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41.
Russian Chemical Bulletin - 相似文献
42.
43.
Zusammenfassung Es wurden zwei Verfahren ausgearbeitet, um Vanadin mit Hilfe von aktivierter Katalyse zu bestimmen. Die Methodik ist geeignet, kleinste Spuren von Vanadin (bis herab zu 0,0006) mit ausreichender Genauigkeit zu ermitteln. Es werden Beleganalysen mitgeteilt.
Summary Two procedures for the determination of vanadium have been worked out, based on activated catalysis, which allow minimal traces (down to 0,0006) of vanadium to be determined with adequate accuracy. Comparison analyses are given in the paper.
Résumé On a élaboré deux procédés pour exécuter le dosage du vanadium à l'aide d'une catalyse activée. La méthode est apte à la détermination des plus petites traces de vanadium (jusqu'à 0,0006) avec une précision suffisante. On communique des analyses documentaires.相似文献
44.
Zusammenfassung Umsetzung von 5,6-Dimethoxy- und [4,5,6-Trimethoxy-benzo[b]thienyl-(3)]-essigsäure mit PCl5 lieferte die methoxysubstituierten [Benzo[b]thienyl-(3)]-essigsäurechloride, die mit sekundären Aminen zu den entsprechenden Amiden reagierten.Die homologen Verbindungen mit einer C3-Brücke wurden durchArndt-Eistert-Reaktion des Diazomethylketons in Gegenwart der entsprechenden sekundären Amine erhalten.
Reaction of 5.6-dimethoxy- and [4.5.6-trimethoxybenzo[b]-thienyl-(3)]-acetic acid with PCl5 gave the methoxy-substituted [benzo[b]thienyl-(3)]-acetic acid chlorides, which reacted with secondary amines to the corresponding amides.The homologous compounds with a C3-bridge were synthesized viaArndt-Eistert reaction of the diazomethyl ketone in presence of the corresponding secondary amines.相似文献
45.
E. G. Ter-Gabriélyan N. P. Gambaryan É. P. Lur'e P. V. Petrovskii 《Russian Chemical Bulletin》1979,28(5):992-995
Conclusions Perfluoro-(2-isobutenyl-1,1,4,4-tetramethyl-1,3-butadiene) yields 1,4 addition products both in nucleophilic addition and in radical chlorination.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1061–1064, May, 1979. 相似文献
46.
Sodium hexafluoromanganate(III) has been synthesized by heating equimolecular quantities of Na2MnF5 and NaF in argon atmosphere. The compound is monoclinic witha=5.56 (1) Å,b=5.84 (1) Å,c=8.10 (2) Å, =90.7 (2) andZ=2. It is a high spin complex with
eff
and the deformation of the octahedra is evident from its IR-spectra. Two enantiotropic transitions (at 562 and 653°C) and the melting point at 800°C have been observed.
8. Mitt.: Mh. Chem.106, 483 (1975). 相似文献
8. Mitt.: Mh. Chem.106, 483 (1975). 相似文献
47.
Thermal degradation of copolymers of styrene and methyl-vinyl-silane by pyrolysis gas chromatography
Pyrolysis gas chromatographic investigations have been carried out on copolymers of styrene with trimethyl-vinyl-silane and of styrene with dimethyl-phenyl-vinyl-silane, in order to study the mechansims of thermal degradation and the copolymer structures. We have identified the pyrolysis products and measured their relative amounts. The experiments show that the controlling factor in the mechanism of the degradation is the nature of the side-group attached to the carbon atom at which chain scission occurs. If this side-group is phenyl, the main degradation process is depropagation; if it is if it is trimethyl-silyl or dimethyl-phenyl-silyl, intramolecular hydrogen abstraction followed by β scission becomes more important than depropagation. From the point of view of degradation mechanism, the nature of the side-group attached to the carbon atom from which the hydrogen is abstracted is of minor importance.We estimated the average copolymer block length from the amounts of products containing both comonomers as well as from the amounts of trimer composed of the same monomer. 相似文献
48.
49.
Summary When measuringQ
–1 and the flexural resonance frequency of bars clamped at one end, constituted by a viscoelastic polymeric material glued to a rigid support of modulusE
1, it is possible to calculate the componentsE
2
andE
2
of the complex elastic modulus of the polymeric material examined. In this work the minimum (critical) value of the ratioa=E
2
/E
1=a
c
and the values of the ratioQ
2
–1/Q
–1=F
1 are evaluated beyond which no exact calculation ofE
2
and ofQ
2
–1 is possible.Within the confidence limits of the linear viscoelasticity theory, these values depend on the accuracy of measurement of both frequency and resonance curve, as well as on the instrument employed, on the operating temperature and on the ratio between the thicknesses of the two coupled materials.In order to keep outside the critical conditions, the most convenient method involves the use of measurements of coupled test-pieces having different ratiosz between their thicknesses and of supports having different modulusE
1, depending on the field of temperature of the analysis ofE
2
and tg 2 concerning and E.P.R. elastomer and a vulcanized cis-1,4 polyisoprene in very wide ranges of temperature comprising the glass transition. Moreover, it is demonstrated by analysis the shift on the temperature axis of the tg maximum of the composite test-piece with respect to the position of the tg maximum of the polymeric material alone.With 11 figures and 1 table 相似文献
50.