全文获取类型
收费全文 | 3038篇 |
免费 | 333篇 |
国内免费 | 267篇 |
专业分类
化学 | 840篇 |
晶体学 | 21篇 |
力学 | 290篇 |
综合类 | 37篇 |
数学 | 1316篇 |
物理学 | 1134篇 |
出版年
2024年 | 4篇 |
2023年 | 46篇 |
2022年 | 55篇 |
2021年 | 79篇 |
2020年 | 104篇 |
2019年 | 130篇 |
2018年 | 97篇 |
2017年 | 103篇 |
2016年 | 92篇 |
2015年 | 94篇 |
2014年 | 157篇 |
2013年 | 303篇 |
2012年 | 167篇 |
2011年 | 136篇 |
2010年 | 137篇 |
2009年 | 166篇 |
2008年 | 182篇 |
2007年 | 161篇 |
2006年 | 163篇 |
2005年 | 135篇 |
2004年 | 162篇 |
2003年 | 133篇 |
2002年 | 108篇 |
2001年 | 90篇 |
2000年 | 87篇 |
1999年 | 92篇 |
1998年 | 77篇 |
1997年 | 51篇 |
1996年 | 49篇 |
1995年 | 38篇 |
1994年 | 37篇 |
1993年 | 24篇 |
1992年 | 26篇 |
1991年 | 22篇 |
1990年 | 12篇 |
1989年 | 15篇 |
1988年 | 10篇 |
1987年 | 15篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1975年 | 5篇 |
1974年 | 4篇 |
排序方式: 共有3638条查询结果,搜索用时 15 毫秒
31.
We consider quasi-isometric mappings of domains in multidimensional Euclidean spaces. We establish that a mapping depends continuously in the sense of the topology of Sobolev classes on its metric tensor to within isometry of the space. In the space of metric tensors we take the topology determined by means of almost everywhere convergence. We show that if the metric tensor of a mapping is continuous then the length of the image of a rectifiable curve is determined by the same formula as in the case of mappings with continuous derivatives. (Continuity of the metric tensor of a mapping does not imply continuity of its derivatives.) 相似文献
32.
We study theoretically a nonlinear response of the planar metal/dielectric nanostructures constituted from periodical array
of ultra thin silver layers and the layers of Kerr-like nonlinear dielectric. We predict hysteresis-type dependences of the
components of the tensor of effective dielectric permittivity on the field intensity allowing the change in material transmission
properties from transparent to opaque and back at extremely low intensities of the light. It makes possible to control the
light by light in all-optical nanoscale devices and circuits. 相似文献
33.
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
34.
35.
36.
The stress tensor of a massless scalar field satisfying a mixed boundary condition in a (1 + 1)-dimensional Reissner- Nordstrom black hole background is calculated by using Wald's axiom. We find that Dirichlet stress tensor and Neumann stress tensor can be deduced by changing the coefficients of the stress tensor calculated under a mixed boundary condition. The stress tensors satisfying Dirichlet and Neumann boundary conditions are discussed. In addition, we also find that the stress tensor in conformal flat spacetime background differs from that in flat spacetime only by a constant. 相似文献
37.
The object of the present paper is to study quasi-conformally flat weakly Ricci symmetric manifolds.
相似文献
38.
Manuel Fernández-López Eduardo García-Río Demir N. Kupeli 《Annals of Global Analysis and Geometry》2002,21(1):1-13
A characterization of time functions on a spacetime is made by using theMöbius equation. It is shown that a time function characterized in this wayyields past timelike geodesic incompleteness and local Lorentzian warpedproduct decomposition of spacetime, provided that the stress-energy tensoris a fluid. Also, by imposing additional assumptions on the stress-energytensor and global analytic structure of the spacetime, more restrictivedecompositions closer to Robertson–Walker spacetimes are obtained. 相似文献
39.
Jaume Haro 《International Journal of Theoretical Physics》2003,42(12):2839-2846
We apply the formal W.K.B. method in the complex plane to the quantum field theory to obtain the Schwinger formula for spin and spinless particles; i.e., we obtain the probability that the vacuum state remains unchanged in presence of a constant electric field. Finally, from Schwinger formula we calculate the probability that n pairs are produced. 相似文献
40.
Y.Charles Li 《Journal of Mathematical Analysis and Applications》2004,292(1):311-315
Isospectral problem of both 2D and 3D Euler equations of inviscid fluids, is investigated. Connections with the Clay problem are described. Spectral theorem of the Lax pair is studied. 相似文献