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   584482篇
  免费   7057篇
  国内免费   1882篇
化学   306145篇
晶体学   8835篇
力学   26229篇
综合类   14篇
数学   71370篇
物理学   180828篇
  2021年   4491篇
  2020年   4954篇
  2019年   5398篇
  2018年   6797篇
  2017年   6900篇
  2016年   10499篇
  2015年   6777篇
  2014年   10507篇
  2013年   27274篇
  2012年   20763篇
  2011年   25280篇
  2010年   17477篇
  2009年   17306篇
  2008年   22829篇
  2007年   23109篇
  2006年   21676篇
  2005年   19221篇
  2004年   17737篇
  2003年   15696篇
  2002年   15544篇
  2001年   17673篇
  2000年   13433篇
  1999年   10704篇
  1998年   8835篇
  1997年   8598篇
  1996年   8375篇
  1995年   7447篇
  1994年   7188篇
  1993年   6985篇
  1992年   7709篇
  1991年   7812篇
  1990年   7411篇
  1989年   7204篇
  1988年   7231篇
  1987年   7055篇
  1986年   6755篇
  1985年   9163篇
  1984年   9297篇
  1983年   7638篇
  1982年   8047篇
  1981年   7837篇
  1980年   7587篇
  1979年   7934篇
  1978年   8016篇
  1977年   7941篇
  1976年   7911篇
  1975年   7635篇
  1974年   7388篇
  1973年   7611篇
  1972年   4922篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
141.
142.
143.
144.
In the last decade, catalytic chemical vapor deposition (CVD) has been intensively explored for the growth of single-layer graphene (SLG). Despite the scattering of guidelines and procedures, variables such as the surface texture/chemistry of catalyst metal foils, carbon feedstock, and growth process parameters have been well-scrutinized. Still, questions remain on how best to standardize the growth procedure. The possible correlation of procedures between different CVD setups is an example. Here, two thermal CVD reactors were explored to grow graphene on Cu foil. The design of these setups was entirely distinct, one being a “showerhead” cold-wall type, whereas the other represented the popular “tubular” hot-wall type. Upon standardizing the Cu foil surface, it was possible to develop a procedure for cm2-scale SLG growth that differed only by the carrier gas flow rate used in the two reactors.  相似文献   
145.
Journal of Thermal Analysis and Calorimetry - Over the last few decades, tremendous consideration is drawn towards corrugation surfaces because of their advantages over the improvement in thermal...  相似文献   
146.
Journal of Thermal Analysis and Calorimetry - In this paper, the variation of thermophysical properties such as the thermal conductivity, thermal energy storage capacity, viscosity, and phase...  相似文献   
147.
Journal of Solid State Electrochemistry - In this work, the use of neodymium electrodes as a basis for the immobilization of magnetite nanoparticles has been carried out. The sensitivity and...  相似文献   
148.
The influenza virus is a global threat to human health causing unpredictable yet recurring pandemics, the last four emerging over the course of a hundred years. As our knowledge of influenza virus evolution, distribution, and transmission has increased, paths to pandemic preparedness have become apparent. In the 1950s, the World Health Organization (WHO) established a global influenza surveillance network that is now composed of institutions in 122 member states. This and other surveillance networks monitor circulating influenza strains in humans and animal reservoirs and are primed to detect influenza strains with pandemic potential. Both the United States Centers for Disease Control and Prevention and the WHO have also developed pandemic risk assessment tools that evaluate specific aspects of emerging influenza strains to develop a systematic process of determining research and funding priorities according to the risk of emergence and potential impact. Here, we review the history of influenza pandemic preparedness and the current state of preparedness, and we propose additional measures for improvement. We also comment on the intersection between the influenza pandemic preparedness network and the current SARS-CoV-2 crisis. We must continually evaluate and revise our risk assessment and pandemic preparedness plans and incorporate new information gathered from research and global crises.Subject terms: Influenza virus, Infectious diseases  相似文献   
149.
High-energy assisted extraction techniques, like ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE), are widely applied over the last years for the recovery of bioactive compounds such as carotenoids, antioxidants and phenols from foods, animals and herbal natural sources. Especially for the case of xanthophylls, the main carotenoid group of crustaceans, they can be extracted in a rapid and quantitative way with the use of UAE and MAE.  相似文献   
150.
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