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   12017篇
  免费   549篇
  国内免费   90篇
化学   8059篇
晶体学   45篇
力学   344篇
数学   2261篇
物理学   1947篇
  2023年   94篇
  2022年   188篇
  2021年   374篇
  2020年   282篇
  2019年   288篇
  2018年   259篇
  2017年   222篇
  2016年   494篇
  2015年   467篇
  2014年   486篇
  2013年   744篇
  2012年   842篇
  2011年   981篇
  2010年   587篇
  2009年   494篇
  2008年   819篇
  2007年   746篇
  2006年   717篇
  2005年   632篇
  2004年   526篇
  2003年   396篇
  2002年   387篇
  2001年   131篇
  2000年   114篇
  1999年   104篇
  1998年   116篇
  1997年   120篇
  1996年   107篇
  1995年   81篇
  1994年   77篇
  1993年   67篇
  1992年   63篇
  1991年   60篇
  1990年   40篇
  1989年   32篇
  1988年   32篇
  1987年   38篇
  1986年   35篇
  1985年   49篇
  1984年   53篇
  1983年   30篇
  1982年   40篇
  1981年   34篇
  1980年   31篇
  1979年   27篇
  1978年   32篇
  1977年   24篇
  1976年   11篇
  1973年   16篇
  1972年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Journal of Dynamics and Differential Equations - In this paper we focus on a class of symmetric vector fields in the context of singularly perturbed fast-slow dynamical systems. Our main question...  相似文献   
2.
3.
Journal of Thermal Analysis and Calorimetry - The aim of this work is to synthesize and characterize a new structured silver–clay dried, calcined or sintered at different temperatures...  相似文献   
4.
5.
Meccanica - Fiber reinforced materials are used in assorted engineering application and for this reason, new additive manufacturing technologies have been developed for this type of materials. With...  相似文献   
6.
Journal of Solid State Electrochemistry - In this study, galvanostatic electrolysis, through the use of the platinum supported on Ti (Ti/Pt) and Ti/TiO2-nanotubes/PbO2 anodes, was conducted in an...  相似文献   
7.
8.
9.
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   
10.
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   
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