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   10204篇
  免费   960篇
  国内免费   904篇
化学   1857篇
晶体学   45篇
力学   1325篇
综合类   171篇
数学   6940篇
物理学   1730篇
  2024年   11篇
  2023年   92篇
  2022年   166篇
  2021年   202篇
  2020年   199篇
  2019年   223篇
  2018年   227篇
  2017年   328篇
  2016年   347篇
  2015年   280篇
  2014年   474篇
  2013年   814篇
  2012年   481篇
  2011年   600篇
  2010年   515篇
  2009年   623篇
  2008年   693篇
  2007年   713篇
  2006年   609篇
  2005年   531篇
  2004年   513篇
  2003年   455篇
  2002年   432篇
  2001年   347篇
  2000年   328篇
  1999年   261篇
  1998年   261篇
  1997年   226篇
  1996年   190篇
  1995年   147篇
  1994年   114篇
  1993年   83篇
  1992年   66篇
  1991年   75篇
  1990年   53篇
  1989年   45篇
  1988年   33篇
  1987年   32篇
  1986年   19篇
  1985年   36篇
  1984年   32篇
  1983年   33篇
  1982年   34篇
  1981年   31篇
  1980年   28篇
  1979年   22篇
  1978年   16篇
  1977年   6篇
  1959年   3篇
  1957年   3篇
排序方式: 共有10000条查询结果,搜索用时 703 毫秒
91.
An initial boundary value problem for the dynamic system of anisotropic elasticity in a half space is studied in the paper. A novel method of finding an exact solution of this problem for a special polynomial form of initial data and inhomogeneous term of the system is described. On the base of this method the simulation of elastic waves in different homogeneous anisotropic half spaces is implemented.  相似文献   
92.
Closed series solution of electromagnetic scattering by an eccentric coated cylinder is achieved in matrix form. Diffracted field patterns are examined for an incident plane transverse magnetic (TM) wave. The solution is found by the classical separation of variables technique and the translational addition theorems. Wave transformation and orthogonality of the complex exponentials are employed to produce an infinite series. Numerical results are then shown by shortening the infinite series to a limited number of terms. Solutions are discussed for a dielectric or a metamaterial coating.  相似文献   
93.
给出了 n元函数极值的一个充分条件 ,并结合矩阵的初等变换建立了 n元函数极值的一种快速判别法 ,最后给出了一个例子  相似文献   
94.
For any Sturm-Liouville problem with a separable boundary condition and whose leading coefficient function changes sign (exactly once), we first give a geometric characterization of its eigenvalues λn using the eigenvalues of some corresponding problems with a definite leading coefficient function. Consequences of this characterization include simple proofs of the existence of the λn's, their Prüfer angle characterization, and a way for determining their indices from the zeros of their eigenfunctions. Then, interlacing relations among the λn's and the eigenvalues of the corresponding problems are obtained. Using these relations, a simple proof of asymptotic formulas for the λn's is given.  相似文献   
95.
In this paper, we give some new explicit relations between two families of polynomials defined by recurrence relations of all order. These relations allow us to analyze, even in the Sobolev case, how some properties of a family of orthogonal polynomials are affected when the coefficients of the recurrence relation and the order are perturbed. In a paper we have already given a method which allows us to study the polynomials defined by a three-term recurrence relation. Also here some generalizations are given.  相似文献   
96.
一种求解混合多目标规划问题的功效函数法   总被引:1,自引:0,他引:1  
逻辑生长函数相对于龚珀兹生长函数具有拐点高和对称性的特点,采用逻辑生长函数形式的功效函数法求解混合多目标规划问题具有形式简单、计算量小、符合实际的优点。证明了用这种方法求出的最优解是有效解。讨论了满意值对有效解的影响。逻辑生长函数还可以应用于多维变量评价的功效系数法中。  相似文献   
97.
We consider a system of focal boundary value problems where the nonlinearities may be singular in the independent variable and may also be singular in the dependent arguments. Using Schauder fixed point theorem, we establish criteria such that the system of boundary value problems has at least one fixed-sign solution.  相似文献   
98.
In this paper we deal with nonlinear second-order boundary value problems with impulses. The impulsive functions depend implicitly on the different considered variables and the boundary value conditions are nonlinear. In both cases functional dependence on the solution is allowed. The existence results follow from the existence of a pair of well-ordered lower and upper solutions.  相似文献   
99.
A uniqueness theorem for two distinct non-constant meromorphic functions that share three values of finite weights is proved, which generalizes two previous results by H.X. Yi, and X.M. Li and H.X. Yi. As applications of it, many known results by H.X. Yi and P. Li, etc. could be improved. Furthermore, with the concept of finite-weight sharing, extensions on Osgood-Yang's conjecture and Mues' conjecture, and a generalization of some prevenient results by M. Ozawa and H. Ueda, ect. could be obtained.  相似文献   
100.
We extend results on square integrable representations of a locally compact group to subrepresentations of a representations induced from a character of a closed subgroup. We do so working in the framework of quotient representations of ∗-algebras.  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