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   14472篇
  免费   978篇
  国内免费   810篇
化学   207篇
晶体学   2篇
力学   1442篇
综合类   166篇
数学   13347篇
物理学   1096篇
  2024年   30篇
  2023年   142篇
  2022年   176篇
  2021年   202篇
  2020年   318篇
  2019年   325篇
  2018年   379篇
  2017年   385篇
  2016年   377篇
  2015年   276篇
  2014年   611篇
  2013年   1152篇
  2012年   651篇
  2011年   766篇
  2010年   679篇
  2009年   941篇
  2008年   988篇
  2007年   1020篇
  2006年   898篇
  2005年   698篇
  2004年   600篇
  2003年   668篇
  2002年   575篇
  2001年   433篇
  2000年   444篇
  1999年   393篇
  1998年   363篇
  1997年   324篇
  1996年   248篇
  1995年   204篇
  1994年   138篇
  1993年   119篇
  1992年   120篇
  1991年   104篇
  1990年   79篇
  1989年   38篇
  1988年   41篇
  1987年   38篇
  1986年   41篇
  1985年   54篇
  1984年   53篇
  1983年   28篇
  1982年   28篇
  1981年   25篇
  1980年   18篇
  1979年   21篇
  1978年   14篇
  1977年   15篇
  1976年   9篇
  1936年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.
The motion of a moored floating body under the action of wave forces, which is influenced by fluid forces, shape of the floating body and mooring forces, should be analysed as a complex coupled motion system. Especially under severe storm conditions or resonant motion of the floating body it is necessary to consider finite amplitude motions of the waves, the floating body and the mooring lines as well as non-linear interactions of these finite amplitude motions. The problem of a floating body has been studied on the basis of linear wave theory by many researchers. However, the finite amplitude motion under a correlated motion system has rarely been taken into account. This paper presents a numerical method for calculating the finite amplitude motion when a floating body is moored by non-linear mooring lines such as chains and cables under severe storm conditions.  相似文献   
232.
Inexact Newton methods for the nonlinear complementarity problem   总被引:2,自引:0,他引:2  
An exact Newton method for solving a nonlinear complementarity problem consists of solving a sequence of linear complementarity subproblems. For problems of large size, solving the subproblems exactly can be very expensive. In this paper we study inexact Newton methods for solving the nonlinear, complementarity problem. In such an inexact method, the subproblems are solved only up to a certain degree of accuracy. The necessary accuracies that are needed to preserve the nice features of the exact Newton method are established and analyzed. We also discuss some extensions as well as an application. This research was based on work supported by the National Science Foundation under grant ECS-8407240.  相似文献   
233.
In this paper we give some new results concerning solvability of the 1-dimensional differential equation y′ = f(x, y) with initial conditions. We study the basic theorem due to Picard. First we prove that the existence and uniqueness result remains true if f is a Lipschitz function with respect to the first argument. In the second part we give a contractive method for the proof of Picard theorem. These considerations allow us to develop two new methods for finding an approximation sequence for the solution. Finally, some applications are given.  相似文献   
234.
In this paper we deal with the following particular case of a weaker conjecture by B. Y. Chen: Are there 2-type Willmore surfaces in E 3? In particular we prove that the above question has a negative answer when the surface is the image under stereographic projection of a minimal surface in S 3.  相似文献   
235.
In this paper,based on the results presented in part Ⅰ of this paper[18],we present a numerical embedding algorithm for solving the nonlinear complementarityproblem, and prove its convergence carefully. Numerical experiments show that thealgorithm is successful.  相似文献   
236.
一类非线性发展方程整体弱解的存在性和稳定性   总被引:2,自引:0,他引:2       下载免费PDF全文
该文考虑一类新的非线性方程(|ut|r-2ut)t-Δutt-Δu-ρ(t)Δut=f(u) 的初边值问题,利用小扰动法证明了整体弱解的 存在性,借用位势井的概念得到了解的稳定性.〖HT5”H〗关键词:〖HT5”SS〗非线性发展方程;初边值问题;整体弱解;稳定性.  相似文献   
237.
The optimum shape of the cylindrical internal deformable (flexible) surface of a gas journal bearing of infinite length is designed. The variational problem of determining the clearance shape giving the maximum bearing load capacity is formulated and solved.  相似文献   
238.
The eigenvalue problem for arbitrary linear combinations kα + μα? of a boson annihilation operator α and a boson creation operator α? is solved. It is shown that these operators possess nondegenerate eigenstates to arbitrary complex eigenvalues. The expansion of these eigenstates into the basic set of number states | n >, (n = 0, 1, 2, …), is found. The eigenstates are normalizable and are therefore states of a Hilbert space for | ζ | < 1 with ζ ? μ/k and represent in this case squeezed coherent states of minimal uncertainty product. They can be considered as states of a rigged Hilbert space for | ζ | ? 1. A completeness relation for these states is derived that generalizes the completeness relation for the coherent states | α 〉. Furthermore, it is shown that there exists a dual orthogonality in the entire set of these states and a connected dual completeness of the eigenstates on widely arbitrary paths over the complex plane of eigenvalues. This duality goes over into a selfduality of the eigenstates of the hermitian operators kα + k* α? to real eigenvalues. The usually as nonexistent considered eigenstates of the boson creation operator α? are obtained by a limiting procedure. They belong to the most singular case among the considered general class of eigenstates with ζ ? μ/k as a parameter.  相似文献   
239.
一个反应扩散方程的门槛结果   总被引:4,自引:0,他引:4  
本文讨论反应扩散方程Cauchy问题解的整体存在性,渐近性质和Blowup问题.其中或者1<q<p<+∞,n=2.得到门槛结果.  相似文献   
240.
该文通过构造特殊形式的有效集来逼近KKT点处的有效集,给出了一个任意初始点下的序列线性方程组新算法,并证明了该算法在没有严格互补松驰条件的情况下具有全局收敛性和一步超线性收敛性。   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