全文获取类型
收费全文 | 93篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 72篇 |
晶体学 | 7篇 |
力学 | 1篇 |
数学 | 2篇 |
物理学 | 14篇 |
出版年
2022年 | 1篇 |
2020年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 17篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 1篇 |
2009年 | 7篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 6篇 |
2004年 | 1篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1976年 | 1篇 |
排序方式: 共有96条查询结果,搜索用时 31 毫秒
11.
Sarmah MP Gonnade RG Shashidhar MS Bhadbhade MM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(7):2103-2110
Racemic 2,4-di-O-acyl-myo-inosityl 1,3,5-orthoesters undergo transesterification catalyzed by sodium carbonate with varying ease of reaction in the solid state; reactions in solution and melt do not show such varied differences. An interesting crystal of a 1:1 molecular complex of highly reactive racemic 2,4-di-O-benzoyl-myo-inosityl 1,3,5-orthoformate and its orthoacetate analogue exhibited better reactivity than the latter component alone. Single-crystal X-ray structures of the reactants have been correlated with the observed differences in the acyl-transfer efficiencies in the solid state. Although each of the derivatives helically self-assembles around the crystallographic 2(1) axis linked through O-H...O hydrogen bonding, the pre-organization of the reactive groups (C=O [El] and OH [Nu]), C-H...O and the C-H...pi interactions are significantly more favourable for the reactive derivatives than the less reactive ones. Bond-length distributions also showed differences; the O-C bond of the axial benzoyl group, which gets cleaved during the reaction, is longer (1.345-1.361 A) relative to the chemically equivalent O-C bond of the equatorial benzoyl group (1.316-1.344 A) in the reactive derivatives. These bond-length differences are not significant in the less reactive derivatives. The overall molecular organization is different too; the strikingly discrete helices, which may be viewed as "reaction tunnels" and are held by interhelical interactions, are clearly evident in the reactive derivatives in comparison with the less reactive ones. 相似文献
12.
Dr. Amit Kumar Chattopadhyay Vu Linh Ly Dr. Shashidhar Jakkepally Dr. Gilles Berger Prof. Dr. Stephen Hanessian 《Angewandte Chemie (International ed. in English)》2016,55(7):2577-2581
Herein we describe the first synthetic efforts toward the total synthesis of isodaphlongamine H, a calyciphylline B‐type alkaloid. The strategy employs a chemoenzymatic process for the preparation of a functionalized cyclopentanol with a quaternary center. This molecule is elaborated to form an enantiopure 1‐aza‐perhydrocyclopentalene core, representing rings A and E of all calyciphylline B‐type alkaloids. Further transformations involve the formation of a cyclic enaminone, 1,4‐conjugate addition with a cyclopentenyl subunit, and intramolecular aldol cyclization to achieve a pentacyclic intermediate, ultimately forming isodaphlongamine H in a total of 24 steps from the commercially available compound 2‐carbethoxycyclopentanone. Isodaphlongamine H exhibits promising inhibitory activity against a panel of human cancer cell lines. 相似文献
13.
K. Manoj S. Devaraj R. G. Gonnade M. M. Bhadbhade M. S. Shashidhar 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(11):o628-o630
The centrosymmetric O—H⋯O‐bonded head‐to‐head dimers of the title compound, C21H22O6, are linked together via bifurcated C—H⋯O interactions along the a axis and via favourable C—H⋯π interactions along the b axis in the crystal structure. 相似文献
14.
15.
Struss AK Pasini P Flomenhoft D Shashidhar H Daunert S 《Analytical and bioanalytical chemistry》2012,402(10):3227-3236
Quorum sensing (QS) allows bacteria to communicate with one another by means of QS signaling molecules and control certain
behaviors in a group-based manner, including pathogenicity and biofilm formation. Bacterial gut microflora may play a role
in inflammatory bowel disease pathogenesis, and antibiotics are one of the available therapeutic options for Crohn’s disease.
In the present study, we employed genetically engineered bioluminescent bacterial whole-cell sensing systems as a tool to
evaluate the ability of antibiotics commonly employed in the treatment of chronic inflammatory conditions to interfere with
QS. We investigated the effect of ciprofloxacin, metronidazole, and tinidazole on quorum sensing. Several concentrations of
individual antibiotics were allowed to interact with two different types of bacterial sensing cells, in both the presence
and absence of a fixed concentration of N-acylhomoserine lactone (AHL) QS molecules. The antibiotic effect was then determined by monitoring the biosensor’s bioluminescence
response. Ciprofloxacin, metronidazole, and tinidazole exhibited a dose-dependent augmentation in the response of both bacterial
sensing systems, thus showing an AHL-like effect. Additionally, such an augmentation was observed, in both the presence and
absence of AHL. The data obtained indicate that ciprofloxacin, metronidazole, and tinidazole may interfere with bacterial
communication systems. The results suggest that these antibiotics, at the concentrations tested, may themselves act as bacterial
signaling molecules. The beneficial effect of these antibiotics in the treatment of intestinal inflammation may be due, at
least in part, to their effect on QS-related bacterial behavior in the gut. 相似文献
16.
17.
The principal dielectric constants of the pentyl to octyl derivatives of 4′-n-alkyl-4-cyanobiphenyl have been measured as functions of temperature in their nematic and isotropic phases. All the compounds
exhibit a strong positive dielectric anisotropy due to the presence of a large dipole moment along the major molecular axis.
The principal dielectric constantsε
‖ andε
⊥ as well as the anisotropy Δε decrease with increasing alkyl chain length. The experimental value of
(ε‖+2ε⊥) decreases with decreasing temperature, and is throughout less than the extrapolated isotropic value, in conformity with
the model of antiferroelectric short range order proposed by Madhusudana and Chandrasekhar. 相似文献
18.
19.
Nagar V. Kar R. Pansare-Godambe L. Chand N. Bute A. Bhale D. Rao A. V. S. S. N. Shashidhar R. Maiti Namita 《Plasma Chemistry and Plasma Processing》2022,42(5):1115-1126
Plasma Chemistry and Plasma Processing - Traditional disinfection methods against pathogens have numerous shortcomings, and inventive methods like cold plasma are required for virus inactivation.... 相似文献
20.
S. L. Brandow J. A. Harrison D. P. Dilella R. J. Colton S. Pfeiffer R. Shashidhar 《Liquid crystals》2013,40(1):163-170
Abstract We present scanning tunnelling microscopy images of a ferroelectric liquid crystal in its chiral smectic C phase. These images show evidence of pronounced interaction between the adjacent lateral dipoles located near the chiral centres of neighbouring molecules. The two dimensional structure at the graphite—liquid crystal interface is found to be highly ordered. Features of this crystal-like order are the pronounced dimer arrangement within a layer and a kinked conformation in which the aromatic core is tilted with respect to the chains. The core axis is tilted at 30° with respect to the layer normal in the plane of the interface. This tilt is very similar to the tilt angle of the bulk material. 相似文献