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   1384篇
  免费   266篇
  国内免费   58篇
化学   42篇
力学   242篇
综合类   25篇
数学   689篇
物理学   710篇
  2024年   3篇
  2023年   12篇
  2022年   17篇
  2021年   16篇
  2020年   34篇
  2019年   25篇
  2018年   27篇
  2017年   42篇
  2016年   45篇
  2015年   46篇
  2014年   50篇
  2013年   102篇
  2012年   76篇
  2011年   64篇
  2010年   70篇
  2009年   77篇
  2008年   99篇
  2007年   90篇
  2006年   107篇
  2005年   110篇
  2004年   76篇
  2003年   70篇
  2002年   51篇
  2001年   52篇
  2000年   45篇
  1999年   35篇
  1998年   29篇
  1997年   16篇
  1996年   27篇
  1995年   21篇
  1994年   19篇
  1993年   20篇
  1992年   23篇
  1991年   15篇
  1990年   17篇
  1989年   12篇
  1988年   8篇
  1987年   8篇
  1986年   10篇
  1985年   6篇
  1984年   4篇
  1982年   9篇
  1981年   7篇
  1980年   4篇
  1979年   4篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
  1969年   1篇
  1957年   1篇
排序方式: 共有1708条查询结果,搜索用时 100 毫秒
121.
The aim of this paper is to deal with the existence of mild solutions and exact controllability for a class of fractional evolution inclusions with damping (FEID, for short) in Banach spaces. Firstly, we provide the representation of mild solutions for FEID by applying the method of Laplace transform and the theory of (α,κ)‐regularized families of operators. Next, we are concerned with the existence and exact controllability of FEID under some suitable sufficient conditions by using the method of measure of noncompactness and an appropraite fixed point theorem. Finally, an application to nonlinear partial differential equations with temporal fractional derivatives is presented to illustrate the effectiveness of our main results. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   
122.
For 1‐D first order quasilinear hyperbolic systems without zero eigenvalues, based on the theory of exact boundary controllability of nodal profile, using an extension method, the exact controllability of nodal profile can be realized in a shorter time by means of additional internal controls acting on suitably small space‐time domains. On the other hand, using a perturbation method, the exact controllability of nodal profile for 1‐D first order quasilinear hyperbolic systems with zero eigenvalues can be realized by additional internal controls to the part of equations corresponding to zero eigenvalues. Furthermore, by adding suitable internal controls to all the equations on suitable domains, the exact controllability of nodal profile for systems with zero eigenvalues can be realized in a shorter time.  相似文献   
123.
By equivalently replacing the dynamical boundary condition by a kind of nonlocal boundary conditions, and noting a hidden regularity of solution on the boundary with a dynamical boundary condition, a constructive method with modular structure is used to get the local exact boundary controllability for 1‐D quasilinear wave equations with dynamical boundary conditions. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
124.
THEEXACTSOLUTIONFORTHICKLAMINATEDCANTILEVERCYLINDBICALSHELLFanJia-rang(范家让)(DepartmentofArchitecturalEngineering,HefeiUnivers...  相似文献   
125.
Summary Exact stationary solutions are constructed for nonlinear dynamic systems subjected to stochastic excitation. The results are then applied to both classical and nonclassical stochastic vibration systems.  相似文献   
126.
二次特征矩阵表示的特征值有界性分析   总被引:1,自引:0,他引:1  
叶建乔 《力学学报》1995,27(3):326-335
采用二次特征矩阵近似表示精确有限元和精确动态子结构分析中得出的超越或非线性动态刚度阵,并证明了在满足一定条件的前提下,二次特征阵给出的特征值是精确刚度阵特征值的上界或下界。  相似文献   
127.
The energy and force characteristics of periodic internal wave beams in a viscous exponentially stratified fluid are analyzed. The exact solutions of linearized problems of generation obtained by integral transformations describe not only three-dimensional internal waves but also the associated boundary layers of two types. The solutions not containing empirical parameters are brought to a form that allows a direct comparison with experimental data for generators of various types (friction, piston, and combined) of rectangular or elliptic shape. The stress tensor and force components acting on the generator are given in quadratures. In the limiting cases, the solutions are uniformly transformed to the corresponding expressions for the problems in a two-dimensional formulation. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 3, pp. 12–23, May–June, 2006  相似文献   
128.
Fürst  D.  Hahn  H.  Hecker  F. 《Nonlinear dynamics》1997,14(3):249-268
High quality multi-axis test facilities used for testing heavy loads and large structures of industrial equipment are usually simulated, designed and controlled based on reduced model equations neglecting the inertia properties of the actuators. The design and control of servo-pneumatic test facilities used for testing small and light structures must take into account extended test facility models including the various inertia properties of the actuators. In this paper (Part I) an extended test facility model is presented including the various inertia properties and joints of the actuators. These extended model equations are represented in a form well suited to be directly implemented in control algorithms based on exact linearization techniques for real time control. This is done by stepwise projecting the inertia properties of the various actuator housings and actuator pistons down to the common mass of the test table and payload. The resulting extended model equations have the same form as the reduced model equations. They only include more complex system matrices and vector functions. These compact model equations turn out to be suitable for an efficient nonlinear controller design of these test facilities. Computer simulations and associated laboratory experiments show the necessity to use extended model equations in case of testing small and light structures. In Part II of this paper [1] the inertia parameters of the planar test facility will be identified in laboratory experiments.  相似文献   
129.
The solitary wave solutions for the Klein-Gordon-Schrodinger Equations were obtained by using the homogeaeous balance principle. The form of the solutions is more generalized than the result that has been proved by pure theoretical and qualitative method in literature;namely, the form of solutions in literature is a particular case of result of the present paper.  相似文献   
130.
EXACT ANALYSIS OF WAVE PROPAGATION IN AN INFINITE RECTANGULAR BEAM   总被引:1,自引:0,他引:1  
The Fourier series method was extended for the exact analysis of wave propagation in an infinite rectangular beam. Initially, by solving the three-dimensional elastodynamic equations a general analytic solution was derived for wave motion within the beam. And then for the beam with stress-free boundaries, the propagation characteristics of elastic waves were presented. This accurate wave propagation model lays a solid foundation of simultaneous control of coupled waves in the beam.  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