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   5811篇
  免费   794篇
  国内免费   549篇
化学   257篇
力学   701篇
综合类   152篇
数学   4838篇
物理学   1206篇
  2024年   12篇
  2023年   49篇
  2022年   79篇
  2021年   90篇
  2020年   143篇
  2019年   141篇
  2018年   169篇
  2017年   202篇
  2016年   241篇
  2015年   131篇
  2014年   240篇
  2013年   492篇
  2012年   276篇
  2011年   337篇
  2010年   303篇
  2009年   347篇
  2008年   401篇
  2007年   371篇
  2006年   371篇
  2005年   335篇
  2004年   306篇
  2003年   251篇
  2002年   260篇
  2001年   198篇
  2000年   220篇
  1999年   163篇
  1998年   141篇
  1997年   142篇
  1996年   102篇
  1995年   116篇
  1994年   72篇
  1993年   77篇
  1992年   59篇
  1991年   37篇
  1990年   48篇
  1989年   27篇
  1988年   21篇
  1987年   20篇
  1986年   22篇
  1985年   16篇
  1984年   19篇
  1983年   8篇
  1982年   16篇
  1981年   6篇
  1980年   9篇
  1979年   9篇
  1978年   13篇
  1977年   13篇
  1974年   7篇
  1973年   7篇
排序方式: 共有7154条查询结果,搜索用时 546 毫秒
991.
We describe matrices with extremal generalized centralizers over algebraically closed fields.  相似文献   
992.
In this paper, we define the generalized diffusion operator ■ for two suitable measures on the line, which includes the generators of the birth-death processes, the one-dimensional diffusion and the gap diffusion among others. Via the standard resolvent approach, the associated generalized diffusion processes are constructed.  相似文献   
993.
The paper extends some well-known results for analytic functions onto solutions of the Vekua equation z W = a W + b W ¯ regarding the existence and construction of the Bergman kernel and of the corresponding Bergman projection operator.  相似文献   
994.
995.
Considering the effect of stochasticity including white noise and colored noise, this paper aims to study a hybrid stochastic cholera epidemic model with waning vaccine-induced immunity and nonlinear telegraph perturbations. First, we derive a critical value ? 0 C related to the basic reproduction number ? 0 of the deterministic model. The key aim of this paper is to generalize the θ-stochastic criterion method proposed by the recent work (Han et al. in Chaos Solit Fract 140:110238, 2020) to eliminate nonlinear telegraph perturbations. Next, via constructing several θ-stochastic Lyapunov functions and using the generalized method, we further prove that the stochastic model have a unique ergodic stationary distribution under ? 0 C > 1. Results show that the prevention and control of cholera epidemic depend on low transmission rate and small telegraph perturbations. Finally, the corresponding numerical simulations are performed to illustrate our analytical results and a practical application on the Somalia cholera outbreak is shown at the end of this paper.  相似文献   
996.
997.
The ball number function is extended here to platonic bodies and corresponding generalized uniform distributions on platonic spheres are considered. A platonic disintegration formula of the Lebesgue measure is proved as well as a thin layers property.  相似文献   
998.
In this paper, we prove that any nonlinear Jordan higher derivation on triangular algebras is an additive higher derivation. As a byproduct, we obtain that any nonlinear Jordan derivation on nest algeb...  相似文献   
999.
Two special classes of conserved densities involving arbitrary smooth functions are explicitly formulated for the generalized Riemann equation at arbitrary N. The particular case when N = 2 covers most of the known conserved densities of the equation, and the result is also extended to the famous Gurevich-Zybin, Monge-Ampere and two-component Hunter-Saxton equations by considering certain reductions.  相似文献   
1000.
Abstract

This article contains the nonlocal elasticity theory to capture size effects in functionally graded (FG) nano-rod under magnetic field supported by a torsional foundation. Torque effect of an axial magnetic field on an FG nano-rod has been defined using Maxwell’s relation. The material properties were assumed to vary according to the power law in radial direction. The Navier equation and boundary conditions of the size-dependent FG nano-rod were derived by the Hamilton’s principle. These equations were solved by employing the generalized differential quadrature method (GDQM). Presented model has the ability to turn into the classical model if the material length scale parameter is taken to be zero. The effects of some parameters, such as inhomogeneity constant, magnetic field and small-scale parameter, were studied. As an important result of this study can be stated that an FG nano-rod model based on the nonlocal elasticity theory behaves softer and has smaller natural frequency.  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