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   57344篇
  免费   4184篇
  国内免费   2964篇
化学   30127篇
晶体学   537篇
力学   3272篇
综合类   287篇
数学   12166篇
物理学   18103篇
  2024年   73篇
  2023年   571篇
  2022年   587篇
  2021年   867篇
  2020年   1116篇
  2019年   1067篇
  2018年   2038篇
  2017年   2199篇
  2016年   1908篇
  2015年   1709篇
  2014年   1930篇
  2013年   2601篇
  2012年   5632篇
  2011年   4918篇
  2010年   3427篇
  2009年   3149篇
  2008年   2259篇
  2007年   2232篇
  2006年   2063篇
  2005年   5600篇
  2004年   4810篇
  2003年   3049篇
  2002年   1216篇
  2001年   838篇
  2000年   644篇
  1999年   819篇
  1998年   686篇
  1997年   644篇
  1996年   706篇
  1995年   547篇
  1994年   504篇
  1993年   409篇
  1992年   539篇
  1991年   474篇
  1990年   389篇
  1989年   308篇
  1988年   256篇
  1987年   191篇
  1986年   166篇
  1985年   154篇
  1984年   115篇
  1983年   86篇
  1982年   59篇
  1981年   54篇
  1976年   99篇
  1975年   65篇
  1974年   67篇
  1973年   59篇
  1972年   53篇
  1969年   45篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
993.
Residual stresses are found in the majority of multilayer thin film structures used in modem technology. The measurement and modeling of such stress fields and the elucidation of their effects on structural reliability and device operation have been a “growth area” in the literature, with contributions from authors in various scientific and engineering disciplines.

In this article the measurement of the residual stresses in thin film structures with X-ray diffraction techniques is reviewed and the interpretation of such data and their relationship to mechanical reliability concerns are discussed.  相似文献   

994.
Behavior of the Bray-Liebhafsky oscillatory reaction in the presence of acid-base polymers with and without ferric ions is analyzed. The influence of hydrogen ions on the overall reaction is shown.  相似文献   
995.
并行“冒泡”排序算法的改进黄干平(武汉大学计算机科学系,武汉,430072)关键词排序,并行算法,冒泡中国法分类号w301.6PBSM并行排序算法是对KazuhirsSado和YoshihideIgarash的并行“冒泡’书r序算法’“的改进,其并行...  相似文献   
996.
Li QG  Xu JG  Huang XZ  Chen GZ 《Talanta》1994,41(12):2049-2054
The effects of media properties including buffers, acidity, solvents and surfactant on horseradish peroxidase-catalyzed fluorogenic reaction were investigated. The results showed that the so-called non-fluorescent hydrogen donors were in fact fluorescent. There existed an acid—base equilibrium in the fluorescent dimer product. For p -hydroxyphenylpropionic acid, a pKa value of 8.0 for the product was obtained from its titration curve. The product fluorescence increased with higher pH, however, a longer time was needed to reach the reaction equilibrium due to the pH mismatch problem. Cationic micelles cetyltrimethylammonium bromide and cetyltrimethylammonium chloride could reduce the pH mismatch and offered a way to further increase the determination sensitivity. Finally, a micelle-enhanced flow-injection analysis of horseradish peroxidase is suggested.  相似文献   
997.
998.
999.
1000.
The intermittency phenomenon is investigated in proton-gold, oxygen-gold, sulphur-gold and sulphur-sulphur collisions at 200 GeV per nucleon. The data were taken with the NA 35 streamer chamber detector at the CERN SPS. The data samples are carefully corrected for double counting of tracks and for contamination from photon conversions, particle decays and secondary interactions. The analysis is carried out in terms of factorial moments, using a new definition, and of correlation integrals. Both methods show the presence of nonstatistical fluctuations (intermittency). The main conclusions are: The observation of the effect for pairs of hadrons with negative charges and its near absence for pairs of opposite charges is consistent with the assumption that Bose-Einstein correlations yield the dominant contribution. The intermittency effect is not proportional to (dn/dy)–1 which would be expected in superposition models. The measured relation between the second and third factorial moment for negative hadrons indicates that genuine 3-particle correlations are small. The predictions of a Monte Carlo simulation which is based on the Lund Fritiof model with the inclusion of Bose-Einstein correlations agree with the experimental results.Deceased  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