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   125篇
  免费   15篇
  国内免费   1篇
化学   129篇
晶体学   2篇
数学   3篇
物理学   7篇
  2022年   4篇
  2021年   3篇
  2020年   11篇
  2019年   5篇
  2018年   6篇
  2017年   4篇
  2016年   6篇
  2015年   6篇
  2014年   8篇
  2013年   9篇
  2012年   7篇
  2011年   1篇
  2010年   8篇
  2009年   4篇
  2008年   8篇
  2007年   4篇
  2006年   2篇
  2005年   2篇
  2003年   3篇
  2002年   1篇
  2001年   1篇
  1999年   3篇
  1998年   9篇
  1997年   1篇
  1995年   1篇
  1993年   2篇
  1991年   2篇
  1990年   1篇
  1989年   2篇
  1988年   2篇
  1987年   1篇
  1986年   3篇
  1985年   2篇
  1984年   2篇
  1983年   2篇
  1977年   1篇
  1976年   2篇
  1975年   1篇
  1961年   1篇
排序方式: 共有141条查询结果,搜索用时 15 毫秒
1.
Research on Chemical Intermediates - The starting 3-(3,5-dimethyl-1H-pyrazol-1-yl)-3-oxopropanenitrile (1) reacts with phenyl isothiocyanate and ethyl bromoacetate to give the corresponding...  相似文献   
2.
3.
Several new pyridine derivatives were prepared via reaction of enaminoketones 1a , 1b , 1c , 1d with active hydrogen reagents. Reaction of the enaminoketones 1a , 1b , 1c with 4‐acetyl‐1,5‐dimethyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐one 2a yielded the pyridines 3a , 3b , 3c . Condensation of the enaminonitrile 1d with compounds 2b , 2c , 2d and compound 8 gave the pyridine derivatives 6a , 6b , 6c and 10 respectively. Also, (3‐(dimethylamino)acryloyl)‐2H‐chromen‐2‐one 1a reacted with active methylenes in diethyl 3‐oxopentanedioate 12 and 4‐methyl‐6‐oxo‐2‐thioxo‐1,2,5,6‐tetrahydropyridine‐3‐carbonitrile 15 to afford the pyridine derivatives 14 and 16 respectively.  相似文献   
4.
Reaction of 3,6‐dichlorocarbazole with propargyl bromide in the presence of a basic medium gave an N‐propargylated carbazole. The latter compound was converted into molecular architectures containing 1,2,3‐triazole moiety through Cu(I)‐catalyzed 1,3‐cycloaddition reaction with different azides. Similarly, 2‐azidomethyl benzothiazole was cliched with N‐Boc‐protected N´‐propargyl glutamate to give the biomolecule 2‐triazolylmethyl product.  相似文献   
5.
The xylidines 1a , 1b undergo condensation with ethyl cyanoacetate 2 and ethyl benzoyl acetate 15 to afford the cyano acetanilides 3a , 3b and the β‐diketones 16a , 16b , respectively. Compounds 3a , 3b react with hydrazine and phenyl hydrazine to afford the azine‐bis derivatives 5a , 5b and 7a , 7b , whereas 16a , 16b react with the same reagents to afford the pyrazolyl amine derivatives 17a , 17b and 18a , 18b , respectively. Compounds 3a , 3b react also with dimethylformamide dimethylacetal to afford the enaminonitriles 8a , 8b , whereas 16a , 16b react with the same reagent to afford only the enaminone 19b . The enaminonitriles 8a , 8b react with hydrazine and phenyl hydrazine to afford also the azine‐bis derivatives 11a , 11b and 14a , 14b , respectively.  相似文献   
6.
Abstract

New spirothiopyran-4-yl indolidene derivatives have been synthesised via a facile one-step method. Structures and reaction mechanisms are also reported and supported by another synthetic route.  相似文献   
7.
A new series of tetrahydroquinoline derivatives having pyrazol and hydrazide moieties were synthesized for the purpose of anticancer cell line evaluation. Syntheses of these compounds were firstly achieved by one pot four reactions. The reaction of 3-amino-tetrahydro-1H-pyrazolo [3,4-b]quinolin with aldehydes, indoline-2,3-dione derivatives to give 9a-c , 11a-c , and 13a,b , respectively. In similar manner for biological comparison, the reactions of compound 5 with the same aldehydes and indoline-2,3-dione derivatives to give 19a-c and 20a-c . The newly synthesized compounds were examined in vitro for their cytotoxic activity against HepG-2 and A549 cancer cells. The compounds 11a-c and 20a-c showed promising activity as anticancer agents against HepG-2 and A549 cancer cells.  相似文献   
8.
Journal of Radioanalytical and Nuclear Chemistry - Nano-silica (Si-AL800) was extracted from the thermally treated rice husk ash by acid leaching route. Coating surface of the extracted silica with...  相似文献   
9.
The newly synthesized ethyl 3‐amino‐5‐phenylpyrazole‐4‐carboxylate 1 was diazotized and coupled with β‐naphthol, active methylene reagents 6 , 9 , 12 , 15 , and the active methine 19 to afford the pyrazolo[5,1‐c]triazines 5 , 8 , 11 , 14 , 17 , 18 , and the pyrazolo[5,1‐ c ]‐1,2,4‐triazoles 21 , 22 , and 23 , respectively. Structures are elucidated and mechanisms are discussed.  相似文献   
10.
Difference in the kinetics of chemiluminescence (CL) and differential scanning calorimetry records for decomposition of originally solid benzoyl peroxide continuing as a melt reaction was outlined. While the main portion of heat measured by DSC is released in the spontaneous decomposition of benzoyl peroxide starting as a homolytic scission of peroxidic bonds, the CL light emission in oxygen comes presumably from the subsequent disproportionation reaction of polyphenyl peroxyl radicals and monitors the induced decomposition of peroxide. Thermogravimetry revealed that oxygen remains partially bound to the products of benzoyl peroxide decomposition.  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