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   597204篇
  免费   6704篇
  国内免费   1630篇
化学   306677篇
晶体学   7684篇
力学   27837篇
综合类   18篇
数学   80340篇
物理学   182982篇
  2021年   4079篇
  2020年   4655篇
  2019年   4969篇
  2018年   12678篇
  2017年   13191篇
  2016年   12724篇
  2015年   6905篇
  2014年   9586篇
  2013年   23940篇
  2012年   21219篇
  2011年   31345篇
  2010年   20889篇
  2009年   20562篇
  2008年   28241篇
  2007年   30779篇
  2006年   19183篇
  2005年   22419篇
  2004年   18555篇
  2003年   16658篇
  2002年   14981篇
  2001年   15824篇
  2000年   12079篇
  1999年   9462篇
  1998年   7912篇
  1997年   7655篇
  1996年   7551篇
  1995年   6813篇
  1994年   6570篇
  1993年   6211篇
  1992年   6979篇
  1991年   7030篇
  1990年   6734篇
  1989年   6638篇
  1988年   6612篇
  1987年   6559篇
  1986年   6184篇
  1985年   8149篇
  1984年   8376篇
  1983年   6735篇
  1982年   7053篇
  1981年   6907篇
  1980年   6540篇
  1979年   7000篇
  1978年   7262篇
  1977年   7006篇
  1976年   7004篇
  1975年   6529篇
  1974年   6412篇
  1973年   6637篇
  1972年   4546篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Journal of Experimental and Theoretical Physics - Dzyaloshinskii–Moriya interaction, DMI in short, represents an antisymmetric type of magnetic interactions that favor orthogonal orientation...  相似文献   
2.
Yang  T. L.  Kao  C. L.  Kuo  C. E.  Yeh  H. C.  Li  W. J.  Li  H. T.  Chen  C. Y. 《Chemistry of Natural Compounds》2022,58(5):825-827
Chemistry of Natural Compounds - A novel bibenzyl derivative, hydrangchinenin (1), was isolated from the stems of Hydrangea chinensis Maxim. (Hydrangeaceae). Its structure was determined on the...  相似文献   
3.
Kinetics and Catalysis - A new ruthenium(II) cage complex with polar terminal groups in the apical substituents has been synthesized; the molecular design of the complex contributes to the...  相似文献   
4.
Russian Journal of General Chemistry - Aminophosphabetaines, i.e., isobutyl {[alkyl(dimethyl)ammonio]methyl}phosphonates with higher alkyl substituents at the nitrogen atom, were obtained by a...  相似文献   
5.
6.
7.
Journal of Structural Chemistry - The structures of Ni(II), Cu(II), and Zn(II) complexes with anions of 2,5-pyrrolyl-disubstituted nitronyl nitroxide (L1) and iminonitroxide (L2) diradicals (HL1 is...  相似文献   
8.
Mechanics of Composite Materials - Carbon fiber (CF)/ polyamide (PA6) composites are one of the most promising thermoplastic materials for automobile applications. However, the interfacial...  相似文献   
9.
In the pursuit to enlarge the library of polyimide materials for energy applications, new polyimide/MWCNTs composite films have been developed by MWCNTs-assisted polycondensation reaction of a hydroxyl and triphenylmethane-containing diamine with benzophenone tetracarboxylic dianhydride targeting to highlight their electrical storage capability as flexible electrodes in micro-supercapacitors (mSCs). The Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance, UV–vis, fluorescence, and Raman spectroscopies were used to demonstrate the evolution of interfacial interactions between MWCNTs and the precursors (diamine monomer and intermediate polyamidic acid) and polyimide matrix that proved to be the origin of MWCNTs homogeneous dispersion. Thus, composite films incorporating 1, 3, 5, and 10 w.t.% MWCNTs were obtained and thoroughly investigated with regard to their morphology, mechanical behavior, thermal stability, and electrical conductivity. The electrochemical performance of these composites was first analyzed in a classical three-electrode cell by cyclic voltammetry and galvanostatic charge-discharge in both aqueous and organic electrolyte systems. By far, the best electrical storage capacity was obtained with the composite polyimide film containing 10% MWCNTs that was further used as both active material and current collector in a flexible symmetric mSC realized by a straightforward and low-cost procedure. In the attempt to better exploit the advantages of this composite film, it was layered with a graphite-containing paint and tested as an electrode in a flexible mSC, which provided satisfactory results. To our knowledge, this is the first report on the electrical charge storage capability of a polyimide/MWCNTs free-standing film as a flexible electrode in mSCs, which do not require time- and resource-consuming processing steps.  相似文献   
10.
Journal of Structural Chemistry - A new polymorph of the [ReCl3(MeCN)(PPh3)2] complex is synthesized and characterized by single crystal X-ray diffraction (XRD). Its recrystallization from the...  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