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排序方式: 共有387条查询结果,搜索用时 15 毫秒
211.
Tushar Kanti Chakraborty N. V. Suresh Kumar Saumya Roy Samit Kumar Dutta Ajit Chand Kunwar Balasubramanian Sridhar Harjinder Singh 《Journal of Physical Organic Chemistry》2011,24(8):720-731
Structural and electronic properties of diastereomers of tetrahydrofuran amino acids (TAA) derived tripeptide, Boc‐TAA‐Leu‐Val‐OMe, are studied using density functional theory. Predicted secondary folding patterns with hydrogen bonded pseudocycles of different sizes in peptides containing (2R,5S)‐cis‐TAA and (2S,5R)‐cis‐TAA are confirmed by detailed NMR studies of both, and single crystal X‐ray analysis of the former. A novel unusual folding pattern emanating from three‐centered hydrogen bond is found in peptide with (2R,5S)‐cis relationship. Stereochemical control on the orientation of interacting sites is substantiated by structural analysis of the peptides. Using natural bonding orbital and atoms in molecules analyses, charge transfer interactions are analyzed. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Ajit Kumar Preeti Kaushik Sandra Incerpi Jens Z. Pedersen Sanjay Goel Ashok K. Prasad Vishwajeet Rohil Virinder S. Parmar Luciano Saso Christophe Len 《Molecules (Basel, Switzerland)》2021,26(16)
The purpose of this study was to examine the free radical scavenging and antioxidant activities of ellagic acid (EA) and ellagic acid peracetate (EAPA) by measuring their reactions with the radicals, 2,2-diphenyl-1-picrylhydrazyl and galvinoxyl using EPR spectroscopy. We have also evaluated the influence of EA and EAPA on the ROS production in L-6 myoblasts and rat liver microsomal lipid peroxidation catalyzed by NADPH. The results obtained clearly indicated that EA has tremendous ability to scavenge free radicals, even at concentration of 1 µM. Interestingly even in the absence of esterase, EAPA, the acetylated product of EA, was also found to be a good scavenger but at a relatively slower rate. Kinetic studies revealed that both EA and EAPA have ability to scavenge free radicals at the concentrations of 1 µM over extended periods of time. In cellular systems, EA and EAPA were found to have similar potentials for the inhibition of ROS production in L-6 myoblasts and NADPH-dependent catalyzed microsomal lipid peroxidation. 相似文献
214.
Ajit A. Diwan 《Journal of Graph Theory》2010,65(3):246-252
Thomassen [J Graph Theory 7 (1983), 261–271] conjectured that for all positive integers k and m, every graph of minimum degree at least k+1 contains a cycle of length congruent to 2m modulo k. We prove that this is true for k?2 if the minimum degree is at least 2k?1, which improves the previously known bound of 3k?2. We also show that Thomassen's conjecture is true for m = 2. © 2010 Wiley Periodicals, Inc. J Graph Theory 65: 246–252, 2010 相似文献
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Ajit Kumar Chakravarty Binayaku Das Kazuo Masuda Hiroyuki Ageta 《Tetrahedron letters》1990,31(52):7649-7652
The structure of chiratenol (2), the first representative of a new triterpenoid skeletal type, has been established on the basis of 1D and 2D NMR spectroscopy. 相似文献
217.
Nonlinear static and dynamic behaviours of freely supported Rhombic sandwich plates have been studied following Banerjee's hypothesis. Numerical results for 0° skew angle are compared with other known results. Results for other skew angles are believed to be new.
Sommario Si studia, seguendo l'ipotesi di Banerjee, il comportamento nonlineare statico e dinamico di piastre rombiche semplicemente appoggiate. Si presentano risultati numerici relativi a piastre rombiche e rettangolari: questi ultimi vengono paragonati a risultati già noti, mentre i primi si ritengono nuovi.相似文献
218.
Basudeb Achari Soumitra Bandyopadhyay Ajit K. Chakravarty Satyesh C. Pakrashi 《Magnetic resonance in chemistry : MRC》1984,22(12):741-746
13C NMR spectra of compounds related to aristolochic acid and aristololactam, the constituents of Aristolochia indica, have been studied to determine the chemical shifts and coupling constants of polysubstituted phenanthrenes. Selective 1H decoupling and long-range couplings were utilized for the assignments. Substituent-induced chemical shifts and also the effects on coupling constants could be deduced in some cases. Anion formation was found to be particularly helpful in the interpretation of the spectra of carboxylic compounds. Shift assignments of some structurally related compounds could also be made. 相似文献
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Sputter‐deposited Ni/Ti double‐bilayer thin film and the effect of intermetallics during annealing 下载免费PDF全文
Ajit Behera R. Suman S. Aich S. S. Mohapatra 《Surface and interface analysis : SIA》2017,49(7):620-629
In the present study, a double bilayer of a Ni/Ti thin film was investigated. A nanoscale NiTi thin film is deposited in a Ni–Ti–Ni–Ti manner to form a double‐bilayer structure on a Si(100) substrate. Ni and Ti depositions were carried out by using d.c. and r.f. power, respectively, in a magnetron sputtering chamber. Four types of bilayers are formed by varying the deposition time of each layer (i.e. 15, 20, 25, and 30 min). The as‐deposited amorphous thin films were annealed at 300, 400, 500, and 600 °C for 1 h to achieve the diffusion in between the layers. Microstructures were analyzed using field‐emission scanning electron microscope and high‐resolution transmission electron microscope. It was found that, with the increase in annealing temperature from 300 to 600 °C, the diffusion at the interface and atomic migration on the surface increase. Cross‐sectional micrographs exhibited the interdiffusion between the two‐layer constituents, especially at higher temperatures, which resulted in diffusion patches along the interface. Phase analyses, performed by grazing incidence X‐ray diffraction, showed the formation of intermetallic compounds with some silicide phases that enhance the mechanical properties. Nanoindentation and atomic force microscopy were carried out to know the mechanical properties and surface profiles of the films. The surface finish is better at higher annealing temperatures. It was found that for annealing temperatures varying from 300 to 600 °C, the increase in annealing temperature resulted in a gradual increase in atomic‐cluster coarsening with improved adatom mobility. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献