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41.
有限群极大子群的θ-子群偶 总被引:21,自引:0,他引:21
N.P.Mukherjee和 P.Bhattacharya在“On theta pairs for a maximal sub-group”(Proc.Amer.Math.Soc,Vl09N3(1990))一文中定义了有限群的极大子群的θ-子群偶概念,研究了极大子群的极大θ-子群偶对群结构的影响,得到了一系列结果.本文在进一步探究θ-子群偶性质的基础上,对该文中一系列主要结果作出了本质性的改进,并给出了可解性、幂零性的一些新刻划. 相似文献
42.
二阶积分微分方程周期边值问题的解的存在性 总被引:4,自引:0,他引:4
通过对比结果,用单调迭代方法证明了Banach空间中二阶积分微分方程的周期边值问题的最大最小解的存在性定理。 相似文献
43.
Ewa Wagner-Wysiecka Paulina Szulc Elbieta Luboch Jarosaw Chojnacki Pawe Sowiski Katarzyna Szwarc-Karabyka 《Molecules (Basel, Switzerland)》2022,27(6)
The preparation and characterization of products of the photochemical and thermochemical rearrangements of 19-membered azoxybenzocrowns with two, bulky, tert-butyl substituents in benzene rings in the para positions to oligooxyethylene fragments (meta positions to azoxy group, i.e., t-Bu-19-Azo-O have been presented. In photochemical rearrangement, two colored typical products were expected, i.e., 19-membered o-hydroxy-m,m′-di-tert-butyl-azobenzocrown (t-Bu-19-o-OH) and 19-membered p-hydroxy-m,m′-di-tert-butyl-azobenzocrown (t-Bu-19-p-OH). In experiments, two colored atypical macrocyclic derivatives, one 6-membered and one 5-membered ring, bearing an aldehyde group (t-Bu-19-al) or intramolecular ester group (t-Bu-20-ester), were obtained. Photochemical rearrangement led to one more macrocyclic product being isolated and identified: a 17-membered colorless compound, without an azo moiety, t-Bu-17-p-OH. The yield of the individual compounds was significantly influenced by the reaction conditions. Thermochemical rearrangement led to t-Bu-20-ester as the main product. The structures of the four crystalline products of the rearrangement—t-Bu-19-o-OH, t-Bu-19-p-OH, t-Bu-20-ester and t-Bu-17-p-OH—were determined by the X-ray method. Structures in solution of atypical derivatives (t-Bu-19-al and t-Bu-20-ester) and t-Bu-19-p-OH were defined using NMR spectroscopy. For the newly obtained hydroxyazobenzocrowns, the azo–phenol⇄quinone–hydrazone tautomeric equilibrium was investigated using spectroscopic methods. Complexation studies of alkali and alkaline earth metal cations were studied using UV-Vis absorption spectroscopy. 1H NMR spectroscopy was additionally used to study the cation recognition of metal cations. Cation binding studies in acetonitrile have shown high selectivity towards calcium over magnesium for t-Bu-19-o-OH. 相似文献
44.
在分析激光主动探测中回波信号的噪声特性和小波变换去噪原理的基础上,提出了一种基于最大信噪比准则的小渡阈值去噪方法。首先用最大信噪比准则对小波变换系数进行阈值选取,然后采用软阂值方法对小波系数进行量化处理后再重构。仿真结果表明最大信噪比准则小波去噪方法改善信噪比效果十分显著,检测下限达到-16.2dB。证明了该方法在激光主动探测系统回波信号检测中的有效性。 相似文献
45.
本文在Sobolev-Lorentz空间W2L2,q(R4)的范数约束下得到了一个最佳的二阶次临界型Adams不等式.进一步,当次临界指标逼近最佳常数时,得到了Adams泛函的上、下界的估计.本文主要采用了Lam和Lu[A new approach to sharp Moser-Trudinger and Adams ... 相似文献
46.
A weighted estimate with power weights is established for the maximal operator associated with the commutator of the Bochner-Riesz operator. An application of this weighted estimate is also given.
47.
在弱$L_p$空间之间建立一类Marcienkiewicz型内插定理并且给出它在现代调和分析理论中的某些应用. 相似文献
48.
49.
I. Kh. Abdukadyrova 《Journal of Applied Spectroscopy》2008,75(3):374-378
The influence of radiation damage on a number of lattice vibration parameters in two SiO2 modifications was investigated using IR reflectance spectroscopy. The radiation kinetics of changes in spectral characteristics
of SiO2 fundamental vibrations in crystalline and glassy states were determined. The reflectivity coefficient and the frequency of
degenerate vibrations as functions of dose showed minima, the locations of which were governed by the type of sample. At high
neutron irradiation doses (1021 cm−2), certain characteristics of the bands had the same values for both modified materials. Features of the radiation kinetics
of sample dynamic parameters were determined. It was deduced that the specific character of the observed radiation-induced
changes in spectral and dynamic parameters of vibrations near degenerate modes was due to both the accumulation of radiation
damage and a change in the force field surrounding bridging bonds, which is related to a change in the SiO2 structure.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 3, pp. 354–358, May–June, 2008. 相似文献
50.
David M. Whalley Hung A. Duong Prof. Michael F. Greaney 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(8):1927-1930
A light-mediated Truce–Smiles arylative rearrangement is described that proceeds in the absence of any photocatalyst. The protocol creates two C−C bonds from simple starting materials, with the installation of an aryl ring and a difluoroacetate moiety across unactivated alkenes. The reaction proceeds via a radical mechanism, utilizing a light-mediated reduction of ethyl bromodifluoroacetate by N,N,N′,N′-tetramethylethylenediamine (TMEDA) to set up intermolecular addition to an unactivated alkene, followed by Truce–Smiles rearrangement. 相似文献