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   281篇
  免费   1篇
  国内免费   1篇
化学   43篇
力学   5篇
数学   89篇
物理学   55篇
综合类   91篇
  2023年   1篇
  2021年   1篇
  2018年   1篇
  2017年   1篇
  2016年   2篇
  2015年   6篇
  2014年   10篇
  2013年   8篇
  2012年   8篇
  2011年   31篇
  2010年   26篇
  2009年   22篇
  2008年   31篇
  2007年   26篇
  2006年   28篇
  2005年   12篇
  2004年   16篇
  2003年   24篇
  2002年   14篇
  2001年   3篇
  2000年   1篇
  1997年   1篇
  1996年   1篇
  1995年   3篇
  1994年   1篇
  1991年   2篇
  1988年   1篇
  1981年   1篇
  1975年   1篇
排序方式: 共有283条查询结果,搜索用时 15 毫秒
101.
102.
党的十七大报告首次将邓小平理论、“三个代表”重要思想以及科学发展观等重大战略思想概括为“中国特色社会主义理论体系”,这一科学概括,从时间维度界定该体系是对改革开放历史新时期中国共产党理论创新成果的科学总结,从内容维度充分展现了该体系是马克思主义中国化最新成果,从特征维度彰显了该体系是不断发展开放的理论体系。这一科学理论体系为我们夺取全面建设小康社会新胜利提供了强大的思想保证,从这三个维度认真学习深刻领会它,对于坚持和发展中国特色社会主义事业具有深远的实践意义。  相似文献   
103.
The simplified PC-SAFT equation of state has been applied to liquid–liquid, vapor–liquid and solid–liquid equilibria for mixtures containing 1- or 2-alkanols with alkanes, aromatic hydrocarbons, CO2 and water. For the alkanols we use generalized pure compound parameters. This means that two of the physical pure compound parameters, m (segment number) and σ (segment diameter), are obtained from linear extrapolations, since m and 3, increase linearly with respect to the molar mass, and moreover, the two association parameters (association energy and association volume) were assumed to be constant for all alkanols. Only the dispersion energy is fitted to experimental data. Thus it is possible to estimate parameters for several 1- and 2-alkanols. The final aim is to develop a group contribution approach for PC-SAFT which is suitable for complex compounds, considering that the motivation of this project is to obtain a thermodynamic model which can be used in the development of sophisticated products such as pharmaceuticals, polymers, detergents or food ingredients. One of the severe limitations in applying SAFT-type equations of state to these compounds is that the procedure for obtaining the pure compound parameters is usually based on fitting to saturated vapor pressure and liquid density data over an extended temperature range. However, such data are rarely available for complex compounds. To verify the new pure compound parameters, comparisons to ordinary optimized alkanol parameters, where all five pure compound parameters were fitted to experimental liquid density and vapor pressure data, were made. The results show that the new generalized alkanol parameters from this work perform at least as well as other alkanol parameter sets.  相似文献   
104.
We discuss relations among notions of (C,1)-convergence, almost-convergence, absolute almost-convergence, and View the MathML source" title="View the MathML source" src="http://ars.els-cdn.com/content/image/1-s2.0-S0022247X07000157-si2.gif">-convergence of a continuous vector-valued function f(t) as t tends to infinity. Equivalent conditions and Tauberian criterions are obtained, and some examples are exhibited.  相似文献   
105.
We present the full-rank representations of {2, 4} and {2, 3}-inverses (with given rank as well as with prescribed range and null space) as particular cases of the full-rank representation of outer inverses. As a consequence, two applications of the successive matrix squaring (SMS) algorithm from [P.S. Stanimirovi?, D.S. Cvetkovi?-Ili?, Successive matrix squaring algorithm for computing outer inverses, Appl. Math. Comput. 203 (2008) 19-29] are defined using the full-rank representations of {2, 4} and {2, 3}-inverses. The first application is used to approximate {2, 4}-inverses. The second application, after appropriate modifications of the SMS iterative procedure, computes {2, 3}-inverses of a given matrix. Presented numerical examples clarify the purpose of the introduced methods.  相似文献   
106.
107.
In this brief letter, we modify the classic social force model of Helbing which is applied to simulate how a pedestrian gets outside a hall full of smoke. As the Vicsek model does, the view radius is introduced to describe the range the pedestrian can see. The relation between the evacuation time and the view radius is studied with different numbers of pedestrians. The results show that the shorter the view radius is, the more time walkers will spend escaping, and even fail to escape. And the relation between the number of remaining walkers and the view radius shows non-monotonicity, if the number of pedestrians is larger than 600. And lastly, we propose to enlarge the width of the exit or to add two small exits in the corners, which may decrease the evacuation time greatly and obviously reduce the number of remaining walkers.  相似文献   
108.
109.
The temporal power-law decay is one class of interesting decay processes, usually indicating a long-time correlation and benefiting for a system to perform functions in various time-scales. In this work, I collect the data of the view times versus lectures of some scientific courses on YouTube, according to some special principles. These data can reflect the dynamical property of the spontaneous learning behavior, influenced by the decay of learning interest. The view times versus lectures show an obviously power-law decay process. The power approximates to 1, a universal constant. This finding brings the learning process into the interesting power-law family. It will be of interest in the fields of the human dynamics, psychology and education.  相似文献   
110.
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