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71.
Stefka Kaloyanova Valeriya M. Trusova Galyna P. Gorbenko Todor Deligeorgiev 《Journal of photochemistry and photobiology. A, Chemistry》2011,217(1):147-156
Sixteen new asymmetric monomethine cyanine dyes have been synthesized and their spectral characteristics and interaction with double stranded DNA have been investigated. The dyes absorb in the region 453–519 nm and have molar absorptivities in the range 37.900–93.100 l M?1 cm?1. The dyes do not have intrinsic fluorescence, but in the presence of dsDNA they exhibited a significant enhancement in fluorescence. The most pronounced increase was found for D9, D10, D12 and D16 allowing the recommendation of these dyes as the most sensitive DNA markers. Thermodynamic analysis of cyanine–DNA complexation was carried out using the McGhee & von Hippel non-cooperative excluded site model, and binding parameters have been derived. A hypothesis describing the DNA–dye binding mode has been proposed. 相似文献
72.
A. N. Antimonova N. V. Uzenkova N. I. Petrenko M. M. Shakirov E. E. Shul’ts G. A. Tolstikov 《Russian Journal of Organic Chemistry》2011,47(4):589-601
Cyanoethylation of lupane triterpenoids was performed. Amide oximes of 3β-O-(2-cyanoethyl)-betulinic acid methyl ester and 3β-O-acetyl-28-O-(2-cyanoethyl)betulin and the corresponding O-[2-(1,2,4-oxadiazol-3-yl)ethyl] lupane derivatives were obtained. 相似文献
73.
The mechanisms of dissociation of oxygen-containing moieties (-OH, -HCO, -COOH) upon the photoreduction of graphite oxide
by UV light have been considered. It has been concluded that the photoreduction, which involves the detachment of the OH group
and the molecular elimination of CO and CO2, occurs in singlet excited states. The energy threshold of the photoreduction processes is determined by the position of
the repulsive terms of the system. 相似文献
74.
The thickness vibrations of elastic inhomogeneous bodies of different geometry under dynamic harmonic loading are studied.
The dependence of the amplitude–frequency characteristics of homogeneous and inhomogeneous bodies on excitation frequency
is analyzed in detail. The frequency spectra for plane, cylindrical, and spherical layers are determined 相似文献
75.
S. A. Osadchii E. E. Shul’ts M. M. Shakirov G. A. Tolstikov 《Russian Chemical Bulletin》2006,55(2):375-379
The structure of 2-bromooreoselon, which was prepared by bromination of peucedanin or oreoselon with molecular bromine, was
established. The compositions and structures of the reaction products of this bromide with amines, such as pyridine, triethylamine,
and morpholine, as well as with sodium acetate and potassium hydroxide were studied. The reaction of peucedanin with m-chloroperoxybenzoic acid affords peuruthenicin isobutyrate.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 362—366, February, 2006. 相似文献
76.
H.S. Kang Y.C. Kang H.D. Park Y.G. Shul 《Applied Physics A: Materials Science & Processing》2005,80(2):347-351
Green-emitting Y2SiO5:Tb phosphor particles with fine size, spherical shape, filled morphology, high crystallinity, and good brightness were synthesized by a spray pyrolysis process. The effect of silicon precursor type on the morphology, crystal structure, crystallinity, and photoluminescence efficiency of Y2SiO5:Tb phosphor particles was investigated. The particles prepared from an artificial colloidal solution obtained by dispersing fumed silica particles had a pure monoclinic X2 crystalline phase, which is more appropriate for application to displays, after post-treatment at 1300 °C. On the other hand, the particles prepared from 100% tetraethyl orthosilicate (TEOS) reagent had an X2 phase and small amounts of X1 and impurity phases such as Y2Si2O7 and Y4.67Si3O13 due to the phase-segregation characteristics of the TEOS precursor. The photoluminescence characteristics of Y2SiO5:Tb phosphor particles were strongly affected by the silicon source used. The photoluminescence intensities increased with the fumed silica/TEOS ratio. The particles prepared from 100% fumed silica showed the maximum photoluminescence intensity, which is 22% higher than that of particles prepared from 100% TEOS. PACS 81.20.Rg; 78.55.Hx; 78.40.Ha; 81.05.Hd; 81.40.Tv 相似文献
77.
Seung‐Jin Yang Wonbong Jang Choonkeun Lee Yong Gun Shul Haksoo Han 《Journal of Polymer Science.Polymer Physics》2005,43(12):1455-1464
To investigate the effect of crosslinking by a hydrophilic group on a sulfonated polyimide electrolyte membrane, sulfonated polyimide end‐capped with maleic anhydride was synthesized using 1,4,5,8‐naphthalenetetracarboxylic dianhydride, 4,4′‐diaminobiphenyl, 2,2′‐disulfonic acid, 2‐bis [4‐(4‐aminophenoxy)phenyl] hexafluropropane and maleic anhydride. The sulfonated polyimides end‐capped with maleic anhydride were self‐crosslinked or crosslinked with poly(ethylene glycol) diacrylate. A series of the crosslinked sulfonated polyimides having various ratios of sulfonated polyimide and poly(ethylene glycol) diacrylate were prepared and compared with uncrosslinked and self‐crosslinked sulfonated polyimides. The synthesized sulfonated polyimide films were characterized for FTIR spectrum, thermal stability, ion exchange capacity, water uptake, hydrolytic stability, morphological structure, and proton conductivity. The formation of sulfonated polyimide was confirmed in FTIR spectrum. Thermal stability was good for all the sulfonated polyimides that exhibited a three‐step degradation pattern. Ion exchange capacity was the same for both the uncrosslinked and the self‐crosslinked sulfonated polyimides (1.30 mEq/g). When the crosslinked sulfonated polyimides with poly(ethylene glycol) were compared, the ion exchange capacity was decreased as 1.27 > 1.25 > 1.23 mEq/g and water uptake was increased as 23.8 < 24.0 < 24.3% with the increase in poly(ethylene glycol) diacrylate content. All the crosslinked sulfonated polyimides with poly(ethylene glycol) diacrylate were stable for over 200 h at 80 °C in deionized water. Morphological structure and mean intermolecular distance were obtained by WAXD. Proton conductivities were measured at 30, 50, 70, and 90 °C. The proton conductivity of the crosslinked sulfonated polyimides with poly(ethylene glycol) diacrylate increased with the increase in poly(ethylene glycol) diacrylate content despite the fact that the ion exchange capacity was decreased. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1455–1464, 2005 相似文献
78.
S. T. Davitadze S. N. Kravchun B. A. Strukov B. M. Gol’tsman V. V. Lemanov S. G. Shul’man 《Physics of the Solid State》1997,39(7):1154-1156
The thermal properties of SrTiO3 thin films are investigated experimentally by recording the amplitude and phase of the temperature oscillations of a flat
probe with the heat flux perpendicular to the plane of the film. Results are given from measurements of the specific heat
and thermal conductivity of a leucosapphire substrate and the thermal conductivity of a SrTiO3 film of thickness 2 μm.
Fiz. Tverd. Tela (St. Petersburg) 39, 1299–1302 (July 1997) 相似文献
79.
N. F. Shul’ga V. V. Syshchenko V. S. Neryabova 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2013,7(2):279-284
The energy quantization of transverse particle motion in continuous potentials of atomic chains and planes can occur when fast charged particles travel in crystals. In the proposed paper, the energy levels of electrons moving in the mode of axial channeling in a system of parallel atomic chains have been found (Si crystal [110] chains have been used as an example). The energy eigenvalues were determined numerically using the so-called spectral method, which shows itself to good advantage in the problem of the plane channeling of charged particles in crystals. 相似文献
80.
M. M. Brzhezinskaya N. A. Vinogradov V. E. Muradyan Yu. M. Shul’ga N. V. Polyakova A. S. Vinogradov 《Physics of the Solid State》2008,50(3):587-594
The C 1s and F 1s x-ray absorption spectra of fluorinated multiwalled carbon nanotubes with different fluorine contents and reference compounds (highly oriented pyrolytic graphite crystals and “white” graphite fluoride) were measured using the equipment of the Russian-German beamline at the BESSY II storage ring with a high energy resolution. The spectra obtained were analyzed with the aim of characterizing multiwalled carbon nanotubes and their products formed upon treatment of the nanotubes with fluorine at a temperature of 420°C. It was established that, within the probing depth (~15 nm) of carbon nanotubes, the process of fluorination occurs uniformly and does not depend on the fluorine concentration. The interaction of fluorine atoms with multiwalled carbon nanotubes in this case proceeds through the covalent attachment of fluorine atoms to graphene layers of the graphite skeleton and is accompanied by a change in the hybridization of the 2s and 2p valence electron states of the carbon atom from the trigonal (sp 2) to tetrahedral (sp 3) hybridization. 相似文献