首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2453篇
  免费   177篇
  国内免费   187篇
化学   94篇
晶体学   1篇
力学   42篇
综合类   18篇
数学   2463篇
物理学   199篇
  2024年   4篇
  2023年   39篇
  2022年   27篇
  2021年   40篇
  2020年   71篇
  2019年   95篇
  2018年   71篇
  2017年   72篇
  2016年   79篇
  2015年   61篇
  2014年   124篇
  2013年   204篇
  2012年   83篇
  2011年   148篇
  2010年   113篇
  2009年   168篇
  2008年   194篇
  2007年   152篇
  2006年   164篇
  2005年   111篇
  2004年   110篇
  2003年   106篇
  2002年   101篇
  2001年   82篇
  2000年   73篇
  1999年   66篇
  1998年   49篇
  1997年   61篇
  1996年   28篇
  1995年   21篇
  1994年   18篇
  1993年   12篇
  1992年   14篇
  1991年   8篇
  1990年   4篇
  1989年   6篇
  1988年   3篇
  1987年   5篇
  1986年   1篇
  1985年   5篇
  1984年   6篇
  1983年   4篇
  1982年   4篇
  1981年   2篇
  1980年   3篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1969年   1篇
排序方式: 共有2817条查询结果,搜索用时 970 毫秒
31.
In this article we prove a strong law of large numbers for Borel measurable nonseparably valued random elements in the case of generalized random sets.

  相似文献   

32.
The educational system has gradually shifted from a face-to-face to an e-learning system, which has become prevalent in advanced countries with the advance of information technology, and connection of global networks. Accordingly, a growing demand is emerging for more reliable individual certification with technical precision in order to measure and record learning achievements and credentials of participants. The present system has a limit in terms of registration capacity, therefore, its accuracy has often been questioned. Against this background, an individual certification system is proposed particularly for access control in e-learning. Under our proposed system, a compact optical correlator for facial recognition is employed. This correlator was previously tested for of biometrics authentication accuracy and proved highly reliable, having recorded remarkably low error rates (below 1%). The recorded error rate is sufficiently robust that the system itself can be regarded as a valid and practical viable attestation system.  相似文献   
33.
We prove a general embedding theorem for Sobolev spaces on open manifolds of bounded geometry and infer from this the module structure theorem. Thereafter we apply this to weighted Sobolev spaces.  相似文献   
34.
Mathieu  P. 《Potential Analysis》1998,9(3):293-300
We investigate the links between Sobolev and Nash inequalities, capacity and hitting times estimates and ultracontractive semigroups, in a non-symmetric setting.  相似文献   
35.
We present simple proofs of the possibility of embedding ultrametric spaces in Hilbert spaces. The main part of the paper deals with ultrametric spaces that we call totally infinite spaces. Related Hilbert spaces, automorphisms of totally infinite spaces, and the corresponding linear operators are considered. Transplated fromMatematicheskie Zametki, Vol. 62, No. 2, pp. 223–237, August, 1997. Translated by V. E. Nazaikinskii  相似文献   
36.
The author has proposed methods of constructing index 2 and 3 current graphs generating triangular embeddings of graphs KnKm with unboundedly large m (as n increases). As a result, triangular embeddings of graphs of many families of graphs KnKm with unboundedly large m were constructed. The paper gives a survey of these results and a short explanation of the methods.  相似文献   
37.
We determine the limit of the bottom of spectrum of Schrödinger operators with variable coefficients on Wiener spaces and path spaces over finite-dimensional compact Riemannian manifolds in the semi-classical limit. These are extensions of the results in [S. Aida, Semiclassical limit of the lowest eigenvalue of a Schrödinger operator on a Wiener space, J. Funct. Anal. 203 (2) (2003) 401-424]. The problem on path spaces over Riemannian manifolds is considered as a problem on Wiener spaces by using Ito's map. However the coefficient operator is not a bounded linear operator and the dependence on the path is not continuous in the uniform convergence topology if the Riemannian curvature tensor on the underling manifold is not equal to 0. The difficulties are solved by using unitary transformations of the Schrödinger operators by approximate ground state functions and estimates in the rough path analysis.  相似文献   
38.
39.
We investigate traces of functions, belonging to a class of functions with dominating mixed smoothness in ℝ3, with respect to planes in oblique position. In comparison with the classical theory for isotropic spaces a few new phenomenona occur. We shall present two different approaches. One is based on the use of the Fourier transform and restricted to p = 2. The other one is applicable in the general case of Besov-Lizorkin-Triebel spaces and based on atomic decompositions.  相似文献   
40.
Two results on product of compact filters are shown to be the common principle behind a surprisingly large number of theorems.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号