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1.
Belkov M. V. Borisevich D. A. Catsalap K. Y. Khodasevich M. A. 《Journal of Applied Spectroscopy》2021,88(5):970-974
Journal of Applied Spectroscopy - Multivariate models were developed on the basis of raw low-resolution LIBS spectra of reference samples of lowalloy steels for calibration of the concentrations of... 相似文献
2.
Khudina O. G. Ivanova A. E. Burgart Ya. V. Pervova M. G. Shatunova T. V. Borisevich S. S. Khursan S. L. Saloutin V. I. 《Russian Journal of Organic Chemistry》2019,55(6):782-791
Russian Journal of Organic Chemistry - The structure of 6-polyfluoroalkyl-2-thiouracils and reactivity of nucleophilic centers in their molecules were analyzed by quantum chemical calculations.... 相似文献
3.
Numerical investigation of viscous gas secondary flows in a rotating cylinder with sources and sinks
A source-sink model of secondary flow excitation in a rotating cylinder, which describes the interaction between a circulator and a rotating gas, is proposed for a nonlinear system of Navier-Stokes equations, and the results of a numerical calculation of the resulting circulating flows are presented. The modified Newton's method employed in the numerical solution makes use of regularizing perturbations to ensure its stability and convergence at low Ekman numbers and high rates of rotation of the cylinder. The combined effect of mechanical and thermal means of flow excitation and the influence of viscous energy dissipation are considered.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 39–44, July–August, 1989. 相似文献
4.
Abstract The fluorescence of anthracene vapors and its derivatives initiated by triplet-triplet excitation is observed. The quantum yield of inverce intersystem crossing of anthracene molecules is estimated (10?2). The fluorescence initiated by triplet excitation is quenched by foreign pentane gas, thus permitting an estimation of the lifetime of highly excited triplet molecules. 相似文献
5.
6.
Chuiko Alexey Philonenko Ludmila Borisevich Anatoly Lozinsky Miron 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract The 1-hydroxyethylidene-1,1-bisphosphonic acid (HEDP) (I) reacts with epichlorohydrine (II) and aminoepoxypropanes (III) in water. Optimum pH for the esterefication is 6–7. The reaction completes in 20–30 h on 60°C at this pH and leads to the mixture of the original HEDP with the mono- and diesters. The mixture of di-Na salts of HEDP and the monochloroester (IV) in ratio 1:1.7 was precipitated from the reaction solution on using of the epichlorohydrine (II). This mixture was used for synthesis of aminoesters (VI a,b) unavailable by direct reaction of HEDP with corresponding aminoepoxides. 相似文献
7.
Chuiko Alexey Philonenko Ludmila Borisevich Anatoly Lozinsky Miron 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Heterocyclic derivatives of gem-bisphosphonates exhibit various biological activities. We have found that thiazolium substituted bisphosphonic acids can be obtained by two-step synthesis from amino-bisphosphonates (I). Reaction of (I) with isothiocyanates in alkohol in the presence of triethylamine led to corresponding thioureas (II) obtained as natrium or triethylamonium salts [1]. Further treatment of (II) with α-bromoketones give aminothiazoles (III) with a good yield. As a rule only less hindered nitrogen atom is involved into the cyclization with formation of one from two of possible isomers. 相似文献
8.
N. A. Borisevich D. K. Buslov V. N. Zhabinskii V. A. Khripach 《Journal of Applied Spectroscopy》2009,76(5):617-622
IR spectra of steroid phytohormones of the stigmastane series (22R, 23R)-28-homocastasterone and (22R,23R)-28-homosecasterol
and their isomers (22S,23S)-28-homocastasterone and (22S,23S)-28-homosecasterol have been analyzed. The 28-homocastasterone
molecule contains diol groups in ring A and in the side chain whereas that of 28-homosecasterol has one diol group in the
side chain. The lack of two OH groups in ring A of homosecasterol compared to homocastasterone results in the appearance of
stretching vibrational bands of H–C= (νmax = 3025 cm–1) and –C=C (νmax = 1656 cm–1) groups of ring A. Substantial changes are observed in the area of OH stretching vibrations. Homocastasterones pressed in
KBr possess twice as many OH groups as homosecasterols such that absorption band total intensities in IR spectra of both isomers
caused by H-bonds of the diol groups in the side chain amount to 65% whereas the share of the 2α,3α group is only 35% of the
total intensity. Hence the contribution from the side-chain OH groups of the studied brassinosteroids to the integral optical
density of the bands exceeds that from the ring-A OH groups. In dilute CHCl3 solutions of the brassinosteroids, the conformations
of the brassinosteroid side chains are not the same. As a result, intramolecular H-bonds of different energy are created.
The optical density Dmax in band maxima of free OH groups for homocastasterones is three times higher than that for the corresponding band maxima
of homosecasterol. This implies that Dmax for bands of free OH groups of the homocastasterone ring-A diol group is greater, in contrast with the relatively greater
Dmax for bands of homosecasterol side-chain OH groups bound by an intermolecular H-bond. The homocastasterone diol groups also
form intramolecular Hbonds more actively. The lack of the diol group in ring A of the homosecasterols does not affect the
frequencies of the C=O stretching vibrations. This leads to the conclusion that the C=O group forms intermolecular H-bonds
only with the side-chain OH groups of brassinosteroids pressed in KBr. 相似文献
9.
10.
We have analyzed the isotope separation in a high-frequency plasma circulating centrifuge operating with a product flow. The rotation of a weakly ionized plasma is ensured by a rotating magnetic field, while the countercurrent flow (circulation) is produced by a traveling magnetic field. We have calculated the dependences of the enrichment factor and the separative power of the centrifuge on a product flow. The optimal characteristics of the separation unit have been determined. 相似文献