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   417104篇
  免费   4437篇
  国内免费   1099篇
化学   207750篇
晶体学   6030篇
力学   19564篇
综合类   7篇
数学   60561篇
物理学   128728篇
  2020年   2070篇
  2019年   2088篇
  2018年   11086篇
  2017年   11961篇
  2016年   8110篇
  2015年   4316篇
  2014年   4773篇
  2013年   14582篇
  2012年   15331篇
  2011年   25936篇
  2010年   15778篇
  2009年   15684篇
  2008年   22959篇
  2007年   26518篇
  2006年   12613篇
  2005年   18460篇
  2004年   13751篇
  2003年   12349篇
  2002年   10192篇
  2001年   10368篇
  2000年   8075篇
  1999年   6231篇
  1998年   5012篇
  1997年   4808篇
  1996年   4970篇
  1995年   4533篇
  1994年   4233篇
  1993年   4037篇
  1992年   4535篇
  1991年   4384篇
  1990年   4128篇
  1989年   3948篇
  1988年   4244篇
  1987年   3901篇
  1986年   3781篇
  1985年   5461篇
  1984年   5570篇
  1983年   4499篇
  1982年   4873篇
  1981年   4918篇
  1980年   4678篇
  1979年   4792篇
  1978年   4812篇
  1977年   4725篇
  1976年   4690篇
  1975年   4593篇
  1974年   4434篇
  1973年   4630篇
  1972年   2609篇
  1971年   1905篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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   
72.
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   
73.
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   
74.
Molecular dynamics simulation was performed to study the formation of cluster structure, interfaces, and surfaces with different curvature radii in a perfect nanocrystal passed through by a nonlinear wave. It is shown that this process is a type of nanostructure self-organization in response to an external energy flux with subsequent development of a strong rotational field.  相似文献   
75.
Journal of Solid State Electrochemistry - Due to their distinctive chemical, electronic, and environmental properties, polypyrrole is used as a blocking barrier for methanol leakage in direct...  相似文献   
76.
Methodology and Computing in Applied Probability - The problem of optimally controlling one-dimensional diffusion processes until they enter a given stopping set is extended to include Markov...  相似文献   
77.
78.
Ding  Q.  Yao  M.  Wu  Sh.  Zeng  M.  Xue  N.  Wu  D.  Xu  J. 《Journal of Applied Spectroscopy》2022,89(4):712-718
Journal of Applied Spectroscopy - Based on partial least squares (PLS) analysis, the effects of different smoothing points and different preprocessing methods on the accuracy and precision of the...  相似文献   
79.
Xu  H. J.  Zhang  Q. G.  Debenest  G. 《Transport in Porous Media》2021,140(3):625-627
Transport in Porous Media - The theme of coupling problems for adsorption, absorption and thermochemical transport in porous media is very important for engineering applications. Based on the...  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