全文获取类型
收费全文 | 5066篇 |
免费 | 1058篇 |
国内免费 | 1549篇 |
专业分类
化学 | 3537篇 |
晶体学 | 211篇 |
力学 | 458篇 |
综合类 | 258篇 |
数学 | 720篇 |
物理学 | 2489篇 |
出版年
2024年 | 6篇 |
2023年 | 51篇 |
2022年 | 175篇 |
2021年 | 191篇 |
2020年 | 195篇 |
2019年 | 165篇 |
2018年 | 187篇 |
2017年 | 244篇 |
2016年 | 203篇 |
2015年 | 268篇 |
2014年 | 339篇 |
2013年 | 391篇 |
2012年 | 403篇 |
2011年 | 408篇 |
2010年 | 381篇 |
2009年 | 446篇 |
2008年 | 452篇 |
2007年 | 400篇 |
2006年 | 415篇 |
2005年 | 388篇 |
2004年 | 285篇 |
2003年 | 204篇 |
2002年 | 212篇 |
2001年 | 233篇 |
2000年 | 225篇 |
1999年 | 141篇 |
1998年 | 104篇 |
1997年 | 65篇 |
1996年 | 68篇 |
1995年 | 52篇 |
1994年 | 44篇 |
1993年 | 67篇 |
1992年 | 54篇 |
1991年 | 36篇 |
1990年 | 25篇 |
1989年 | 25篇 |
1988年 | 27篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 9篇 |
1964年 | 2篇 |
1962年 | 2篇 |
1960年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有7673条查询结果,搜索用时 78 毫秒
11.
FengSHI HongYangLI XiaoJunPENG RongZHANG XiaoQiangCHEN JiangLiFAN LiChengSUN 《中国化学快报》2004,15(12):1407-1410
As photosensitizer for solar cell, a new ruthenium (Ⅱ) complex with four ester groups had been synthesized, in which a phenol substituted by {[(2-hydroxy-5-tert-butylbenzyl)(pyridyl-2-methyl)amino]methyl} is covalently linked to ruthenium (Ⅱ) tris-bipyridine. The structures of the new compounds were confirmed by NMR and ESI-MS spectra. The electrochemical and photochemical properties were also studied. 相似文献
12.
The adsorption of asymmetrical triblock copolymers from a non-selective solvent on solid surface has been studied by using Scheutjens-Fleer mean-field theory and Monte Carlo simulation method on lattice model. The main aim of this paper is to provide detailed computer simulation data, taking A8-kB20Ak as a key example, to study the influence of the structure of copolymer on adsorption behavior and make a comparison between MC and SF results. The simulated results show that the size distribution of various configurations and density-profile are dependent on molecular structure and adsorption energy. The molecular structure will lead to diversity of adsorption behavior. This discrepancy between different structures would be enlarged for the surface coverage and adsorption amount with increasing of the adsorption energy. The surface coverage and the adsorption amount as well as the bound fraction will become larger as symmetry of the molecular structure becomes gradually worse. The adsorption layer becomes thicker with increasing of symmetry of the molecule when adsorption energy is smaller but it becomes thinner when adsorption energy is higher. It is shown that SF theory can reproduce the adsorption behavior of asymmetrical triblock copolymers. However, systematic discrepancy between the theory and simulation still exists.The approximations inherited in the mean-filed theory such as random mixing and the allowance of direct back folding may be responsible for those deviations. 相似文献
13.
14.
15.
基于VAGUE集多准则决策的模糊TOPSIS方法 总被引:3,自引:0,他引:3
给出了V AGUE集之间距离的新定义,在此基础上,提出一个基于V AGUE集多准则决策的模糊TOP-S IS方法,它为决策系统提供了一个有用的工具,并通过例子阐明本文方法的有效性. 相似文献
16.
17.
X-ray emission spectra for L-shell of Li-like aluminium ions are simulated by using the flexible atomic code based on the collisional radiative model. Atomic processes including radiative recombination, dielectronic recombination, collisional ionization and resonance excitation from the neighbouring ion (Al^9+ and Al^11+ ) charge states of the target ion (Al^10+) are considered in the model. In addition, the contributions of different atomic processes to the x-ray spectrum are analysed. The results show that dielectronic recombination, radiative recombination, collisional ionization and resonance excitation, other than direct collisional excitation, are very important processes. 相似文献
18.
19.
A highly stereoselective synthesis of the side Chain enantiomers of brassinolide and dolicholide through an aldol reaction of 2-(4-methoxy benzyloxyl) proplonylaldehyde (5) with the anion of 1- ( tert -butyldimethylsiloxy )-3-methyl-2-butanone ( 6 ) is described. 相似文献
20.