全文获取类型
收费全文 | 766篇 |
免费 | 19篇 |
国内免费 | 5篇 |
专业分类
化学 | 472篇 |
晶体学 | 23篇 |
力学 | 10篇 |
数学 | 146篇 |
物理学 | 139篇 |
出版年
2023年 | 8篇 |
2022年 | 16篇 |
2021年 | 9篇 |
2020年 | 14篇 |
2019年 | 7篇 |
2016年 | 11篇 |
2015年 | 15篇 |
2014年 | 19篇 |
2013年 | 45篇 |
2012年 | 33篇 |
2011年 | 46篇 |
2010年 | 18篇 |
2009年 | 18篇 |
2008年 | 44篇 |
2007年 | 44篇 |
2006年 | 38篇 |
2005年 | 41篇 |
2004年 | 37篇 |
2003年 | 23篇 |
2002年 | 47篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1993年 | 7篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1978年 | 12篇 |
1977年 | 11篇 |
1976年 | 8篇 |
1975年 | 9篇 |
1974年 | 8篇 |
1973年 | 5篇 |
1969年 | 4篇 |
1968年 | 3篇 |
1967年 | 6篇 |
1966年 | 3篇 |
排序方式: 共有790条查询结果,搜索用时 8 毫秒
781.
Cyclic hypervalent iodine reagents are now frequently used in synthetic organic chemistry, either as oxidants or group-transfer reagents. Vinylbenziodoxol(on)es (VBXs) bearing alkene substituents have been less investigated than the corresponding trifluoromethyl or alkynyl reagents. Nevertheless, since 2016 the development of new synthetic methods to access VBXs has awakened the interest of the synthetic community, leading to new transformations highlighting their unique reactivity as electrophilic alkene synthons. In this review, an overview of the synthesis and applications of VBX reagents will be presented. The review is organized according to the two main classes of VBX reagents reported so far – simple alkyl/aryl-substituted VBXs and heteroatom (S, O, N, X)-substituted VBXs – as they differ significantly from the point of view of synthetic access. 相似文献
782.
783.
784.
785.
Lijuan J. Wang Margaret L. Grapperhaus Barnett S. Pitzele Timothy J. Hagen Kam F. Fok Jeffrey A. Scholten Dale P. Spangler Mihaly V. Toth Gina M. Jerome William M. Moore Pamela T. Manning James A. Sikorski 《Heteroatom Chemistry》2002,13(1):77-83
The efficient syntheses of two new types of conformationally constrained S‐[2‐[(1‐iminoethyl)amino]ethyl]homocysteine derivatives, 1‐amino‐3‐[2[(1‐iminoethyl)amino]ethylthio]cyclobutane carboxylic Acid ( 5 ) and (4S)‐4‐[[2‐[(1‐Iminoethyl)amino]ethyl]thio]‐L‐proline ( 6 ), are reported. These molecules represent the first attempts to probe conformational constraint near the α‐amino acid moiety of known homocysteine‐based inhibitors of nitric oxide synthase. Targets 5 and 6 were evaluated as potential inhibitors of the three human isoforms of nitric oxide synthase. © 2002 John Wiley & Sons, Inc. Heteroatom Chem 13:77–83, 2002; DOI 10.1002/hc.1109 相似文献
786.
J. Mary Linet S. Dinakaran S. Mary Navis Priya S. Jerome Das 《Crystal Research and Technology》2009,44(2):173-176
Semiorganic single crystals of thiosemicarbazide cadmium chloride (TSCCC) and mercury ions doped thiosemicarbazide cadmium chloride were synthesized by slow solvent evaporation technique. The grown crystals were subjected to powder X‐ray analysis and both the crystals were found to crystallize in the monoclinic system. EDAX analysis was carried out for chemical analysis of the grown crystals. The UV‐Vis‐NIR spectrum shows that both the materials have wide transparency window in the visible and near IR region. The dielectric studies were carried out to estimate the dielectric constant and dielectric loss with respect to frequency for both the crystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
787.
788.
789.
790.