全文获取类型
收费全文 | 1486篇 |
免费 | 65篇 |
国内免费 | 4篇 |
专业分类
化学 | 1301篇 |
晶体学 | 4篇 |
力学 | 9篇 |
数学 | 107篇 |
物理学 | 134篇 |
出版年
2024年 | 1篇 |
2023年 | 20篇 |
2022年 | 29篇 |
2021年 | 40篇 |
2020年 | 39篇 |
2019年 | 26篇 |
2018年 | 28篇 |
2017年 | 26篇 |
2016年 | 51篇 |
2015年 | 60篇 |
2014年 | 71篇 |
2013年 | 90篇 |
2012年 | 104篇 |
2011年 | 103篇 |
2010年 | 61篇 |
2009年 | 56篇 |
2008年 | 94篇 |
2007年 | 97篇 |
2006年 | 87篇 |
2005年 | 78篇 |
2004年 | 57篇 |
2003年 | 44篇 |
2002年 | 58篇 |
2001年 | 13篇 |
2000年 | 28篇 |
1999年 | 17篇 |
1998年 | 14篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 18篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 11篇 |
1991年 | 12篇 |
1990年 | 10篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 1篇 |
1981年 | 6篇 |
1980年 | 1篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有1555条查询结果,搜索用时 15 毫秒
961.
Petra M. Erne Laura S. vanBezouwen Peter tacko Derk Jan vanDijken Jiawen Chen Marc C. A. Stuart Egbert J. Boekema Ben L. Feringa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(50):15337-15342
The facile assembly of higher‐order nanoarchitectures from simple building blocks is demonstrated by the loading of vesicles into soft amphiphilic nanotubes using osmosis. The nanotubes are constructed from rigid interdigitated bilayers which are capped with vesicles comprising phospholipid‐based flexible bilayers. When a hyperosmotic gradient is applied to these vesicle‐capped nanotubes, the closed system loses water and the more flexible vesicle bilayer is pulled inwards. This leads to inclusion of vesicles inside the nanotubes without affecting the tube structure, showing controlled reorganization of the self‐assembled multicomponent system upon a simple osmotic stimulus. 相似文献
962.
Dr. Gaëlle Valot Dr. Damien Mailhol Dr. Christopher S. Regens Dr. Daniel P. O'Malley Dr. Edouard Godineau Dr. Hiroshi Takikawa Petra Philipps Prof. Alois Fürstner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2398-2408
The marine natural products amphidinolide C ( 1 ) and F ( 4 ) differ in their side chains but share a common macrolide core with a signature 1,4‐diketone substructure. This particular motif inspired a synthesis plan predicating a late‐stage formation of this non‐consonant (“umpoled”) pattern by a platinum‐catalyzed transannular hydroalkoxylation of a cycloalkyne precursor. This key intermediate was assembled from three building blocks ( 29 , 41 and 47 (or 65 )) by Yamaguchi esterification, Stille cross‐coupling and a macrocyclization by ring‐closing alkyne metathesis (RCAM). This approach illustrates the exquisite alkynophilicity of the catalysts chosen for the RCAM and alkyne hydroalkoxylation steps, which activate triple bonds with remarkable ease but left up to five other π‐systems in the respective substrates intact. Interestingly, the inverse chemoselectivity pattern was exploited for the preparation of the tetrahydrofuran building blocks 47 and 65 carrying the different side chains of the two target macrolides. These fragments derive from a common aldehyde precursor 46 formed by an exquisitely alkene‐selective cobalt‐catalyzed oxidative cyclization of the diunsaturated alcohol 44 , which left an adjacent acetylene group untouched. The northern sector 29 was prepared by a two‐directional Marshall propargylation strategy, whereas the highly adorned acid subunit 41 derives from D ‐glutamic acid by an intramolecular oxa‐Michael addition and a proline‐mediated hydroxyacetone aldol reaction as the key steps; the necessary Me3Sn‐group on the terminus of 41 for use in the Stille coupling was installed via enol triflate 39 , which was obtained by selective deprotonation/triflation of the ketone site of the precursor 38 without competing enolization of the ester also present in this particular substrate. 相似文献
963.
964.
965.
966.
967.
968.
969.
Gerhard Bettermann Petra Look Dietmar Schomburg Reinhard Schmutzler 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):499-502
Abstract A novel type of mixed valence diphosphorus compound, involving the grouping Cl-P(-)-P(+)-NEt2, with the two phosphorus atoms doubly bridged by N.N'-dimethylurea, has become readily available. Reactions of this type of compound have furnished a variety of new structural elements, involving two directly bonded phosphorus atoms in two different oxidation states and / or coordination numbers. 相似文献