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   942篇
  免费   18篇
化学   384篇
晶体学   7篇
力学   38篇
数学   145篇
物理学   386篇
  2021年   17篇
  2020年   17篇
  2019年   11篇
  2018年   33篇
  2017年   36篇
  2016年   47篇
  2015年   15篇
  2014年   35篇
  2013年   44篇
  2012年   44篇
  2011年   40篇
  2010年   34篇
  2009年   31篇
  2008年   36篇
  2007年   26篇
  2006年   24篇
  2005年   19篇
  2004年   18篇
  2003年   14篇
  2002年   21篇
  2001年   21篇
  2000年   16篇
  1999年   8篇
  1997年   11篇
  1996年   15篇
  1995年   9篇
  1994年   12篇
  1993年   8篇
  1992年   12篇
  1991年   12篇
  1990年   12篇
  1989年   12篇
  1988年   8篇
  1987年   9篇
  1984年   7篇
  1983年   8篇
  1981年   16篇
  1980年   7篇
  1979年   14篇
  1977年   14篇
  1976年   12篇
  1975年   14篇
  1974年   15篇
  1973年   21篇
  1972年   8篇
  1971年   13篇
  1970年   12篇
  1968年   7篇
  1966年   7篇
  1965年   8篇
排序方式: 共有960条查询结果,搜索用时 31 毫秒
11.
12.
Abstract

New chiral methylbenzylammonium salts of aryldithiophosphonic acids containing glucofuranose, allofuranose, and galactopyranose diacetonide substituents were obtained using (S)-(–)-α-methylbenzylamine, (R)-(+)-α-methylbenzylamine, and (R,S)-(±)-α-methylbenzylamine. Salts obtained possess antimicrobial activity.  相似文献   
13.
Polyacetylene films irradiated by-rays up to 100 MRad were studied by means of TMA, DTG and DSC methods.It is shown that as the irradiation dose increases the concentration of topological branching knots into the polymer chains and theT g values decrease, the total mass loss and the enthalpy of the thermal isomerization reaction also decrease.  相似文献   
14.
Groups of spacetime transformations of the second class are constructed. It is shown that the minimum group of spacetime transformations that satisfy the principles of the special theory of relativity isD=P(2,4)O(2,4)O(1,3).D. V. Efremov Institute of Electrophysical Apparatus. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 101, No. 1, pp. 136–157, October, 1994.  相似文献   
15.
Analysis of mass and heat balance in the reaction node of the process of ethylene dimerization into but-1-ene under the industrial conditions is performed. It is found that ethylene concentration in the reactor liquid phase by a complex way depends on the reactor temperature, pressure and but-1-ene concentration in the liquid phase. Optimal process temperature is 80–90°C, operating pressure in the reactor is 0.6–0.8 MPa. Increase in pressure above 1 MPa practically excludes heat withdraw via but-1-ene evaporation and makes the system of heat withdrawing ineffective.  相似文献   
16.
6-Substituted 2,4-bis(trichloromethyl)-sym-triazet:es containing the 2,6-di-tert-butylphenol group are synthesized by simultaneous cyclotrimerization of trichloroacetonitrile with the nitrile or thiocyanate derivative of the sterically hindered phenol in the presence of gaseous HCl. Significant amounts of 2,4,6-tris(trichloromethyl)-sym-triazene are formed as a byproduct.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 240–243, February, 1994. Original article submitted January 19, 1994.  相似文献   
17.
A discussion is presented of a discovery that the anionic part of sodium salts introduced into the catalyst by impregnation of -Al2O3 after deposition of palladium salts and their reduction in that catalyst affects the activity and dynamic properties of the catalysts in the oxidation reaction of CO into CO2 at stoichiometric ratios of CO/O2 = 2.Scientific-Production Association Gos. In-t Prikl. Khim., Leningrad. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 5, pp. 591–595, September–October, 1991. Original article submitted July 17, 1991.  相似文献   
18.
19.
Among nuclides, 195m Pt isomer is characterized by a number of properties that make it suitable for use in nuclear medicine. Effective ways of optimizing the Pt isomer yield at low impurity contents must be sought. The method based on double neutron capture by the 193Ir target nucleus with subsequent populating of 195m Pt through β decay allows chemical isolation of the isomer. In this work, the problem is analyzed, test experiments on Ir activation with neutrons are conducted, and theoretical estimates of the 195m Pt yield are presented. Full-scale model experiments on the IBR-2 reactor in Dubna should confirm the effectiveness of the method.  相似文献   
20.
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