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   621308篇
  免费   6829篇
  国内免费   1668篇
化学   315444篇
晶体学   9447篇
力学   29252篇
综合类   16篇
数学   85391篇
物理学   190255篇
  2021年   4559篇
  2020年   5164篇
  2019年   5602篇
  2018年   13041篇
  2017年   13558篇
  2016年   13712篇
  2015年   7434篇
  2014年   10734篇
  2013年   25699篇
  2012年   22414篇
  2011年   32131篇
  2010年   21915篇
  2009年   21724篇
  2008年   29324篇
  2007年   31422篇
  2006年   20475篇
  2005年   22792篇
  2004年   19183篇
  2003年   17347篇
  2002年   15687篇
  2001年   16803篇
  2000年   12842篇
  1999年   9888篇
  1998年   8252篇
  1997年   7977篇
  1996年   7819篇
  1995年   7044篇
  1994年   6936篇
  1993年   6674篇
  1992年   7487篇
  1991年   7475篇
  1990年   7237篇
  1989年   6993篇
  1988年   7016篇
  1987年   6920篇
  1986年   6500篇
  1985年   8504篇
  1984年   8679篇
  1983年   7181篇
  1982年   7281篇
  1981年   7115篇
  1980年   6712篇
  1979年   7267篇
  1978年   7409篇
  1977年   7180篇
  1976年   7166篇
  1975年   6720篇
  1974年   6677篇
  1973年   6880篇
  1972年   4766篇
排序方式: 共有10000条查询结果,搜索用时 531 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.
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   
3.
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   
4.
5.
6.
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   
7.
Kinetics and Catalysis - The results of studies in the field of synthesis and characterization of layered double hydroxides (LDHs) obtained using solid-phase reactions are summarized. The effect of...  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