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981.
982.
983.
H. -O. Carmesin D. W. Heermann K. Binder 《Zeitschrift für Physik B Condensed Matter》1986,65(1):89-102
Instead of the standard assumption in the theory of phase separation where an instantaneous quench from an initial equilibrium state to the final state in the two-phase region is assumed, we consider the more realistic situation that the change of the external control parameter (e.g. temperature) can only be performed with finite rates. During the initial stages of spinodal decomposition the system then has some memory of the states intermediate between the initial and the final one. This influence of the finite quench rate in continuous quenching procedures is studied within the linearized theory of spinodal decomposition, with the Langer-Baron-Miller decoupling, and with Monte Carlo simulations. Both the case of thermally activated mobilities (applicable to solid metallic alloys) and the case of nearly temperature-independent mobilities (applicable to fluid polymer mixtures) are treated, and possible experimental applications are discussed. We find drastic deviations from the standard instantaneous quench situations in all cases of experimental interest. 相似文献
984.
The detailed temperature variation of the Mössbauer spectral intensity in Sn(CH3)4 displays a pronounced drop of the Debye temperature from
D
96K below the transition temperature (T
t
43K) to
D
76K above it. The transition atT
t
is discussed in terms of recent INS and NMR results where increased motion of inequivalent CH3 groups has been observed around the temperatureT
t
.Supported by the U.S.-Israel Binational Science Foundation 相似文献
985.
986.
E. A. Kuznetsova S. V. Zhuravlev T. N. Stepanova 《Chemistry of Heterocyclic Compounds》1970,4(2):183-185
The reduction of some dihydrothiazolobenzothiazolium salts with sodium borohydride may take place in two directions: with the formation of thiazolidino[2, 3-b]benzathiazolines and with the cleavage of the C-S bond to give N-(-mercaptoethyl)benzothiazolines. The behavior of thiazolidino[2, 3-b]benzothiazoline under the conditions of acid and alkaline hydrolysis has been studied.For communication VI, see [1]. 相似文献
987.
Dihydroheptazethrene (V) and 1:14,11:12-dibenzo-5,7-dihydro-pentacene (VI) were synthesized. The former gave heptazethrene (VII) on dehydrogenation, whilst the latter polymerized immediately. This difference is explained by the fact that heptazethrene (VII) can be formulated with a Kekulé structure and the dehydrogenation product of VI cannot. Heptazethrene is a basis hydrocarbon and is closely related to dibenzoheptazethrene (VIII). Heptazethrenequinone (II) is a true quinone giving a blue vat, whilst the isomer (IV) is a diketone and does not give a vat. 相似文献
988.
F. Jancik W. Czysz E. Svatek M. Rittich J. S. Dunnett et al. 《Fresenius' Journal of Analytical Chemistry》1989,333(2):171-175
Abstracts2 Particular products and fields of application
2.6 Foods 相似文献989.
Dr. H. Demel Dipl.-Ing H. J. Grießer Prof. Dr. K. Hummel 《Colloid and polymer science》1977,255(11):1131-1132
Ohne ZusammenfassungMit 1 Abbildung und 1 Tabelle 相似文献
990.
Abstract— The rates of photosensitized oxidation of a number of sulphides were determined under standard conditions in 1, 1, 2,2-tetrachloroethane and in methanol. It was found that the ratio of the rates of reaction in the two solvents was not constant for different sulphides and that t -butyl sulphide does not react in methanol. It is inferred that the presence of an H atom in the α position is essential for reaction in polar solvents and an appropriate mechanism is suggested. The results indicate that reaction in chlorinated solvents may take place by a different mechanism which possibly involves H-abstraction by triplet sensitizer. 相似文献