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   300796篇
  免费   8810篇
  国内免费   4906篇
化学   165641篇
晶体学   3587篇
力学   14279篇
综合类   294篇
数学   33859篇
物理学   96852篇
  2021年   2844篇
  2020年   3514篇
  2019年   3656篇
  2018年   4329篇
  2017年   4233篇
  2016年   6190篇
  2015年   4326篇
  2014年   6332篇
  2013年   13246篇
  2012年   11199篇
  2011年   13204篇
  2010年   9344篇
  2009年   9117篇
  2008年   11705篇
  2007年   11675篇
  2006年   10949篇
  2005年   9676篇
  2004年   8697篇
  2003年   7815篇
  2002年   7652篇
  2001年   8091篇
  2000年   6476篇
  1999年   5150篇
  1998年   4563篇
  1997年   4415篇
  1996年   3973篇
  1995年   3840篇
  1994年   3909篇
  1993年   3499篇
  1992年   3965篇
  1991年   3886篇
  1990年   3798篇
  1989年   3607篇
  1988年   3661篇
  1987年   3563篇
  1986年   3344篇
  1985年   4432篇
  1984年   4675篇
  1983年   3871篇
  1982年   3992篇
  1981年   3887篇
  1980年   3844篇
  1979年   3817篇
  1978年   4136篇
  1977年   4061篇
  1976年   4127篇
  1975年   3796篇
  1974年   3861篇
  1973年   4004篇
  1972年   2822篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Journal of Fluorescence - This report describes a combined immunofluorescence and fluorescence viability stain applied as one staining solution for rapid detection of live Legionella...  相似文献   
2.
Kinetics and Catalysis - The catalytic properties of a nickel phosphide catalyst supported on silica gel in the reductive amination of carbonyl compounds were studied in a flow reactor using...  相似文献   
3.
Kinetics and Catalysis - A new ruthenium(II) cage complex with polar terminal groups in the apical substituents has been synthesized; the molecular design of the complex contributes to the...  相似文献   
4.
Research on Chemical Intermediates - Owing to the simultaneous utilization of photogenerated electrons and holes, coupling light-driven hydrogen (H2) evolution reaction (HER) and biomass-derived...  相似文献   
5.
Automotive proton exchange membrane fuel cell stacks need to meet manufacturer specified rated beginning-of-life (BOL) performance before being assembled into vehicles and shipped off to customers. The process of “breaking-in” of a freshly assembled stack is often referred to as “conditioning.” It has become an intensely researched area especially in automotive companies, where imminent commercialization of fuel cell electric vehicles (FCEVs) demands a short, energy- and cost-efficient, and practical conditioning protocol. Significant advances in reducing the conditioning time from 1 to 2 days to as low as 4h or less, in some cases without the use of additional inert gases such as nitrogen, and with minimal use of hydrogen, and specialized test stations will be discussed.  相似文献   
6.
7.
Chemistry of Natural Compounds - O- and N-propylamino-derivatives of betulin and betulonic acid oxime and methyl ester were synthesized. Their antitumor activity against a panel of 60 human cancer...  相似文献   
8.
Refractory wounds have always been an important issue to healthcare systems, whose healing process is always delayed by multiple factors, including bacterial infections, chronic inflammation, and excessive exudates, etc. Employing multifunctional wound dressings is recognized as an effective strategy to deal with refractory wounds, which has yielded promising outcomes in recent years. Among these advanced wound dressings, fibrous dressings have gained growing attention due to their unique merits. Such wound dressings have demonstrated great potential in delivering theranostic agents, such as antibacterial agents, anti-inflammatory drugs, growth factors, and diagnostic probes, etc., for the purposes of accelerating wound healing. This paper reviews the development of multifunctional fibrous dressings and their applications in treating refractory wounds. The construction approaches of novel fibrous dressing with capabilities of antibacterial, anti-inflammation, exudate management and diagnosis were also introduced. Furthermore, the existing problems and challenges are also discussed briefly.  相似文献   
9.
Journal of Structural Chemistry - The structures of Ni(II), Cu(II), and Zn(II) complexes with anions of 2,5-pyrrolyl-disubstituted nitronyl nitroxide (L1) and iminonitroxide (L2) diradicals (HL1 is...  相似文献   
10.
Xu  Feixiang  Luo  Jiangchen  Jiang  Liqun  Zhao  Zengli 《Cellulose (London, England)》2022,29(3):1463-1472
Cellulose - In this research, the production of levoglucosan (LG) and levoglucosenone (LGO) was improved from acid-impregnated cellulose via fast pyrolysis. Thermogravimetric and kinetic analysis...  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