全文获取类型
收费全文 | 303篇 |
免费 | 0篇 |
专业分类
化学 | 302篇 |
物理学 | 1篇 |
出版年
2023年 | 1篇 |
2020年 | 19篇 |
2019年 | 27篇 |
2018年 | 4篇 |
2017年 | 26篇 |
2016年 | 9篇 |
2015年 | 4篇 |
2014年 | 11篇 |
2013年 | 8篇 |
2012年 | 8篇 |
2011年 | 13篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 16篇 |
2007年 | 10篇 |
2006年 | 8篇 |
2005年 | 14篇 |
2004年 | 12篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 10篇 |
2000年 | 18篇 |
1999年 | 8篇 |
1998年 | 18篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1995年 | 16篇 |
排序方式: 共有303条查询结果,搜索用时 953 毫秒
11.
12.
13.
14.
Hao Guo Lie-Wei Zhang Hao Zhou Dr. Wei Meng Dr. Yu-Fei Ao Prof. Dr. De-Xian Wang Prof. Dr. Qi-Qiang Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(7):2645-2649
An artificial system of substrate-induced dimerization assembly of chiral macrocycle catalysts enables a highly cooperative hydrogen-bonding activation network for efficient enantioselective transformation. These macrocycles contain two thiourea and two chiral diamine moieties and dimerize with sulfate to form a sandwich-like assembly. The macrocycles then adopt an extended conformation and reciprocally complement the hydrogen-bonding interaction sites. Inspired by the guest-induced dynamic assembly, these macrocycles catalyze the decarboxylative Mannich reaction of cyclic aldimines containing a sulfamate heading group. The imine substrate can be activated toward nucleophilic attack of β-ketoacid by a cooperative hydrogen-bonding network enabled by sulfamate-induced dimerization assembly of the macrocycle catalysts. Highly efficient (>95 % yield in most cases) and enantioselective (up to 97.5:2.5 er) transformation of a variety of substrates using only 5 mol % macrocycle was achieved. 相似文献
15.
Hao Wang Dr. Hari Krishna Bisoyi Dr. Bing-Xiang Li Dr. Michael E. McConney Dr. Timothy J. Bunning Prof. Quan Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(7):2706-2709
Visible-light-driven molecular switches endowing reversible modulation of the functionalities of self-organized soft materials are currently highly sought after for fundamental scientific studies and technological applications. Reported herein are the design and synthesis of two novel halogen bond donor based chiral molecular switches that exhibit reversible photoisomerization upon exposure to visible light of different wavelengths. These chiral molecular switches induce photoresponsive helical superstructures, that is, cholesteric liquid crystals, when doped into the commercially available room-temperature achiral liquid crystal host 5CB, which also acts as a halogen-bond acceptor. The induced helical superstructure containing the molecular switch with terminal iodo atoms exhibits visible-light-driven reversible unwinding, that is, a cholesteric–nematic phase transition. Interestingly, the molecular switch with terminal bromo atoms confers reversible handedness inversion to the helical superstructure upon irradiation with visible light of different wavelengths. This visible-light-driven, reversible handedness inversion, enabled by a halogen bond donor molecular switch, is unprecedented. 相似文献
16.
17.
18.
19.
20.