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   463205篇
  免费   6734篇
  国内免费   2105篇
化学   257300篇
晶体学   6928篇
力学   19348篇
综合类   57篇
数学   52225篇
物理学   136186篇
  2020年   3087篇
  2019年   3114篇
  2018年   3160篇
  2016年   5975篇
  2015年   4793篇
  2014年   6595篇
  2013年   20444篇
  2012年   15009篇
  2011年   18624篇
  2010年   11912篇
  2009年   11730篇
  2008年   17027篇
  2007年   17280篇
  2006年   16604篇
  2005年   15120篇
  2004年   13670篇
  2003年   12108篇
  2002年   11926篇
  2001年   13946篇
  2000年   10711篇
  1999年   8601篇
  1998年   6876篇
  1997年   6731篇
  1996年   6769篇
  1995年   6178篇
  1994年   5906篇
  1993年   5613篇
  1992年   6456篇
  1991年   6210篇
  1990年   5880篇
  1989年   5765篇
  1988年   5962篇
  1987年   5706篇
  1986年   5447篇
  1985年   7681篇
  1984年   7783篇
  1983年   6387篇
  1982年   6827篇
  1981年   6830篇
  1980年   6482篇
  1979年   6752篇
  1978年   6933篇
  1977年   6820篇
  1976年   6710篇
  1975年   6490篇
  1974年   6290篇
  1973年   6473篇
  1972年   3917篇
  1968年   3375篇
  1967年   3278篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
85.
86.
87.
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   
88.
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   
89.
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   
90.
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   
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