全文获取类型
收费全文 | 257篇 |
免费 | 18篇 |
专业分类
化学 | 246篇 |
晶体学 | 1篇 |
力学 | 4篇 |
数学 | 7篇 |
物理学 | 17篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 10篇 |
2014年 | 11篇 |
2013年 | 11篇 |
2012年 | 24篇 |
2011年 | 28篇 |
2010年 | 12篇 |
2009年 | 12篇 |
2008年 | 11篇 |
2007年 | 30篇 |
2006年 | 28篇 |
2005年 | 13篇 |
2004年 | 11篇 |
2003年 | 16篇 |
2002年 | 7篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 2篇 |
1990年 | 2篇 |
排序方式: 共有275条查询结果,搜索用时 15 毫秒
231.
Enantiogroup‐Differentiating Biocatalytic Reductions of Prochiral Cs‐Symmetrical Dicarbonyl Compounds to meso Compounds 下载免费PDF全文
Marc Skoupi Dr. Carine Vaxelaire Prof. Dr. Carsten Strohmann Prof. Dr. Mathias Christmann Prof. Dr. Christof M. Niemeyer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(24):8701-8705
The stereoselective reduction of symmetrical prochiral dicarbonyl compounds bearing enantiotopic carbonyl groups yields several stereogenic centers in one step. In a proof‐of‐concept study, a new approach is described for the enzymatic desymmetrization of 5‐nitrononane‐2,8‐dione via sequential biocatalytic reduction steps utilizing ketoreductases to yield all possible diastereomers of 5‐nitrononane‐2,8‐diol. 相似文献
232.
233.
234.
235.
236.
237.
Benzene adsorption behavior in a large family of 12R window zeolites (X, Y, EMT, Beta and LTL) has been examined by means of in-situ FTIR spectroscopy and correlated with the zeolite structure, the type and number of counter-ions, and the negative charge on framework oxygen atoms of zeolites. The effect of coadsorption of HCl, NH3 and CH3NH2 on the benzene location has also been studied. The present work illustrates that besides the benzene adsorption on counter ions of zeolites, the 12R windows could also be the adsorption sites for benzene. Upon adsorption of coadsorbates such as HCl, NH3 and CH3NH2, the migration of preadsorbed benzene molecules from one type of adsorption sites towards another, i.e. from 12R windows towards the cations for HCl and opposite direction for NH3 and CH3NH2, has been evidenced. The lack of adsorption of benzene on 12R windows of NaBeta even upon coadsorption of a series of basic molecules reveals that benzene adsorption on 12R windows is most likely governed by a molecular recognition effect where benzene molecule and 12R window should have the adapted chemical and structural properties like in enzyme-substrate system and zeolites can be referred to as solid enzymes or zeo-enzymes. This paper indicates also that the adsorption properties of zeolites can be modified and accommodated by introduction of a co-adsorbate. 相似文献
238.
Stphanie Parra Olivier Vitse Vronique Bnzech Carine Deleuze‐Masqufa Guy Subra Jacques Bompart Roger Escale Jean P. Chapat Pierre A. Bonnet 《Journal of heterocyclic chemistry》2001,38(1):41-44
The n‐butyllithium and lithium 2,2,6,6‐tetramethylpiperidide metalation and the halogen‐metal exchange of imidazo[1,2‐a]quinoxaline derivatives followed by quenching with various electrophiles were studied. The reaction conditions have been optimized and various C1 substituted imidazo[1,2‐a]quinoxalines were obtained in high yields. 相似文献
239.
240.
Nitrone 3 analogue of 5-deoxy-l-lyxose was derived from d-ribose. Its reduction with aqueous SO2 gave the corresponding 4-amino-sugar 2, a potent α-l-fucosidase inhibitor. 1,3-Dipolar cycloaddition of 3 with alkenes allowed the synthesis of acetohydroxamic acid and ethane-phosphonate derivatives. Hydroxy-ethane derivative 15 is a nanomolar α-l-fucosidase inhibitor. 相似文献