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51.
A. A. Nafikova R. M. Aminova A. V. Aganov V. S. Reznik 《Journal of Structural Chemistry》2007,48(1):S64-S78
The effects of weak noncovalent interactions on the nuclear magnetic screening (NMS) constants (σ 1H), (σ 13C) and charge distribution (q t ) on atoms in van der Waals model associates of unsubstituted and substituted pyrimidines and substituted uracil are considered. The NMS constants were calculated by the UB3LYP/6-31G(d,p) with GIAO functions. The correlation dependences of the 1H and 13C σ constants on the charge q on atoms whre constructed. It were shown that they can be represented as polynomials that include the terms that are linear and quadratic relative to the charge. The relations obtained in this way are similar in form and close in magnitude to the coefficients of the known Buckingham and Augspurger functions that describe the electric field effects on the nuclear magnetic screening constants. It was found that the coefficients in these polynomials have a definite physical sense in that they characterize nuclear magnetic screening and the “screening polarizability” tensor in the unperturbed molecule and associate, respectively. The NMS constants and charge distribution in pyrimidine base associates and accordingly the coefficients that reflect their values in polynomials depend on the form, size, and composition of the associate and can vary significantly depending on the position of the pyrimidine base in the associate. 相似文献
52.
We study the deformation of the wind velocity profile due to resonant interactions with waves radiated by the flow over a
statistically homogeneous topography. The wind whose velocity vector changes its direction within a layer of finite thickness
is considered. Quasilinear equations for the velocity components of the mean flow are derived under large Richardson, numbers
and small Froude numbers. It is shown that the modulus of the wind velocity is constant in time and its direction angle satisfies
the Riemann equation for simple waves. The flow deformation is determined by the average wave resistance force per unit square.
The deformation of the wind velocity profile takes place within the layer between the Earth’s surface and the level where
the wind change its direction to the opposite one. At large time scales, the wind velocity vector in this layer approaches
the direction opposite to the near-surface one.
Institute of Applied Physics, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 42, No. 3, pp. 255–265, March 1999. 相似文献
53.
We reveal a mechanism of resonant excitation of non-dispersive coastal Kelvin waves by pairs of incident/reflected inertia-gravity waves in the rotating stratified fluid. In the simplest rotating shallow water model on the semi-infinite plane we show that the mechanism works for a continuum of incoming waves, and thus should be ubiquitous in the ocean. Subsequent slow evolution of thus excited Kelvin waves is governed by harmonically forced simple-wave equation and leads to nontrivial transport and mixing properties. 相似文献
54.
A. V. Kozlov V. E. Semenov A. S. Mikhailov A. V. Il’yasov V. S. Reznik Sh. K. Latypov 《Russian Chemical Bulletin》2009,58(12):2499-2505
The conformation of macrocycles consisting of the uracil and two thiopyrimidine moieties linked by polymethylene spacers depends
on the spacer length, intramolecular hydrogen bonds, and the solvent nature. In CDCl3 the intramolecular hydrogen bond (NH) appreciably stabilizes the “skew” conformation but only for the macrocycles with methylene
spacers consisting of five carbon atoms. Protonation leads to the cleavage of intramolecular hydrogen bonds, destabilization
of the “skew” conformation, and self-association due to the strong intermolecular hydrogen bond involving the acid counterion,
and the intermolecular bond is cleaved in a polar solvent. 相似文献
55.
56.
A technique is described for the preparation of transmission electron microscopy cross-sectional samples of pyrolytical carbon layers deposited on polycrystalline boron nitride substrates. To solve the problem of different abrasion rates of C and BN a filler material, Si wafers, has been bonded to both sides of the pre-thinned BN substrate. Correspondence between color and thickness of Si wafers facilitates controlled sample thickness reduction during dimpling. The samples prepared by this technique even without ion milling are thin enough for HRTEM studies. 相似文献
57.
N. K. Vdovicheva M. A. Galin A. N. Reznik I. A. Shereshevsky 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(2):145-148
A technique for the profiling of free carrier concentration N(z) in semiconductors, based on the near-field measurements in microwave frequency range, is proposed. A high accuracy in retrieving
the N(z) function with characteristic spatial scales of 10–100 nm using 2–3 probes with apertures of 3–15 μm is demonstrated. 相似文献
58.
A review of the theory of quasigeostrophic singular vortices embedded in regular flows is presented with emphasis on recent results. The equations governing the joint evolution of singular vortices and regular flow, and the conservation laws (integrals) yielded by these equations are presented. Using these integrals, we prove the nonlinear stability of a vortex pair on the f-plane with respect to any small regular perturbation with finite energy and enstrophy. On the β-plane, a new exact steady-state solution is presented, a hybrid regular-singular modon comprised of a singular vortex and a localized regular component. The unsteady drift of an individual singular β-plane vortex confined to one layer of a two-layer fluid is considered. Analysis of the β-gyres shows that the vortex trajectory is similar to that of a barotropic monopole on the β-plane. Non-stationary behavior of a dipole interacting with a radial flow produced by a point source in a 2D fluid is examined. The dipole always survives after collision with the source and accelerates (decelerates) in a convergent (divergent) radial flow. 相似文献
59.
M. V. Mezhennyi M. G. Mil’vidskii V. F. Pavlov V. Ya. Reznik 《Physics of the Solid State》2001,43(1):47-50
The specific features of the dislocation motion in dislocation-free silicon wafers (single crystals are grown by the Czochralski method) heat-treated at 450 and 650°C have been investigated. It is found that the low-temperature treatment of silicon wafers with an oxygen content of (7–8)×1017 cm?3 substantially affects the dynamic properties of dislocations generated into silicon wafers during their four-point bending and brings about an increase in the starting stresses of the onset of the dislocation motion. A characteristic spatial inhomogeneity is observed in the generation and propagation of dislocations from indentations upon the bending of heat-treated wafers. The reasons for the regularities revealed are discussed. 相似文献
60.
Study of the factors determining the outcome of cycloaddition of isocyanurato-substituted azides to [60]fullerene 总被引:2,自引:0,他引:2
Sinyashin O. G. Romanova I. P. Yusupova G. G. Nafikova A. A. Kovalenko V. I. Azancheev N. M. Fattakhov S. G. Reznik V. S. 《Russian Chemical Bulletin》2001,50(11):2162-2171
The final outcome of cycloaddition of isocyanuratoalkyl azides to C60 depends on the temperature, the thermal stability of azides, the substituents in the isocyanurate ring, and the number of methylene groups in the alkyl radical. The thermal transformations of the monoadducts obtained were studied. 相似文献