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   1504675篇
  免费   32098篇
  国内免费   8321篇
化学   654437篇
晶体学   19993篇
力学   74015篇
综合类   104篇
数学   238798篇
物理学   362771篇
无线电   194976篇
  2021年   14739篇
  2020年   17345篇
  2019年   17509篇
  2016年   29170篇
  2015年   21588篇
  2014年   32737篇
  2013年   78494篇
  2012年   39085篇
  2011年   34624篇
  2010年   38458篇
  2009年   43572篇
  2008年   38393篇
  2007年   34951篇
  2006年   43330篇
  2005年   34438篇
  2004年   36443篇
  2003年   34479篇
  2002年   35727篇
  2001年   34784篇
  2000年   31140篇
  1999年   28725篇
  1998年   27344篇
  1997年   27223篇
  1996年   26803篇
  1995年   24604篇
  1994年   24060篇
  1993年   23436篇
  1992年   23085篇
  1991年   23303篇
  1990年   22028篇
  1989年   21702篇
  1988年   20835篇
  1987年   19609篇
  1986年   18447篇
  1985年   24948篇
  1984年   26165篇
  1983年   22164篇
  1982年   23606篇
  1981年   22816篇
  1980年   22056篇
  1979年   21876篇
  1978年   23216篇
  1977年   22753篇
  1976年   22349篇
  1975年   21040篇
  1974年   20635篇
  1973年   21196篇
  1972年   15369篇
  1968年   13044篇
  1967年   13146篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Wireless Personal Communications - Besides anti-malware usage for the eradication of malicious attacks, researchers have developed epidemic models in order to gain more insights into the spread...  相似文献   
72.
Telecommunication Systems - Energy saving in User Equipment (UE) is one of the important issues for limited sources of power in the device. It is critical for the UE to maximize its energy...  相似文献   
73.
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid...  相似文献   
74.
Journal of Communications Technology and Electronics - A new design of wavelets based on the convolution of a compactly supported function with a rectangular pulse is proposed and theoretically...  相似文献   
75.
Journal of Communications Technology and Electronics - A statistical study of the effectiveness of the non-threshold search procedure for a noise-like phase-shift keyed signal by the delay time is...  相似文献   
76.
Journal of Communications Technology and Electronics - In recent years, there has been a rapid improvement in photonics products due to the use of multilayer heterostructures grown on the basis of...  相似文献   
77.
Mobile Networks and Applications - Project MindCatcher is an art/research project which has the intention to explore the potential of interactive artistic environments for measuring and a better...  相似文献   
78.
Sohrabi  M. 《Analysis Mathematica》2021,47(2):421-435
Analysis Mathematica - In this paper, we discuss measure theoretic characterizations for Moore-Penrose inverse of Lambert conditional operators, denoted by (MwEMu)?, in some operator classes...  相似文献   
79.
Surface passivation treatment is a widely used strategy to resolve trap-mediated nonradiative recombination toward high-efficiency metal-halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well as an in-depth understanding of its passivation mechanism. Here, a systematic study on a mixed-salt passivation strategy of formamidinium bromide (FABr) coupled with different F-substituted alkyl lengths of ammonium iodide is demonstrated. It is obtained better device performance with decreasing chain length of the F-substituted alkyl ammonium iodide in the presence of FABr. Moreover, they unraveled a synergistic passivation mechanism of the mixed-salt treatment through surface reconstruction engineering, where FABr dominates the reformation of the perovskite surface via reacting with the excess PbI2. Meanwhile, ammonium iodide passivates the perovskite grain boundaries both on the surface and top perovskite bulk through penetration. This synergistic passivation engineer results in a high-quality perovskite surface with fewer defects and suppressed ion migration, leading to a champion efficiency of 23.5% with mixed-salt treatment. In addition, the introduction of the moisture resisted F-substituted groups presents a more hydrophobic perovskite surface, thus enabling the decorated devices with excellent long-term stability under a high humid atmosphere as well as operational conditions.  相似文献   
80.
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