全文获取类型
收费全文 | 412篇 |
免费 | 82篇 |
国内免费 | 7篇 |
专业分类
化学 | 497篇 |
物理学 | 4篇 |
出版年
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 23篇 |
2019年 | 16篇 |
2018年 | 15篇 |
2017年 | 12篇 |
2016年 | 34篇 |
2015年 | 23篇 |
2014年 | 23篇 |
2013年 | 59篇 |
2012年 | 30篇 |
2011年 | 27篇 |
2010年 | 41篇 |
2009年 | 19篇 |
2008年 | 21篇 |
2007年 | 31篇 |
2006年 | 17篇 |
2005年 | 17篇 |
2004年 | 8篇 |
2003年 | 32篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1995年 | 2篇 |
1987年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有501条查询结果,搜索用时 15 毫秒
1.
Dr. Felipe L. Coelho Eduarda S. Gil Dr. Paulo F. B. Gonçalves Dr. Leandra F. Campo Dr. Paulo H. Schneider 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(34):8157-8162
In this work, a series of 2-chalcogenylindoles was synthesized by an efficient methodology, starting from chalcogenoalkynes, including a previously unreported tellurium indole derivative. For the first time, these 2-substituted chalcogenylindoles were obtained in the absence of metal catalyst or base, under thermal conditions only. In addition, the results described herein represent a methodology with inverse regioselectivity for the chalcogen functionalization of indoles. 相似文献
2.
Chan Sik Cho Jun Ho KimHeung-Jin Choi Tae-Jeong KimSang Chul Shim 《Tetrahedron letters》2003,44(14):2975-2977
Anilines react with epoxides in dioxane at 180°C in the presence of a catalytic amount of a ruthenium catalyst along with tin(II) chloride to afford 2-substituted indoles in moderate to good yields. 相似文献
3.
Giorgio AbbiatiAntonio Arcadi Egle BeccalliElisabetta Rossi 《Tetrahedron letters》2003,44(28):5331-5334
Intramolecular cyclization of 2-acyl-1-propargyl-1H-indoles in the presence of ammonia provides an easy entry to pyrazino[1,2-a]indole nucleus. 相似文献
4.
5.
N. M. Przheval'skii N. S. Skvortsova I. V. Magedov 《Chemistry of Heterocyclic Compounds》2003,39(2):161-167
Arylhydrazones were obtained by the reaction of arylhydrazines with -(N-acylamino)acetophenones and were converted into 3-(N-acylamino)-2-phenylindoles with substituents at positions 1, 5, 6, and 7 by Fischer cyclization. 相似文献
6.
Kozhevnikov D. N. Kataeva N. N. Rusinov V. L. Chupakhin O. N. 《Russian Chemical Bulletin》2004,53(6):1295-1300
A simple procedure was developed for the synthesis of 1,2,4-triazines and their 4-oxides containing the ClCH2, Cl2CH, or CCl3 group at position 3 by cyclization of 2-aryl-2-hydrazono-1-oximinoethanes with the corresponding chloroacetonitriles. The reaction pathway depends on the number of halogen atoms in the acetonitrile used. The reactions with trichloroacetonitrile, monochloroacetonitrile, and dichloroacetonitrile afford 3-trichloromethyl-1,2,4-triazines, 3-chloromethyl-1,2,4-triazine 4-oxides, and a mixture of the corresponding dichloromethyltriazines and their 4-oxides, respectively. The reactions of 3-trichloromethyl-1,2,4-triazines with indoles and phenols are accompanied by tele-substitution with elimination of halogen from the trichloromethyl group to give 5-indolyl- (or 5-hydroxyphenyl)-3-dichloromethyl-1,2,4-triazines. 相似文献
7.
A novel indole alkaloid, viz., macrodasine A, incorporating fused spirocyclic tetrahydrofuran rings onto a macroline-like moiety, was obtained from a Malayan Alstonia species. The structure, which is also notable for the presence of an unprecedented spiroacetal moiety in an indole alkaloid, was established by spectroscopic analysis. 相似文献
8.
Béla Pete 《Tetrahedron letters》2003,44(12):2537-2539
Valuable new synthetic intermediates, 4- or 6-chloromethyl-1H-indole-2-carboxylates, were prepared by the elimination of SO2 from 2-ethoxycarbonyl-1H-indole-4- or 6-methanesulfonic acids, respectively, which are easily accessible by Fischer-type indolization. 相似文献
9.
M. A. Bastrakov A. M. Starosotnikov V. V. Kachala E. N. Nesterova S. A. Shevelev 《Russian Chemical Bulletin》2007,56(8):1603-1607
Reaction of different anionic S-nucleophiles with 3-R-2-aryl-4,6-dinitroindoles led to a regiospecific nucleophilic substitution
of the nitro group in position 4 with 6-NO2 group remaining intact. The representatives of some peri-annulated polycyclic systems were synthesized on the basis of the substitution products.
Dedicated to Academician V. A. Tartakovsky in honor of his 75th anniversary.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1543–1547, August, 2007. 相似文献
10.
Reflux of equimolecular amounts 2-aminobenzylamine and isatins in acetic acid produced indolo[3,2-c]quinolin-6-ones in good yields. A proposed mechanism involving initial formation of a spiro compound is given. This isolable intermediate subsequently rearranges via a sequential isocyanate ring opening and a cyclisation process to a urea derivative which finally cyclized to the indolo[3,2-c]quinolin-6-ones. The urea derivative could be prepared separately and cyclized selectively to indolo[3,2-c]quinolin-6-one. Reaction of N-acetylisatin with 2-aminobenzylamine at room temperature yielded the 1,4-benzodiazepinone 3-(2-acetamidophenyl)-1,5-dihydro-1,4-benzodiazepin-2-one whereas its isomer 2(2-acetamidophenyl)-4,5-dihydro-1,4-benzodiazepin-3-one was obtained from 2-(2-acetylaminophenyl)-N-(2-aminobenzyl)-2-oxoacetamide in acetic acid at room temperature.The previously unknown linear isomer of indolo[3,2-c]quinolin-6-one, i.e. indolo[2,3-b]quinolin-11-one, has been prepared by thermal (260°C) cyclization of methyl 2-phenylamino indole-3-carboxylate, which in turn was prepared in two steps from methyl indole-3-carboxylate. 相似文献