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   221828篇
  免费   11703篇
  国内免费   3521篇
化学   135543篇
晶体学   3066篇
力学   10322篇
综合类   215篇
数学   24000篇
物理学   63906篇
  2021年   2076篇
  2020年   3285篇
  2019年   5086篇
  2018年   4614篇
  2017年   4398篇
  2016年   7736篇
  2015年   5640篇
  2014年   7352篇
  2013年   11591篇
  2012年   9108篇
  2011年   9478篇
  2010年   8993篇
  2009年   9068篇
  2008年   9369篇
  2007年   8732篇
  2006年   7707篇
  2005年   7066篇
  2004年   6639篇
  2003年   6047篇
  2002年   6865篇
  2001年   6641篇
  2000年   5172篇
  1999年   3361篇
  1998年   2791篇
  1997年   2603篇
  1996年   2374篇
  1995年   2148篇
  1994年   2095篇
  1993年   2112篇
  1992年   2140篇
  1991年   2446篇
  1990年   2366篇
  1989年   2413篇
  1988年   2301篇
  1987年   2326篇
  1986年   2148篇
  1985年   2695篇
  1984年   2689篇
  1983年   2334篇
  1982年   2379篇
  1981年   2290篇
  1980年   2082篇
  1979年   2399篇
  1978年   2556篇
  1977年   2652篇
  1976年   2732篇
  1975年   2539篇
  1974年   2474篇
  1973年   2639篇
  1972年   2156篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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   
92.
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   
93.
94.

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   
95.
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   
96.
Crystallography Reports - The specific features of the formation of concentration inhomogeneities in crystals grown by the Czochralski method (GaSb:Te, Ge:Ga) and by the Bridgman method...  相似文献   
97.
Journal of Radioanalytical and Nuclear Chemistry - In the present work the final products of coumarin radiation chemical transformation are investigated by chromatography. During radiolysis of...  相似文献   
98.
99.
Exosomes are nanovesicles secreted by most cellular types that carry important biochemical compounds throughout the body with different purposes, playing a preponderant role in cellular communication. Because of their structure, physicochemical properties and stability, recent studies are focusing in their use as nanocarriers for different therapeutic compounds for the treatment of different diseases ranging from cancer to Parkinson's disease. However, current bioseparation protocols and methodologies are selected based on the final exosome application or intended use and present both advantages and disadvantages when compared among them. In this context, this review aims to present the most important technologies available for exosome isolation while discussing their advantages and disadvantages and the possibilities of being combined with other strategies. This is critical since the development of novel exosome‐based therapeutic strategies will be constrained to the effectiveness and yield of the selected downstream purification methodologies for which a thorough understanding of the available technological resources is needed.  相似文献   
100.
Physics of Atomic Nuclei - The paper presents a comparison of three neutrons identifying methods in scintillators based on ZnS with 6Li and 10B: charge integration method, pulse gradient analysis,...  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