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1.
A. F. Blinokhvatov O. V. Markovtseva M. N. Nikolaeva 《Chemistry of Heterocyclic Compounds》1992,28(3):266-268
Substituted 4H-pyrans were obtained in high preparative yields by the reaction of 1,5-diketones with acetic anhydride and boron trifluoride etherate in diethyl ether. It is assumed that the heterocyclization of 1,5-diketones includes a step involving the formation and transformations of an acyloxy carbonium ion.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 320–322, March, 1992. 相似文献
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S. N. Nikolaeva A. S. Zolotareva S. V. Ponomarev V. S. Petrosyan 《Russian Chemical Bulletin》1994,43(5):857-861
Dialkylamino- and alkoxytrialkylstannanes have been studied as N- and O-nucleophilic reagents in substitution reactions at the B-Br bond. The previously unknown bis(dialkylamino)- and dialkoxyboryl trialkylsilyl ketenes were synthesized. Some peculiarities of the reactivity of these compounds have been studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 911–915, May, 1994.This research was carried out in the framework of the Universities of Russia State Program. 相似文献
4.
S. V. Nikolaeva V. V. Zorin S. S. Zlotskii D. L. Rakhmankulov 《Chemistry of Heterocyclic Compounds》1986,22(2):210-214
The homolytic addition of 1,3-oxathiolane to olefins takes place with the formation of 2-substituted 1,3-oxathiolanes and insignificant amounts of functional derivatives of sulfides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 259–263, February, 1986. 相似文献
5.
The influence of phenol on the habit of sodium chloride crystals was studied quantitatively. At small concentrations the presence of phenol has no influence whatsoever on the growth rate of the (100) face. At greater concentrations this growth rate increases. Spiral growth was observed on the (100) face by surface dissolution. Phenol slows down the growth rate of the (111) face, the energy barrier being about 600 cal/mole. Roughening of this face is observed when crystallization takes place from pure solutions and in the presence of small amounts of phenol. At a phenol concentration of 0.065 mole/l the growth rates of the (100) and (111) faces become equal. 相似文献
6.
Maria E. Nikolaeva Andrey V. Nechaev Elena V. Shmendel Roman A. Akasov Mikhail A. Maslov Andrey F. Mironov 《Molecules (Basel, Switzerland)》2022,27(9)
Upconverting nanoparticles have unique spectral and photophysical properties that make them suitable for development of theranostics for imaging and treating large and deep-seated tumors. Nanoparticles based on NaYF4 crystals doped with lanthanides Yb3+ and Er3+ were obtained by the high-temperature decomposition of trifluoroacetates in oleic acid and 1-octadecene. Such particles have pronounced hydrophobic properties. Therefore, to obtain stable dispersions in aqueous media for the study of their properties in vivo and in vitro, the polyethylene glycol (PEG)-glycerolipids of various structures were obtained. To increase the circulation time of PEG-lipid coated nanoparticles in the bloodstream, long-chain substituents are needed to be attached to the glycerol backbone using ether bonds. To prevent nanoparticle aggregation, an L-cysteine-derived negatively charged carboxy group should be included in the lipid molecule. 相似文献
7.
Leonid G. Sokoletsky Olga V. Nikolaeva Leonid P. Bass Victor S. Kuznetsov 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(13):1132-5779
Several numerical and analytical solutions of the radiative transfer equation (RTE) were compared for plane albedo in a problem of solar light reflection by sea water. The study incorporated the simplest case—a semi-infinite one-dimensional plane—parallel absorbing and scattering homogeneous layer illuminated by a monodirectional light beam. Inelastic processes (such as Raman scattering and fluorescence), polarization and air-water surface refraction-reflection effects, were not considered. Algorithms were based on the invariant imbedding method and two different variants of the discrete ordinate method (DOM). Calculations were performed using parameters across all possible ranges (single-scattering albedo ω0 and refracted solar zenith angle θ1), but with a special emphasis on natural waters. All computations were made for two scattering phase functions, which included an almost isotropic Rayleigh phase function and strongly anisotropic double-peaked Fournier-Forand-Mobley phase function. Models were validated using quasi-single-scattering (QSSA) and exponential approximations, which represent the extreme cases of ω0→0 and ω0→1, respectively. All methods yielded relative differences within 1.8% for modeled natural waters. An analysis of plane albedo behavior resulted in the development of a new extended QSSA approximation, which when applied in conjunction with the extended Hapke approximation developed earlier, resulted in a maximum relative error of 2.7%. The study results demonstrated that for practical applications, the estimation of inherent optical properties from observed reflectance can best be achieved using an extended Hapke approximation. 相似文献
8.
V. I. Minkin A. D. Dubonosov V. A. Bren’ O. G. Nikolaeva A. V. Tsukanov O. N. Burov A. Yu. Fedyanina 《Russian Journal of Organic Chemistry》2013,49(3):374-378
Schiff bases were synthesized from 3-hydroxy-6-oxo-6H-benzo[c]chromene-4-carbaldehyde, 5-hydroxy-4,7-dimethyl-2-oxo-2H-chromene-6-carbaldehyde, 6,7-dihydroxy-4-methyl-2-oxo-2H-chromene-8-carbaldehyde, 5,7-dihydroxy-4-methyl-2-oxo-2H-chromene-6,8-dicarbaldehyde, and 5-hydroxy-4,7-dimethyl-2-oxo-2H-chromene-6,8-dicarbaldehyde and (15N)aniline or aminobenzo-15-crown-5 (2,3,5,6,8,9,11,12-octahydrobenzo[b][1,4,7,10,13]pentaoxacyclopentadecin-15-amine), and tautomeric equilibrium between the hydroxy enimino and keto enamino forms of the 4- and 8-iminomethyl derivatives in solution was revealed by 1H NMR and electronic spectroscopy. Addition of alkaline earth cations to their solutions in acetonitrile displaced the tautomeric equilibrium toward the hydroxy enimino structure due to complex formation with the crown ether fragment. 相似文献
9.
Boyko K. M. Nikolaeva A. Yu. Bakunova A. K. Stekhanova T. N. Rakitina T. V. Popov V. O. Bezsudnova E. Yu. 《Crystallography Reports》2021,66(5):802-807
Crystallography Reports - Pyridoxal 5′-phosphate (PLP)-dependent transaminases catalyze the stereospecific amino-group transfer from an amino acid or amine to ketone or keto acid.... 相似文献