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   16228篇
  免费   435篇
  国内免费   133篇
化学   11170篇
晶体学   134篇
力学   510篇
数学   2509篇
物理学   2473篇
  2021年   149篇
  2020年   218篇
  2019年   199篇
  2018年   184篇
  2017年   147篇
  2016年   313篇
  2015年   269篇
  2014年   311篇
  2013年   780篇
  2012年   760篇
  2011年   1037篇
  2010年   485篇
  2009年   437篇
  2008年   844篇
  2007年   879篇
  2006年   929篇
  2005年   854篇
  2004年   779篇
  2003年   710篇
  2002年   682篇
  2001年   227篇
  2000年   197篇
  1999年   159篇
  1998年   190篇
  1997年   199篇
  1996年   224篇
  1995年   167篇
  1994年   178篇
  1993年   142篇
  1992年   144篇
  1991年   152篇
  1990年   128篇
  1989年   112篇
  1988年   146篇
  1987年   141篇
  1986年   107篇
  1985年   211篇
  1984年   231篇
  1983年   167篇
  1982年   235篇
  1981年   219篇
  1980年   222篇
  1979年   206篇
  1978年   198篇
  1977年   181篇
  1976年   182篇
  1975年   152篇
  1974年   162篇
  1973年   154篇
  1972年   75篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
Those who have worked in the Royal Institution of Great Britain have, since its foundation in 1799, made significant contributions to scientific knowledge, to its practical application, and to its communication to a wide variety of audiences. Such work cannot be carried out in an architectural vacuum, and in this paper we examine how the buildings of the Royal Institution, 20 and 21 Albemarle Street in central London, have shaped the work undertaken within its walls and how, on a number of occasions, the buildings have been reconfigured to take account of the evolving needs of scientific research and communication. This paper is based on the Conservation Plan of the Royal Institution that we wrote during 2003. The Conservation Plan did not examine the land owned by the Royal Institution to the north (i.e., 22 and 23 Albemarle Street; for this area see Richard Garnier, “Grafton Street, Mayfair,” Georgian Group Journal 13 (2003), 210–272), but it did discuss 18 and 19 Albemarle Street. In this paper we concentrate on the core Royal Institution buildings at 20 and 21 Albemarle Street. Other studies of the relationship of architecture,space, and science include Crosbie Smith and Jon Agar, ed., Making Space for Science: Territorial Themes in the Shaping of Knowledge (Basingstoke: Macmillan, 1997); Peter Galison and Emily Thompson, ed., The Architecture of Science (Cambridge, Mass.: MIT Press, 1999); and Sophie Forgan,“The architecture of science and the idea of a university,” Studies in History and Philosophy of Science 20 (1989), 405–434. Frank A.J.L. James is Professor of the History of Science at the Royal Institution; he has written widely on the history of nineteenth-century science in its social and cultural contexts and is editor of the Correspondence of Michael Faraday. He is President of the British Society for the History of Science. Anthony Peers is an Associate of Rodney Melville and Partners where he works in the field of building conservation as an architectural historian. He is a Council member of the Ancient Monument Society.  相似文献   
62.
A one-pot reaction of carboxylic acids with sulfonamides to afford sulfonylureas is described.  相似文献   
63.
A new algorithm is presented for computing the topological entropy of a unimodal map of the interval. The accuracy of the algorithm is discussed and some graphs of the topological entropy which are obtained using the algorithm are displayed.  相似文献   
64.
65.
66.
The synthesis of chiral oxazolidinedione derived bicalutamide analogs has been discussed.  相似文献   
67.
The palladium-catalysed cross-coupling reaction of various arylboronic acids with α-bromoenones and α-chloroenones offers an operationally simple approach to the synthesis of both cyclic and acyclic α-arylenones.  相似文献   
68.
In this paper we study a widely used zero equation model of turbulence. The governing equations are derived by applying to the incompressible Navier-Stokes equations the Reynolds time averaging procedure. We achieve closure by employing the eddy viscosity concept. Using the Implicit Function Theorem we obtain an existence and uniquencess result. We also discuss the existence of nonsingular solutions. Finally, we present an algorithm for solving the modeled equations.  相似文献   
69.
70.
Five different analytical schemes for examining isothermal and nonisothermal degradation of polymers were reviewed and found inadequate for describing multistage decomposition. The different schemes were experimentally tested using thermogravimetric analysis data for an ethylene-vinyl acetate (EVA) copolymer, which exhibited a well-behaved two-step decomposition process in a nitrogen environment. Based on these experimental and analytical findings, a generalized methodology was developed capable of describing the exhibited complex decomposition behavior of polymers by combining two or more kinetic mechanisms in a series or parallel arrangement. This composite of combinational methodology thus extends established analytical schemes for describing complex decomposition of polymers in a rational manner, incorporating both experimental and theoretical considerations.  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