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401.
N. P. Yevlampieva A. P. Khurchak Yu. N. Luponosov E. A. Kleimyuk S. A. Ponomarenko E. I. Ryumtsev 《Russian Journal of Applied Chemistry》2013,86(5):747-755
Star-thiophene derivatives with a silicon atom as the branching center were investigated by absorption spectroscopy and electro-optical Kerr effect in solutions at variations in a number and chemical structure of branches. The star-shaped oligomers were compared with dendritic analogues containing silicon atoms at the points of branching. It is shown that thiophene-containing moieties determine both spectral and electrooptical properties of the molecules. Molecular parameters of the star-shaped oligomers of various structure vary identically with increasing the number of branches. The absorption of star-shaped oligomers is additive due to the autonomy of the absorption of radiation by the separate branches. For dendritic molecules the additive nature of the absorption is kept, but their electro-optical properties are independent of a generation number. It was shown that the latter is a consequence of the manifestation by dendrimers of deformation flexibility, which is not peculiar to the starshaped derivatives. 相似文献
402.
Multiphoton and electron-impact ionization of a gas-dynamic beam of xenon atoms are compared in order to determine the effective multiphoton ionization cross sections. The three-photon ionization cross section of the xenon atom is determined. 相似文献
403.
Lorin Crawford Vadim Ponomarenko Jason Steinberg Marla Williams 《Results in Mathematics》2014,66(1-2):227-245
For certain \({a,b \in \mathbb{N}}\) , an Arithmetic Congruence Monoid M(a, b) is a multiplicatively closed subset of \({\mathbb{N}}\) given by \({\{x\in\mathbb{N}:x \equiv a \pmod{b}\} \cup\{1\}}\) . An irreducible in this monoid is any element that cannot be factored into two elements, each greater than 1. Each monoid element (apart from 1) may be factored into irreducibles in at least one way. The elasticity of a monoid element (apart from 1) is the longest length of a factorization into irreducibles, divided by the shortest length of a factorization into irreducibles. The elasticity of the monoid is the supremum of the elasticities of the monoid elements. A monoid has accepted elasticity if there is some monoid element that has the same elasticity as the monoid. An Arithmetic Congruence Monoid is local if gcd(a, b) is a prime power (apart from 1). It has already been determined whether Arithmetic Congruence Monoids have accepted elasticity in the non-local case; we make make significant progress in the local case, i.e. for many values of a, b. 相似文献
404.
D. D. Kul’minskii V. I. Ponomarenko A. S. Karavaev M. D. Prokhorov 《Technical Physics》2016,61(5):639-647
We propose a system of concealed information transfer based on a delayed feedback oscillator with switchable chaotic regimes. The proposed system is analyzed numerically and experimentally. The dependences of the bit error rate during transmission of a binary information signal on the signal-to-noise ratio, attenuation of the signal in the communication channel, and the duration of the time interval during which a bit is transferred are constructed. The high stability of the system to noise and amplitude distortions of a signal in the communication channel is demonstrated. 相似文献
405.
N. M. Surin O. V. Borshchev Yu. N. Luponosov S. A. Ponomarenko A. M. Muzafarov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(11):1979-1985
The luminescence spectral properties of oligothiophenesilane dendrite macromolecules were studied. It was found that the chromophores
responsible for the formation of the absorption and luminescence spectra were dendrimer fragments separated by silicon atoms;
all the chromophores are equally involved in the formation of the absorption spectra of dendritic macromolecules of the zero,
first, second, and third generations. It was shown that for dendrites of the first, second, and third generations, the luminescence
spectrum is mainly formed by the chromophore fragments lying in the internal layers of the dendritic macromolecule due to
the induction resonance energy transfer of electronic excitation from peripheral to internal chromophore fragments. The conclusion
was drawn that synthesis of dendritic macromolecules with internal chromophore fragments possessing a high quantum yield of
fluorescence can give actively luminescing nanosized objects with the molar extinction coefficient proportional to the number
of fragments ɛmax ≈ 106 l/(mol cm). These compounds can find wide application in transducers for converting various types of ionizing radiation into
optical radiation in electroluminescent devices. 相似文献
406.
Lebedev B. V. Kulagina T. G. Ryabkov M. V. Ponomarenko S. A. Makeev E. A. Boikov N. I. Shibaev V. P. Rebrov E. A. Muzafarov A. M. 《Journal of Thermal Analysis and Calorimetry》2003,71(2):481-492
The thermodynamic properties of carbosilane dendrimer of second generation with terminal methoxyundecylene groups were studied
between 6 and 340 K by adiabatic vacuum calorimetry: the temperature dependence of the molar heat capacity Cp
0 was measured, the physical transformations were established and their thermodynamic characteristics were obtained. The experimental
data were used to calculate the thermodynamic functions Cp
0 (T), H
0(T)-H
0(0), S0(T), G
0(T)-H
0(0) of the compound in the range 0 to 340 K. from the relation Cp
0 (T) the fractal dimension of the dendrimer was experimentally determined. The heat capacity of the dendrimer was compared with
the corresponding additive values calculated from the properties of its constituents - a dendritic matrix (carbosilane dendrimer
of second generation) and the corresponding amount of moles of methyl ester of 11-(tetramethyldisiloxy)undecanoic acid serving
as terminal groups.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
407.
Chen Xie Lijun Zhang Dr. Haibo Mei Dr. Romana Pajkert Dr. Maksym Ponomarenko Dr. Yi Pan Prof. Dr. Gerd‐Volker Röschenthaler Prof. Dr. Vadim A. Soloshonok Dr. Jianlin Han 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(21):7036-7040
A new chiral reagent has been developed for generalized installation of pharmacophoric (S)‐ or (R)‐2‐(alkoxyphosphono)‐1‐amino‐2,2‐difluoroethyl group into organic compounds. The original synthetic application of this new reagent is exemplified by Friedel–Crafts reactions with indoles, which proceed efficiently with excellent diastereoselectivity to give enantiomerically pure products. 相似文献