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101.
Sk. Safique Ahmad 《Linear and Multilinear Algebra》2013,61(9):1244-1266
We discuss the perturbation analysis for eigenvalues and eigenvectors of structured homogeneous matrix polynomials with Hermitian, skew-Hermitian, H-even and H-odd structure. We construct minimal structured perturbations (structured backward errors) such that an approximate eigenvalue and eigenvector pair (finite or infinite eigenvalues) is an exact eigenvalue eigenvector pair of an appropriately perturbed structured matrix polynomial. We present various comparisons with unstructured backward errors and previous backward errors constructed for the non-homogeneous case and show that our results generalize previous results. 相似文献
102.
F. Rahaman Peter K. F. Kuhfittig K. Chakraborty A. A. Usmani Saibal Ray 《General Relativity and Gravitation》2012,44(4):905-916
This paper discusses the observed flat rotation curves of galaxies in the context of noncommutative geometry. The energy density
of such a geometry is diffused throughout a region due to the uncertainty encoded in the coordinate commutator. This intrinsic
property appears to be sufficient for producing stable circular orbits, as well as attractive gravity, without the need for
dark matter. 相似文献
103.
104.
Sengupta Arijit Deb Ashish Kumar Singha Gupta Nishesh Kumar Kumar Parveen Dasgupta Kinshuk Ali Sk. Musharaf 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(2):331-340
Journal of Radioanalytical and Nuclear Chemistry - Herein, sorption of pentavalent neptunium from aqueous acidic solution was carried out onto 1st and 2nd generation of poly(amidoamine) dendrimer... 相似文献
105.
Stefan Schernich Dr. Mathias Laurin Dr. Yaroslava Lykhach Dr. Nataliya Tsud Dr. Marek Sobota Dr. Tomáš Skála Dr. Kevin C. Prince Dr. Nicola Taccardi Valentin Wagner Prof. Dr. Hans-Peter Steinrück Prof. Dr. Vladimír Matolín Prof. Dr. Peter Wasserscheid Prof. Dr. Jörg Libuda 《Chemphyschem》2013,14(16):3673-3677
106.
Sk. Manirul Islam Sumantra Paul Manir Mobarok Anupam Singha Roy Paramita Mondal 《Transition Metal Chemistry》2013,38(1):7-14
Polymer-anchored azo complexes of Cu(II) and Ni(II) were synthesized by the reaction of chloromethylated polystyrene, 3-aminophenol, and 1-nitroso-2-naphthol with the metal chlorides. The catalytic activities of these complexes were studied in the oxidation of various organic substrates including alkenes, alcohols, alkanes, and sulfides with 30 % aqueous hydrogen peroxide. The structures of both catalysts have been investigated by physiochemical methods. Both catalysts proved to be very stable and could be reused more than five times without significant loss of activity. Furthermore, these catalysts require very mild reaction conditions. 相似文献
107.
108.
Mubasher Jamil Farook Rahaman 《The European Physical Journal C - Particles and Fields》2009,64(1):97-105
We here investigate a cosmological model in which three fluids interact with each other, involving certain coupling parameters
and energy exchange rates. The motivation of the problem stems from the puzzling ‘triple coincidence problem’ which naively
asks why the cosmic energy densities of matter, radiation and dark energy are almost of the same order of magnitude at the
present time. In our model, we determine the conditions under which triple interacting fluids will cross the phantom divide. 相似文献
109.
F. Rahaman Saibal Ray M. Kalam M. Sarker 《International Journal of Theoretical Physics》2009,48(11):3124-3138
We perform a survey whether higher dimensional Schwarzschild space-time is compatible with some of the solar system phenomena.
As a test we examine four well known solar system effects, viz., (1) Perihelion shift, (2) Bending of light, (3) Gravitational
redshift, and (4) Gravitational time delay. It is shown, under a N-dimensional solutions of Schwarzschild type very narrow class of metrics, that the results related to all these physical
phenomena are mostly incompatible with the higher dimensional version of general relativity. We compare all these restricted
results with the available data in the literature. 相似文献
110.
Sk. Sheriff Shah Maniklal Shee Yarra Venkatesh Amit Kumar Singh Samya Samanta Prof. N. D. Pradeep Singh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3703-3708
The combination of an organic photocatalyst [4CzIPN (1,2,3,5-tetrakis(carbazol-9-yl)-4,6 dicyanobenzene) or 5MeOCzBN (2,3,4,5,6-pentakis(3,6-dimethoxy-9 H-carbazol-9-yl)benzonitrile)], quinuclidine, and tetra-n-butylammonium phosphate (hydrogen-bonding catalyst) was employed for amide bond formations. The hydrogen-bonded OH group activated the adjacent C−H bond of alcohols towards hydrogen atom transfer (HAT) by a radical species. The quinuclidinium radical cation, generated through single-electron oxidation of quinuclidine by the photocatalyst, employed to abstract a hydrogen atom from the α-C−H bond of alcohols selectively due to a polarity effect-produced α-hydroxyalkyl radical, which subsequently converted to the corresponding aldehyde under aerobic conditions. Then the coupling of the aldehyde and an amine formed a hemiaminal intermediate that upon photocatalytic oxidation produced the amide. 相似文献