全文获取类型
收费全文 | 1553篇 |
免费 | 41篇 |
国内免费 | 7篇 |
专业分类
化学 | 1103篇 |
晶体学 | 6篇 |
力学 | 13篇 |
数学 | 279篇 |
物理学 | 200篇 |
出版年
2020年 | 16篇 |
2019年 | 15篇 |
2017年 | 12篇 |
2016年 | 23篇 |
2015年 | 31篇 |
2014年 | 32篇 |
2013年 | 62篇 |
2012年 | 26篇 |
2011年 | 37篇 |
2010年 | 37篇 |
2009年 | 38篇 |
2008年 | 76篇 |
2007年 | 53篇 |
2006年 | 68篇 |
2005年 | 54篇 |
2004年 | 44篇 |
2003年 | 57篇 |
2002年 | 55篇 |
2001年 | 42篇 |
2000年 | 31篇 |
1999年 | 31篇 |
1998年 | 27篇 |
1997年 | 25篇 |
1996年 | 29篇 |
1995年 | 28篇 |
1994年 | 44篇 |
1993年 | 37篇 |
1992年 | 52篇 |
1991年 | 23篇 |
1990年 | 15篇 |
1989年 | 17篇 |
1988年 | 21篇 |
1987年 | 34篇 |
1986年 | 24篇 |
1985年 | 23篇 |
1984年 | 24篇 |
1983年 | 29篇 |
1982年 | 22篇 |
1981年 | 17篇 |
1980年 | 23篇 |
1979年 | 22篇 |
1978年 | 29篇 |
1977年 | 18篇 |
1976年 | 12篇 |
1975年 | 17篇 |
1974年 | 25篇 |
1973年 | 20篇 |
1972年 | 16篇 |
1971年 | 21篇 |
1970年 | 12篇 |
排序方式: 共有1601条查询结果,搜索用时 687 毫秒
131.
Let E be a separable Banach space ordered by a reproducing cone with empty interior. We prove the existence of operator functions A : [0, ) P (P the cone of monotone increasing linear operators) and of initial values x0 such that the solution of x (t) = A(t) x(t), x(0) = x0, is dense in E.Received: 27 February 2004 相似文献
132.
133.
Stolcic D Fischer M Ganteför G Kim YD Sun Q Jena P 《Journal of the American Chemical Society》2003,125(10):2848-2849
Using ultraviolet photoelectron spectroscopy, we provide direct experimental evidence that di-oxygen species are stable on anionic gold dimer and tetramer clusters at room temperature. The stabilization of molecular oxygen is crucial for the high activities of the low-temperature reactions on gold catalysts. 相似文献
134.
A new a posteriori L2 norm error estimator is proposed for thePoisson equation. The error estimator can be applied to anisotropictetrahedral or triangular finite element meshes. The estimatoris rigorously analysed for Dirichlet and Neumann boundary conditions. The lower error bound relies on specifically designed anisotropicbubble functions and the corresponding inverse inequalities.The upper error bound utilizes non-standard anisotropic interpolationestimates. Its proof requires H2 regularity of the Poisson problem,and its quality depends on how good the anisotropic mesh resolvesthe anisotropy of the problem. This is measured by a so-calledmatching function. A numerical example supports the anisotropic error analysis. 相似文献
135.
Gil M. Barretto Peter J. Collings Dirk Bennemann Detlef L
tzsch Gerd Heppke 《Liquid crystals》2001,28(4):629-635
Optical activity measurements in the isotropic phase of two antiferroelectric liquid crystal systems in which the chirality can be varied reveal unusual behaviour of the short range order. In one system the phase sequence as the chirality is increased is smectic A, smectic C*A, and smectic Q. In the other system the phase sequence is smectic C*, smectic C*A, and smectic Q as the chirality is increased. The short range order of the isotropic phase behaves similarly for these systems, showing mean field behaviour at low chirality and far above the phase transition, but deviating from this behaviour significantly as the chirality is increased and the phase transition is approached. These optical activity results indicate how different is the short range order in the isotropic phase for these antiferroelectric liquid crystal systems and demonstrates the crucial role played by chirality. Past theoretical work that includes smecticlike fluctuations in the calculation of short range order in the isotropic phase is capable of qualitatively explaining these results. 相似文献
136.
137.
138.
139.
140.
Gerd Teschke Mariya Zhariy Maria Joana Soares 《Mathematical Methods in the Applied Sciences》2008,31(5):575-587
We develop a regularization technique for Perona–Malik diffusion equations that relies on multiresolution techniques. The main result of this paper is to show that the chosen discretization overcomes the ill posedness of the nonlinear Perona–Malik model. The resulting algorithm is tested and the results are compared with pixel‐based methods. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献