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   3910篇
  免费   386篇
  国内免费   220篇
化学   229篇
晶体学   15篇
力学   399篇
综合类   85篇
数学   3358篇
物理学   430篇
  2025年   25篇
  2024年   96篇
  2023年   77篇
  2022年   47篇
  2021年   77篇
  2020年   119篇
  2019年   108篇
  2018年   131篇
  2017年   163篇
  2016年   155篇
  2015年   105篇
  2014年   141篇
  2013年   304篇
  2012年   169篇
  2011年   181篇
  2010年   142篇
  2009年   160篇
  2008年   180篇
  2007年   225篇
  2006年   212篇
  2005年   198篇
  2004年   153篇
  2003年   170篇
  2002年   168篇
  2001年   158篇
  2000年   128篇
  1999年   118篇
  1998年   94篇
  1997年   87篇
  1996年   64篇
  1995年   66篇
  1994年   49篇
  1993年   38篇
  1992年   37篇
  1991年   28篇
  1990年   19篇
  1989年   11篇
  1988年   12篇
  1987年   9篇
  1986年   9篇
  1985年   11篇
  1984年   13篇
  1983年   4篇
  1982年   7篇
  1981年   8篇
  1980年   16篇
  1979年   8篇
  1978年   3篇
  1977年   7篇
  1936年   1篇
排序方式: 共有4516条查询结果,搜索用时 0 毫秒
31.
The one-dimensional compressible Navier-Stokes-Vlasov-Fokker-Planck system with density-dependent viscosity and drag force coefficients isinvestigated in the present paper. The existence, uniqueness, and regularityof global weak solution to the initial value problem for general initial data areestablished in spatial periodic domain. Moreover, the long time behavior ofthe weak solution is analyzed. It is shown that as the time grows, the distribution function of the particles converges to the global Maxwellian, and boththe fluid velocity and the macroscopic velocity of the particles converge to thesame speed.  相似文献   
32.
    
In this paper, we consider initial boundary value problem for the equations of one-dimensional nonlinear thermoelasticity with second sound in R^+. First, we derive decay rates for linear systems which, in fact, is a hyperbolic systems with a damping term. Then, using this linear decay rates, we get L^1 and L^∞ decay rates for nonlinear systems. Finally, combining with L^2 estimates and a local existence theorem, we prove a global existence and uniqueness theorem for small smooth data.  相似文献   
33.
A generalized preimage theorem in global analysis   总被引:7,自引:0,他引:7  
The concept of locally fine point and generalized regular value of a C1 map between Banach spaces were carried over C1 map between Banach manifolds. Hence the preimage theorem, a principle constructing Banach manifolds in global analysis, is generalized.  相似文献   
34.
In this paper,a nonlinear nonautonomous predator-prey dispersion model with continuous distributed delay is studied,where all parameters are time-dependent.In this system consisting of n-patches the prey species can disperse among n-patches,but the predator species is confined to one patch and cannot disperse.It is proved that the system is uniformly persistent under any dispersion rate effect.Furthermore,some sufficient conditions are established for the existence of a unique almost periodic solution of the system.The example shows that the criteria in the paper are new,general and easily verifiable.  相似文献   
35.
In this paper we study a free boundary problem modelling tumor growth, proposed by A. Friedman in 2004. This free boundary problem involves a nonlinear second-order parabolic equation describing the diffusion of nutrient in the tumor, and three nonlinear first-order hyperbolic equations describing the evolution of proliferative cells, quiescent cells and dead cells, respectively. By applying Lp theory of parabolic equations, the characteristic theory of hyperbolic equations, and the Banach fixed point theorem, we prove that this problem has a unique global classical solution.  相似文献   
36.
A smoothing method for mathematical programs with equilibrium constraints   总被引:15,自引:0,他引:15  
Received May 3, 1996 / Revised version received November 19, 1997 Published online January 20, 1999  相似文献   
37.
A problem very often arising in applications is presented: finding the minimal root of an equation with the objective function being multiextremal and nondifferentiable. Applications from the field of electronic measurements are given. Three methods based on global optimization ideas are introduced for solving this problem. The first one uses an a priori estimate of the global Lipschitz constant. The second method adaptively estimates the global Lipschitz constant. The third algorithm adaptively estimates local Lipschitz constants during the search. All the methods either find the minimal root or determine the global minimizers (in the case when the equation under consideration has no roots). Sufficient convergence conditions of the new methods to the desired solution are established. Numerical results including wide experiments with test functions, stability study, and a real-life applied problem are also presented.  相似文献   
38.
A stochastic global optimization method is applied to the challenging problem of finding the minimum energy conformation of a cluster of identical atoms interacting through the Lennard-Jones potential. The method proposed incorporates within an already existing and quite successful method, monotonic basin hopping, a two-phase local search procedure which is capable of significantly enlarging the basin of attraction of the global optimum. The experiments reported confirm the considerable advantages of this approach, in particular for all those cases which are considered in the literature as the most challenging ones, namely 75, 98, 102 atoms. While being capable of discovering all putative global optima in the range considered, the method proposed improves by more than two orders of magnitude the speed and the percentage of success in finding the global optima of clusters of 75, 98, 102 atoms.  相似文献   
39.
In this paper, we propose a general smoothing Broyden-like quasi-Newton method for solving a class of nonsmooth equations. Under appropriate conditions, the proposed method converges to a solution of the equation globally and superlinearly. In particular, the proposed method provides the possibility of developing a quasi-Newton method that enjoys superlinear convergence even if strict complementarity fails to hold. We pay particular attention to semismooth equations arising from nonlinear complementarity problems, mixed complementarity problems and variational inequality problems. We show that under certain conditions, the related methods based on the perturbed Fischer–Burmeister function, Chen–Harker–Kanzow–Smale smoothing function and the Gabriel–Moré class of smoothing functions converge globally and superlinearly.  相似文献   
40.
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