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   512702篇
  免费   29218篇
  国内免费   18590篇
化学   290214篇
晶体学   7060篇
力学   22929篇
综合类   30篇
数学   62226篇
物理学   178051篇
  2021年   3458篇
  2020年   4168篇
  2019年   4739篇
  2018年   5052篇
  2017年   5628篇
  2016年   8736篇
  2015年   7344篇
  2014年   9063篇
  2013年   24027篇
  2012年   19725篇
  2011年   24656篇
  2010年   20395篇
  2009年   20336篇
  2008年   21081篇
  2007年   20602篇
  2006年   19817篇
  2005年   18677篇
  2004年   17860篇
  2003年   15628篇
  2002年   15209篇
  2001年   17007篇
  2000年   12889篇
  1999年   10742篇
  1998年   8527篇
  1997年   8287篇
  1996年   8627篇
  1995年   8242篇
  1994年   8163篇
  1993年   7961篇
  1992年   8362篇
  1991年   7951篇
  1990年   7324篇
  1989年   7176篇
  1988年   7383篇
  1987年   6530篇
  1986年   6239篇
  1985年   8134篇
  1984年   8305篇
  1983年   6454篇
  1982年   7199篇
  1981年   6984篇
  1980年   6727篇
  1979年   6923篇
  1978年   7020篇
  1977年   7010篇
  1976年   7176篇
  1975年   6329篇
  1974年   6183篇
  1973年   6546篇
  1972年   4115篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
91.
Journal of Thermal Analysis and Calorimetry - In the present study, numerical simulations have been carried out on thermal characteristics and second-law analysis of turbulent Cu–H2O...  相似文献   
92.
93.
94.
95.
96.
97.
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   
98.
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   
99.
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   
100.
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