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   5948篇
  免费   260篇
  国内免费   266篇
化学   70篇
力学   460篇
综合类   41篇
数学   5556篇
物理学   347篇
  2024年   7篇
  2023年   52篇
  2022年   44篇
  2021年   57篇
  2020年   105篇
  2019年   117篇
  2018年   115篇
  2017年   128篇
  2016年   130篇
  2015年   113篇
  2014年   186篇
  2013年   531篇
  2012年   218篇
  2011年   264篇
  2010年   223篇
  2009年   356篇
  2008年   386篇
  2007年   390篇
  2006年   295篇
  2005年   269篇
  2004年   202篇
  2003年   219篇
  2002年   191篇
  2001年   176篇
  2000年   174篇
  1999年   147篇
  1998年   189篇
  1997年   147篇
  1996年   114篇
  1995年   81篇
  1994年   89篇
  1993年   75篇
  1992年   69篇
  1991年   44篇
  1990年   45篇
  1989年   36篇
  1988年   42篇
  1987年   42篇
  1986年   47篇
  1985年   43篇
  1984年   41篇
  1983年   24篇
  1982年   34篇
  1981年   30篇
  1980年   44篇
  1979年   39篇
  1978年   28篇
  1977年   26篇
  1976年   33篇
  1974年   7篇
排序方式: 共有6474条查询结果,搜索用时 15 毫秒
61.
On the basis of the general framework of H-maximal monotonicity (also referred to as H-monotonicity in the literature), a generalization to Rockafellar’s theorem in the context of solving a general inclusion problem involving a set-valued maximal monotone operator using the proximal point algorithm in a Hilbert space setting is explored. As a matter of fact, this class of inclusion problems reduces to a class of variational inequalities as well as to a class of complementarity problems. This proximal point algorithm turns out to be of interest in the sense that it plays a significant role in certain computational methods of multipliers in nonlinear programming. The notion of H-maximal monotonicity generalizes the general theory of set-valued maximal monotone mappings to a new level. Furthermore, some results on general firm nonexpansiveness and resolvent mapping corresponding to H-monotonicity are also given.  相似文献   
62.
We study boundary value problems for fractional integro-differential equations involving Caputo derivative of order α ∈ (n-1,n) in Banach spaces. Existence and uniqueness results of solutions are established by virtue of the Holder's inequality, a suitable singular Gronwall's inequality and fixed point theorem via a priori estimate method. At last, examples are given to illustrate the results.  相似文献   
63.
64.
In this paper we investigate maximum principles for functionals defined on solutions to special partial diff'erential equations of elliptic type, extending results by Payne and Philippin. We apply such maximum principles to investigate one overdetermined problem.  相似文献   
65.
Novel classes of dynamical systems are introduced, including many-body problems characterized by nonlinear equations of motion of Newtonian type (“acceleration equals forces”) which determine the motion of points in the complex plane. These models are solvable, namely their con?guration at any time can be obtained from the initial data by algebraic operations, amounting to the determination of the zeros of a known time-dependent polynomial in the independent variable z. Some of these models are multiply periodic, isochronous or asymptotically isochronous; others display scattering phenomena.  相似文献   
66.
Abstract

This article treats of adaptive finite difference methods for the Dirichlet boundary value problems of Poisson-type equations on a sector or a disk. It is assumed that the exact solutions have singular derivatives on a part or the whole of the boundary. Some stretching functions are used to generate nonuniform grid points. It is then shown that, under some assumptions, the adaptive finite difference solutions are convergent and the convergence can be accelerated by varying parameters in the stretching functions. Numerical examples are given to illustrate how the accuracy of numerical solutions depends on the parameters.  相似文献   
67.
Meibao Ge  Yue Yu 《Applicable analysis》2017,96(10):1681-1697
The inverse problems of textile materials design on heat and moisture transfer properties are important and indispensable in applications in the body-clothing-environment system. We present an inverse problem of textile porosity determination (IPTPD) based on a nonlinear heat and moisture transfer model. Adopting the idea of the least-squares, the mathematical formulation of IPTPD is deduced to a regularized optimization problem with collocation method applied. The continuity of the regularized minimization problem is proved. By means of genetic algorithm (GA), the approximate solution of the IPTPD is numerically obtained. To reduce the computational cost, an improved algorithm based on BP neural network with GA is proposed in the numerical simulation. Compared with the direct GA searching, the computational cost is greatly reduced, which presents a similar result.  相似文献   
68.
In this paper some new eighth algebraic order symmetric eight-step methods are introduced. For these methods a direct formula for the computation of the phase-lag is given. Based on this formula, the calculation of free parameters is done in order the phase-lag to be minimal. The new methods have better stability properties than the classical one. Numerical illustrations on the radial Schrödinger equation indicate that the new method is more efficient than older ones.  相似文献   
69.
This paper is devoted to outlining precisely the basic mathematics of a classical isoperimetric problem of the calculus of variations and showing how significant fluid mechanical problems in fluidization and spouting can be addressed using this approach.  相似文献   
70.
建立了用于各向异性摩擦接触分析的一个新型互补模型:二阶锥线性互补模型.通过与弹翅性力学的类比,并引入线性二阶锥互补的概念,将正交各向异性摩擦接触定律表达为一个二阶锥线性互补模型.在此基础上,在参变量变分原理的框架下,建立了正交各向异性摩擦接触问题的有限元列式.由于避免了对摩擦锥的显式线性化,使得该文模型的变量个数较线性互补模型小很多,而解的精度又高很多.文末通过算例,说明了方法对于正交各向异性摩擦接触分析的有效性.  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