全文获取类型
收费全文 | 22683篇 |
免费 | 812篇 |
国内免费 | 23篇 |
专业分类
化学 | 14957篇 |
晶体学 | 164篇 |
力学 | 367篇 |
数学 | 3867篇 |
物理学 | 4163篇 |
出版年
2023年 | 145篇 |
2022年 | 155篇 |
2021年 | 256篇 |
2020年 | 331篇 |
2019年 | 346篇 |
2018年 | 457篇 |
2017年 | 409篇 |
2016年 | 841篇 |
2015年 | 660篇 |
2014年 | 689篇 |
2013年 | 1456篇 |
2012年 | 1434篇 |
2011年 | 1454篇 |
2010年 | 879篇 |
2009年 | 822篇 |
2008年 | 1271篇 |
2007年 | 1318篇 |
2006年 | 1184篇 |
2005年 | 1085篇 |
2004年 | 981篇 |
2003年 | 763篇 |
2002年 | 658篇 |
2001年 | 519篇 |
2000年 | 468篇 |
1999年 | 361篇 |
1998年 | 242篇 |
1997年 | 232篇 |
1996年 | 305篇 |
1995年 | 219篇 |
1994年 | 237篇 |
1993年 | 200篇 |
1992年 | 192篇 |
1991年 | 179篇 |
1990年 | 182篇 |
1989年 | 155篇 |
1988年 | 143篇 |
1987年 | 136篇 |
1986年 | 135篇 |
1985年 | 194篇 |
1984年 | 196篇 |
1983年 | 126篇 |
1982年 | 129篇 |
1981年 | 143篇 |
1980年 | 138篇 |
1979年 | 95篇 |
1978年 | 96篇 |
1977年 | 103篇 |
1976年 | 84篇 |
1975年 | 88篇 |
1973年 | 71篇 |
排序方式: 共有10000条查询结果,搜索用时 801 毫秒
101.
József Kaizer József Pap Gábor Speier Marius Réglier Michel Giorgi 《Transition Metal Chemistry》2004,29(6):630-633
The preparation, spectroscopic properties, and crystal structure of [Cu(ind)(mco)] [ind is the anion of 1,3-bis(2-pyridylimino)isoindoline and mco is the anion of 3-hydroxy-(4H)-benzopyran-4-one] are reported. The complex exhibits a distorted square pyramidal geometry. The oxygenation of the title compound results in oxidative cleavage of the heterocyclic ring to give the (acetylsalicylato)copper(II) complex [Cu(asp)(ind)] (asp is the anion of acetylsalicylic acid) and CO as primary products, which reaction resembles the enzymatic reaction of quercetinase. 相似文献
102.
103.
104.
Dávid Szegvári Romána Zelkó Péter Horváth András Gergely 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):169-172
Enantioselective solubility of rac-norgestrel was found in the presence of γ-cyclodextrin or hydroxypropyl-γ-cyclodextrin.
In both cases the efficacious enantiomer was dissolved in greater extent. Calculating the molar absorptivity and molar ellipticity
spectra of the γ- and hydroxypropyl-γ-cyclodextrin aqueous complexes, a simple and rapid direct circular dichroism (CD) spectrometric
method was obtained for the determination of the enantiomer ratio in aqueous solutions. 相似文献
105.
Perdigón-Melón J. A. Auroux A. Bonnetot B. 《Journal of Thermal Analysis and Calorimetry》2003,72(2):443-451
As supported palladium oxide catalysts present the best performances in methane combustion in lean conditions, microcalorimetric
studies of the interaction between methane and palladium oxide or metallic palladium supported on Al2O3, ZrO2 and BN have been performed at 673 K. At this temperature methane reduced the palladium oxide, and the heat of reduction of
palladium oxide was shown to depend on the dispersion and on the support. The lowest heats of reduction corresponded to the
highest rates of methane combustion. Moreover methane reforming occurred on metallic palladium, producing hydrogen, and again
methane decomposition was shown to depend on the support.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
106.
C. Torres O. Alejos C. de Francisco J.M. Muñoz P. Hernández-Gómez 《Applied Physics A: Materials Science & Processing》2003,77(3-4):543-547
This paper describes a robust and fast fitting procedure applicable for relaxing processes that cannot be understood as a discrete sum of single processes but require an activation energy distribution. The method is based on a set of closed-form expressions that allow the computation of the relaxation parameters directly from the isochronal curves obtained experimentally. The usefulness of this method is checked by analyzing the isochronal curves given by a theoretical energy distribution and the magnetic disaccommodation spectra observed in yttrium iron garnet (YIG) samples. PACS 02.60.Ed; 75.60.Lr; 75.50.Gg 相似文献
107.
The aim of the paper is to investigate the limit behaviour of the least squares estimator of the shift parameter of nearly unstable, nearly stable, and nearly explosive AR(1) models. Both zero start and stationary cases are treated. Connection with the maximum likelihood estimator of the shift parameter of continuous time AR(1) processes is also discussed. 相似文献
108.
Algebraic Formulation of Quantum Decoherence 总被引:1,自引:0,他引:1
An algebraic formalism for quantum decoherence in systems with continuous evolution spectrum is introduced. A certain subalgebra, dense in the characteristic algebra of the system, is defined in such a way that Riemann–Lebesgue theorem can be used to explain decoherence in a well defined final pointer basis. 相似文献
109.
Bruzón M. S. Gandarias M. L. Muriel C. Ramírez J. Saez S. Romero F. R. 《Theoretical and Mathematical Physics》2003,137(1):1367-1377
We use the classical and nonclassical methods to obtain symmetry reductions and exact solutions of the (2+1)-dimensional integrable Calogero–Bogoyavlenskii–Schiff equation. Although this (2+1)-dimensional equation arises in a nonlocal form, it can be written as a system of differential equations and, in potential form, as a fourth-order partial differential equation. The classical and nonclassical methods yield some exact solutions of the (2+1)-dimensional equation that involve several arbitrary functions and hence exhibit a rich variety of qualitative behavior. 相似文献
110.
Periodica Mathematica Hungarica - 相似文献