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   433548篇
  免费   4919篇
  国内免费   1328篇
化学   204915篇
晶体学   6200篇
力学   22589篇
综合类   15篇
数学   74221篇
物理学   131855篇
  2021年   3379篇
  2020年   3757篇
  2019年   4045篇
  2018年   15359篇
  2017年   15377篇
  2016年   13882篇
  2015年   5637篇
  2014年   8099篇
  2013年   17950篇
  2012年   17180篇
  2011年   26058篇
  2010年   17088篇
  2009年   17246篇
  2008年   20862篇
  2007年   22787篇
  2006年   13665篇
  2005年   12886篇
  2004年   12167篇
  2003年   11280篇
  2002年   10373篇
  2001年   11202篇
  2000年   8418篇
  1999年   6453篇
  1998年   5463篇
  1997年   5255篇
  1996年   5107篇
  1995年   4365篇
  1994年   4322篇
  1993年   4306篇
  1992年   4570篇
  1991年   4660篇
  1990年   4486篇
  1989年   4352篇
  1988年   4122篇
  1987年   4255篇
  1986年   4000篇
  1985年   5101篇
  1984年   5123篇
  1983年   4290篇
  1982年   4410篇
  1981年   4122篇
  1980年   4046篇
  1979年   4284篇
  1978年   4316篇
  1977年   4274篇
  1976年   4194篇
  1975年   3985篇
  1974年   3911篇
  1973年   3974篇
  1972年   2743篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Journal of Experimental and Theoretical Physics - The nature of the training effect in exchange-biased compounds is studied. This effect consists in a decrease in the exchange bias field (HEB)...  相似文献   
122.
Journal of Solid State Electrochemistry - Due to their distinctive chemical, electronic, and environmental properties, polypyrrole is used as a blocking barrier for methanol leakage in direct...  相似文献   
123.
Popel  S. I.  Golub’  A. P. 《JETP Letters》2022,115(10):596-601
JETP Letters - One of the main features of the dusty plasma compared to the conventional plasma (without charged dust particles is anomalous dissipation that is caused by the charging of dust...  相似文献   
124.
Russian Journal of General Chemistry - Highly dispersed CaO has been synthesized by heating an aqueous solution of calcium nitrate and D-glucose up to 800°C. Calcium oxide is formed with an...  相似文献   
125.
Russian Journal of Organic Chemistry - Methyl (Z)-3-[(2R,3R,4S,5S)-5-(2-methoxy-2-oxoethyl)-3,4-(isopropylidenedioxy)tetrahydrofuran-2-yl]-prop-2-enoate was synthesized, and its intramolecular...  相似文献   
126.

A procedure was suggested for preparing brominated polyols of reduced viscosity for the synthesis of foamed polyurethanes of reduced flammability. The flame-retarding action of the synthesized polyol tetrabromophthalate in polyurethane was studied in comparison with that of other widely used flame retardants. Evaluation of the effect exerted on the flammability of the polurethane compound by the polyol tetrabromophthalate synthesized, melamine, and aluminum hydroxide shows that all the samples containing flame retardants are self-extinguishing. The shortest combustion time was observed for the sample containing 6% polyol tetrabromophthalate synthesized. The sample containing as a flame retardant additive solely the synthesized polyole tetrabromophthalate also exhibits the highest performance as a heat-insulating material from the viewpoint of thermal conductivity.

  相似文献   
127.
Russian Journal of Organic Chemistry - The reaction of selenium dichloride with methyl and ethyl propiolates leads to formation of anti-Markovnikov adducts. The regio- and stereoselective synthesis...  相似文献   
128.
Shanin  A. V.  Korolkov  A. I.  Kniazeva  K. S. 《Acoustical Physics》2022,68(4):316-325
Acoustical Physics - The problem of pulsed excitation of an acoustic waveguide with a constant cross section is considered. Absorption is ignored. As the most general model of such a waveguide,...  相似文献   
129.
Russian Physics Journal - The article describes the collocation method for the numerical solution of mathematical physics boundary value problems. By arranging the collocation nodes in a special...  相似文献   
130.

A model with 16 moments is here presented in the framework of RET of polyatomic gases. It furnishes as principal subsystem the relativistic counterpart of a work by Arima T., Ruggeri T., Sugiyama M.; this is present in literature and treats the non relativistic case which incorporates relaxation processes of molecular rotation and vibration. Another principal subsystem is the natural extension of the 14 moments model by Pennisi S. and Ruggeri T.; this is also present in literature in the relativistic framework but where the trace of the third balance equation is neglected. Its extension is found here for the case when this trace isn’t neglected.

  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