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961.
R. Haase U. Illgen J. Scheve I. W. Schulz 《Reaction Kinetics and Catalysis Letters》1985,28(2):395-400
The formation of needle shaped crystallites of V6O13 at low V concentrations on V2O5-anatase coated catalysts explains the low selectivity for phthalic anhydride during o-xylene oxidation. The (010) plane of V-oxide, most active for selective oxidation of o-xylene, is not accessible and the contact of this plane with the anatase faces promotes the anatase-rutile transformation and the incorporation and blocking of V4+ ions.
V6O13 V , V2O5-, -. (010) , -, , - V+4.相似文献
962.
I. A. Gailyunas E. M. Tsyrlina G. A. Tolstikov S. I. Spivak V. D. Komissarov 《Reaction Kinetics and Catalysis Letters》1984,26(3-4):317-322
Kinetics and products of the epoxidation of several substituted sila-cyclo-3-pentenes by tert-butylhydroperoxide (ROOH) in the presence of Mo(CO)6 at 70°C in chlorobenzene have been studied and an epoxidation mechanism is suggested. Effective rate constants have beeb shown to be practically independent of the structure of olefins examined.
, -3- (I–VI-) . (ROOH) Mo(CO)6 70°C . , .相似文献
963.
Summary Clarithromycin and its main metabolite R-OH-clarithromycin are determined in human serum and urine. The method is based on liquid-liquid extraction, reversed-phase chromatography and dual-mode coulometric detection. The method is fairly selective. No interferences were observed in samples from human volunteers. Detection limits were 0.05 mg/l serum and 1.3 mg/l urine. 相似文献
964.
E. S. Vostrov A. A. Novikov A. N. Maslivets Z. G. Aliev 《Russian Journal of Organic Chemistry》2007,43(2):224-227
2-Carboxyphenylamides of aroylacetic acids undergo cyclization when treated with dehydrating agents to give 2-[(Z)-2-aryl-2-hydroxy-1-ethenyl]-4H-3,1-benzoxazin-4-ones. Crystal and molecular structure of the latter phenyl derivative was studied by X-ray crystallography.
Original Russian Text ? E.S. Vostrov, A.A. Novikov, A.N. Maslivets, Z.G. Aliev, 2007, published in Zhurnal Organicheskoi Khimii,
2007, Vol. 43, No. 2, pp. 232–235. 相似文献
965.
Summary A thin-layer Chromatographic method was developed for the detection and estimation of the steroid sapogenins of fenugreek seeds and plant at its various stages of growth. It depends on the initial separation of the constituent sapogenins (diosgenin, tigogenin and gitogenin) effectively on silica gel and alumina chromatoplates (n-hexane/ethylacetate as solvent) followed by direct photometric estimation of each product separately with reference to a calibration curve. Errors of ± 6% were found with synthetic mixtures.
Dünnschicht-chromatographischer Nachweis und Bestimmung von Steroidsapogeninen in BockshornkleeSteroidsapogenine. XIV
Zusammenfassung Das Verfahren wurde zur Untersuchung der Samen und der Pflanze (Trigonella foenum graecum L.) in verschiedenen Wachstumsstufen angewendet. Die Sapogenine (Diosgenin, Tigogenin und Gitogenin) wurden auf Dünnschichten aus Silicagel oder Aluminiumoxid mit Hilfe von n-Hexan/Äthylacetat-Gemischen getrennt und anschließend photometrisch mit Phosphormolybdänsäure direkt auf der Platte bestimmt. In synthetischen Gemischen wurden Fehler von ± 6% gefunden.相似文献
966.
The homotopic method has been used to analyze the kinetic model of three-stageCO oxidation on two nonuniform surface patches conjugated byCO
2 spillover. Diagrams of steady states depending on the portion of surface patchm
1 at various temperatures and pressure ratiosP(O
2)/P(CO) have been constructed. The ratios of different type patches corresponding to the maximum overall reaction rate have been found. 相似文献
967.
Alkylation of 4-ethoxy-2-hydroxypyrimidines (10a, b), via their anions, provides a convenient procedure for preparing N1-substituted derivatives. Reaction of 10a, b with t-butyl 4-bromo-2-benzyloxycarbamidobutyrate (17) gives good yields of the N1-alkylated products 18a, b. The latter have been converted to uracil- (20a), thymine- (20b) and cytosine- (21) substituted -aminobutyric acids. 相似文献
968.
Summary Rapid indirect polarographic and visual micromethods have been developed for the determination of the quinone and azoxy groups by reduction with titanium(III) at pH values of 3 and 5.5, respectively. The excess of reductant is first determined polarographically followed by visual back-titration of the same solution with iron(III) using thiocyanate as indicator a drop of neutral red is added in case of the quinone function. Although the results obtained by the two finishes are of approximately the same order of accuracy (±0.46%), yet the polarographic finish proved to be of more general applicability particularly for quinones that give rise, after reduction, to a variety of colours on adding the iron(III) solution.
Part III: Mikrochim. Acta 1969, 44. 相似文献
Anwendung der Polarographie in der organischen AnalyseIV. Bestimmung von Chinon- und Azoxygruppen durch Reduktion mit Titan(III)
Zusammenfassung Zur schnellen Bestimmung von Chinon- und Azoxygruppen durch Reduktion mit Titan(III) bei pH 3 bzw. 5,5 werden indirekte polarographische und visuelle Mikromethoden beschrieben. Der Überschuß an Reduktionsmittel wird zunächst polarographisch und anschließend volumetrisch durch Rücktitration mit Eisen(III)-lösung bestimmt, wobei Thiocyanat (bei der Chinongruppe noch zusätzlich Neutralrot) als Indicator dient. Beide Ergebnisse weisen etwa dieselbe Genauigkeit auf (±0,46%); doch ist die polarographische Methode allgemeiner anwendbar, besonders bei Chinonen, die nach der Reduktion auf Zusatz Eisen(III) verschiedenartige Färbungen hervorrufen.
Part III: Mikrochim. Acta 1969, 44. 相似文献
969.
The structure and stability of endohedral X@Si20H20 complexes (X = Li0/+, Na0/+, K0/+, Be0/2+, Mg0/2+, Ca0/2+) have been studied at the B3LYP/6-31G* level of density functional theory. It is found that complexes with X = Na0/+, K0/+, Mg and Ca0/2+ are energy minimum structures with X at the cage center in Ih symmetry, while those with X = Li0/+, Be0/2+, Mg2+ have off-centered structures with X towards one pentagon face in C5v symmetry. Large electron or charge transfer between the Si20H20 cage and the encapsulated X has been observed. 相似文献
970.
Summary Foliosidine acetonide has been isolated from the mixture of alkaloids fromH. foliosum.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 724–727, November–December, 1970. 相似文献