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   1518篇
  免费   87篇
  国内免费   215篇
化学   52篇
晶体学   1篇
力学   65篇
综合类   23篇
数学   1552篇
物理学   127篇
  2023年   4篇
  2022年   7篇
  2021年   10篇
  2020年   18篇
  2019年   40篇
  2018年   46篇
  2017年   40篇
  2016年   46篇
  2015年   32篇
  2014年   70篇
  2013年   106篇
  2012年   77篇
  2011年   89篇
  2010年   96篇
  2009年   98篇
  2008年   86篇
  2007年   116篇
  2006年   119篇
  2005年   73篇
  2004年   66篇
  2003年   75篇
  2002年   62篇
  2001年   46篇
  2000年   55篇
  1999年   59篇
  1998年   53篇
  1997年   34篇
  1996年   29篇
  1995年   12篇
  1994年   12篇
  1993年   9篇
  1992年   11篇
  1991年   9篇
  1990年   4篇
  1989年   2篇
  1988年   2篇
  1987年   5篇
  1986年   8篇
  1985年   11篇
  1984年   11篇
  1983年   7篇
  1982年   13篇
  1981年   11篇
  1980年   7篇
  1979年   10篇
  1978年   9篇
  1977年   6篇
  1976年   3篇
  1975年   4篇
  1973年   1篇
排序方式: 共有1820条查询结果,搜索用时 171 毫秒
81.
Let be the unit disc of and let be such that . For 1$">, let . We study the behavior of on . In particular, we prove that . As a consequence, besides conditions for , we prove a conjecture of C. Cowen in case and are univalent mappings.

  相似文献   

82.
We study (set-valued) mappings of bounded -variation defined on the compact interval I and taking values in metric or normed linear spaces X. We prove a new structural theorem for these mappings and extend Medvedev's criterion from real valued functions onto mappings with values in a reflexive Banach space, which permits us to establish an explicit integral formula for the -variation of a metric space valued mapping. We show that the linear span GV (I;X) of the set of all mappings of bounded -variation is automatically a Banach algebra provided X is a Banach algebra. If h:I× X Y is a given mapping and the composition operator is defined by (f)(t)=h(t,f(t)), where tI and f:I X, we show that :GV (I;X) GV (I;Y) is Lipschitzian if and only if h(t,x)=h0(t)+h1(t)x, tI, xX. This result is further extended to multivalued composition operators with values compact convex sets. We prove that any (not necessarily convex valued) multifunction of bounded -variation with respect to the Hausdorff metric, whose graph is compact, admits regular selections of bounded -variation.  相似文献   
83.
The mapping version of Pöschel's theory on differentiable foliation structures of invariant tori is presented and the relevant estimates explicitly in terms of the diophantine constant and the nondegeneracy parameters of frequency maps are given. As a direct application of the main result, a generalization of Moser's small twist theorem to high dimensions is given.  相似文献   
84.
We introduce numerical invariants of holomorphic singular foliations under bimeromorphic transformations of surfaces. The basic invariant is a foliated version of the Kodaira dimension of compact complex manifolds.The author was supported by CNPq-Brazil in 1998 and Conseil Régional de Bourgogne in 1999.  相似文献   
85.
本文用多管落球法测得原始实验数据,运用最小二乘法进行处理,求得无限广延液体粘滞系数,并与直接作图法进行比较。  相似文献   
86.
介绍利用导数建立等价无穷小关系的三个方法,并举例说明.  相似文献   
87.
We consider a class of noncooperative stochastic games with general state and action spaces and with a state dependent discount factor. The expected time duration between any two stages of the game is not bounded away from zero, so that the usual N-stage contraction assumption, uniform over all admissible strategies, does not hold. We propose milder sufficient regularity conditions, allowing strategies that give rise with probability one to any number of simultaneous stages. We give sufficient conditions for the existence of equilibrium and ∈-equilibrium stationary strategies in the sense of Nash. In the two-player zero-sum case, when an equilibrium strategy exists, the value of the game is the unique fixed point of a specific functional operator and can be computed by dynamic programming.  相似文献   
88.
We prove expansion mappings theorems in various spaces i.e., metric spaces, generalized metric spaces, probabilistic metric spaces and fuzzy metric spaces, which generalize the results of various authors like Daffer and Kaneko [11], Ahmad, Ashraf and Rhoades [1], Vasuki [38], Rhoades [31] and Wang, Li, Gao and Iseki [40] etc. In the memory of 65th birthday anniversary of his Father Late Sh. Ram Phool Sharma  相似文献   
89.
90.
In this paper, we consider the weak and strong convergence of an implicit iterative process with errors for two finite families of asymptotically nonexpansive mappings in the framework of Banach spaces. Our results presented in this paper improve and extend the recent ones announced by many others.  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