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   399115篇
  免费   4433篇
  国内免费   1272篇
化学   213271篇
晶体学   4733篇
力学   18208篇
综合类   16篇
数学   45454篇
物理学   123138篇
  2020年   3009篇
  2019年   3292篇
  2018年   4097篇
  2017年   4104篇
  2016年   6439篇
  2015年   4291篇
  2014年   6364篇
  2013年   17170篇
  2012年   13211篇
  2011年   16333篇
  2010年   11111篇
  2009年   11022篇
  2008年   15193篇
  2007年   15446篇
  2006年   14570篇
  2005年   13358篇
  2004年   12154篇
  2003年   10882篇
  2002年   10138篇
  2001年   11609篇
  2000年   8736篇
  1999年   6520篇
  1998年   5404篇
  1997年   5476篇
  1996年   5161篇
  1995年   5021篇
  1994年   5093篇
  1993年   4661篇
  1992年   5385篇
  1991年   5406篇
  1990年   5090篇
  1989年   4982篇
  1988年   5050篇
  1987年   4947篇
  1986年   4645篇
  1985年   6478篇
  1984年   6752篇
  1983年   5560篇
  1982年   5809篇
  1981年   5659篇
  1980年   5575篇
  1979年   5560篇
  1978年   5919篇
  1977年   5849篇
  1976年   5872篇
  1975年   5526篇
  1974年   5478篇
  1973年   5698篇
  1972年   3839篇
  1971年   3018篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The Bcl-2 family small molecule inhibitor navitoclax is being clinically evaluated to treat multiple cancers including lymphoid malignancies and small cell lung cancer. A sensitive and reliable method was developed to quantitate navitoclax in human plasma using liquid chromatography with tandem mass spectrometry with which to perform detailed pharmacokinetic studies. Sample preparation involved protein precipitation using acetonitrile. Separation of navitoclax and the internal standard, navitoclax-d8, was achieved with a Waters Acquity UPLC BEH C18 column using isocratic flow over a 3 min total analytical run time. A SCIEX 4500 triple quadrupole mass spectrometer operated in positive electrospray ionization mode was used for the detection of navitoclax. The assay range was 5–5,000 ng/ml and proved to be accurate (89.5–104.9%) and precise (CV ≤ 11%). Long-term frozen plasma stability for navitoclax at −70°C was at least 43 months. The method was applied for the measurement of total plasma concentration of navitoclax in a patient receiving a 250 mg daily oral dose.  相似文献   
42.
43.
44.
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   
45.
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   
46.
Yang  T. L.  Kao  C. L.  Kuo  C. E.  Yeh  H. C.  Li  W. J.  Li  H. T.  Chen  C. Y. 《Chemistry of Natural Compounds》2022,58(5):825-827
Chemistry of Natural Compounds - A novel bibenzyl derivative, hydrangchinenin (1), was isolated from the stems of Hydrangea chinensis Maxim. (Hydrangeaceae). Its structure was determined on the...  相似文献   
47.
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   
48.
Moscow University Chemistry Bulletin - This review is devoted to the development, properties, and application of biosensors based on graphene nanomaterials. It is shown that such biosensors are...  相似文献   
49.
Fan  K.  Lu  R. S.  Liang  K. K.  Hou  Z. C. 《High Energy Chemistry》2022,56(4):264-269
High Energy Chemistry - Modification of Polyvinylidene fluoride (PVDF) by radiation grafting is a research hotspot in recent years. In this study, the monomer 2-Hydroxyethyl methacrylate (HEMA) was...  相似文献   
50.
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   
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