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   9952篇
  免费   816篇
  国内免费   600篇
化学   1327篇
晶体学   145篇
力学   770篇
综合类   105篇
数学   7370篇
物理学   1651篇
  2024年   23篇
  2023年   82篇
  2022年   119篇
  2021年   127篇
  2020年   265篇
  2019年   259篇
  2018年   261篇
  2017年   282篇
  2016年   299篇
  2015年   234篇
  2014年   422篇
  2013年   917篇
  2012年   373篇
  2011年   550篇
  2010年   549篇
  2009年   614篇
  2008年   697篇
  2007年   633篇
  2006年   565篇
  2005年   504篇
  2004年   432篇
  2003年   399篇
  2002年   356篇
  2001年   282篇
  2000年   237篇
  1999年   241篇
  1998年   181篇
  1997年   186篇
  1996年   163篇
  1995年   117篇
  1994年   114篇
  1993年   86篇
  1992年   72篇
  1991年   63篇
  1990年   55篇
  1989年   36篇
  1988年   44篇
  1987年   31篇
  1986年   46篇
  1985年   52篇
  1984年   59篇
  1983年   42篇
  1982年   54篇
  1981年   43篇
  1980年   40篇
  1979年   48篇
  1978年   30篇
  1977年   19篇
  1976年   23篇
  1973年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
In the context of the weak solutions of the Navier-Stokes equations we study the regularity of the pressure and its derivatives in the space-time neighbourhood of regular points. We present some global and local conditions under which the regularity is further improved.  相似文献   
32.
In this paper, we present a new relaxation method for mathematical programs with complementarity constraints. Based on the fact that a variational inequality problem defined on a simplex can be represented by a finite number of inequalities, we use an expansive simplex instead of the nonnegative orthant involved in the complementarity constraints. We then remove some inequalities and obtain a standard nonlinear program. We show that the linear independence constraint qualification or the Mangasarian–Fromovitz constraint qualification holds for the relaxed problem under some mild conditions. We consider also a limiting behavior of the relaxed problem. We prove that any accumulation point of stationary points of the relaxed problems is a weakly stationary point of the original problem and that, if the function involved in the complementarity constraints does not vanish at this point, it is C-stationary. We obtain also some sufficient conditions of B-stationarity for a feasible point of the original problem. In particular, some conditions described by the eigenvalues of the Hessian matrices of the Lagrangian functions of the relaxed problems are new and can be verified easily. Our limited numerical experience indicates that the proposed approach is promising.  相似文献   
33.
Second order mixed type dual is introduced for multiobjective programming problems. Results about weak duality, strong duality, and strict converse duality are established under generalized second order (F,ρ)-convexity assumptions. These results generalize the duality results recently given by Aghezzaf and Hachimi involving generalized first order (F,ρ)-convexity conditions.  相似文献   
34.
For abstract linear functional differential equations with an almost automorphic forcing term, we establish a result on the existence of almost automorphic solutions, which extends the classical theorem due to Massera on the existence of periodic solutions for linear periodic ordinary differential equations.  相似文献   
35.
In this paper, a generalized anti–maximum principle for the second order differential operator with potentials is proved. As an application, we will give a monotone iterative scheme for periodic solutions of nonlinear second order equations. Such a scheme involves the Lp norms of the growth, 1 ≤ p ≤ ∞, while the usual one is just the case p = ∞.  相似文献   
36.
We investigate the six-dimensional Schrödinger equation for a three-body system with central pair interactions of a more general form than Coulomb interactions. Regular general and special physical solutions of this equation are represented by infinite asymptotic series in integer powers of the distance between two particles and in the sought functions of the other three-body coordinates. Constructing such functions in angular bases composed of spherical and bispherical harmonics or symmetrized Wigner D-functions is reduced to solving simple recursive algebraic equations. For projections of physical solutions on the angular bases functions, we derive boundary conditions at the pair impact point.  相似文献   
37.
For an integer n3 and any positive number , we establish the existence of smooth functions K on n {0} with |K–1|, such that the equation has a smooth positive solution which blows up at the origin (i.e., u does not have slow decay near the origin). Furthermore, we show that in some situations K can be extended as a Lipschitz function on n . These provide counter-examples to a conjecture of C.-S. Lin when n>4, and a question of Taliaferro. Mathematics Subject Classification (2000)Primary 35J60; Secondary 53C21  相似文献   
38.
本文利用比较定理,控制收敛定理和积分平均的方法,讨论一类具有无限时滞的非自治,非卷积的捕食者-食饵系统的一致持久性和正周期解。  相似文献   
39.
In this paper we give the existence and uniqueness of solutions for boundary value problems of the form u" = f(t, u,u', T1u,T2u), g(u(0),u(1)) = 0, h(w(0), u(1),u'(0), u'(1)) = 0 by means of the upper and lower solution method.  相似文献   
40.
In this paper we obtain some sufficient conditions for the existence of non-constant periodic solutions of the following planar system with six delaysOur approach is based on the continuation theorem of the coincidence degree.  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