排序方式: 共有78条查询结果,搜索用时 514 毫秒
31.
Sergei Avdonin Jonathan Bell Victor Mikhaylov Karlygash Nurtazina 《Mathematical Methods in the Applied Sciences》2019,42(15):5029-5039
Avdonin and Kurasov proposed a leaf peeling method based on the boundary control to recover a potential for the wave equation on a tree. Avdonin and Nicaise considered a source identification problem for the wave equation on a tree. This paper extends the methodology to the wave equation with unknown potential and source distributed parameters defined on a general tree graph. 相似文献
32.
I. V. Mikhaylov O. V. Borisov A. A. Darinskii F. A. M. Leermakers T. M. Birshtein 《Polymer Science Series A》2017,59(5):772-783
The effect of branching on the Helfrich mean k C and Gaussian k G bending moduli of polymer brushes consisting of dendrons grafted to both sides of a thin impermeable surface (membrane) is studied theoretically. The case of an athermal solvent is considered. The moduli are calculated from a change in the free energy of a brush upon cylindrical and spherical bending of the grafting surface, respectively. The grafting density σ, the total number of monomer units N, and the number of generations g in tethered dendrons are varied. Two variants of the self-consistent field method are applied: the analytical approach and the numerical Scheutjens-Fleer method. The first method is applied at small values of σ, when the density profile of monomer units of grafted chains is parabolic in shape. The second method is free of these restrictions. The universal ratio between moduli is found: k G =?64/105k C . Both methods predict that the values of moduli decrease with increasing g at constant N and σ. The scaling dependence N 3 remains valid for the moduli of dendritic brushes with different generation numbers g at all of the considered values of σ. The analytical approach also gives the universal scaling dependence k C ~ k G ~ σ7/3; however, the numerical method predicts that the dependences of moduli on σ become stronger with increasing degree of branching of tethered dendrons. 相似文献
33.
A. A. Mikhaylov A. G. Medvedev D. A. Grishanov T. A. Tripol’skaya E. A. Mel’nik P. V. Prikhodchenko O. Lev 《Russian Journal of Inorganic Chemistry》2017,62(12):1624-1631
A composite based on sodium germanate and reduced graphene oxide was obtained for the first time by precipitating the initial peroxogermanate on a graphene oxide followed by heat treatment in vacuum. According to powder X-ray diffraction, sodium germanate crystallizes during the heat treatment in vacuum at 500°C. Scanning transmission electron microscopy examination showed that sodium peroxogermanate nanoparticles form a thin film on the surface of graphene oxide flakes. The electrochemical characteristics of composites obtained with different heat treatment conditions were studied as the anodes of lithium ion batteries. 相似文献
34.
S.?A.?Mikhaylov N.?A.?Mamonov L.?M.?Kustov M.?N.?MikhaylovEmail author 《Russian Chemical Bulletin》2017,66(11):2073-2080
MFI zeolite materials (ZSM-5) with crystal sizes in the range from 0.10 to 1.70 μm have been synthesized. Acidic and surface properties, phase and morphological composition of the prepared zeolites have been studied by the IR sprectroscopy, nitrogen porosimetry, XRD, and scanning electron microscopy. Increasing crystal size was shown to decrease the general acidity of the zeolite. Synthesized zeolites served as supports for molybden-containing catalysts for methane aromatization prepared by using the solid phase synthesis approach. Diffuse reflectance IR spectroscopy, thermoprogrammed desoption of ammonia and 27Al NMR spectroscopy were used to characterize the physicochemical properties of the catalysts. An increase in the crystallite size of the zeolite favors a decrease in the acidity of the catalysts and inhibits the formation of alumina molybdate during the catalyst preparation. As a result, a tendency to coke formation is suppressed and the performance of the catalysts in methane aromatization improved: methane conversion and aromatic hydrocarbon yield increase. 相似文献
35.
S.?A.?Mikhaylov N.?A.?Mamonov L.?M.?Kustov M.?N.?MikhaylovEmail author 《Russian Chemical Bulletin》2017,66(11):2066-2072
Large crystallite mesoporous MFI (ZSM-5) zeolite was synthesized by using carbon nano-powder as a secondary template. The surface properties, morphological and phase composition of the synthesized material and of the commercial ZSM-5 (Zeolyst) zeolite were studied by nitrogen porosimetry, XRD and scanning electron microscopy. The results showed that the volume of mesopores volume increases with development of a secondary mesoporosity in the structure of zeolite. The obtained zeolite supports were used to prepare molybdenum-containing catalysts for the methane aromatization by solid phase preparation technique. Based on the XPS data, molybdenum particles in these catalysts are characterized by more uniform size distribution. The formation of a secondary pore structure restrains the carbon deposit formation as well as increases the methane conversion and the yield of the aromatic compounds. 相似文献
36.
Andrey A. Mikhaylov Alexander D. Dilman Marina I. StruchkovaYulia A. Khomutova Alexander A. KorlyukovSema L. Ioffe Vladimir A. Tartakovsky 《Tetrahedron》2011,67(25):4584-4594
A method for the introduction of a halogen atom into the methyl group attached to the C-3 atom of five- and six-membered cyclic nitronates (isoxazoline N-oxides and oxazine N-oxides, respectively) has been studied. The process involves silylation of starting 3-methyl-substituted cyclic nitronates followed by halogenation of the resulting N-(silyloxy)enamines. While five- and six-membered cyclic enamines behave similarly toward elemental bromine and iodine, their reactions with NBS give different products, that were rationalized by stereoelectronic effects. The obtained halogenated nitronates were coupled with various nucleophiles affording new nitronates functionalized at the C-3 position. 相似文献
37.
Mikhaylov A. N. Belov A. I. Kostyuk A. B. Zhavoronkov I. Yu. Korolev D. S. Nezhdanov A. V. Ershov A. V. Guseinov D. V. Gracheva T. A. Malygin N. D. Demidov E. S. Tetelbaum D. I. 《Physics of the Solid State》2012,54(2):368-382
Physics of the Solid State - A comprehensive comparative study of SiO2 and Al2O3 oxide layers with Si nanocrystals formed by Si+ ion implantation and high-temperature annealing has been performed.... 相似文献
38.
D. I. Tetelbaum A. N. Mikhaylov A. I. Belov V. K. Vasiliev A. I. Kovalev D. L. Wainshtein Y. Golan A. Osherov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(5):702-708
Luminescent and structural characteristics of SiO2 layers exposed to double implantation by Si+ and C+ ions in order to synthesize nanosized silicon carbide inclusions have been investigated by the photoluminescence, electron spin resonance, transmission electron microscopy, and electron spectroscopy methods. It is shown that the irradiation of SiO2 layers containing preliminary synthesized silicon nanocrystals by carbon ions is accompanied by quenching the nanocrystal-related photoluminescence at 700–750 nm and by the enhancement of light emission from oxygen-deficient centers in oxide in the range of 350–700 nm. Subsequent annealing at 1000 or 1100°C results in the healing of defects and, correspondingly, in the weakening of the related photoluminescence peaks and also recovers in part the photoluminescence of silicon nanocrystals if the carbon dose is less than the silicon dose and results in the intensive white luminescence if the carbon and silicon doses are equal. This luminescence is characterized by three bands at ~400, ~500, and ~625 nm, which are related to the SiC, C, and Si phase inclusions, respectively. The presence of these phases has been confirmed by electron spectroscopy, the carbon precipitates have the sp 3 bond hybridization. The nanosized amorphous inclusions in the Si+ + C+ implanted and annealed SiO2 layer have been revealed by high-resolution transmission electron microscopy. 相似文献
39.
Tikhov S. V. Gorshkov O. N. Belov A. I. Antonov I. N. Morozov A. I. Koryazhkina M. N. Mikhaylov A. N. 《Technical Physics》2019,64(6):873-880
Technical Physics - The peculiarities of resistive switching in capacitors with yttria-stabilized hafnia layers were studied. The characteristics of current transport in the initial state and after... 相似文献
40.
I. M. Borisov D. A. Mikhaylov S. L. Khursan 《Reaction Kinetics and Catalysis Letters》1999,68(2):271-275
Enthalpies of the addition of radicals HO•, HO2
•, CH3
•, CH3O•, CH3O2
• to the C=0 bond of model aldehydes, ketones, acids and esters have been calculated by thermodynamic and quantum chemical
methods. It has been shown that the exothermic effect of these reactions decreases in the row HO•>CH3O•>CH3
•>HOO•>CH3OO•. 相似文献