全文获取类型
收费全文 | 3126篇 |
免费 | 92篇 |
国内免费 | 9篇 |
专业分类
化学 | 2473篇 |
晶体学 | 31篇 |
力学 | 45篇 |
数学 | 286篇 |
物理学 | 392篇 |
出版年
2023年 | 17篇 |
2022年 | 44篇 |
2021年 | 70篇 |
2020年 | 55篇 |
2019年 | 70篇 |
2018年 | 40篇 |
2017年 | 32篇 |
2016年 | 91篇 |
2015年 | 74篇 |
2014年 | 82篇 |
2013年 | 156篇 |
2012年 | 214篇 |
2011年 | 255篇 |
2010年 | 144篇 |
2009年 | 108篇 |
2008年 | 226篇 |
2007年 | 210篇 |
2006年 | 216篇 |
2005年 | 162篇 |
2004年 | 140篇 |
2003年 | 106篇 |
2002年 | 116篇 |
2001年 | 52篇 |
2000年 | 46篇 |
1999年 | 37篇 |
1998年 | 30篇 |
1997年 | 23篇 |
1996年 | 31篇 |
1995年 | 34篇 |
1994年 | 32篇 |
1993年 | 31篇 |
1992年 | 25篇 |
1991年 | 22篇 |
1990年 | 27篇 |
1989年 | 20篇 |
1988年 | 18篇 |
1987年 | 21篇 |
1986年 | 18篇 |
1985年 | 11篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1978年 | 6篇 |
1976年 | 11篇 |
1974年 | 6篇 |
1972年 | 6篇 |
1970年 | 5篇 |
1969年 | 5篇 |
排序方式: 共有3227条查询结果,搜索用时 0 毫秒
971.
Bradley M. Berven Richard O. Oviasuyi Robert J. Klassen Mike Idacavage Elizabeth R. Gillies Paul J. Ragogna 《Journal of polymer science. Part A, Polymer chemistry》2013,51(3):499-508
The first anion with four polymerizable groups has been synthesized and used to produce durable, crosslinked polyelectrolyte (PE) coatings in a single step. Sodium tetrakis(4‐vinylphenyl)borate (NaBSty4) was produced by the reaction of BCl3 and the Grignard of 4‐bromostyrene. The full series of borates NaBPhxSty4?x, x = 1?3, were also synthesized analogously by reaction of the styryl‐Grignard and PhBCl2, Ph2BCl, or Ph3B. Anion exchange of the borates with tributyl 4‐vinylbenzylphosphonium chloride gave a family of organic salts developed for applications in photopolymerized coatings. The percent UV cure of the polymer films was determined by infrared spectroscopy and this relative level of curing was corroborated by differential scanning calorimetry analysis. The degree of crosslinking imparted to the polymer films by the different monomers has resulted in varied mechanical properties, which were probed by diamond tip scratch tests and nanoindentation. These clearly demonstrated that as the number of polymerizable groups increased, the film hardness increased correspondingly. The final hardness of the films exceeds those of other related systems and identifies styryl borates as viable crosslinking additives in UV curable technologies, especially in the production of durable PE films. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
972.
973.
Lorraine M. Deck Jacob A. Greenberg Taylor S. Busby Elizabeth R. Bright Lisa J. Whalen David L. Vander Jagt Robert E. Royer 《Tetrahedron letters》2013
As part of ongoing research to investigate structural requirements for lactate dehydrogenase inhibition by highly substituted naphthoic and indenoic acids, certain naphthalene and indene precursors to those types of compounds are required. Described here are efficient preparations of 1-naphthoic acid precursors 6-benzyl-2,3-dimethoxy-1-propylnaphthalenes, including compounds with substituted benzyl groups and 7-benzyl-2,3-dimethoxy-1-propylnaphthalene. Also described are the syntheses of indenoic acid precursors 2-benzyl-5,6-dimethoxy-7-propyl-1H-indenes, including compounds with substituted benzyl groups. These compounds were made from the key intermediates 6,7-dimethoxy-5-propyl-1-tetralone, 6,7-dimethoxy-8-propyl-1-tetralone, and 5,6-dimethoxy-4-propyl-1-indanone. 相似文献
974.
Prof. Dr. Valentine G. Nenajdenko Dr. Aleksey A. Goldberg Dr. Vasily M. Muzalevskiy Prof. Dr. Elizabeth S. Balenkova Dr. Aleksey V. Shastin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(7):2370-2383
A convenient and simple three‐step pathway to the new family of CF2CF2S‐bridged alkanes and CF2S‐, CF2O‐bridged alkenes and alkynes was elaborated by using catalytic olefination reaction as a key step of the synthetic sequence. The obtained compounds revealed attractive liquid crystalline characteristics. 相似文献
975.
976.
977.
978.
979.
980.
Massimiliano Lamberto Elizabeth E. Rastede Françisco M. Raymo 《Tetrahedron letters》2010,51(42):5618-5620
Viologens are generally synthesized by N-alkylating 4,4′-bipyridine with alkyl halides. Under conventional heating conditions, however, their synthesis suffers from long reaction times and, often, low yields. In this work, symmetric and asymmetric viologens were synthesized under the assistance of microwave irradiation in good to excellent yields and in short reaction times. 相似文献