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   4863篇
  免费   436篇
  国内免费   486篇
化学   41篇
力学   165篇
综合类   126篇
数学   5037篇
物理学   416篇
  2024年   7篇
  2023年   51篇
  2022年   57篇
  2021年   97篇
  2020年   123篇
  2019年   128篇
  2018年   127篇
  2017年   154篇
  2016年   160篇
  2015年   98篇
  2014年   247篇
  2013年   391篇
  2012年   236篇
  2011年   317篇
  2010年   285篇
  2009年   356篇
  2008年   387篇
  2007年   327篇
  2006年   314篇
  2005年   270篇
  2004年   201篇
  2003年   194篇
  2002年   209篇
  2001年   141篇
  2000年   150篇
  1999年   146篇
  1998年   127篇
  1997年   94篇
  1996年   75篇
  1995年   51篇
  1994年   36篇
  1993年   33篇
  1992年   28篇
  1991年   23篇
  1990年   19篇
  1989年   9篇
  1988年   7篇
  1987年   8篇
  1986年   13篇
  1985年   11篇
  1984年   14篇
  1983年   5篇
  1982年   9篇
  1981年   8篇
  1980年   11篇
  1979年   4篇
  1978年   7篇
  1977年   3篇
  1976年   7篇
  1936年   5篇
排序方式: 共有5785条查询结果,搜索用时 359 毫秒
901.
For any , a truncated symmetric α-stable process is a symmetric Lévy process in with a Lévy density given by for some constant c. In this paper we study the potential theory of truncated symmetric stable processes in detail. We prove a Harnack inequality for nonnegative harmonic functions of these processes. We also establish a boundary Harnack principle for nonnegative functions which are harmonic with respect to these processes in bounded convex domains. We give an example of a non-convex domain for which the boundary Harnack principle fails. The research of Panki Kim is supported by Research Settlement Fund for the new faculty of Seoul National University. The research of Renming Song is supported in part by a joint US-Croatia grant INT 0302167.  相似文献   
902.
We establish sufficient conditions for a cohomology class of a discrete subgroup Γ of a connected semisimple Lie group with finite center to be representable by a bounded differential form on the quotient by Γ of the associated symmetric space; furthermore if \(\rho : \Gamma\to\mathrm{PU}(1,q)\) is any representation of any discrete subgroup Γ of SU (1, p), we give an explicit closed bounded differential form on the quotient by Γ of complex hyperbolic space which is a representative for the pullback via ρ of the Kähler class of PU(1,q). If G,G′ are Lie groups of Hermitian type, we generalize to representations \(\rho : \Gamma\to G'\) of lattices Γ < G the invariant defined in [Burger, M., Iozzi, A.: Bounded cohomology and representation variates in PU (1,n). Preprint announcement, April 2000] for which we establish a Milnor–Wood type inequality. As an application we study maximal representations into PU(1, q) of lattices in SU(1,1).  相似文献   
903.
We derive strong uniform approximations for the eigenvalues in general Laguerre and Hermite -ensembles by showing that the maximal discrepancy between the suitably scaled eigenvalues and roots of orthogonal polynomials converges almost surely to zero when the dimension converges to infinity. We also provide estimates of the rate of convergence. In the special case of a normalized real Wishart matrix , where denotes the dimension and the degrees of freedom, the rate is , if with , and the rate is , if with . In the latter case we also show the a.s. convergence of the largest eigenvalue of to the corresponding quantile of the Marcenko-Pastur law.

  相似文献   

904.
Assuming that a Nash type inequality is satisfied by a non-negative self-adjoint operator , we prove a Nash type inequality for the fractional powers of . Under some assumptions, we give ultracontractivity bounds for the semigroup generated by .

  相似文献   

905.
This paper is devoted to discuss the regularity of the weak solution to a class of non-linear equations corresponding to Hardy-Sobolev type inequality on the H-type group. Combining the Serrin's idea and the Moser's iteration, Lp estimates of the weak solution are obtained, which generalize the results of Garofalo and Vassilev in [6, 14]. As an application, asymptotic behavior of the weak solution has been discussed. Finally, doubling property and unique continuation of the weak solution are given. *This material is based upon work funded by Zhejiang Provincial Natural Science Foundation of China under Grant No. Y606144.  相似文献   
906.
塑性全量理论的变分不等式模式及其无迭代解   总被引:1,自引:0,他引:1  
变分不等式是解决一类带单侧约束的定常力学问题的有效数学工具.本文就弹塑性全量理论构造了等价的变分不等式模式,解除了弹塑性问题本构约束的不等式关系,比一般能量形式的描述更为简洁.它便于计算,具有可靠的数学依据,可以用二次规划法求解.计算时无需分级加载迭代,一步即可得收敛解.  相似文献   
907.
The Hölder continuity is proved for the gradient of the solution Jo the one-sided obstacle problem of the following variational inequality in the case 1相似文献   
908.
Basic equations for large deflection theory of thin orthotropic circular plate with variable thickness are derived in this paper. The modified iteration method is adopted to solve the large deflection problem of thin orthotropic circular plate with variable thickness under uniform pressure. If ε=0, then the solution derived from the result in this paper coincides completely with the result given by J. Nowinski (using perturbation method) for solving large deflection problem of thin orthotropic circular plate with constant thickness under uniform pressure.  相似文献   
909.
In this paper,we consider the vector nonlinear boundary value problem:εy~v=f(x,y,z,y′,ε),y(0)=A_1,y(1)=B_1εz~v=g(x,y,z,z′,ε),z(0)=A_2,z(1)=B_2whereε>0 is a small parameter,0≤x≤1 ,f and g are continuous functions in R~4,Under appropriate assumptions,by means of the differential inequalities,we demonstratethe existence and estimation,involving boundary and interior layers,of the solutions to theabove problem.  相似文献   
910.
Recently,many authors have generalized the famous Ky Fan’s minimaxinequality.In this paper,we put forward T-diagonal convexity(concavity)conditions anddevelop the main results in this respect.Next.we discuss some fixed point problems,andgeneralize the Fan-Glicksberg’s fixed point theorem.  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