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   1293篇
  免费   26篇
  国内免费   4篇
化学   1064篇
晶体学   16篇
力学   7篇
数学   73篇
物理学   163篇
  2023年   9篇
  2022年   9篇
  2021年   108篇
  2020年   44篇
  2019年   38篇
  2018年   51篇
  2017年   45篇
  2016年   54篇
  2015年   35篇
  2014年   44篇
  2013年   90篇
  2012年   75篇
  2011年   86篇
  2010年   52篇
  2009年   55篇
  2008年   66篇
  2007年   51篇
  2006年   53篇
  2005年   47篇
  2004年   38篇
  2003年   29篇
  2002年   23篇
  2001年   19篇
  2000年   12篇
  1999年   10篇
  1997年   6篇
  1996年   5篇
  1994年   4篇
  1993年   7篇
  1991年   10篇
  1989年   5篇
  1988年   8篇
  1987年   11篇
  1986年   8篇
  1985年   4篇
  1984年   5篇
  1983年   3篇
  1982年   5篇
  1981年   8篇
  1979年   6篇
  1978年   5篇
  1977年   5篇
  1976年   5篇
  1974年   7篇
  1973年   8篇
  1972年   5篇
  1971年   8篇
  1970年   8篇
  1969年   5篇
  1968年   3篇
排序方式: 共有1323条查询结果,搜索用时 31 毫秒
1.
Journal of Thermal Analysis and Calorimetry - The work concerns the alumina–graphene materials sintered by two different pressure methods. The different particle sizes of graphene were used....  相似文献   
2.
Russian Physics Journal - Using the potentials, generated by a tight binding approximation, the equilibrium atomic structure and the phonon spectra of Cr and Ni thin films (one monolayer) deposited...  相似文献   
3.
Polyurethanes incorporated with rhenium diimine complexes were synthesized. The polymers exhibited interesting morphologies and solution properties. Results from gel permeation chromatography suggested the formation of polymer aggregates in solutions. The polymers could act as probes for metal ions. The addition of metal ions to polymer solutions led to significant changes in the electronic absorption properties of the polymer solutions. This was attributed to the interactions between the polyether moieties and metal ions. The metal complexes could also act as efficient photosensitizers. After doping with charge‐transport viologens, the photoconductivity of the polymers was greatly enhanced. The experimental quantum efficiency was simulated with Onsager's theory. The thermalization distances and the primary yields were typically 12–14 Å and 10?3, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1708–1715, 2003  相似文献   
4.
A two-dimensional mathematical model for the transport of reactants in a fuel cell with a solid polymer electrolyte is developed. The model is used for analyzing spatial distributions of the concentration of reactants and current density over the cell. The effect of the catalytic-layer activity, reactant speed, bipolar-plate geometry, thickness and porosity of current collector and/or gas-diffusion sublayer, and the reaction mixture composition on the fuel cell efficiency is estimated theoretically and experimentally.  相似文献   
5.
6.
7.
8.
9.
Summary Halogen derivatives of the N-alkylmonoamides and N-alkylimides of maleic and citraconic acid containing the strongly electronegative group CF3 in the alkyl radical, previously unreported in the literature, have been synthesized.  相似文献   
10.
It has been shown that the most efficient catalysts for the synthesis of 4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridine from 1,2,5-trimethylpyridin-4-one and acetylene under Trofimov conditions are rubidium and potassium hydroxides. Use of Triton B or a mixture of trimethylbenzylammonium chloride with rubidium hydroxide as catalyst gives O-alkylated oxime. Their configurations and conformations were established through separation of the individual isomers of 1-vinyl-4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridines. Acetyl nitrate nitration of the cis isomer of this compound gave the 2- and 3-nitro derivatives. Similar nitration of 4,5,7-trimethyl-4,5,6,7-tetrahydropyrrolo[3,2-c]pyridine gave the 2-nitro-7-hydroxy derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1375–1380, October, 1991.  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