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   6055篇
  免费   155篇
  国内免费   52篇
化学   102篇
晶体学   2篇
力学   44篇
综合类   9篇
数学   5053篇
物理学   297篇
无线电   755篇
  2023年   7篇
  2022年   12篇
  2021年   7篇
  2020年   11篇
  2019年   48篇
  2018年   46篇
  2017年   28篇
  2016年   37篇
  2015年   36篇
  2014年   70篇
  2013年   215篇
  2012年   191篇
  2011年   194篇
  2010年   192篇
  2009年   884篇
  2008年   789篇
  2007年   622篇
  2006年   330篇
  2005年   307篇
  2004年   276篇
  2003年   308篇
  2002年   397篇
  2001年   366篇
  2000年   110篇
  1999年   46篇
  1998年   38篇
  1997年   35篇
  1996年   53篇
  1995年   61篇
  1994年   57篇
  1993年   58篇
  1992年   48篇
  1991年   41篇
  1990年   55篇
  1989年   43篇
  1988年   34篇
  1987年   40篇
  1986年   29篇
  1985年   61篇
  1984年   23篇
  1983年   3篇
  1982年   13篇
  1981年   7篇
  1980年   10篇
  1979年   5篇
  1978年   7篇
  1977年   7篇
  1976年   5篇
排序方式: 共有6262条查询结果,搜索用时 15 毫秒
151.
We study the optimal reinsurance policy and dividend distribution of an insurance company under excess of loss reinsurance. The objective of the insurer is to maximize the expected discounted dividends. We suppose that in the absence of dividend distribution, the reserve process of the insurance company follows a compound Poisson process. We first prove existence and uniqueness results for this optimization problem by using singular stochastic control methods and the theory of viscosity solutions. We then compute the optimal strategy of reinsurance, the optimal dividend strategy and the value function by solving the associated integro-differential Hamilton–Jacobi–Bellman Variational Inequality numerically.  相似文献   
152.
T.S. Blyth  jie Fang  J.C. Varlet 《代数通讯》2013,41(11):3605-3615
The variety pO consists of those algebras (L; ?, ?, f,*, 0,1) of type (2,2,1,1,0,0) where (L; ?, ?, f, 0,1) is an Ockham algebra, (Z; ?, ?,*, 0,1) is a p-algebra, and the unary operations f and * commute. We describe completely the structure of the subdirectly irreducible algebras that belong to the subclass pK1,1, characterised by the property f3 = f.  相似文献   
153.
154.
155.
This work deals with the study of an initial-boundary value problem in linear theory of thermo-viscoelastic dielectrics. A variational formulation of this problem is provided and the existence of its solution is proved by an auxiliary Faedo-Galerkin scheme. Finally, the uniqueness of the solution is obtained as a corollary of the existence proof.  相似文献   
156.
We introduce a new concept of generalized Knaster–Kuratowski–Mazurkiewicz (KKM) family of sets and related to this we obtain fixed point theorems and sections results in homotopically trivial spaces.  相似文献   
157.
158.
In this paper, we consider a method of centers for solving multi-objective programming problems, where the objective functions involved are concave functions and the set of feasible points is convex. The algorithm is defined so that the sub-problems that must be solved during its execution may be solved by finite-step procedures. Conditions are given under which the algorithm generates sequences of feasible points and constraint multiplier vectors that have accumulation points satisfying the KKT conditions. Finally, we establish convergence of the proposed method of centers algorithm for solving multiobjective programming problems.  相似文献   
159.
In this article, the authors mainly discuss the law of large number under Kalikow's condition for multi-dimensional random walks in random environment with holding times. The authors give an expression to the escape speed of random walks in terms of the Lyapounov exponents, which have been precisely used in the context of large deviation.  相似文献   
160.
We prove that if X and Y are compact Hausdorff spaces, then every fC(X × Y)+, i.e. f(x, y) ≥ 0 for all (x, y) ∈ X × Y, can be approximated uniformly from below and above by elements of the form , where fiC(X)+ and giC(Y)+ for i = 1, 2, …, n. The proof uses only elementary topology. We use this result, in conjuction with Kakutani's M-spaces representation theorem, to obtain an alternative proof for a known property of Fremlin's Riesz space tensor product of Archimedean Riesz spaces.  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