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   7697篇
  免费   263篇
  国内免费   110篇
化学   5722篇
晶体学   50篇
力学   402篇
数学   750篇
物理学   1146篇
  2024年   71篇
  2023年   67篇
  2022年   282篇
  2021年   375篇
  2020年   395篇
  2019年   403篇
  2018年   374篇
  2017年   363篇
  2016年   497篇
  2015年   349篇
  2014年   459篇
  2013年   838篇
  2012年   636篇
  2011年   554篇
  2010年   357篇
  2009年   347篇
  2008年   348篇
  2007年   297篇
  2006年   205篇
  2005年   177篇
  2004年   120篇
  2003年   117篇
  2002年   96篇
  2001年   32篇
  2000年   18篇
  1999年   26篇
  1998年   19篇
  1997年   21篇
  1996年   21篇
  1995年   10篇
  1994年   14篇
  1993年   10篇
  1992年   13篇
  1991年   10篇
  1990年   10篇
  1989年   9篇
  1988年   6篇
  1987年   14篇
  1986年   5篇
  1985年   12篇
  1984年   14篇
  1982年   14篇
  1981年   7篇
  1980年   15篇
  1979年   7篇
  1978年   8篇
  1977年   4篇
  1976年   5篇
  1973年   3篇
  1971年   3篇
排序方式: 共有8070条查询结果,搜索用时 15 毫秒
111.
Research on Chemical Intermediates - In this paper, tributyl(carboxymethyl)phosphonium bromotrichloroferrate as a new magnetic ionic liquid bearing acetic acid tags was synthesized and...  相似文献   
112.
Structural Chemistry - A new series of 4-oxobenzo[d]1,2,3-triazin-pyridinium-phenylacetamide hybrids 8a–p was designed, synthesized, and screened as the potential cholinesterase inhibitors...  相似文献   
113.
Mohammad A  Fatima N  Tiwari S 《Talanta》1992,39(2):159-171
Trituration and capillary solid-state spot-tests for 25 anions with a number of organic and inorganic reagents have been examined. A comparative study of the corresponding reactions in solution has also been made. Incorporation of a glass-wool plug in the capillary improves the selectivity. Schemes are presented for possible use of the technique.  相似文献   
114.
115.
116.
Russian Journal of Applied Chemistry - Titanium dioxide (TiO2) is widely used in the paint industry as a white pigment. To reduce the high cost of TiO2, mineral fillers such as different calcites...  相似文献   
117.
JPC – Journal of Planar Chromatography – Modern TLC - A simple and robust thin-layer chromatography (TLC) method has been developed and validated for the simultaneous quantitative...  相似文献   
118.
Microchimica Acta - A carbon paste electrode (CPE) was modified with graphene and ethyl 2-(4-ferrocenyl-[1,2,3]triazol-1-yl) acetate (EFTA) and used for electrocatalytic oxidation of levodopa....  相似文献   
119.
    
Li‐ and Mn‐rich layered oxides are among the most promising cathode materials for Li‐ion batteries with high theoretical energy density. Its practical application is, however, hampered by the capacity and voltage fade after long cycling. Herein, a finite difference method for near‐edge structure (FDMNES) code was combined with in situ X‐ray absorption spectroscopy (XAS) and transmission electron microscopy/electron energy loss spectroscopy (TEM/EELS) to investigate the evolution of transition metals (TMs) in fresh and heavily cycled electrodes. Theoretical modeling reveals a recurring partially reversible LiMn2O4‐like sub‐nanodomain formation/dissolution process during each charge/discharge, which accumulates gradually and accounts for the Mn phase transition. From the modeling of spectra and maps of the valence state over large regions of the cathodes, it was found that the phase change is size‐dependent. After prolonged cycling, the TMs displayed different levels of inactivity.  相似文献   
120.
Chitosan–starch blend films (thickness 0.2 mm) of different composition were prepared by casting and their mechanical properties were studied. To improve the properties of chitosan–starch films, glycerol and mustard oil of different composition were used. Chitosan–starch films, incorporated with glycerol and mustard oil, were further modified with monomer 2-hydroxyethyl methacrylate (HEMA) using gamma radiation. The modified films showed improvement in both tensile strength and elongation at break than the pure chitosan–starch films. Water uptake of the films reduced significantly than the pure chitosan–starch film. Thermo gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) showed that the modified films experience less thermal degradation than the pure films. Scanning electron microscopy (SEM) and FTIR were used to investigate the morphology and molecular interaction of the blend film, respectively.  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