羽习 +2 位作者 郭彩霞 胡利 冯鹏 《工程力学》 EI CSCD 北大核心 2020年第1期98-107,共10页
重复加载和锈胀开裂均会导致钢筋混凝土粘结性能退化,进而对钢筋混凝土构件力学性能产生不利影响。该文开展了一系列偏心拔出试验,研究了重复加载以及锈胀开裂对粘结滑移性能的耦合影响规律。主要研究变量包括重复加载次数、应力水平以... 重复加载和锈胀开裂均会导致钢筋混凝土粘结性能退化,进而对钢筋混凝土构件力学性能产生不利影响。该文开展了一系列偏心拔出试验,研究了重复加载以及锈胀开裂对粘结滑移性能的耦合影响规律。主要研究变量包括重复加载次数、应力水平以及钢筋锈蚀程度。结果表明:重复加载对非锈蚀试件和锈胀开裂试件粘结强度及峰值滑移没有显著影响,但会导致钢筋和混凝土之间不断累积残余滑移。重复加载后,粘结应力-滑移曲线形态特征与单调加载试件相似。该文还发现表面锈胀裂缝宽度对粘结强度、峰值滑移以及残余滑移的增长规律有明显影响。锈胀开裂会导致钢筋混凝土试件粘结疲劳寿命显著下降。基于试验数据及文献中研究结论,该文建立了重复及单调荷载作用下非锈蚀及锈胀开裂试件的局部粘结应力-滑移本构关系模型,推导得到了粘结疲劳寿命预测模型。 展开更多
关键词 粘结 钢筋 重复加载 裂缝宽度 粘结滑移
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Silver-mediated aminophosphinoylation of propargyl alcohols with aromatic amines and H-phosphine oxides leading to α-aminophosphine oxides
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作者 Qiang Huang Lei Zhu +2 位作者 Dong Yi Xiaohui Zhao Wei Wei 《中国化学快报:英文版》 SCIE CAS CSCD 2020年第2期373-376,共4页
A new silver mediated aminophosphinoylation of propargyl alcohols with aromatic amines and Hphosphine oxides for the construction of a-aminophosphine oxides has been developed.The C-N and C-P bond could be efficiently... A new silver mediated aminophosphinoylation of propargyl alcohols with aromatic amines and Hphosphine oxides for the construction of a-aminophosphine oxides has been developed.The C-N and C-P bond could be efficiently formed in one pot operation via sequential C-C and C-O bond cleavage of propargylic alcohols.This present methodology,which not only provides a simple and alternative strategy for the synthesis of α-aminophosphine oxides,but also opens a new window for the cleavage reactions of propargyl alcohols via dealkynalation coupling. 展开更多
关键词 SILVER Aminophosphinoylation C-C bond cleavage Propargylic alcohols α-Aminophosphine oxides
Amides as surrogates of aldehydes for C–C bond formation:amide-based direct Knoevenagel-type condensation reaction and related reactions
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作者 Wei Ou Pei-Qiang Huang 《中国科学:化学英文版》 SCIE EI CAS CSCD 2020年第1期11-15,共5页
Aldehydes are perhaps the most versatile compounds that enable many C-C bond forming reactions,which are not amenable for other subclasses of carbonyl compounds.We report the first use of amides as surrogates of aldeh... Aldehydes are perhaps the most versatile compounds that enable many C-C bond forming reactions,which are not amenable for other subclasses of carbonyl compounds.We report the first use of amides as surrogates of aldehydes for C-C bond formation,namely,the direct Knoevenagel-type condensation based on amides.The one-pot method consists of controlled reduction of an amide with LDBIPA[LiAlH(iBu)2(OiPr)],Lewis acid-mediated release of a reactive iminium ion intermediate,nucleophilic addition,and in situ elimination of amine.The reaction shows good functional group tolerance.We also demonstrated that the Schwartz reagent could be used as an alternative of LDBIPA.The employment of nitromethane and a silyl enol ether as the nucleophiles opens an avenue for the unprecedented amide-based nitro-aldol condensation reaction and aldol condensation reaction,respectively. 展开更多
关键词 AMIDES Knoevenagel condensation C–C bond formation one-pot reaction amide transformation
迭代学习在音圈电机轨迹跟踪中的应用研究 预览
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作者 贺云波 曾志强 张昌 《机械设计与制造》 北大核心 2020年第4期258-261,共4页
为实现高密度LED焊线机上邦头运动轨迹的精确跟踪,降低因其轨迹偏差而产生的废品率。提出了一种基于迭代学习做前馈控制的前馈+反馈二自由度控制算法。首先对音圈电机进行机理分析,建立了其数学模型,以此为基础,给出了音圈电机轨迹跟踪... 为实现高密度LED焊线机上邦头运动轨迹的精确跟踪,降低因其轨迹偏差而产生的废品率。提出了一种基于迭代学习做前馈控制的前馈+反馈二自由度控制算法。首先对音圈电机进行机理分析,建立了其数学模型,以此为基础,给出了音圈电机轨迹跟踪的整体控制方案,并且结合焊线机上邦头超高加速度(>20g)和整定时间短的运动特点后设计了带遗忘因子的PD型闭环迭代学习控制算法。对所提出的带遗忘因子的PD型闭环迭代学习控制的收敛性进行了理论分析,并且通过MATLAB中的SIMULINK模块进行了动态仿真,验证了该算法下的音圈电机系统响应速度显著提升,位置误差的收敛稳定可靠,改善了高密度LED焊线机上邦头的轨迹跟踪性能。 展开更多
关键词 音圈电机 邦头 遗忘因子 迭代学习
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Remarkably reducing carbon loss and H2 consumption on Ni–Ga intermetallic compounds in deoxygenation of methyl esters to hydrocarbons 预览
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作者 Ning Zhao Ying Zheng Jixiang Chen 《能源化学:英文版》 SCIE EI CAS CSCD 2020年第2期194-208,共15页
Ni–Ga alloy(Ni/Ga atomic ratio of 8),Ni3Ga and Ni5Ga3 intermetallic compounds(IMCs)catalysts were prepared from Ni–Mg-Al-Ga layered double hydroxides(LDHs)for the deoxygenation of methyl esters to hydrocarbons.In th... Ni–Ga alloy(Ni/Ga atomic ratio of 8),Ni3Ga and Ni5Ga3 intermetallic compounds(IMCs)catalysts were prepared from Ni–Mg-Al-Ga layered double hydroxides(LDHs)for the deoxygenation of methyl esters to hydrocarbons.In the alloy and IMCs,the presence of Ga reduced the surface Ni atom density,and the charge transfer from Ga to Ni increased the electron density of Ni.In the deoxygenation of methyl laurate,the Ni catalyst gave a complete hydrogenolysis of methyl laurate to CH4at 330°C and 3.0 MPa,while the presence of Ga promoted the HDO pathway and suppressed C–C bond hydrogenolysis and methanation.The Ni5Ga3 catalyst exhibited the best desired performance.Even at 400°C,it gave the yield of C11 and C12 hydrocarbons of ~99%,and the selectivity to CH4(SCH4) was only 2.4%.In the deoxygenation of methyl octanoate and methyl palmitate,the Ni5Ga3 catalyst also gave the yield of hydrocarbons above95%.Reactivity evaluation and methyl propionate-TPD and TPSR results indicate that the C–OCH3 bond instead of the O–CH3 one was cleaved on both Ni and bimetallic Ni–Ga catalysts.It is highlighted that methanol,derived from the C–OCH3 bond hydrogenolysis,mainly decomposed to CO and H2 on IMCs,while it was converted to methane on metallic Ni and alloy.It is of great significance that H2 could be yielded from the methyl ester itself.In short,the utilization of Ni–Ga IMCs can effectively reduce carbon loss and H2 consumption,all of which are ascribed to the geometric and electronic effects of Ga. 展开更多
关键词 Ni–Ga intermetallic compounds Methyl ester Decarbonylation/decarboxylation HYDRODEOXYGENATION C–C bond hydrogenolysis Methanation
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Controlled synthesis of high-quality W-Y2O3 composite powder precursor by ascertaining the synthesis mechanism behind the wet chemical method
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作者 Zhi Dong Nan Liu +5 位作者 Weiqiang Hu Zongqing Ma Chong Li Chenxi Liu Qianying Guo Yongchang Liu 《材料科学技术:英文版》 SCIE EI CAS CSCD 2020年第1期118-127,共10页
As an emerging preparation technology,wet chemical method has been employed widely to produce lots of alloy materials such as W and Mo based alloys,owing to its unique technical advantages.Ascertaining the synthesis m... As an emerging preparation technology,wet chemical method has been employed widely to produce lots of alloy materials such as W and Mo based alloys,owing to its unique technical advantages.Ascertaining the synthesis mechanism behind wet chemical method is indispensable for controlled synthesis of highquality W-Y2 O3 composite powder precursor.The co-deposition mechanism of yttrium and tungsten component behind the wet chemical method of preparing yttrium-doped tungsten composite nanopowder was investigated systematically in this work.A series of co-deposited composite powders fabricated under different acidity conditions were used as research targets for investigating the effect of surface composition and structure on co-deposition efficiency.It was found that white tungstic acid has more W-OH bonds and much higher co-deposition efficiency with Y^3+ions than yellow tungstic acid.It is illustrated that the coordination reaction between W-OH bonds on tungstic acid particles and Y^3+ions brings the co-deposition of yttrium and tungsten component into being.Through displacing H^+ions in W-OH bonds,Y^3+ions can be adsorbed on the surface of or incorporated into tungstic acid particles in form of ligand.Consequently,to control and regulate Y2 O3 content in powder precursor accurately,H^+ion concentration in wet chemical reaction should be in range of 0.55-2.82 mol L^-1 to obtain white tungstic acid.Besides,H^+ion concentration also has prominent effect on the grain size and morphology of reduced powder precursor.The optimal value should be around 1.58 mol L^-1,which can lead to minimum W grain size(about 17 nm) without bimodal structure.The chemical mechanism proposed in this work could produce great sense to preparation of high-quality precursor for sintering high-performance Y2 O3 dispersion strengthened W based alloys.Our work may also shed light on the approach to exploit analogous synthesis mechanism in other alloy systems. 展开更多
关键词 W-Y2O3 Wet chemical method W-OH bond LIGAND Co-deposition mechanism
Predictable site-selective radical fluorination of tertiary ethers
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作者 Junyang Ma Wentao Xu Jin Xie 《中国科学:化学英文版》 SCIE EI CAS CSCD 2020年第2期187-191,共5页
In this communication,we disclose the first example of metal-free and site-selective radical fluorination of readily available tertiary alkyl ethers,enabled by synergistic photocatalysis and organocatalysis.This catal... In this communication,we disclose the first example of metal-free and site-selective radical fluorination of readily available tertiary alkyl ethers,enabled by synergistic photocatalysis and organocatalysis.This catalytic combination allows for exclusive fluorination of tertiary C–O bonds under mild conditions even in the presence of competing reaction sites.The excellent functional group tolerance affords valuable access to sterically hindered alkyl fluorides through late-stage modification of complex molecules.The successful use of tertiary alkyl ethers in radical fluorination enhances the structural diversity of aliphatic fluorides that can be derived from naturally abundant alcohols. 展开更多
关键词 cooperative catalysis C–O bond activation radical fluorination polarity-matching effect UMPOLUNG
Transformations of N-arylpropiolamides to indoline-2,3-diones and acids via C≡C triple bond oxidative cleavage and C(sp^2)–H functionalization
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作者 Ming-Bo Zhou Yang Li +1 位作者 Xuan-Hui Ouyang Jin-Heng Li 《中国科学:化学英文版》 SCIE EI CAS CSCD 2020年第2期222-227,共6页
A new palladium-catalyzed oxidative conversion of N-arylpropiolamides and H2O to various indoline-2,3-diones and acids through the C≡C triple bond cleavage and C(sp2)–H functionalization is described,which is promot... A new palladium-catalyzed oxidative conversion of N-arylpropiolamides and H2O to various indoline-2,3-diones and acids through the C≡C triple bond cleavage and C(sp2)–H functionalization is described,which is promoted by a cooperative action of catalytic CuBr2,2,2,6,6-tetramethyl-1-piperidinyloxy(TEMPO)and O2.The method provides a practical tool for transformations of alkynes by means of a C–H functionalization strategy,which enables the formation of one C–C bond and multiple C–O bonds in a single reaction with high substrates compatibility and excellent functional group tolerance. 展开更多
关键词 ALKYNES indoline-2 3-diones ACIDS C≡C bond oxidative cleavage C–H functionalization
Divergent intramolecular reactions between phosphines and alkynes
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作者 Yanying Song Lili Wang +1 位作者 Zheng Duan Francois Mathey 《中国化学快报:英文版》 SCIE CAS CSCD 2020年第2期329-332,共4页
A divergent intramolecular reaction of phosphine tethered alkyne in protic solvent was developed.This provided a novel and simple access to a large variety of(Z)-alkenylphosphine oxides and phospholane oxides.Our prel... A divergent intramolecular reaction of phosphine tethered alkyne in protic solvent was developed.This provided a novel and simple access to a large variety of(Z)-alkenylphosphine oxides and phospholane oxides.Our preliminary studies suggested that these divergent reactions are closely related to the reaction condition and molecular structure.A possible mechanism of C-P bond cleavage of a pentacoordinated hydroxyphosphorane intermediate was proposed. 展开更多
关键词 C-P bond cleavage PHOSPHINE ALKYNE Alkenylphosphine Phospholane
德国土地抵押权证券化 预览
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作者 王志勤 《上海大学学报:社会科学版》 CSSCI 北大核心 2020年第2期104-119,共16页
德国土地抵押权在日耳曼习惯法与罗马法的融合发展中逐渐形成了由担保抵押权、流通抵押权和土地债务并存的土地抵押权体系。为了融通资金,从法律制度设计上逐渐增强了土地抵押权的独立性和流通性。当具有一定独立性和流通性的土地抵押... 德国土地抵押权在日耳曼习惯法与罗马法的融合发展中逐渐形成了由担保抵押权、流通抵押权和土地债务并存的土地抵押权体系。为了融通资金,从法律制度设计上逐渐增强了土地抵押权的独立性和流通性。当具有一定独立性和流通性的土地抵押权和证券技术相结合后,德国土地抵押权证券化迅速发展起来,并影响了整个欧洲大陆。从历史上看,德国土地抵押权证券化选择了两条道路并行,即直接证券化和间接证券化,两者几乎是同时产生、相互渗透、相互促进、交错发展的,在法律实践中逐步完善并走向国际,最终使不动产(含土地)抵押债券成长为欧洲乃至世界上最大的债券市场之一,为德国农业经济作出了不可低估的贡献。 展开更多
关键词 土地抵押权 独立性 债券 直接证券化 间接证券化
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Recent advances in sulfenylation of C(sp^3)-H bond under transition metal-free conditions
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作者 Xin-Ming Xu De-Mao Chen Zu-Li Wang 《中国化学快报:英文版》 SCIE CAS CSCD 2020年第1期49-57,共9页
In recent years,the transition metal-free sulfenylation of C-H bond for C-S formation has been rapidly advanced and has become an eco-friendly synthetic tool for pharmacists and organic chemists.Various natural or bio... In recent years,the transition metal-free sulfenylation of C-H bond for C-S formation has been rapidly advanced and has become an eco-friendly synthetic tool for pharmacists and organic chemists.Various natural or bioactive molecules such as(hetero)arenes,olefins,carbonyl compounds,alkanes,have been employed for sulfenylating reactions.This review will focus on the recent five-year advances in C-S bond formation via direct sulfenylation of C(sp^3)-H bonds under metal-free conditions and elaborate their mechanisms from a new perspective. 展开更多
关键词 SULFENYLATION C(sp^3)-H bond METAL-FREE Reaction mechanism Synthetic method
Infrared Spectroscopy of Neutral and Cationic Pyrrolidine Monomer in Supersonic Jet 预览
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作者 Min Xie Zhao-li Zhang +3 位作者 Yu Zhang Xiao-nan Sun Fu-fei Sun Yong-jun Hu 《化学物理学报》 SCIE CAS CSCD 2020年第1期43-47,I0005,I0006,共7页
Pyrrolidine,a five membered heterocyclic molecule,is widely existing in organism.Herein,infrared spectra of pyrrolidine monomer in neutral and cationic states were obtained by vacuum ultraviolet ionization,infrared ph... Pyrrolidine,a five membered heterocyclic molecule,is widely existing in organism.Herein,infrared spectra of pyrrolidine monomer in neutral and cationic states were obtained by vacuum ultraviolet ionization,infrared photodissociation and time of flight mass spectrometry.Both in neutral and cationic states,it is found that their CH stretching vibration bands are red shifted.In the IR spectrum of neutral pyrrolidine,because the electric dipole moment of NH is small,we have not observed the NH stretching vibration bands.However,the NH stretching vibration band of pyrrolidine is greatly enhanced after ionization,and this band red-shifts compared with the previous experiment.The red shifts of CH stretching vibrations in neutral and cationic states are caused by the negative and positive hyperconjugation,respectively.The enhancement and red shift of the NH stretching band are owing to the ejection of the electrons on the N atom after ionization.Through the calculations,it is found that the acidity of the CH bond is a little stronger than that of NH bond.These kinds of studies would be helpful to understand the intrinsic properties of biomolecules in neutral and cationic states,and to provide reference for the further study of living organic macromolecules. 展开更多
关键词 IR spectroscopy HYPERCONJUGATION Cationic state CH bond acidity Gas phase
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C-S coupling with nitro group as leaving group via simple inorganic salt catalysis
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作者 Maojie Xuan Chunlei Lu Bo-Lin Lin 《中国化学快报:英文版》 SCIE CAS CSCD 2020年第1期84-90,共7页
An efficient and practical synthetic protocol to synthesize nonsymmetrical aryl thioethers by nucleophilic aromatic substitution(S_NAr)reaction of nitroarenes by thiols with potassium phosphate as the catalyst is desc... An efficient and practical synthetic protocol to synthesize nonsymmetrical aryl thioethers by nucleophilic aromatic substitution(S_NAr)reaction of nitroarenes by thiols with potassium phosphate as the catalyst is described.Various moderate to strong electron-withdrawing functional groups are tolerated by the system to provide thioethers in a good to excellent yields.We also showed that the present method allows access to 3 drug examples in a short reaction time.Finally,mechanistic studies suggest that the reaction may form the classic Meisenheimer complex through a two-step additionelimination mechanism. 展开更多
关键词 Inorganic-salt catalysis Nucleophilic aromatic substitution C-S bond Denitrification coupling Kinetic isotope effect Meisenheimer complex
Preparation and reducing-responsive property of a novel functional polyurethane nanoemulsion
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作者 He Qin Hong Zhang +3 位作者 Xiaoteng Zhou Danfei Gu Lingxiao Li Chengyou Kan 《中国化学快报:英文版》 SCIE CAS CSCD 2020年第1期292-294,共3页
As a kind of stimuli-responsive materials,the disulfide-containing material has received a tremendous amount of interest.A novel functional disulfide-containing waterborne polyurethane(DS-WPU)nanoemulsion was prepared... As a kind of stimuli-responsive materials,the disulfide-containing material has received a tremendous amount of interest.A novel functional disulfide-containing waterborne polyurethane(DS-WPU)nanoemulsion was prepared via a one-step in situ phase inverse emulsification technique and its reducing-responsive prope rty was investigated using dithiothreitol as the reductant.Results showed that the DS-WPU nanoemulsion had a uniform particle size in nanoscale and a good film-forming characteristic,and the DS-WPU latex film exhibited great responsiveness along with a self-assembled behavior in the reducing environment to form WPU emulsion again,including a long-to-short process of the polymer chains. 展开更多
关键词 POLYURETHANE Disulfide bond NANOEMULSION Reducing-responsiveness Self-assembly
理论与现实:中国虚拟经济的货币视角评估 预览
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作者 王志远 《新疆财经大学学报》 2020年第1期5-18,共14页
当前,尽管经济“脱实向虚”问题受到了社会各界的广泛关注,但在金融化时代,中国虚拟经济问题仍然存在理论界定上的困惑。基于马克思的虚拟资本理论,构建金融政治经济学的货币流量分析方法,可以实现概念界定和趋势分析的双重目的。虚拟... 当前,尽管经济“脱实向虚”问题受到了社会各界的广泛关注,但在金融化时代,中国虚拟经济问题仍然存在理论界定上的困惑。基于马克思的虚拟资本理论,构建金融政治经济学的货币流量分析方法,可以实现概念界定和趋势分析的双重目的。虚拟经济是一把“双刃剑”,中国数据表明,曾在2002年—2009年发挥“正”向作用的虚拟经济,自2010年开始出现快速增长态势,其主要脉络可在货币流向中体现出来。规制虚拟经济不能因噎废食,应采取必要且可行的措施,积极拓展企业债券融资等,防范货币从实体经济部门“回流”。 展开更多
关键词 金融政治经济学 虚拟经济 货币 资金流量 债券
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Increasing the Solubility of a Hydrophobic Molecule with Thymine-like Face by DNA via Supramolecular Interaction
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作者 SHI Peijun ZHANG Zhe +5 位作者 LIU Mingchun SUN Teng HE Xiaoyan MAO Chengde FANG Liang ZUO Hua 《高等学校化学研究:英文版》 SCIE CAS CSCD 2020年第2期281-284,共4页
Poor water-solubility of hydrophobic drugs greatly hampers drug design and creats delivery problems.The traditional way to improve the solubility is to add hydrotropes or excipients to supress aggregations.Here,a nove... Poor water-solubility of hydrophobic drugs greatly hampers drug design and creats delivery problems.The traditional way to improve the solubility is to add hydrotropes or excipients to supress aggregations.Here,a novel mechanisim has been proposed based on supramolecular interactions and demonstrated with a small molecule,pvromellitic diimide(PD).This compound contains thymine-like ‘face’ and can interact with adenines through Wat-son-Crick and Hoogsteen hydrogen-bonding.Given the high water solubility of poly adenines[poly(A)],it is expectec that poly(A)will greatly increase the PD solubility.Indeed,such an increased solubility was confirmed by ultravio­let-visible spectroscopy(UV-Vis)and polyacrylamide gel electrophoresis(PAGE)analysis.We believe that this stra­tegy could be used to improve the solubility of other similar hydrophobic molecules. 展开更多
关键词 Polyadenine[poly(A)] Pyromellitic diimide Hydrogen bond force Increased solubility
减少板坯连铸过程粘结报警分析研究 预览
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作者 许建飞 王利双 张杰 《华北理工大学学报:自然科学版》 CAS 2020年第1期30-35,共6页
为了减少板坯连铸过程粘结漏钢及误报警行为,结合唐钢中厚板材有限公司实际生产过程,从影响粘结行为的设备状态、保护渣、工艺状况等行为进行分析,提出了相应的预防措施。研究结果表明,漏钢预报误报警率降低了20%,有效地减少了粘结漏钢... 为了减少板坯连铸过程粘结漏钢及误报警行为,结合唐钢中厚板材有限公司实际生产过程,从影响粘结行为的设备状态、保护渣、工艺状况等行为进行分析,提出了相应的预防措施。研究结果表明,漏钢预报误报警率降低了20%,有效地减少了粘结漏钢及误报警的发生。 展开更多
关键词 粘结 漏钢预报 误报警 保护渣
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Site-specific protein modification by genetic encoded disulfide compatible thiols
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作者 Xinyu Ling Heqi Chen +3 位作者 Wei Zheng Liying Chang Yong Wang Tao Liu 《中国化学快报:英文版》 SCIE CAS CSCD 2020年第1期163-166,共4页
Cysteine chemistry provides a low cost and convenient way for site-specific protein modification.However,recombinant expression of disulfide bonding containing protein with unpaired cysteine is technically challenging... Cysteine chemistry provides a low cost and convenient way for site-specific protein modification.However,recombinant expression of disulfide bonding containing protein with unpaired cysteine is technically challenging and the resulting protein often suffers from significantly reduced yield and activity.Here we used genetic code expansion technique to introduce a surface exposed self-paired dithiol functional group into proteins,which can be selectively reduced to afford active thiols.Two compounds containing self-paired disulfides were synthesized,and their genetic incorporations were validated using green fluorescent proteins(GFP).The compatibility of these self-paired di-thiols with natural disulfide bond was demonstrated using antibody fragment to afford site-specifically labeled antibody.This work provides another valuable building block into the chemical tool-box for site-specific labeling of proteins containing internal disulfides. 展开更多
关键词 Cysteine chemistry Genetic code expansion Protein modification Biorthogonal chemistry Disulfide bond
论农地经营权的法律性质——以三权分置为视角 预览
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作者 陈林峰 方金华 +1 位作者 林景祥 马晓赟 《安徽农业科学》 CAS 2020年第1期257-260,共4页
三权分置所构造的所有权、承包权、经营权分离的农地权利体系是继家庭联产承包责任制后又一农村土地改革制度创新。厘清经营权在权利体系中的定位是构造三权分置制度的关键。土地经营权用益物权论与“权能分离原则”和“一物一权”原则... 三权分置所构造的所有权、承包权、经营权分离的农地权利体系是继家庭联产承包责任制后又一农村土地改革制度创新。厘清经营权在权利体系中的定位是构造三权分置制度的关键。土地经营权用益物权论与“权能分离原则”和“一物一权”原则相悖。相互龃龉的过多的权利设置只会导致农地权利体系混乱。将土地经营权定性为债权,符合权利的生成逻辑,具有节约制度变革的优势,既能契合农地经营权的设立语境,又能避免多层用益物权权利结构之弊。 展开更多
关键词 三权分置 经营权 用益物权 债权
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Synthesis of core-shell structured Au@Bi2S3 nanorod and its application as DNA immobilization matrix for electrochemical biosensor construction
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作者 Feng Gao Juan Song +4 位作者 Bin Zhang Hidekazu Tanaka Fei Gao Weiwei Qiu Qingxiang Wang 《中国化学快报:英文版》 SCIE CAS CSCD 2020年第1期181-184,共4页
The core-shell structured Au@Bi2S3 nanorods have been prepared through direct in-situ growth of Bi2S3 at the surface of pre-synthesized gold nanorods.The product was characterized by X-ray diffraction,transmission ele... The core-shell structured Au@Bi2S3 nanorods have been prepared through direct in-situ growth of Bi2S3 at the surface of pre-synthesized gold nanorods.The product was characterized by X-ray diffraction,transmission electron microscopy and energy-dispersive X-ray spectroscopy.Then the obtained Au@Bi2S3 nanorods were coated onto glassy carbon electrode to act as a scaffold for fabrication of electrochemical DNA biosensor on the basis of the coordination of-NH2 modified on 5’-end of probe DNA and Au@Bi2S3.Electrochemical characterization assays demonstrate that the Au@Bi2S3 nanorods behave as an excellent electronic transport channel to promote the electron transfer kinetics and increase the effective surface area by their nanosize effect.The hybridization experiments reveal that the Au@Bi2S3 matrix-based DNA biosensor is capable of recognizing complementary DNA over a wide concentration ranging from 10 fmol/L to 1 nmol/L.The limit of detection was estimated to be 2 fmol/L(S/N=3).The biosensor also presents remarkable selectivity to distinguish fully complementa ry sequences from basemismatched and non-complementary ones,showing great promising in practical application. 展开更多
关键词 DNA biosensor Au@Bi2S3 nanorods Electrochemical impedance spectroscopy Core-shell structure Bi^3+-N bond Probe immobilization
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