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   551篇
  免费   37篇
  国内免费   21篇
化学   389篇
晶体学   1篇
力学   43篇
数学   71篇
物理学   105篇
  2023年   9篇
  2022年   13篇
  2021年   22篇
  2020年   35篇
  2019年   29篇
  2018年   45篇
  2017年   27篇
  2016年   66篇
  2015年   28篇
  2014年   45篇
  2013年   59篇
  2012年   39篇
  2011年   29篇
  2010年   32篇
  2009年   21篇
  2008年   23篇
  2007年   20篇
  2006年   20篇
  2005年   15篇
  2004年   9篇
  2003年   5篇
  2002年   8篇
  2001年   1篇
  1999年   1篇
  1998年   1篇
  1997年   1篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1990年   1篇
  1989年   1篇
  1985年   1篇
排序方式: 共有609条查询结果,搜索用时 15 毫秒
1.
2.
Journal of Thermal Analysis and Calorimetry - Artificial neural network/kriging interpolation method optimization method which is evaluated concerned the hybrid nanofluid composed of iron oxide...  相似文献   
3.
Journal of Thermal Analysis and Calorimetry - In this study, the efficacy of incorporating phase change material (PCM) into the building walls on the annual heat transfer reduction is examined....  相似文献   
4.
A new ammonia optical sensor was designed using bis(acetylacetoneethylendiamine)tributylphosphin cobalt(III) tetraphenylborate complex, coated on transparent triacetylcellulose film as membrane. The change in the absorbance of the optode at the maximum wavelength of 408 nm was related to ammonia concentration in aqueous samples. A buffer solution with a pH of 9 (sodium borate-HCl) was used. The optode was fully regenerated in pH 2. The linear dynamic range for determination of ammonia was 3.3 x 10(-4) to 6.9 x 10(-3) mol l(-1) with a detection limit of 5.0 x 10(-5) mol l(-1) and a response time range of 4 - 6 min. This membrane was successfully applied for determination of ammonia in drinking water.  相似文献   
5.
Polyfunctional quinolines were synthesized using Friedlander method catalyzed by molecular iodine in high yields at 60 °C under solvent‐free conditions.  相似文献   
6.
7.
A one-pot synthesis of substituted imidazoles is described. The cornerstone of this methodology involves the thiazolium-catalyzed addition of an aldehyde to an acyl imine to generate the corresponding alpha-ketoamide in situ followed by ring closure to the imidazole in a one-pot sequence. The extension of this methodology to the one-pot synthesis of substituted oxazoles and thiazoles is also described. [reaction: see text]  相似文献   
8.
Tribromoisocyanuric acid (TBCA) and Oxone®‐MX systems were used as effective oxidizing agents for the oxidation of thiols to their corresponding disulfides under mild conditions at room temperature with good to excellent yields.  相似文献   
9.
Nitro aromatic compound can be obtained in high yields via nitration of aromatic compound with wet carbon-based solid acid and NaNO_3 under solvent free oxidation at room temperature.  相似文献   
10.
The equilibrium constants and the thermodynamic parameters were spectrophotometrically measured for the 1:1 adduct formation of [Co(Salen)(PPh3)]ClO4.H2O, and [Co(7,7′-Me2Salen)(PPh3)]ClO4.H2O as acceptors, with P(OR)3 (R = methyl, ethyl, and i-propyl) as donors, in acetonitrile (CH3CN) and dimethylformamide (DMF) as solvents at constant ionic strength (I = 0.1 M NaClO4), and various temperatures (t = 10–50 °C). Our results revealed the following trends: stability of the cobalt(III) Schiff base complexes toward a given phosphite donor, [Co(7,7′-Me2Salen)(PPh3)]+ < [Co(Salen)(PPh3)]+; binding of the donors (phosphites) toward a given cobalt(III) Schiff base complex, P(OEt)3 > P(OMe)3 > P(O-iPr)3; influence of solvent on the stability of a given cobalt(III) Schiff base complex toward a given phosphite donor, CH3CN < DMF.  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