全文获取类型
收费全文 | 8480篇 |
免费 | 903篇 |
国内免费 | 533篇 |
专业分类
化学 | 1930篇 |
晶体学 | 17篇 |
力学 | 553篇 |
综合类 | 121篇 |
数学 | 3849篇 |
物理学 | 1627篇 |
无线电 | 1819篇 |
出版年
2024年 | 11篇 |
2023年 | 104篇 |
2022年 | 161篇 |
2021年 | 185篇 |
2020年 | 231篇 |
2019年 | 276篇 |
2018年 | 220篇 |
2017年 | 297篇 |
2016年 | 331篇 |
2015年 | 288篇 |
2014年 | 449篇 |
2013年 | 663篇 |
2012年 | 553篇 |
2011年 | 476篇 |
2010年 | 399篇 |
2009年 | 497篇 |
2008年 | 515篇 |
2007年 | 543篇 |
2006年 | 461篇 |
2005年 | 374篇 |
2004年 | 322篇 |
2003年 | 342篇 |
2002年 | 342篇 |
2001年 | 245篇 |
2000年 | 217篇 |
1999年 | 199篇 |
1998年 | 179篇 |
1997年 | 171篇 |
1996年 | 114篇 |
1995年 | 118篇 |
1994年 | 87篇 |
1993年 | 85篇 |
1992年 | 46篇 |
1991年 | 42篇 |
1990年 | 44篇 |
1989年 | 31篇 |
1988年 | 31篇 |
1987年 | 33篇 |
1986年 | 25篇 |
1985年 | 31篇 |
1984年 | 33篇 |
1983年 | 16篇 |
1982年 | 18篇 |
1981年 | 17篇 |
1980年 | 19篇 |
1979年 | 17篇 |
1978年 | 10篇 |
1977年 | 15篇 |
1976年 | 10篇 |
1975年 | 8篇 |
排序方式: 共有9916条查询结果,搜索用时 8 毫秒
11.
In this note we show that all diffeomorphisms close enough to the time-one map of the frame flow on certain negatively curved manifolds are ergodic. As a simple corollary we deduce that the frame flows are ergodic for all compact manifolds with curvature pinched sufficiently close to –1, thus providing results in the case of manifolds of dimension 7 or 8 which were missing from the results of Brin and Karcher. 相似文献
12.
A least‐squares meshfree method based on the first‐order velocity–pressure–vorticity formulation for two‐dimensional incompressible Navier–Stokes problem is presented. The convective term is linearized by successive substitution or Newton's method. The discretization of all governing equations is implemented by the least‐squares method. Equal‐order moving least‐squares approximation is employed with Gauss quadrature in the background cells. The boundary conditions are enforced by the penalty method. The matrix‐free element‐by‐element Jacobi preconditioned conjugate method is applied to solve the discretized linear systems. Cavity flow for steady Navier–Stokes problem and the flow over a square obstacle for time‐dependent Navier–Stokes problem are investigated for the presented least‐squares meshfree method. The effects of inaccurate integration on the accuracy of the solution are investigated. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
13.
Wolfgang Knirsch 《Mathematische Nachrichten》2004,265(1):15-23
On weighted spaces with strictly plurisubharmonic weightfunctions the canonical solution operator of and the ‐Neumann operator are bounded. In this paper we find a class of strictly plurisubharmonic weightfunctions with certain growth conditions, so that they are Hilbert‐Schmidt operators between weighted spaces with different weightfunctions, if they are restricted to forms with holomorphic coefficients. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
14.
A new grid‐free upwind relaxation scheme for simulating inviscid compressible flows is presented in this paper. The non‐linear conservation equations are converted to linear convection equations with non‐linear source terms by using a relaxation system and its interpretation as a discrete Boltzmann equation. A splitting method is used to separate the convection and relaxation parts. Least squares upwinding is used for discretizing the convection equations, thus developing a grid‐free scheme which can operate on any arbitrary distribution of points. The scheme is grid free in the sense that it works on any arbitrary distribution of points and it does not require any topological information like elements, faces, edges, etc. This method is tested on some standard test cases. To explore the power of the grid‐free scheme, solution‐based adaptation of points is done and the results are presented, which demonstrate the efficiency of the new grid‐free scheme. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
15.
Yao Ping HOU 《数学学报(英文版)》2005,21(4):955-960
A signed graph is a graph with a sign attached to each edge. This paper extends some fundamental concepts of the Laplacian matrices from graphs to signed graphs. In particular, the relationships between the least Laplacian eigenvalue and the unbalancedness of a signed graph are investigated. 相似文献
16.
A. Debussche 《Journal de Mathématiques Pures et Appliquées》1998,77(10):967-988
The notion of random attractor for a dissipative stochastic dynamical system has recently been introduced. It generalizes the concept of global attractor in the deterministic theory. It has been shown that many stochastic dynamical systems associated to a dissipative partial differential equation perturbed by noise do possess a random attractor. In this paper, we prove that, as in the case of the deterministic attractor, the Hausdorff dimension of the random attractor can be estimated by using global Lyapunov exponents. The result is obtained under very natural assumptions. As an application, we consider a stochastic reaction-diffusion equation and show that its random attractor has finite Hausdorff dimension. 相似文献
17.
E. D. Nursultanov 《Mathematical Notes》1998,63(2):205-214
In this paper we prove theorems on multiplicators of Fourier series inL
p, where the conditions depend on a parameterp. An example illustrating the importance of these conditions is constructed.
Translated fromMatematicheskie Zametki, Vol. 63, No. 2, pp. 235–247, February, 1998. 相似文献
18.
19.
S. V. Tyshkevich 《Mathematical Notes》2007,81(5-6):851-853
20.
A new approach to identify the independent amplitudes along with their partial wave multipole expansions, for photo-and electro-production
is suggested, which is generally applicable to mesons with arbitrary spin-parity. These amplitudes facilitate direct identification
of different resonance contributions.
相似文献