全文获取类型
收费全文 | 3541篇 |
免费 | 64篇 |
国内免费 | 15篇 |
专业分类
化学 | 2539篇 |
晶体学 | 8篇 |
力学 | 34篇 |
数学 | 476篇 |
物理学 | 563篇 |
出版年
2016年 | 45篇 |
2015年 | 59篇 |
2014年 | 66篇 |
2013年 | 106篇 |
2012年 | 66篇 |
2011年 | 82篇 |
2010年 | 72篇 |
2009年 | 61篇 |
2008年 | 113篇 |
2007年 | 118篇 |
2006年 | 105篇 |
2005年 | 90篇 |
2004年 | 93篇 |
2003年 | 89篇 |
2002年 | 100篇 |
2001年 | 72篇 |
2000年 | 71篇 |
1999年 | 54篇 |
1998年 | 45篇 |
1997年 | 44篇 |
1996年 | 52篇 |
1995年 | 50篇 |
1994年 | 71篇 |
1993年 | 53篇 |
1992年 | 75篇 |
1991年 | 34篇 |
1989年 | 29篇 |
1988年 | 33篇 |
1987年 | 51篇 |
1986年 | 46篇 |
1985年 | 45篇 |
1984年 | 34篇 |
1983年 | 35篇 |
1982年 | 38篇 |
1981年 | 39篇 |
1980年 | 37篇 |
1979年 | 33篇 |
1978年 | 47篇 |
1977年 | 30篇 |
1975年 | 29篇 |
1974年 | 42篇 |
1973年 | 30篇 |
1972年 | 32篇 |
1965年 | 45篇 |
1964年 | 95篇 |
1963年 | 126篇 |
1962年 | 160篇 |
1961年 | 142篇 |
1960年 | 140篇 |
1958年 | 45篇 |
排序方式: 共有3620条查询结果,搜索用时 31 毫秒
11.
The paper addresses bivariate surface fitting problems, where data points lie on the vertices of a rectangular grid. Efficient
and stable algorithms can be found in the literature to solve such problems. If data values are missing at some grid points,
there exists a computational method for finding a least squares spline by fixing appropriate values for the missing data.
We extended this technique to arbitrary least squares problems as well as to linear least squares problems with linear equality
constraints. Numerical examples are given to show the effectiveness of the technique presented.
AMS subject classification (2000) 65D05, 65D07, 65D10, 65F05, 65F20 相似文献
12.
Matthias Heydenreich Andreas Koch E. Kleinpeter Thomas Zimmermann 《Fresenius' Journal of Analytical Chemistry》1997,357(5):517-521
Dynamic NMR investigations of a number of 2-amino-3-aroyl-4,6-diaryl-pyrylium salts were carried out. The barrier to rotation
of the partial C, N double bond was determined and proved to be in the range of 62 to 63 kJ/mol. Quantum chemical calculations
of bond orders and electron densities of the different atoms in the molecules show the distinct double bond character of the
exocyclic C, N bond. This is in agreement with the relatively high barrier to rotation. By quantum chemical ab initio 3-21G
calculations, the dynamic behaviour of this kind of compounds was simulated; two pairs (image and mirror image) of ground
state conformations, in coincidence with the experiment, were obtained.
Received: 10 May 1996 / Revised: 1 July 1996 / Accepted: 4 July 1996 相似文献
13.
14.
15.
16.
Bruno Zimmermann 《Monatshefte für Mathematik》2002,135(3):253-258
We give a list including all finite groups G which admit smooth orientation preserving actions on homology 3-spheres (arbitrary actions, i.e. possibly with fixed points;
if the action is free then the group G has periodic cohomology and the classification of such groups is well known). The main work in this direction is due to M.
Reni. In the present paper, we complete and extend his results for the case of nonsolvable groups G.
Received 19 March 2001; in revised form 15 September 2001 相似文献
17.
18.
19.
The tunneling of single electrons in small capacitance tunnel junctions is influenced by charging effects and by the fluctuations of the elecromagnetic environment. We study the effect of an external circuit with arbitrary impedance on the tunneling of quasiparticles and Cooper pairs in voltage driven Josephson junctions. We present results at finite temperatures and also consider an acdriven system. 相似文献
20.
The paper deals with a singularly perturbed reaction diffusionmodel problem. The focus is on reliable a posteriori error estimatorsfor the H1 seminorm that can be applied to anisotropic finiteelement meshes. A residual error estimator and a local problemerror estimator are proposed and rigorously analysed. They arelocally equivalent, and both bound the error reliably. Threemodifications of these estimators are introduced and discussed. Much attention is given to the performance of the error estimatorin numerical experiments. This helps to identify those estimatorsthat are suitable for practical applications. 相似文献