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   532685篇
  免费   5445篇
  国内免费   1492篇
化学   273828篇
晶体学   8383篇
力学   25279篇
综合类   16篇
数学   64646篇
物理学   167470篇
  2021年   4277篇
  2020年   4726篇
  2019年   5314篇
  2018年   7272篇
  2017年   7407篇
  2016年   10460篇
  2015年   6066篇
  2014年   10012篇
  2013年   23863篇
  2012年   18186篇
  2011年   22003篇
  2010年   16028篇
  2009年   15880篇
  2008年   20055篇
  2007年   20084篇
  2006年   18614篇
  2005年   16430篇
  2004年   15200篇
  2003年   13618篇
  2002年   13544篇
  2001年   15498篇
  2000年   11770篇
  1999年   9181篇
  1998年   7835篇
  1997年   7731篇
  1996年   7233篇
  1995年   6487篇
  1994年   6575篇
  1993年   6224篇
  1992年   6939篇
  1991年   7112篇
  1990年   6883篇
  1989年   6668篇
  1988年   6546篇
  1987年   6616篇
  1986年   6277篇
  1985年   8080篇
  1984年   8376篇
  1983年   6997篇
  1982年   7162篇
  1981年   6853篇
  1980年   6801篇
  1979年   7022篇
  1978年   7358篇
  1977年   7236篇
  1976年   7270篇
  1975年   6728篇
  1974年   6797篇
  1973年   6992篇
  1972年   4961篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
121.
Shinkorenko  A. S. 《JETP Letters》2022,116(10):759-759
JETP Letters - An Erratum to this paper has been published: https://doi.org/10.1134/S0021364022400028  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.
Bruzy  N.  Coret  M.  Huneau  B.  Kermouche  G.  Mondon  M.  Bertrand  E.  Stainier  L. 《Experimental Mechanics》2019,59(8):1145-1157

The allotropic phase change from ferrite to austenite represents a moment of massive interplay between the microstructural and mechanical states of iron. The difference of compacity between the two phases induces a microplastic accommodation in the material at grain scale. However, mechanical heterogeneities resulting from the transformation process remain challenging to characterise due to the high temperature conditions it is associated with. We developed experimental equipment for in situ observation of α ? γ and γ ? α transformations. Images of the surface of an iron sample taken by an optical camera were used as input for a Digital Image Correlation (DIC) routine. Special care was taken to maximize image resolution to capture sub-grain phenomena. Observations show that, at the mesoscopic scale, shear strain fields exhibit strong localisations that are evidence of transformations that are occurring.

  相似文献   
124.
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   
125.
Radiophysics and Quantum Electronics - Wind-related weather hazards remain difficult to recognize targets for weather radars. Methods that use estimates of the width of the reflected-signal...  相似文献   
126.
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   
127.
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   
128.

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   
129.
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   
130.
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   
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