全文获取类型
收费全文 | 9907篇 |
免费 | 1602篇 |
国内免费 | 1563篇 |
专业分类
化学 | 4470篇 |
晶体学 | 71篇 |
力学 | 1686篇 |
综合类 | 9篇 |
数学 | 1688篇 |
物理学 | 5148篇 |
出版年
2024年 | 18篇 |
2023年 | 328篇 |
2022年 | 251篇 |
2021年 | 289篇 |
2020年 | 318篇 |
2019年 | 209篇 |
2018年 | 169篇 |
2017年 | 282篇 |
2016年 | 278篇 |
2015年 | 408篇 |
2014年 | 596篇 |
2013年 | 669篇 |
2012年 | 877篇 |
2011年 | 814篇 |
2010年 | 768篇 |
2009年 | 780篇 |
2008年 | 713篇 |
2007年 | 750篇 |
2006年 | 838篇 |
2005年 | 608篇 |
2004年 | 430篇 |
2003年 | 423篇 |
2002年 | 372篇 |
2001年 | 370篇 |
2000年 | 246篇 |
1999年 | 275篇 |
1998年 | 175篇 |
1997年 | 160篇 |
1996年 | 102篇 |
1995年 | 92篇 |
1994年 | 64篇 |
1993年 | 75篇 |
1992年 | 45篇 |
1991年 | 36篇 |
1990年 | 22篇 |
1989年 | 25篇 |
1988年 | 88篇 |
1987年 | 75篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 7篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1971年 | 6篇 |
1963年 | 1篇 |
1957年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
991.
Cheng Y Cui W Chen Q Tung CH Ji M Zhang F 《Journal of computer-aided molecular design》2011,25(2):171-180
Aurora kinase family is one of the emerging targets in oncology drug discovery and several small molecules targeting aurora
kinases have been discovered and evaluated under early phase I/II trials. Among them, PHA-739358 (compound 1r) is a 3-aminopyrazole
derivative with strong activity against Aurora A under early phase II trial. Inhibitory potency of compound 1r (the benzylic
substituent at the pro-R position) is 30 times over that of compound 1s (the benzylic substituent at the pro-S position).
In present study, the mechanism of how different configurations influence the binding affinity was investigated using molecular
dynamics (MD) simulations, free energy calculations and free energy decomposition analysis. The predicted binding free energies
of these two complexes are consistent with the experimental data. The analysis of the individual energy terms indicates that
although the van der Waals contribution is important for distinguishing the binding affinities of these two inhibitors, the
electrostatic contribution plays a more crucial role in that. Moreover, it is observed that different configurations of the
benzylic substituent could form different binding patterns with protein, thus leading to variant inhibitory potency of compounds
1r and 1s. The combination of different molecular modeling techniques is an efficient way to interpret the chirality effects
of inhibitors and our work gives valuable information for the chiral drug design in the near future. 相似文献
992.
In present work, a superlubricity phenomenon of phosphoric acid (H(3)PO(4)) was found under ambient conditions. An ultralow friction coefficient of about 0.004 between glass/Si(3)N(4) and sapphire/sapphire tribopairs was obtained under the lubrication of a phosphoric acid aqueous solution (pH 1.5) at high contact pressure (the maximum pressure can reach about 1.65 GPa) after a running-in period of about 600 s. The experimental results indicate that the superlow friction state was very stable for more than 3 h. In such a state, solidlike films formed on the two sliding surfaces, which are hydrates of phosphoric acid with a hydrogen-bonded network according to the Raman spectrum. The superlubricity mechanism is mainly attributed to the hydrogen bond effect that forms a hydrated water layer with low shearing strength, and the dipole-dipole effects that form an interfacial Coulomb repulsion force also make some contributions to low friction. This work may help us to introduce a new approach to superlubricity and may lead to the wide application of superlubricity in future technological and biomedical areas. 相似文献
993.
Zhu W Tao S Tao CA Li W Lin C Li M Wen Y Li G 《Langmuir : the ACS journal of surfaces and colloids》2011,27(13):8451-8457
On the basis of the combination of colloidal and mesophase templating, as well as molecular imprinting, a general and effective approach for the preparation of hierarchically structured trimodal porous silica films was developed. With this new methodology, controlled formation of well-defined pore structures not only on macro- and mesoscale but also on microscale can be achieved, affording a new class of hierarchical porous materials with molecular recognition capability. As a demonstration, TNT was chosen as template molecule and hierarchically imprinted porous films were successfully fabricated, which show excellent sensing properties in terms of sensitivity, selectivity, stability, and regeneracy. The pore system reported here combines the multiple benefits arising from all length scales of pore size and simultaneously possesses a series of distinct properties such as high pore volume, large surface area, molecular selectivity, and rapid mass transport. Therefore, our described strategy and the resulting pore systems should hold great promise for various applications not only in chemical sensors, but also in catalysis, separation, adsorption, or electrode materials. 相似文献
994.
NaYF4:Eu/Sr nanocrystals were synthesized by a hydrothermal method. Tunable photoluminescence of the NaYF4:Eu nanocrystals was successfully achieved by codoping with Sr2+ ions. With increasing Sr2+ concentration, not only the X-ray diffraction peaks of the nanocrystals become broader, but also the positions of them shift toward larger lattice parameters. Eu3+ and Eu2+ have been found to coexist in an NaYF4:Eu/Sr. The Eu3+/Eu2+ emission intensity ratio changed with the Sr2+ concentration and excitation wavelength. More interestingly, the spectral configurations of Eu2+ and Eu3+ also varied with the excitation wavelength, indicating that the nanocrystals have multiple luminescence centers or emitting states. 相似文献
995.
996.
Yang H Li Y Jiang M Wang J Fu H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(20):5652-5660
A simple and general copper-catalyzed method has been developed for transformations of various functional groups (-I, -N(3), -SO(2)R, -OH, -NH(2), and -NO(2)) on aromatic rings from arylboronic acids in water under air. The protocol uses cheap and readily available inorganic salts (KI, NaN(3), NaSO(2)R, NaOH, NaNO(2)) and aqueous ammonia as the functional-group sources, simple Cu(2)O/NH(3) as the catalyst system, environmentally friendly water as the solvent, and oxygen in air as the oxidant. Importantly, the copper catalyst system in water was recyclable. This study should provide a useful strategy for interconversions of the functional groups on aromatic rings. 相似文献
997.
A facile method to control the synthesis and self‐assembly of monodisperse Ag and Ag2S nanocrystals with a narrow‐size distribution is described. Uniform Ag nanoparticles of less than 4 nm were obtained by thermolysis of Ag–oleate complexes in the presence of oleic acid and dodecylamine, and monodisperse Ag nanoparticles of less than 10 nm were also prepared in one step by using dodecylamine and oleic acid as capping agents. Moreover, the surface‐enhanced Raman scattering (SERS) properties of the Ag substrates have also been investigated. It is worth mentioning that these Ag nanoparticles and assemblies show great differences in the SERS activities of Rhodamine B dye. In addition, the superlattices of Ag2S nanocrystals were synthesized with Ag–oleate complexes, alkanethiol, and sulfur as the reactants. The resulting highly monodisperse nanocrystals can easily self‐assemble into interesting superstructures in the solution phase without any additional assembly steps. This method may be extended to the size‐controlled preparation and assembly of many other noble‐metal and transition‐metal chalcogenide nanoparticles. These results will aid the study of the physicochemical properties of the superlattice assemblies and construction of functional macroscopic architectures or devices. 相似文献
998.
Cai H Huang ZH Shi L Zhao YF Kunz H Li YM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(23):6396-6406
The membrane‐bound tumor‐associated glycoprotein MUC1 is aberrantly glycosylated in cancer cells compared with normal cells, and is therefore considered an attractive target for cancer immunotherapy. However, tumor‐associated glycopeptides from MUC1 do not elicit a sufficiently robust immune response. Therefore, antitumor vaccines were developed, which consist of MUC1 glycopeptides as the B epitopes and immune‐stimulating toll‐like receptor 2 (TLR 2) lipopeptide ligands. These fully synthetic vaccine candidates were prepared by solid‐phase synthesis of the MUC1 glycopeptides. The Pam3Cys lipopeptide, also synthesized on solid‐phase, was C‐terminally coupled to oligovalent lysine cores, which N‐terminally incorporate O‐propargyl oligoethylene glycol acyl side chains. The MUC1 glycopeptides and lipopeptide lysine constructs were then conjugated by click chemistry to give oligovalent synthetic vaccines. Oligovalent glycopeptide–lipopeptide conjugates are considered more immunogenic than their monovalent analogues. 相似文献
999.
In this paper, we demonstrate a simple and general "dispersion-decomposition" approach to the synthesis of metal sulfide nanocrystals with the assistance of alkylthiol. This is a direct heating process without precursor injection. By using inorganic metal salts and alkylthiol as the raw materials, high-quality Ag(2)S, Cu(2)S, PbS, Ni(3)S(4), CdS, and ZnS nanocrystals were successfully synthesized. The mechanism study shows that the reaction undergoes two steps. A key intermediate compound, metal thiolate, is generated first. It melts and disperses into the solvent at a relatively low temperature, and then it decomposes into metal sulfide as a single precursor upon heating. This method avoids using toxic phosphine agent and injection during the reaction process. The size and shape of the nanocrystal can be also controlled by the concentration of the reactant and ligands. Furthermore, the optical properties and assembly of the nanocrystals have also been studied. This report provides a facile, direct-heating "dispersion-decomposition" approach to synthesize metal sulfides nanocrystals that has potential for future large-scale synthesis. 相似文献
1000.
We successfully synthesized Au-ZnO hybrid nanoparticles with a novel hexagonal pyramid-like structure. The growth process of the as-prepared hybrid nanopyramids is clearly discussed. Because of their homogeneous composition and controlled morphology, the Au-ZnO hybrid nanopyramids demonstrate better photocatalytic efficiency than pure ZnO nanocrystals. 相似文献