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   9804篇
  免费   855篇
  国内免费   1219篇
化学   207篇
晶体学   1篇
力学   338篇
综合类   208篇
数学   9187篇
物理学   1937篇
  2024年   18篇
  2023年   116篇
  2022年   126篇
  2021年   148篇
  2020年   222篇
  2019年   268篇
  2018年   254篇
  2017年   291篇
  2016年   307篇
  2015年   230篇
  2014年   500篇
  2013年   739篇
  2012年   422篇
  2011年   577篇
  2010年   563篇
  2009年   754篇
  2008年   715篇
  2007年   760篇
  2006年   636篇
  2005年   559篇
  2004年   476篇
  2003年   491篇
  2002年   457篇
  2001年   303篇
  2000年   335篇
  1999年   341篇
  1998年   280篇
  1997年   265篇
  1996年   167篇
  1995年   81篇
  1994年   82篇
  1993年   47篇
  1992年   40篇
  1991年   34篇
  1990年   23篇
  1989年   24篇
  1988年   27篇
  1987年   13篇
  1986年   8篇
  1985年   19篇
  1984年   28篇
  1983年   15篇
  1982年   23篇
  1981年   16篇
  1980年   21篇
  1979年   17篇
  1978年   14篇
  1977年   8篇
  1976年   5篇
  1936年   4篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
81.
李松鹰 《数学进展》2000,29(3):193-213
本文是一份综合报告,它基于作者的一部份研究工作和他在北京师范大学的五次讲演稿,以奇异分算子作为桥梁联结函数空间的结果和偏微分方程的结果作了阐述,它包括奇次空间上的调和分析,并应用到多复变函数论上,综述了右的结果并提出未解决的问题。  相似文献   
82.
The purpose of this note is to present some fixed point and data dependence theorems in complete gauge spaces and in hyperconvex metric spaces for the so-called Meir-Keeler multivalued operators and admissible multivalued aα-contractions. Our results extend and generalize several theorems of Espínola and Kirk [R. Espínola, W.A. Kirk, Set-valued contractions and fixed points, Nonlinear Anal. 54 (2003) 485-494] and Rus, Petru?el, and Sînt?m?rian [I.A. Rus, A. Petru?el, A. Sînt?m?rian, Data dependence of the fixed point set of some multivalued weakly Picard operators, Nonlinear Anal. 52 (2003) 1947-1959].  相似文献   
83.
We directly use the quantum-invariant operator method to obtain the closed-form solution to the one-dimensional Dirac equation with a time-changing mass with a little manipulation. The solution got is also applicable forthe case with time-independence mass.  相似文献   
84.
In this study, we identify a generalization of q-Bernstein type operators and investigate approximation properties of a sequence of these operators . We estimate rate of approximation by modulus of continuity. We prove Voronovskaya type theorem for these operators.  相似文献   
85.
We deal with some extensions of the space-fractional diffusion equation, which is satisfied by the density of a stable process (see Mainardi et al. (2001)): the first equation considered here is obtained by adding an exponential differential (or shift) operator expressed in terms of the Riesz–Feller derivative. We prove that this produces a random component in the time-argument of the corresponding stable process, which is represented by the so-called Poisson process with drift. Analogously, if we add, to the space-fractional diffusion equation, a logarithmic differential operator involving the Riesz-derivative, we obtain, as a solution, the transition semigroup of a stable process subordinated by an independent gamma subordinator with drift. Finally, we show that an extension of the space-fractional diffusion equation, containing both the fractional shift operator and the Feller integral, is satisfied by the transition density of the process obtained by time-changing the stable process with an independent linear birth process with drift.  相似文献   
86.
The pullback asymptotic behavior of the solutions for 2D Nonautonomous G-Navier-Stokes equations is studied, and the existence of its $L^2$-pullback attractors on some bounded domains with Dirichlet boundary conditions is investigated by using the measure of noncompactness. Then the estimation of the fractal dimensions for the 2D G-Navier-Stokes equations is given.  相似文献   
87.
We present a new derivation of the formula appearing in Babenko (1978) and Mayer and Roepstorff (1987) that gives the probability distribution of τ−nτn in terms of the eigenvalues of a symmetric operator. Here ττ is the well-known Gauss-map.  相似文献   
88.
We obtain global bounds in Lorentz–Morrey spaces for gradients of solutions to a class of quasilinear elliptic equations with low integrability data. The results are then applied to obtain sharp existence results in the framework of Morrey spaces for Riccati type equations with a gradient source term having growths below the natural exponent of the operator involved. A special feature of our results is that they hold under a very general assumption on the nonlinear structure, and under a mild natural restriction on the boundary of the ground domain.  相似文献   
89.
The linear operator plays an important role in the computational process of Homotopy Analysis Method (HAM). In HAM frame any kind of linear operator can be chosen to develop a solution. Hence, it is easy to introduce the modified/physical parameter dependent linear operators. The effective use of these operators has been judged through solving fluid flow problems. Modification in linear operators affects the solution and improves the computational efficiency of HAM for larger values of parameters. The convergence rate of the solution is rapid and several times higher resulting in less computational time.  相似文献   
90.
We consider time-dependent Schrödinger equations with a double well potential and an external nonlinear, both local and non-local, perturbation. In the semiclassical limit, the finite dimensional eigenspace associated to the lowest eigenvalues of the linear operator is almost invariant for times of the order of the beating period and the dominant term of the wavefunction is given by means of the solutions of a finite dimensional dynamical system. In the case of local nonlinear perturbation, we assume the spatial dimension d=1 or d=2.  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