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   339篇
  免费   2篇
  国内免费   13篇
化学   319篇
晶体学   1篇
数学   6篇
物理学   28篇
  2023年   1篇
  2022年   4篇
  2021年   2篇
  2020年   10篇
  2019年   11篇
  2018年   18篇
  2017年   14篇
  2016年   11篇
  2015年   4篇
  2014年   8篇
  2013年   85篇
  2012年   11篇
  2011年   11篇
  2010年   13篇
  2009年   24篇
  2008年   26篇
  2007年   31篇
  2006年   11篇
  2005年   7篇
  2004年   3篇
  2003年   1篇
  2002年   10篇
  2001年   12篇
  2000年   7篇
  1999年   10篇
  1998年   4篇
  1997年   1篇
  1996年   1篇
  1994年   1篇
  1986年   1篇
  1984年   1篇
排序方式: 共有354条查询结果,搜索用时 15 毫秒
41.
Journal of Thermal Analysis and Calorimetry - In recent decades, the growth of heat transfer using nanomaterials in the conventional base fluid has caught the attention of researchers...  相似文献   
42.
Molecular Diversity - A new series of azo chromene dyes were synthesized via a facile cyclocondensation reaction of (E)-1,2-diphenyl-1-diazene and 4-aminocoumarin with 1:2 molar ratio catalyzed by...  相似文献   
43.
44.
Silica‐supported Preyssler nanoparticles (H14[NaP5W30O110])/SiO2 are used as a new and recyclable catalyst for the preparation of 1,3‐diaryl‐5‐spirohexahydropyrimidines via a one‐pot condensation of anilines, formaldehyde, and cyclohexanone.  相似文献   
45.
Only 10 mol% of l-Proline in ethanol proved to be a very efficient catalyst for the one-pot synthesis of a wide variety of highly substituted tetrahydrobenzo[c]acridin-8(7H)-ones at room temperature. The key advantages of this process are high yields, cost effectiveness of the catalyst, easy work-up and the products can be directly recrystallized from hot ethanol.  相似文献   
46.
47.
The reaction of 4-amino-5-ethyl-2H-1,2,4-triazole-3(4H)-thione (AETT, L1) with 2-thiophen carbaldehyde in methanol leads to the corresponding Schiff-base HL1a. The reaction of L1 with AgNO3 in ethanol gives the ionic complex [{[Ag(L1)]NO3}2]n (1). The ionic complex [(PPh3)2Ag(HL1a)2]NO3 · CH3CN (2) can be obtained by the reaction of HL1a with [(PPh3)2Ag]NO3 in methanol and acetonitrile solution, while its reaction with [(PPh3)2PdCl2] in the presence of sodium acetate in methanol leads to the neutral complex [(PPh3)2Pd(L1a)2] · 4MeOH (3). All the compounds were characterized by infrared spectroscopy, elemental analyses as well as by X-ray diffraction studies.  相似文献   
48.
An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, 2-naphthol and urea or amides, in the presence of HClO4-SiO2 as a heterogeneous catalyst. The reactions were carried out under reflux and solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, easy work-up and ecofriendly reaction condition. The catalyst is easily prepared, stable, reusable and efficient under the reaction conditions.  相似文献   
49.
ZnO nanostructures were synthesised in a hydrothermal reaction of zinc acetate in the presence of molybdophosphoric acid (H3[PMo12O40]) as well as its vanadium-substituted acid (H4[PMo11VO40]) at various times, temperatures, and concentrations. The ZnO nanostructures were characterised by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The results demonstrated that the synthesised products are crystalline with a zincite hexagonal phase. Various ZnO nanostructures, such as nanoparticles, microrods, and nanosheets, were produced by changing the experimental conditions. The photocatalytic degradation of methyl orange was also investigated using the ZnO nanoparticles thus prepared. These particles exhibited high performance in the photocatalytic degradation of MO and almost 100 % decolourisation occurred within only 20 min.  相似文献   
50.
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