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   1057篇
  免费   69篇
  国内免费   52篇
化学   134篇
力学   15篇
综合类   13篇
数学   905篇
物理学   111篇
  2023年   9篇
  2022年   9篇
  2021年   8篇
  2020年   26篇
  2019年   29篇
  2018年   33篇
  2017年   37篇
  2016年   20篇
  2015年   21篇
  2014年   40篇
  2013年   103篇
  2012年   23篇
  2011年   45篇
  2010年   34篇
  2009年   72篇
  2008年   60篇
  2007年   64篇
  2006年   56篇
  2005年   50篇
  2004年   45篇
  2003年   46篇
  2002年   35篇
  2001年   32篇
  2000年   35篇
  1999年   26篇
  1998年   31篇
  1997年   31篇
  1996年   21篇
  1995年   18篇
  1994年   11篇
  1993年   11篇
  1992年   9篇
  1991年   4篇
  1990年   8篇
  1989年   3篇
  1988年   4篇
  1987年   3篇
  1986年   5篇
  1985年   10篇
  1984年   5篇
  1982年   7篇
  1981年   7篇
  1980年   5篇
  1979年   2篇
  1978年   3篇
  1977年   8篇
  1976年   4篇
  1975年   2篇
  1973年   2篇
  1969年   2篇
排序方式: 共有1178条查询结果,搜索用时 0 毫秒
31.
We study a generalization of the classical Marcinkiewicz–Zygmund inequalities. We relate this problem to the sampling sequences in the Paley–Wiener space and by using this analogy we give sharp necessary and sufficient computable conditions for a family of points to satisfy the Marcinkiewicz–Zygmund inequalities.  相似文献   
32.
The design of a robust mixed H 2/H controller for a class of uncertain neutral systems with discrete, distributed, and input time-varying delays is considered. More precisely, the proposed robust mixed H 2/H controller minimizes an upper bound of the H 2 performance measure, while guaranteeing an H norm bound constraint. Based on the Lyapunov-Krasovskii functional theory, a delay-dependent criterion is derived for the existence of a desired mixed H 2/H controller, which can be constructed easily via feasible linear matrix inequalities (LMIs). Furthermore, a convex optimization problem satisfying some LMI constraints is formulated to obtain a suboptimal robust mixed H 2/H controller achieving the minimization of an upper bound of the closed-loop H 2 performance measure. Finally, a numerical example is illustrated to show the usefulness of the obtained design method.The research reported here was supported by the National Science Council of Taiwan, ROC under Grant NSC 94-2213-E-507-002.  相似文献   
33.
We consider paths of functionals starting with one which is invariant under the action of an arbitrary group of symmetries. We give conditions for the existence of an unbounded sequence of critical values of the non-symmetric functional at the end of the path in terms of the growth of the critical values of the symmetric one. We apply this to obtain a multiplicity result for a system of elliptic equations whose symmetries are perturbed by a linear term and a non-homogeneous boundary condition.  相似文献   
34.
关于Banach空间中凸泛函的广义次梯度不等式   总被引:2,自引:0,他引:2  
姚云飞  徐森林 《应用数学》2003,16(3):136-140
本文在前人^[1,2]的基础之上,以凸泛函的次梯度不等式为工具,将Jensen不等式推广到Banach空间中的凸泛函,导出了Banach空间中的Bochner积分型的广义Jensen不等式,给出其在Banach空间概率论中某些应用,从而推广了文献[3—6]的工作.  相似文献   
35.
设是可列非齐次马氏链,本文通过利用[1]中提出的在Wiener概率空间的一种实现,而给出了一个对任意可列非齐次马氏链普遍成立的强极限定理。  相似文献   
36.
We fix a rich probability space (,F,P). Let (H,) be a separable Hilbert space and let be the canonical cylindrical Gaussian measure on H. Given any abstract Wiener space (H,B,) over H, and for every Hilbert–Schmidt operator T: HBH which is (|{}|,)-continuous, where |{}| stands for the (Gross-measurable) norm on B, we construct an Ornstein–Uhlenbeck process : (,F,P)×[0,1](B,|{}|) as a pathwise solution of the following infinite-dimensional Langevin equation d t =db t +T( t )dt with the initial data 0=0, where b is a B-valued Brownian motion based on the abstract Wiener space (H,B,). The richness of the probability space (,F,P) then implies the following consequences: the probability space is independent of the abstract Wiener space (H,B,) (in the sense that (,F,P) does not depend on the choice of the Gross-measurable norm |{}|) and the space C B consisting of all continuous B-valued functions on [0,1] is identical with the set of all paths of . Finally, we present a way to obtain pathwise continuous solutions :d t =
db t + t dt with initial data 0=0, where ,R,0 and 0<.  相似文献   
37.
§1Introductionandresults A2-parameterGaussianprocess{Z(t,s);t,s≥0}iacalleda2-parameterfractional Wienerprocesswithorderα(0<α<1),ifZ(0,0)=0a.s.EZ(s,t)=0anditscovariance EZ(t1,s1)Z(t2,s2)={|t1|2α+|t2|2α-|t2-t1|2α}{|s1|2α+|s2|2α-|s2-s1|2α}/4.LetR=[x1,x2]×[y1,y2],DT={(x,y)∶0≤x,y≤bT,xy≤T}.Let0相似文献   
38.
The paper deals with spectral approximation of Wiener-Hopf operators acting on Lp -spaces by their

finite sections. The generating functions of the Wiener-Hopf operators are supposed to be continuous plus almost

periodic.While the usual spectra of the finite sections drastically fail to converge to the spectrum of the Wiener-Hopf

operator,it turns out that other spectral approximants, viz. the pseudospectra and the numerical ranges, do converge

perfectly.The proof requires a modified approach to the finite section method for Wiener-Hopf operators. This note

generalizes results obtained by Böttcher, Grudsky and Silbermann for the case of continuous generating

functions.  相似文献   
39.
Let G be a connected graph and η(G)=Sz(G)−W(G), where W(G) and Sz(G) are the Wiener and Szeged indices of G, respectively. A well-known result of Klav?ar, Rajapakse, and Gutman states that η(G)≥0, and by a result of Dobrynin and Gutman η(G)=0 if and only if each block of G is complete. In this paper, a path-edge matrix for the graph G is presented by which it is possible to classify the graphs in which η(G)=2. It is also proved that there is no graph G with the property that η(G)=1 or η(G)=3. Finally, it is proved that, for a given positive integer k,k≠1,3, there exists a graph G with η(G)=k.  相似文献   
40.
可以接轨道得到带白噪声的随机耗散Camassa-Holm方程的唯—解并且可以检验该解产生随机动力系统,从而证明了该随机动力系统在H02中存在紧的随机吸引子.  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