全文获取类型
收费全文 | 219篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
化学 | 98篇 |
晶体学 | 2篇 |
力学 | 29篇 |
数学 | 52篇 |
物理学 | 39篇 |
出版年
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 11篇 |
2012年 | 8篇 |
2011年 | 22篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 24篇 |
2007年 | 18篇 |
2006年 | 13篇 |
2005年 | 10篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 3篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1979年 | 3篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有220条查询结果,搜索用时 15 毫秒
1.
The kinetics of hydrolysis of a series of N-acylsulfamate esters p-XC6H4OSO2NHCOR as models for more complex, biologically important compounds has been examined. Structure-reactivity, solvent-reactivity, thermodynamic data, etc. support a bimolecular mechanism involving water in the transition state (TS). 相似文献
2.
Douglas R. Hurst Kristen L. French April J. Angel Angela R. Williams Mary E. Rampey Tina S. Guion Kam W. Chan Camille M. Kassis Shannon L. Studer Martinez Charles F. Beam 《Journal of heterocyclic chemistry》1998,35(6):1357-1359
Several acetoacetanilides were trilithiated in excess lithium diisopropylamide, and the resulting polylithiated intermediates were regioselectively condensed with lithiated methyl salicylates followed by acid cyclization to substituted 4-oxo-N-aryl-4H-1-benzopyran-2-acetamides (benzopyranone-2-acetamides). 相似文献
3.
Colette Deschamps-Vallet Jean-Baptiste Ilots Michle Meyer-Dayan Darius Molho 《Journal of heterocyclic chemistry》1982,19(1):97-101
3-Phenyl-1-benzopyrylium percholorates 1a, 1i react exculusively at C-2 with ethanol and isopropyl alcohol, affording mixed acetals 2a, 3a, 3i . Aqueous ammonia gives symmetrical secondary amines 4a, 4b or bis(3-phenyl-2H-1-benzopyran-2-yl)amines, while with aqueous aliphatic amines (40%) bis-acetals 5a, 5b or 2,2′-oxy-bis(3-phenyl-2H-1-benzopyrans) are characterized. In some other acidic conditions, 5a and 5b are also obtained. 相似文献
4.
J. Muntasell M. Barrio J. Font D. O. López J. Li. Tamarit M. A. Cuevas Diarte J. Guion M. Teisseire N. B. Chanh Y. Haget 《Journal of Thermal Analysis and Calorimetry》1991,37(10):2395-2398
The paper gives some comments about the potential use of plastic crystals in energy storage. The main point deals with the possibilities of binary solid solution formation. Three binary phase diagrams in the pentaerythritol series are commented on. 相似文献
5.
A series of new polyfluorinated dienes 3, containing the novel -CFCHCHCF-, pattern has been synthesized (50–70% yields) by reacting perfluoroalkyl iodides with perfluoroalkyl-ethylenes in the presence of copper. The monoalkenes RfCFCHCH2CF2R′f and the saturated compounds RfCF2CH2CH2CF2R′f were obtained by varying the experimental conditions. The 1H and 19F NMR spectra are analysed and the reaction mechanism is discussed. 相似文献
6.
Hydrosilylation is an important process, not only in the silicon industry to produce silicon polymers, but also in fine chemistry. In this review, the development of rhenium-based catalysts for the hydrosilylation of unsaturated bonds in carbonyl-, cyano-, nitro-, carboxylic acid derivatives and alkenes is summarized. Mechanisms of rhenium-catalyzed hydrosilylation are discussed. 相似文献
7.
8.
This work describes a new microfluidic device developed for the rapid screening of solubility diagrams. In several parallel channels, hundreds of nanolitre volume droplets of a given solution are first stored with a gradual variation in the solute concentration. Then, the application of a temperature gradient along these channels enables us to read directly and quantitatively phase diagrams, concentration vs. temperature. We show, using a solution of adipic acid, that we can measure ten points of the solubility curve in less than 1 hr and with only 250 microL of solution. 相似文献
9.
Linda Axelsson Jean-Baptiste VeronJonas Sävmarker Jonas LindhLuke R. Odell Mats Larhed 《Tetrahedron letters》2014
A palladium(II)-catalyzed decarboxylative protocol for the synthesis of aryl ketones has been developed. The addition of TFA was shown to improve the reaction yield and employing THF as solvent enabled the use of solid nitriles and in only a small excess. Using this method, five different benzoic acids reacted with a wide range of nitriles to produce 29 diverse (hetero)aryl ketone derivatives in up to 94% yield. 相似文献
10.
Madlene U. Koller Katrina L. Peariso Tina S. Guion Shannon Studer Martinez Charles F. Beam 《合成通讯》2013,43(19):2963-2974
2-, 3-, or 4-Picolyllithium was prepared in excess lithium diiso-propylamide and condensed with several hydroxy-benzaldehydes and 4-hydroxy-acetophenone to afford substituted hydroxyphenyl-pyridyl-ethanols and α-hydroxyphenyl-α-methylpyridineethanols. In two instances. 3-picolyllithium condensed with aldehydes to presumably form the hydroxyphenyl-pyridyl-ethanol, which underwent linear dehydration to the substituted pyridyl-ethylenyl-phenol. 相似文献