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排序方式: 共有65条查询结果,搜索用时 15 毫秒
1.
O. I. Gyrdasova V. N. Krasil’nikov I. G. Grigorov G. V. Bazuev 《Russian Journal of Inorganic Chemistry》2006,51(6):949-955
The effect of ethylene glycol (EG) on the formation of whiskers and fibers of complex oxides with the general formula MCo2O4 upon the thermolysis of M1/3Co2/3C2O4 (M = Zn, Mn) oxalates has been studied. New compounds (solvates) are formed when powdered oxalates are heated with EG. In the solvates, EG molecules substitute for water molecules according to the reaction M1/3Co2/3C2O4 · 2H2O + HOCH2CH2OH = M1/3Co2/3C2O4(HOCH2CH2OH) + 2H2O. The solvates have been characterized using X-ray powder diffraction, microscopy, IR spectroscopy, thermogravimetry, and chemical analysis. The shape, structure, and particle size of the thermolysis products of EG-modified oxalates have been determined using scanning electron microscopy. 相似文献
2.
Sanchez-sanz M; Blyth MG 《The Quarterly Journal of Mechanics and Applied Mathematics》2007,60(2):125-138
Unsteady, axisymmetric stagnation flow about a circular cylinderis examined when the far-field flow is a periodic function oftime with a fixed time average and an oscillatory part of prescribedamplitude and frequency. Solutions are computed for arbitraryvalues of the Reynolds number, quantifying the effects of surfacecurvature, and a frequency parameter based on the period ofthe far-field flow. It is found that solutions remain regularand periodic provided that the far-field amplitude lies belowa critical value. Above this value, solutions terminate in afinite-time singularity. The blow-up time is delayed by increasingthe curvature of the surface. These results are corroboratedby asymptotic predictions valid in the limits of small and largeamplitude and frequency. For large Reynolds number, the problemreduces to the two-dimensional stagnation-point flow againsta plane wall studied by previous authors. 相似文献
3.
We investigate some issues of minimax estimation of spectral intensity of acoustic sources in cases when the noise and the spectral amplitudes satisfy quadratic constraints. Recursive minimax filters are obtained.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 58, pp. 116–119, 1986. 相似文献
4.
E. Taskaev M. Karaivanova T. Grigorov 《Journal of Radioanalytical and Nuclear Chemistry》1988,120(1):75-82
A procedure for platinum and gold determination utilizing, neutron activation combined with radiochemical separation, has been developed. The reaction198Pt (n, )199
is used for Pt determination. Four procedures for gold separation are examined: (1) adsorption on untreated polyurethane foam (UPF). (2) extraction with dibutyl sulphide. (3) reduction of gold to elementary state in conc. H2SO4, and extraction of gold as diethyldithiocarbamate complex. The extraction with Cu(DDC)2 is chosen as the most suitable process and applied to platinum and gold determinations in Bowen's Kale and mice organs, previously treated with Biocisplatinum® specimens. 相似文献
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V. V. Glukhikh A. E. Shkuro N. M. Mukhin E. I. Ostanina I. G. Grigorov O. V. Stoyanov 《Polymer Science Series D》2014,7(2):122-126
The effect of vinylacetate unit content in sevilen used as a polymer matrix or polyethylene compatibilizer on the properties of wood-polymer composites with a thermoplastic binders and filler of plant origin is studied. It is shown that the introduction of vinylacetate units decreases the tensile strength, contact elastic modulus, Brinell hardness, and water absorption of the composites, but increases the relative tensile elongation and impact viscosity without notch. 相似文献
7.
S -nitrosothiols have many biological activities and may act as nitric oxide (NO) carriers and donors, prolonging NO half-life in vivo. In spite of their great potential as therapeutic agents, most S -nitrosothiols are too unstable to isolate. We have shown that the S -nitroso adduct of N -acetylcysteine (SNAC) can be synthesized directly in aqueous and polyethylene glycol (PEG) 400 matrix by using a reactive gaseous (NO/O2 ) mixture. Spectral monitoring of the S–N bond cleavage showed that SNAC, synthesized by this method, is relatively stable in nonbuf-fered aqueous solution at 25°C in the dark and that its stability is greatly increased in PEG matrix, resulting in a 28-fold decrease in its initial rate of thermal decomposition. Irradiation with UV light (λ= 333 nm) accelerated the rate of decomposition of SNAC to NO in both matrices, indicating that SNAC may find use for the photogeneration of NO. The quantum yield for SNAC decomposition decreased from 0.65 ± 0.15 in aqueous solution to 0.047 ± 0.005 in PEG 400 matrix. This increased stability in PEG matrix was assigned to a cage effect promoted by the PEG microenvironment that increases the rate of geminated radical pair recombination in the homolytic S–N bond cleavage process. This effect allowed for the storage of SNAC in PEG at −20°C in the dark for more than 10 weeks with negligible decomposition. Such stabilization may represent a viable option for the synthesis, storage and handling of S -nitrosothiol solutions for biomedical applications. 相似文献
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9.
Martin Ferus Svatopluk Civiš Petr Kubelík Václav Nevrlý Petr Bitala Eva Grigorová Michal Střižík Pavel Kubát Zdeněk Zelinger 《Plasma Chemistry and Plasma Processing》2011,31(3):417-426
The environmentally important decomposition of halogenated species CF3Br and CF3CHFCF3 in helium discharge plasma was investigated by time-resolved high-resolution Fourier transform infrared emission spectroscopy.
Contrary to classical pyrolysis, a deeper fragmentation of precursors up to atoms and lower molecular species was observed.
Excited molecular products CF, CF2 and CF4 achieved the maximal concentration in the afterglow. The high concentration of all these species is in agreement with a kinetic
model based on radical chemistry. The non-detectable concentration of CF3 can be connected to its high reactivity and the formation of more stable products, CF4 and CF2, by addition or release of a fluorine atom, respectively. Other products included HF, HBr, CO and cyano compounds that were
produced by secondary reactions with traces of water vapor, atmospheric oxygen and nitrogen present in original industrial
samples as impurities. 相似文献
10.