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961.
962.
963.
964.
If G is a group and if the upper hypercenter, Z, of G is such that G∕Z is finite then a recent theorem shows that G contains a finite normal subgroup L such that G∕L is hypercentral. The purpose of the current paper is to obtain a version of this result for subgroups G of GL(F,A), when A is an infinite dimensionalF-vector space. 相似文献
965.
Leonid A. Solovyov Nicolay N. Golovnev Maxim K. Lesnikov 《Journal of Coordination Chemistry》2017,70(12):1984-1993
A polymeric coordination compound, [Ba(H2O) 2(Hba)2] (1) (H2ba – barbituric acid, C4H4N2O3), was obtained. The structure of 1 was solved using powder X-ray diffraction methods. The Ba2+ ion in 1 formed a three-capped trigonal prism. The BaO9 polyhedra, connected with each other by the edges and faces, formed a chain. Several 4- and 12-membered cycles due to the bridging μ2-H2O and bridging μ3-Hba– also formed implementing a 3-D polymer structure. The structures of 1 and other thiobarbiturate complexes were compared. The replacement of a S atom by an O atom in the heterocyclic ligand Htba? (thiobarbiturate ion) of the compound Ba(H2O)2(Htba)2 resulted in changes of the coordination number Ba(II) and supramolecular structure. The intermolecular hydrogen bonds O–H?O and N–H?O formed a 3-D net where pronounced 2-D layers of Hba– ions could be found. A new topological net in 1 was observed. The IR and thermal stability were investigated. 相似文献
966.
967.
We prove that the exactness of direct limits in an abelian category with products and an injective cogenerator J is equivalent to a condition on J which is well-known to characterize pure-injectivity in module categories, and we describe an application of this result to the tilting theory. We derive our result as a consequence of a more general characterization of when inverse limits in the Eilenberg–Moore category of a monad on the category of sets preserve regular epimorphisms. 相似文献
968.
969.
Gottesman R Shukla S Perkas N Solovyov LA Nitzan Y Gedanken A 《Langmuir : the ACS journal of surfaces and colloids》2011,27(2):720-726
Colloidal silver has gained wide acceptance as an antimicrobial agent, and various substrates coated with nanosilver such as fabrics, plastics, and metal have been shown to develop antimicrobial properties. Here, a simple method to develop coating of colloidal silver on paper using ultrasonic radiation is presented, and the coatings are characterized using X-ray diffraction (XRD), high resolution scanning electron microscope (HRSEM), and thermogravimetry (TGA) measurements. Depending on the variables such as precursor concentrations and ultrasonication time, uniform coatings ranging from 90 to 150 nm in thickness have been achieved. Focused ion beam (FIB) cross section imaging measurements revealed that silver nanoparticles penetrated the paper surface to a depth of more than 1 μm, resulting in highly stable coatings. The coated paper demonstrated antibacterial activity against E. coli and S. aureus, suggesting its potential application as a food packing material for longer shelf life. 相似文献
970.
Omelchenko IV Shishkin OV Gorb L Leszczynski J Fias S Bultinck P 《Physical chemistry chemical physics : PCCP》2011,13(46):20536-20548
The degree of aromaticity of six-membered monoheterocycles with IV-VI group heteroatoms (C(6)H(5)X, where X = SiH, GeH, N, P, As, O(+), S(+), Se(+)) was analyzed using the results of ab initio calculations at the MP2/cc-pvtz level. Values of common aromaticity indices including those based on electronic delocalization properties, structural-dynamic features and magnetic properties all indicate high aromaticity of all considered heterocycles. A decrease in aromaticity is observed with increasing atomic number of the heteroatom, except in the case of the pyrylium cation. However, not all types of indices or even different indices within the same type correlate well among each other. Ring currents have been obtained at the HF/cc-pvdz level using the ipsocentric formulation. Ring current maps indicate that in the case of cationic heterocycles the ring current persists in all molecules under consideration. The different conclusions reached depending on the type of index used are a manifestation of the fact that when not dealing with hydrocarbons, aromaticity is ill-defined. One should always express explicitly which property of the molecules is considered to establish a degree of "aromaticity". 相似文献