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991.
Weiting Yu Junzhang Lin Xiudong Liu Hongguo Xie Wei Zhao Xiaojun Ma 《Journal of membrane science》2010
The semi-permeable membrane of alginate–chitosan (AC) microcapsules has been proven important to control the microcapsule stability and selective substance diffusion rate. Therefore, a novel and operable methodology based on gel permeation chromatography (GPC) was established for quantitative characterization of the membrane formation process, so as to provide guidance on performance improvement of AC microcapsules in biomedical applications. Not only the molecular weight (Mw) and its distribution of chitosan can be obtained by GPC, but also the area integral of molecular weight peaks can be linearly correlated to chitosan concentration in certain range. The dynamic membrane formation process was then obtained by quantitatively analyzing reaction amount of chitosan with time, which showed that for chitosan molecules with wide Mw distribution, only parts of molecules bind with alginate to form microcapsule membrane. Moreover, the contribution of chitosan molecules participating in the membrane formation process was also different. These new findings, therefore, are helpful for adjusting and controlling the membrane formation process and properties of microcapsule membrane. 相似文献
992.
Qing-Song Ye Xi-Zhu Chen Ming-Jin Xie Wei-Ping Liu Jia-Lin Chen Zai-Fu Pan 《Transition Metal Chemistry》2010,35(5):585-590
Dirhodium tetraoctanoate (1), without any exogenous axial ligands, has been obtained in crystalline form by slow evaporation from ethanol. The molecules
are linked by axially ligating each other to form infinite chains, which is similar to the only other two structurally characterized
rhodium(II) carboxylates, Rh2(O2CCF3)4 and Rh2(O2CC3H7)4, which also lack exogenous axial ligands. The infinite chains of 1 are cleaved by strong donor solvents such as pyridine to produce the corresponding pyridine adduct (2). Both the complexes were characterized by elemental analysis, MS, IR and NMR spectra. 相似文献
993.
采用AAO模板及后处理方法合成了圆盘状a-Co(OH)2并研究了其电化学电容性能.在该合成方法中,先采用阳极氧化铝模板结合交流电沉积的方法获得钴纳米线,而后将其在碱液中通过溶解氧氧化生成终端产物.用红外光谱(FT-IR),X射线衍射(XRD)和场发射扫描电子显微镜(FE-SEM)表征了产物的结构和形貌;用循环伏安、恒电流充放电测试方法对其电化学性能进行了测试.此外,对圆盘状Co(OH)2的形成机理进行了初步探讨.结果表明,用此方法合成的Co(OH)2具有圆盘状形貌,属a相态,且表现出较好的电容特性. 相似文献
994.
Xu F Zhang H Ilavsky J Stanciu L Ho D Justice MJ Petrache HI Xie J 《Langmuir : the ACS journal of surfaces and colloids》2010,26(24):19199-19208
The dispersion of Nafion ionomer particles and Pt/C catalyst aggregates in liquid media was studied using both ultra-small-angle X-ray scattering (USAXS) and cryogenic TEM. A systematic approach was taken to study first the dispersion of each component (i.e., ionomer particles and Pt/C aggregates), then the combination of the components, and last the catalyst ink. Multiple-level curve fitting was used to extract the particle size, size distribution, and geometry of the Pt/C aggregates and the Nafion particles in liquid media from the scattering data. The results suggest that the particle size, size distribution, and geometry are not uniform throughout the systems but rather vary significantly. It was found that the interaction of each component (i.e., the Nafion ionomer particles and the Pt/C aggregates) occurs in the dispersion. Cryogenic TEM was used to observe the size and geometry of the particles in liquid directly and to validate the scattering results. The TEM results showed excellent agreement. 相似文献
995.
Zhuo Wang Feng‐Ying Bai Yong‐Heng Xing Prof. Dr. Yan Xie Mao‐Fa Ge Shu‐Yun Niu 《无机化学与普通化学杂志》2010,636(8):1570-1575
Two new lanthanide complexes [Sm2(ad)2.5(BSA)(H2O)2]n ( 1 ) and [Nd2(ad)2.5(BSA)(H2O)2]n ( 2 ) (H2ad = adipic acid, HBSA = benzenesulfonic acid) were synthesized hydrothermally from the reaction of the lanthanide ions (Ln3+) with flexible aliphatic dicarboxylate and the rigid benzene sulfonic acid and characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. They crystallize monoclinic in space group P21/ c. Structural analyses revealed that the two complexes have intricate 3D net structures constructed by the bridging adipic ligand and benzenesulfonic acid. The thermogravimetric analysis of 1 and 2 , as well as photoluminescent properties of 1 are discussed in detail. 相似文献
996.
Jost M Zocher G Tarcz S Matuschek M Xie X Li SM Stehle T 《Journal of the American Chemical Society》2010,132(50):17849-17858
Fungal indole prenyltransferases participate in a multitude of biosynthetic pathways. Their ability to prenylate diverse substrates has attracted interest for potential use in chemoenzymatic synthesis. The fungal indole prenyltransferase FtmPT1 catalyzes the prenylation of brevianamide F in the biosynthesis of fumitremorgin-type alkaloids, which show diverse pharmacological activities and are promising candidates for the development of antitumor agents. Here, we report crystal structures of unliganded Aspergillus fumigatus FtmPT1 as well as of a ternary complex of FtmPT1 bound to brevianamide F and an analogue of its isoprenoid substrate dimethylallyl diphosphate. FtmPT1 assumes a rare α/β-barrel fold, consisting of 10 circularly arranged β-strands surrounded by α-helices. Catalysis is performed in a hydrophobic reaction chamber at the center of the barrel. In combination with mutagenesis experiments, our analysis of the liganded and unliganded structures provides insight into the mechanism of catalysis and the determinants of regiospecificity. Sequence conservation of key features indicates that all fungal indole prenyltransferases possess similar active site architectures. However, while the dimethylallyl diphosphate binding site is strictly conserved in these enzymes, subtle changes in the reaction chamber likely allow for the accommodation of diverse aromatic substrates for prenylation. In support of this concept, we were able to redirect the regioselectivity of FtmPT1 by a single mutation of glycine 115 to threonine. This finding provides support for a potential use of fungal indole prenyltransferases as modifiable bioreactors that can be engineered to catalyze highly specific prenyl transfer reactions. 相似文献
997.
Yajuan Xu Tunhai Xu Yue Liu Shengxu Xie Yunshan Si Tonghua Liu Dongming Xu 《Chemistry of Natural Compounds》2010,46(2):242-245
The structures of five furostanol glycosides (1–5), of which the 26-O-β-D-glucopyranosyl-(25S),5α-furost20(22)-en-12-one-2α,3β,26-triol-3-O-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside (1) was new, from the leaves of Tribulus terrestris L. were established using chemical and NMR spectroscopic methods. 相似文献
998.
Zhongyue Zhou Mingfeng Xie Tang Tang Yijun Zhang Tao Yuan Fei Qi Tom Ni Xueyu Qian 《Plasma Chemistry and Plasma Processing》2010,30(3):391-400
Capacitive radio frequency (RF) discharge of c-C4F8 (octafluorocyclobutane) has been studied with synchrotron vacuum ultraviolet (SVUV) photoionization mass spectrometry (PIMS)
at 4 Torr and 33.33 kHz. Various free radicals and reactive intermediates have been identified through measurement of photoionization
mass spectra and photoionization efficiency (PIE) spectra. CF2=CF2 is main product in the plasma, indicating that the dissociation of c-C4F8 into CF2=CF2 is one of prominent reactions in the present experimental conditions. The observation of large species including C5F8, C5F10 and C6F10 is presented in our work. Besides, the dependences of the signals of neutral species in the discharge of c-C4F8 on RF power are presented in this paper. 相似文献
999.
In this paper we report the anaerobic Escherichia coli biofilm formation on solid substrate under redox-controlled extracellular environment by an electrochemical quartz crystal microbalance (EQCM) method. Both biomass and electrochemical activity were monitored in situ. Larger biomass was yielded under redox-controlled condition comparing with natural biofilm growth, which was also confirmed by optical observation. Surface-colonizing cells responded more sensitively to their redox environment than planktonic cells. Cyclic voltammogram (CV) obtained during the time course of biofilm development indicates the emergence of redox active phenotype under redox-controlled condition but not in natural condition. Our results suggest an effective means to control biofilm development with desired metabolic adaptation and also to in situ monitor the biomass yield and the emergent catalytic property simultaneously. 相似文献
1000.
Xiao-Tao Wang Ying-Kui Yang Zhi-Fang Yang Xing-Ping Zhou Yong-Gui Liao Chen-Chen Lv Feng-Chih Chang Xiao-Lin Xie 《Journal of Thermal Analysis and Calorimetry》2010,102(2):739-744
Vinylated polyhedral oligomeric silsesquioxane (POSS-M) was prepared by the reaction of POSS containing amine groups with
acrylic acid. Azobenzene liquid crystalline copolymer (LCP-POSS) was then synthesized with 6.0 mol% POSS-M and 94.0 mol% acrylate
monomer containing azobenzene liquid crystalline moiety (Azo-M) by free-radical copolymerization. Homopolymer of Azo-M (LCP)
was also synthesized under the same conditions. Their thermal properties and liquid crystallinity were characterized by Thermal
gravimetric analysis (TG), differential scanning calorimetry (DSC), Wide-angle X-ray diffraction experiments (XRD) and polarized
optical micrographs (POM). The results showed that LCP-POSS has higher thermal stability and glass transition temperature
than pure LCP due to the incorporation of the rigid cage-like POSS. Especially, LCP-POSS exhibits enantiotropic smectic and
nematic liquid crystalline behaviors, its smectic-nematic transition temperature (T
SN) and nematic-isotropic transition temperature (T
NI) are higher than those of pure LCP, which may promote and extend its applications on stimuli-responsive materials and devices. 相似文献