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   6059篇
  免费   208篇
  国内免费   34篇
化学   3758篇
晶体学   25篇
力学   193篇
数学   1209篇
物理学   1116篇
  2024年   15篇
  2023年   75篇
  2022年   161篇
  2021年   216篇
  2020年   193篇
  2019年   153篇
  2018年   129篇
  2017年   116篇
  2016年   244篇
  2015年   231篇
  2014年   240篇
  2013年   338篇
  2012年   414篇
  2011年   467篇
  2010年   275篇
  2009年   251篇
  2008年   381篇
  2007年   339篇
  2006年   312篇
  2005年   298篇
  2004年   238篇
  2003年   176篇
  2002年   190篇
  2001年   72篇
  2000年   46篇
  1999年   64篇
  1998年   53篇
  1997年   68篇
  1996年   49篇
  1995年   49篇
  1994年   45篇
  1993年   34篇
  1992年   25篇
  1991年   28篇
  1990年   21篇
  1989年   20篇
  1988年   22篇
  1987年   25篇
  1986年   19篇
  1985年   26篇
  1984年   22篇
  1983年   13篇
  1982年   22篇
  1981年   13篇
  1980年   14篇
  1979年   15篇
  1978年   17篇
  1977年   9篇
  1973年   7篇
  1972年   6篇
排序方式: 共有6301条查询结果,搜索用时 15 毫秒
171.
172.
173.
An overview is given of the present status of parity violation tests in neutron decay and nuclear beta decay. Prospects for improved and new measurements are discussed as well.  相似文献   
174.
175.
In this work electronic and optoelectronic properties of InGaN/GaN nanocolumn quantum disk LEDs have been studied with the multiscale simulation tool tiberCAD. Calculations have been performed with an atomistic tight-binding model. Results shows that emission energies have a minor dependence on the nanocolumn dimension while In concentration in the active region is a critical parameter.  相似文献   
176.
This study presents a new formula for the surface tension prediction of alkenes. As a first step, an analysis of the available data of the experimental surface tension data for alkenes was performed. The experimental data were collected, after a careful literature survey, for the following pure fluids: propene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-tetradecene, and 1-pentadecene. Then, the experimental data were regressed with the most reliable semi-empirical correlating methods based on the corresponding state theory existing in the literature. As a final step, an analysis of the available data of the experimental surface tension data for alkenes was performed starting from the two recently proposed equations for the prediction of the surface tension of refrigerants based on the corresponding states principle. To minimize the deviation between the predicted data and the experimental data and to find the optimal equation coefficients for experimental data regression, a (μ + λ)-evolution strategy was adopted. The analysis showed that the equation that gave the best results for the prediction of the surface tension of alkenes was the one with a very limited number of parameters. The finally proposed equation is very simple and gives a noticeable improvement with respect to the existing equations. It is based on the corresponding state principle, containing the acentric factor, the critical temperature, and pressure.  相似文献   
177.
178.
In this article we establish an interaction between non-smooth systems, geometric singular perturbation theory and synchronization phenomena. We find conditions for a non-smooth vector fields be locally synchronized. Moreover its regularization provide a singular perturbation problem with attracting critical manifold. We also state a result about the synchronization which occurs in the regularization of the fold-fold case. We restrict ourselves to the 3-dimensional systems ( = 3) and consider the case known as a T-singularity.  相似文献   
179.
Nonlinear Dynamics - A new model-free robust control scheme for payload swing angle attenuation of two-dimensional crane systems with varying rope length is introduced in this work. The proposed...  相似文献   
180.
Journal of Dynamics and Differential Equations - In this paper we focus on a class of symmetric vector fields in the context of singularly perturbed fast-slow dynamical systems. Our main question...  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