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   536756篇
  免费   6644篇
  国内免费   1519篇
化学   288573篇
晶体学   7735篇
力学   23623篇
综合类   18篇
数学   62472篇
物理学   162498篇
  2021年   4377篇
  2020年   4915篇
  2019年   5277篇
  2018年   6795篇
  2017年   6650篇
  2016年   10359篇
  2015年   6549篇
  2014年   10045篇
  2013年   24396篇
  2012年   18721篇
  2011年   23113篇
  2010年   16143篇
  2009年   16022篇
  2008年   21168篇
  2007年   21124篇
  2006年   19692篇
  2005年   17721篇
  2004年   16313篇
  2003年   14317篇
  2002年   14231篇
  2001年   15991篇
  2000年   12153篇
  1999年   9504篇
  1998年   8028篇
  1997年   7701篇
  1996年   7412篇
  1995年   6695篇
  1994年   6650篇
  1993年   6370篇
  1992年   7169篇
  1991年   7271篇
  1990年   6901篇
  1989年   6732篇
  1988年   6754篇
  1987年   6597篇
  1986年   6245篇
  1985年   8076篇
  1984年   8306篇
  1983年   6684篇
  1982年   6884篇
  1981年   6758篇
  1980年   6317篇
  1979年   6848篇
  1978年   7075篇
  1977年   6868篇
  1976年   6865篇
  1975年   6419篇
  1974年   6461篇
  1973年   6400篇
  1972年   4495篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
171.
172.
173.
174.
175.
Journal of Solid State Electrochemistry - Oxygen transport in ceramic oxide materials has been actively explored over the past decades. This is due to the desire to design high-temperature...  相似文献   
176.
A fully quantitative theory of the relationship between protein conformation and optical spectroscopy would facilitate deeper insights into biophysical and simulation studies of protein dynamics and folding. In contrast to intense bands in the far-ultraviolet, near-UV bands are much weaker and have been challenging to compute theoretically. We report some advances in the accuracy of calculations in the near-UV, which were realised through the consideration of the vibrational structure of the electronic transitions of aromatic side chains.  相似文献   
177.
Russian Journal of General Chemistry - The technical legal acts that regulate the quality and safety parameters of mineral waters out were analyzed. Seven samples of mineral waters produced in...  相似文献   
178.
Stozharov  V. M. 《Technical Physics》2020,65(7):1071-1075
Technical Physics - Glasslike dielectrics are investigated by methods of plasmon dispersion and asymmetry of the number of localized electrons in the region in which total external reflection of...  相似文献   
179.
Metabolomics is a potential tool for the discovery of new biomarkers in the early diagnosis of diseases. An ultra-fast gas chromatography system equipped to an electronic nose detector (FGC eNose) was used to identify the metabolomic profile of Volatile Organic Compounds (VOCs) in type 2 diabetes (T2D) urine from Mexican population. A cross-sectional, comparative, and clinical study with translational approach was performed. We recruited twenty T2D patients and twenty-one healthy subjects. Urine samples were taken and analyzed by FGC eNose. Eighty-eight compounds were identified through Kovats's indexes. A natural variation of 30% between the metabolites, expressed by study groups, was observed in Principal Component 1 and 2 with a significant difference (p < 0.001). The model, performed through a Canonical Analysis of Principal coordinated (CAP), allowed a correct classification of 84.6% between healthy and T2D patients, with a 15.4% error. The metabolites 2-propenal, 2-propanol, butane- 2,3-dione and 2-methylpropanal, were increased in patients with T2D, and they were strongly correlated with discrimination between clinically healthy people and T2D patients. This study identified metabolites in urine through FGC eNose that can be used as biomarkers in the identification of T2D patients. However, more studies are needed for its implementation in clinical practice.  相似文献   
180.
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