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   355189篇
  免费   2277篇
  国内免费   879篇
化学   158385篇
晶体学   5430篇
力学   19710篇
综合类   11篇
数学   69012篇
物理学   105797篇
  2020年   1725篇
  2019年   1919篇
  2018年   18723篇
  2017年   19327篇
  2016年   12048篇
  2015年   3683篇
  2014年   3930篇
  2013年   9467篇
  2012年   13343篇
  2011年   27618篇
  2010年   16709篇
  2009年   17161篇
  2008年   22134篇
  2007年   27061篇
  2006年   7071篇
  2005年   13687篇
  2004年   10048篇
  2003年   9946篇
  2002年   7061篇
  2001年   6498篇
  2000年   5171篇
  1999年   3688篇
  1998年   2958篇
  1997年   2845篇
  1996年   2882篇
  1995年   2622篇
  1994年   2472篇
  1993年   2310篇
  1992年   2932篇
  1991年   2843篇
  1990年   2778篇
  1989年   2810篇
  1988年   2843篇
  1987年   2844篇
  1986年   2708篇
  1985年   3423篇
  1984年   3441篇
  1983年   2727篇
  1982年   2828篇
  1981年   2880篇
  1980年   2657篇
  1979年   3005篇
  1978年   3001篇
  1977年   3026篇
  1976年   2887篇
  1975年   2616篇
  1974年   2565篇
  1973年   2565篇
  1972年   1755篇
  1968年   1808篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
We consider complete ideals supported on finite sequences of infinitely near points, in regular local rings with dimensions greater than two. We study properties of factorizations in Lipman special *-simple complete ideals. We relate it to a type of proximity, linear proximity, of the points, and give conditions in order to have unique factorization. Several examples are presented. Received: 2 February 2000 / in final form: 14 March 2001 / Published online: 18 January 2002  相似文献   
52.
53.

An A-loop is a loop in which every inner mapping is an automorphism. A problem which had been open since 1956 is settled by showing that every diassociative A-loop is Moufang.

  相似文献   

54.
The principal physics goals of the Compact Muon Solenoid experiment under construction at the Large Hadron Collider at CERN in Geneva are reviewed. Procedures to search for the Standard Model Higgs boson, supersymmetric Higgses and other supersymmetric particles are described.  相似文献   
55.
The scattering of heavy ion with a multilevel Rydberg atom in the presence of an electromagnetic field is studied. The interaction of Rydberg atom and the e.m field is explored using non-perturbative quasi-energy technique. Although the results are presented for selected excitations but in actual calculations we have included many levels of the atom. The effect of various parameters are shown on collisional excitation process. As an illustration detailed calculations are performed for the inelastic proton-Na Rydberg atom collision accompanied by the transfer of photons and the effects of dressing due to the field are considered. The emphasis of the present work is on collision induced transitions especially the case that involves change of orbital as well as principal quantum number. Received 26 December 2001 / Received in final form 8 April 2002 Published online 19 July 2002  相似文献   
56.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 55, No. 4, pp. 624–629, October, 1991.  相似文献   
57.
Cognitive style refers to differences that can be perceived in individuals due to differing cognitive structures. There has been a large amount of research on how cognitive style affects managerial decision-making, particularly in the context of management information systems, but little or no attempt to relate these findings to operational research. This paper reviews the findings of cognitive-style research from the perspective of operational research, and draws a number of useful inferences concerning the matching of OR aids to managers, the presentation of information and recommendations, the use and acceptance of OR, and the structure of OR groups. Further, it is argued that cognitive-style findings help to give a justification to the move towards ‘soft’ approaches to analysis.  相似文献   
58.
59.
Partially supported by the general research fund at the University of Kansas  相似文献   
60.
The objective of this research is to evaluate a new methodology, data envelopment analysis (DEA), as a tool for measuring and evaluating the operational efficiency of US Air Force organizations. This study involves the application of DEA to locate possible inefficiencies in the performance of US Air Force real-property maintenance activities. Dynamic behaviour, as exhibited via window analyses, is reviewed along with static counterparts. The testing was done in close coordination with Air Force officials, who reviewed the results for accuracy, validity and relevance. We conclude that this type of efficiency analysis does have value for the Air Force, where it can serve as a guide to auditors, budget programmers, managers and others in measuring, evaluating and enhancing operational efficiency.  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