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   7896篇
  免费   501篇
  国内免费   433篇
化学   87篇
力学   555篇
综合类   87篇
数学   7721篇
物理学   380篇
  2024年   13篇
  2023年   88篇
  2022年   65篇
  2021年   87篇
  2020年   178篇
  2019年   176篇
  2018年   194篇
  2017年   207篇
  2016年   199篇
  2015年   159篇
  2014年   278篇
  2013年   730篇
  2012年   308篇
  2011年   369篇
  2010年   307篇
  2009年   468篇
  2008年   501篇
  2007年   524篇
  2006年   393篇
  2005年   383篇
  2004年   278篇
  2003年   307篇
  2002年   281篇
  2001年   232篇
  2000年   232篇
  1999年   189篇
  1998年   238篇
  1997年   193篇
  1996年   150篇
  1995年   107篇
  1994年   104篇
  1993年   84篇
  1992年   83篇
  1991年   54篇
  1990年   48篇
  1989年   37篇
  1988年   47篇
  1987年   48篇
  1986年   53篇
  1985年   53篇
  1984年   56篇
  1983年   31篇
  1982年   38篇
  1981年   35篇
  1980年   54篇
  1979年   41篇
  1978年   36篇
  1977年   33篇
  1976年   41篇
  1974年   7篇
排序方式: 共有8830条查询结果,搜索用时 15 毫秒
71.
72.
The paper aims to obtain existence and uniqueness of the solution as well as asymptotic estimate of the solution for singularly perturbed nonlinear third- order Robin boundary value problem with a turning point.In order to achieve this aim,existence and uniqueness of the solution for third-order nonlinear Robin boundary value problem is derived first based on the upper and lower solutions method under relatively weaker conditions.In this manner,the goal of this paper is gained by applying the existence and uniqueness results mentioned above.  相似文献   
73.
Asymptotic methods for contact problems are expounded. Some typical integral equations are considered  相似文献   
74.
Consider a system of nonlinear wave equationsfor i = 1, … , m, where F, (i = 1, … , m) are smooth functions of degree 2 near the origin of their arguments, and u = (u1, … ,um), while u and x u represent the first and second derivatives of u, respectively. In this paper, the author presents a new class of nonlineaxity for which the global existence of small solutions is ensured. For example, global existence of small solutions for arbitrary cubic terms,arbitrary cubic termswill be established, provided that c12 ≠ c22.  相似文献   
75.
Calleja et al. [Calleja, P., Borm, P., Hendrickx, R., 2005. Multi-issue allocation situations. European Journal of Operational Research 164, 730–747] introduced multi-issue allocation situations with awards. In this paper, we extend the classical model of cooperative games with transferable utility to the cooperative games with transferable utility and awards. We define a run-to-the-bank rule for cooperative games with transferable utility and awards and characterise it in terms of a property of balanced contributions. We apply our main result to bankruptcy problems and multi-issue allocation situations with awards.  相似文献   
76.
关于《一类奇异边值问题的正解》的注记   总被引:3,自引:0,他引:3  
柴国庆 《数学学报》2003,46(6):1087-109
文[4]通过构造反例断言文[1]中定理的必要性证明有误,本文首先指出文[4] 的这个断言不正确,然后对文[4]中定理2.1作了本质性的改进.  相似文献   
77.
An exponentially fitted special second-order finite difference method is presented for solving singularly perturbed two-point boundary value problems with the boundary layer at one end (left or right) point. A fitting factor is introduced in a tri-diagonal finite difference scheme and is obtained from the theory of singular perturbations. Thomas Algorithm is used to solve the system and its stability is investigated. To demonstrate the applicability of the method, we have solved several linear and non-linear problems. From the results, it is observed that the present method approximates the exact solution very well.  相似文献   
78.
This paper discusses a class of second-order derivative nonlinear Schrödinger equations which are used to describe the upper-hybrid oscillation propagation. By establishing a variational problem, applying the potential well argument and the concavity method, we prove that there exists a sharp condition for global existence and blow-up of the solutions to the nonlinear Schrödinger equation. In addition, we also answer the question: how small are the initial data, the global solutions exist?  相似文献   
79.
The nonlocal boundary value problems for anisotropic partial differential-operator equations with a dependent coefficients are studied. The principal parts of the appropriate generated differential operators are nonself-adjoint. Several conditions for the maximal regularity and the fredholmness in Banach-valued Lp-spaces of these problems are given. These results permit us to establish that the inverse of corresponding differential operators belongs to Schatten q-class. Some spectral properties of the operators are investigated. In applications, the nonlocal BVP's for quasielliptic partial differential equations and for systems of quasielliptic equations on cylindrical domain are studied.  相似文献   
80.
A multi-dimensional transient drift-diffusion model for (at most) three charged particles, consisting of the continuity equations for the concentrations of the species and the Poisson equation for the electric potential, is considered. The diffusion terms depend on the concentrations. Such a system arises in electrophoretic modeling of three species (neutrally, positively and negatively charged) and in semiconductor theory for two species (positively charged holes and negatively charged electrons). Diffusion terms of degenerate type are also possible in semiconductor modeling. For the initial boundary value problem with mixed Dirichlet - Neumann boundary conditions and general reaction rates, a global existence result is proved. Uniqueness of solutions follows in the Dirichlet boundary case if the diffusion terms are uniformly parabolic or if the initial and boundary densities are strictly positive. Finally, we prove that solutions exist which are positive uniformly in time and globally bounded if the reaction rates satisfy appropriate growth conditions.  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