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   548篇
  免费   17篇
  国内免费   47篇
化学   24篇
晶体学   1篇
力学   15篇
数学   480篇
物理学   92篇
  2023年   2篇
  2022年   7篇
  2021年   7篇
  2020年   7篇
  2019年   13篇
  2018年   7篇
  2017年   9篇
  2016年   7篇
  2015年   16篇
  2014年   27篇
  2013年   31篇
  2012年   26篇
  2011年   51篇
  2010年   38篇
  2009年   57篇
  2008年   40篇
  2007年   41篇
  2006年   31篇
  2005年   27篇
  2004年   23篇
  2003年   16篇
  2002年   22篇
  2001年   14篇
  2000年   13篇
  1999年   13篇
  1998年   14篇
  1997年   16篇
  1996年   6篇
  1995年   4篇
  1994年   7篇
  1993年   3篇
  1992年   4篇
  1991年   1篇
  1990年   1篇
  1987年   2篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1978年   1篇
  1977年   1篇
  1969年   1篇
排序方式: 共有612条查询结果,搜索用时 31 毫秒
1.
A bounded linear operator T acting on a Hilbert space is called Coburn operator if ker(T ? λ) = {0} or ker(T ? λ)*= {0} for each λ ∈ C. In this paper, the authors define other Coburn type properties for Hilbert space operators and investigate the compact perturbations of operators with Coburn type properties. They characterize those operators for which has arbitrarily small compact perturbation to have some fixed Coburn property.Moreover, they study the stability of these properties under small compact perturbations.  相似文献   
2.
为数值求解低雷诺数下不可压流体在电磁场作用下的流动,提出一种四阶紧致差分方法.由二维原始变量的MHD方程组出发,推导出具有较少未知量的电流密度-涡量-流函数形式MHD方程组.建立了求解二维非定常不可压MHD方程组的电流密度-涡量-流函数形式的四阶精度紧致差分格式.为验证本文提出的高精度紧致差分方法的精确性和可靠性,对有解析解的二维非定常不可压MHD方程组的初边值问题进行数值模拟,数值结果证明本文所建立的高阶紧致格式精确有效并且无条件稳定.  相似文献   
3.
In recent years the coincidence of the operator relations equivalence after extension (EAE) and Schur coupling (SC) was settled for the Hilbert space case. For Banach space operators, it is known that SC implies EAE, but the converse implication is only known for special classes of operators, such as Fredholm operators with index zero and operators that can in norm be approximated by invertible operators. In this paper we prove that the implication EAE ? SC also holds for inessential Banach space operators. The inessential operators were introduced as a generalization of the compact operators, and include, besides the compact operators, also the strictly singular and strictly co-singular operators; in fact they form the largest ideal such that the invertible elements in the associated quotient algebra coincide with (the equivalence classes of) the Fredholm operators.  相似文献   
4.
5.
6.
Using the nice properties of the w-divisible weight and the w-divisible groups, we prove a factorization theorem for compact abelian groups K; namely, K = K tor  × K d , where K tor is a bounded torsion compact abelian group and K d is a w-divisible compact abelian group. By Pontryagin duality this result is equivalent to the same factorization for discrete abelian groups proved in [9 Galindo , J. , Macario , S. ( 2011 ). Pseudocompact group topologies with no infinite compact subsets . J. Pure and Appl. Algebra 215 : 655663 .[Crossref], [Web of Science ®] [Google Scholar]].  相似文献   
7.
Gaussian random fields defined over compact two-point homogeneous spaces are considered and Sobolev regularity and Hölder continuity are explored through spectral representations. It is shown how spectral properties of the covariance function associated to a given Gaussian random field are crucial to determine such regularities and geometric properties. Furthermore, fast approximations of random fields on compact two-point homogeneous spaces are derived by truncation of the series expansion, and a suitable bound for the error involved in such an approximation is provided.  相似文献   
8.
The Kakutani–Bebutov Theorem (1968) states that any compact metric real flow whose fixed point set is homeomorphic to a subset of R embeds into the Bebutov flow, the R-shift on C(R,[0,1]). An interesting fact is that this universal space is a function space. However, it is not compact, nor locally compact. We construct an explicit countable product of compact subspaces of the Bebutov flow which is a universal space for all compact metric real flows, with no restriction; namely, into which any compact metric real flow embeds. The result is compared to previously known universal spaces.  相似文献   
9.
10.
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