全文获取类型
收费全文 | 2689篇 |
免费 | 323篇 |
国内免费 | 181篇 |
专业分类
化学 | 742篇 |
晶体学 | 9篇 |
力学 | 467篇 |
综合类 | 31篇 |
数学 | 844篇 |
物理学 | 1100篇 |
出版年
2024年 | 2篇 |
2023年 | 41篇 |
2022年 | 70篇 |
2021年 | 62篇 |
2020年 | 106篇 |
2019年 | 77篇 |
2018年 | 84篇 |
2017年 | 103篇 |
2016年 | 106篇 |
2015年 | 73篇 |
2014年 | 142篇 |
2013年 | 171篇 |
2012年 | 138篇 |
2011年 | 148篇 |
2010年 | 154篇 |
2009年 | 172篇 |
2008年 | 195篇 |
2007年 | 153篇 |
2006年 | 145篇 |
2005年 | 171篇 |
2004年 | 150篇 |
2003年 | 130篇 |
2002年 | 87篇 |
2001年 | 83篇 |
2000年 | 54篇 |
1999年 | 45篇 |
1998年 | 43篇 |
1997年 | 43篇 |
1996年 | 34篇 |
1995年 | 23篇 |
1994年 | 25篇 |
1993年 | 16篇 |
1992年 | 20篇 |
1991年 | 19篇 |
1990年 | 17篇 |
1989年 | 8篇 |
1988年 | 12篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1976年 | 2篇 |
1971年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有3193条查询结果,搜索用时 15 毫秒
1.
2.
Natalia L. Calvo Sebastian O. SimonettiRubén M. Maggio Teodoro S. Kaufman 《Analytica chimica acta》2015
Exposure of cimetidine (CIM) to dry heat (160–180 °C) afforded, upon cooling, a glassy solid containing new and hitherto unknown products. The kinetics of this process was studied by a second order chemometrics-assisted multi-spectroscopic approach. Proton and carbon-13 nuclear magnetic resonance (NMR), as well as ultraviolet and infrared spectroscopic data were jointly used, whereas multivariate curve resolution with alternating least squares (MCR-ALS) was employed as the chemometrics method to extract process information. It was established that drug degradation follows a first order kinetics. 相似文献
3.
Guy Bayada 《Journal of Mathematical Analysis and Applications》2003,282(1):212-231
The asymptotic behaviour of a Stokes flow with Tresca free boundary friction conditions when one dimension of the fluid domain tends to zero is studied. A specific Reynolds equation associated with variational inequalities is obtained and uniqueness is proved. 相似文献
4.
5.
A. A. Dokukin 《Computational Mathematics and Mathematical Physics》2006,46(5):914-918
To validate approximate optimization schemes for estimate calculation algorithms (ECAs), it is necessary to compute the optimal height, which cannot be done in a reasonable amount of time. A variety of samples are built for which the optimal height of the ECAs is known by construction. 相似文献
6.
M.B. Xu 《Applied Acoustics》2003,64(7):731-752
The forced vibration of an infinite elastic circular cylindrical shell filled with fluid is studied. Three methods are employed to analyze the forced vibration problem of this shell-fluid coupled system, that is, wave propagation approach (wave mode superposition), theorem of residues and a numerical integral method. In order to explain these methods more explicitly, before being used to investigate the vibration of an infinite fluid-filled elastic circular cylindrical shell, all these three methods are employed firstly to analyze the forced vibration problem of an infinite beam and an infinite elastic circular cylindrical shell in vacuo. Advantage and disadvantage of these three methods are discussed and their interesting relationship is revealed. That is, to any circumferential wavenumber and frequency of the external force, there is an unchangeable relationship between the general coordinates of various waves in the wave propagation approach and the residuals in the theorem of residues. 相似文献
7.
8.
Two structure functions W1(x,Q2) and W2(x,Q2) are determined by using the cross sections measured in the deep inelastic electron-proton scattering experiments at Stanford Linac in the energy range of 5 to 20 GeV. In this paper an alternative mathematical approach have been used in such determination, resulting in a larger number of points in the graphs of the structure functions. 相似文献
9.
采用Dirac Brueckner-Hartree-Fock理论方法, 计算了零温核物质中每核子的结合能、压强和单核子能量, 着重讨论了不同的T矩阵协变表示对核物质中Hugenholtz-Van Hove(HVH)定理满足程度的影响. 结果表明: 不同的协变表示对核子自能各分量的动量相关性和密度依赖性均有重要影响, 进而对核介质中HVH定理的满足程度产生重要影响. 在完全的膺矢量表示下, HVH定理遭到了相当大程度的破坏, 从而体现出基态关联效应对单核子性质的重要性, 并与非相对论BHF理论方法得到的结论一致, 因而完全的膺矢量表示要优于膺标量表示. 相似文献
10.