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171.
在硒催化下,苯胺和硫醇在一氧化碳和氧气作用下发生氧化羰基化反应直接生成相应的硫代氨基甲酸酯,收率从中等到良好. 反应在室温无溶剂条件下进行. 催化剂硒能方便地回收且能循环使用. 相似文献
172.
173.
Hu W Liu J Luo Q Han Y Wu K Lv S Xiong S Wang F 《Rapid communications in mass spectrometry : RCM》2011,25(10):1429-1436
Hydrogen/deuterium exchange mass spectrometry (H/DX MS) has become a powerful tool to investigate protein-protein and protein-ligand interactions, but it is still challenging to localize the interaction regions/sites of ligands with pepsin-resistant proteins such as lipocalins. β-Lactoglobulin (BLG), a member of the lipocalin family, can bind a variety of small hydrophobic molecules including retinols, retinoic acids, and long linear fatty acids. However, whether the binding site of linear molecules locates in the external groove or internal cavity of BLG is controversial. In this study we used H/DX MS combined with docking simulation to localize the interaction sites of a tested ligand, sodium dodecyl sulfate (SDS), binding to BLG. H/DX MS results indicated that SDS can bind to both the external and the internal sites in BLG. However, neither of the sites is saturated with SDS, allowing a dynamic ligand exchange to occur between the sites at equilibrium state. Docking studies revealed that SDS forms H-bonds with Lys69 in the internal site and Lys138 and Lys141 in the external site in BLG via the sulfate group, and interacts with the hydrophobic residues valine, leucine, isoleucine and methionine within both of the sites via its hydrocarbon tail, stabilizing the BLG-SDS complex. 相似文献
174.
Synthesis of functional microcapsules containing suspensions responsive to electric fields 总被引:2,自引:0,他引:2
A sort of functional microcapsules, which contain a suspension responsive to electric fields, is prepared by in situ polymerization of urea and formaldehyde. The suspension is made up of pigment phthalocyanine green (PPG) and tetrachloroethylene. In order to solve the particles' separation from the suspension during the microencapsulation and to obtain microcapsules applying to electronic ink display, the dispersibility of the particles, the contact angles between the particles and the tetrachloroethylene, and the influences of different emulsifiers on the microencapsulation are investigated. It is found that the dispersion extent and lipophilicity of the PPG particles are improved due to their surface modification with octadecylamine. The contact angles between the modified PPG particles and the tetrachloroethylene increase, and the PPG particles modified with 2 wt% octadecylamine have the best affinity for tetrachloroethylene. The interfacial tension between C(2)Cl(4) and H(2)O with urea-formaldehyde prepolymer descends from 43 to 35 mN/m, which indicates that the polymer has certain surface activity. However, water-soluble emulsifiers have an important influence during the microencapsulation because they can absorb on the surfaces of internal phase and prevent the resin of urea-formaldehyde from depositing there. From the SEM images of shell surface and cross section, the microcapsules have relatively smooth surfaces and the average thickness is about 4.5 mum. When the microcapsules are prepared with agitation rates of 1000 and 600 rpm, the mean diameters of the obtained microcapsules are 11 and 155 mum, respectively. The particles in the capsules move toward positive electrode with a responsive time of several hundred milliseconds while providing an electric field. 相似文献
175.
Zhen-Yu Wang Guang-Qiang Xu Li Zhou Cheng-Dong Lv Ru-Lin Yang Bing-Zhe Dong Qing-Gang Wang 《高分子科学》2021,39(6):709-715
The isoselective ring-opening polymerization of racemic lactide was achieved by combining N-heterocyclic olefin(NHO) with mono(thio)ureas or bis(thio)ureas as catalytic systems. The polymerization process shows high stereoselectivity, controllability and reactivity,delivering multi-block isotactic polylactides with high chain-end fidelity and narrow molecular weight distributions. The enhancement of catalytic performance was observed in the following order: bisthiourea(DTU) monothiourea(TU) bisurea(DU) urea(U). The highest Pm(probability of forming a meso dyad) = 0.91 was observed at-70 °C when using NHO/U1 catalytic system and the high stereoselectivity was attributed to chain-end control mechanism. 相似文献
176.
Wei Lv Chun Wang Xing-Chi Lin Xiao-Fei Mei Wen Wang E Yang Qi-Dan Ling Zheng-Huan Lin 《高分子科学》2021,39(9):1177-1184
Solid-stated smart polymers responsive to external stimuli have attracted much attention for potential application in the field of photoelectron devices, logic gates, sensor, data storage and security. However, it is a bigger challenge for polymers than that for small molecules in solid state to acquire stimuli-responsive properties, because polymers with high molecular weight are not as easy to change the packing structure as small molecules under external stimulation. Here, a D-A type alternat... 相似文献
177.
178.
Shuhui Lv Xiaojuan Liu Hongping Li Lin Han Zhongchang Wang Jian Meng 《Journal of computational chemistry》2012,33(16):1433-1439
The ground state of double perovskite oxide La2CoMnO6 (LCMO) and how it is influenced by external pressure and antisite disorder are investigated systematically by first‐principles calculations. We find, on the consideration of both the electron correlation and spin–orbital coupling effect, that the LCMO takes on insulating nature, yet is transformed to half metallicity once the external pressure is introduced. Such tuning is accompanied by a spin‐state transition of Co2+ from the high‐spin state (te) to low‐spin state (te) because of the enhancement of crystal‐field splitting under pressure. Using mean‐field approximation theory, Curie temperature of LCMO with Co2+ being in low‐spin state is predicted to be higher than that in high‐spin state, which is attributed to the enhanced ferromagnetic double exchange interaction arising from the shrinkage of Co? O and Mn? O bonds as well as to the increase in bond angle of Co? O? Mn under pressure. We also find that antisite disorder in LCMO enables such transition from insulating to half‐metallic state as well, which is associated with the spin‐state transition of antisite Co from high to low state. It is proposed that the substitution of La3+ for the rare‐earth (RE) ions with smaller ionic radii could open up an avenue to induce a spin‐state transition of Co, rendering thereby the RE2CoMnO6 a promising half‐metallic material. © 2012 Wiley Periodicals, Inc. 相似文献
179.
Dr. Ya‐Guang Sun Tian‐Yi Lv Xin Gao Gang Xiong Di Sun Ling‐Ling He Zhen‐He Xu Shu‐Ju Wang Fu Ding 《无机化学与普通化学杂志》2012,638(14):2365-2369
Three new lanthanide‐organic coordination polymers, {[Ln2(bpdc)2(H2O)6(NO3)] · NO3} [Ln = La ( 1 ), Ce ( 2 ), Pr ( 3 )] (H2bpdc = 2, 2′‐bipyridine‐6, 6′‐dicarboxylic acid) were synthesized under hydrothermal conditions and structurally characterized by elemental analysis, IR spectroscopy as well as single‐crystal and powder X‐ray diffraction. Single‐crystal X‐ray diffraction analysis revealed that compounds 1 – 3 are isostructural, composed of two dimensional honeycomb network linked by bpdc ligands. The magnetic property of compound 3 was investigated. 相似文献
180.