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N. D. Kagramanov A. A. Kutin E. I. Mysov K. N. Makarov L. L. Gervits 《Russian Chemical Bulletin》1990,39(5):925-930
The primary and final products arising from the pyrolysis of perfluoro-2,4-dimethyl-3-ethylpentane, perfluoro-3-isopropyl-4-methyl-2-pentene, perfluoro-2-methyl-3-isopropyl-2-pentene, perfluoro-2,4-dimethyl-3-heptene, and perfluoro-4-methyl-2-pentene have been studied using low-energy mass spectrometry and chromatography-mass spectrometry. Thermal decomposition of hexafluoropropene oligomers, containing perfluoroisopropyl groups attached to a double bond, occurs via loss of a radical pair to form perfluorodienes, as well as via abstraction of a hexafluoropropene molecule from the iso-C3F7 group. A correlation between the principal fragmentation pathway observed under electron impact and the primary process in the main thermolysis pathway was detected only in the case of perfluoro-4-methyl-2-pentene and perfluoro-2,4-dimethyl-3-heptene, which are capable of cleavage of.CF3 and.C2F5 radicals, respectively, to give a single possible allyl radical structure.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1037–1041, May, 1990. 相似文献
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The reaction of fluorobenzene with urotropine in trifluoroacetic acid (TFAA) at high pressures and temperatures affords predominantly fluorobenzaldehydes andN-(fluorophenylmethyl)trifluoroacetamides. The yields of these products depend considerably on the reaction conditions. The rates of their formation have the maximum values at the momemt of the phase transition (PT) of TFAA. A new efficient cyclic (dynamic) regime is proposed for the synthesis at high pressures. The regime involves periodically occurring PT of the solvent. The change in the relative rate of product formation with the degree of fluorobenzene conversion is wave-like.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 319–323, February, 1995. 相似文献
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AA Yan LI Kai CAO ZhongHua & HU WenRui Key Laboratory of Microgravity 《中国科学:物理学 力学 天文学(英文版)》2011,(2)
The dependency of the critical Marangoni number on the geometrical aspect ratio of the floating half zone is essential to predict the onset of oscillatory thermocapillary convection.The experimental studies in the microgravity conditions on floating half zones of several centimeters in diameter have predicted that the critical Marangoni number increases with the increasing aspect ratio,and the terrestrial experimental studies have predicted the contradictory conclusion for floating half zones of several mil... 相似文献
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Non-Gravitational Effects with Density-Matching in Evaluating the Influence of Sedimentation on Colloidal Coagulation 下载免费PDF全文
The method of density matching between the solid and liquid phases is often adopted to effectively eliminate the effect of sedimentation of suspensions in studies on dynamic behaviour of a colloidal system. However, the associated changes in the solvent composition may bring side effects to the properties investigated and therefore might lead to a faulty conclusion if the relevant correction is not made. To illustrate the importance of this side effect, we present an example of the sedimentation influence on the coagulation rate of suspensions of 2μm (diameter) polystyrene. The liquid mixtures, in the proper proportions of water (H2O), deuterium oxide (D2O) and methanol (MeOH) as the liquid phase, density-matched and unmatched experiments are performed. Besides the influence of viscosity, the presence of methanol in solvent media, used to enhance the sedimentation effect, causes significant changes (reduction) in rapid coagulation rates compared to that in pure water. Without the relevant corrections for those non-gravitational factors it seems that gravitational sedimentation would retard the coagulation. The magnitude of the contribution from the non-gravitational factor is quantitatively determined, making the relevant correction possible. After necessary the influence of the sedimentation on coagulation rates at corrections for all factors, our experiments show that the initial stage of the coagulation is not observable. 相似文献
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B. M. Ginzburg Sh. Tuichiev D. Rashidov S. Kh. Tabarov T. E. Sukhanova M. E. Vylegzhanina A. A. Kutin V. L. Ugolkov 《Polymer Science Series A》2011,53(6):488-501
On the basis of the literature data, a retrospective analysis of the thermodynamic characteristics of dissolution of fullerene
C60 in a series of single-ring aromatic solvents is presented. The effect of the molecular structure of a solvent on its dissolving
capacity with respect to fullerene is studied. The parameter of the boiling temperature of the solvent normalized to its molecular
mass is introduced. The correlation of this parameter with the dissolving capacity of the solvent is discussed. Special emphasis
is placed on the effect of halogen-containing solvents on the dissolution of fullerene and indirectly on the development of
the mechanical characteristics of films prepared from common solutions of fullerene and low-density polyethylene. For comparison,
the films prepared from PE melts modified with low concentrations of fullerene are considered. The film structure is studied
via X-ray analysis, optical microscopy, AFM, small-angle scattering of linearly polarized light, and DSC. The films with the
maximum strength are prepared from solutions in halogen-containing solvents at a concentration of fullerene below 1 wt %.
In this case, spherulites are 5–10 times smaller than those in the films cast from solutions in other solvents. In the films
cast from common solutions of PE and fullerene in bromobenzene, crystal solvates C60 · 2C6H5Br are formed. It seems that the formation of the crystal solvates binds the residual solvent and thus affects the mechanical
behavior of the films, thereby eliminating the plasticizing effect of residual bromobenzene. Localization of fullerene in
various regions of the supramolecular structure of the films is discussed, and the morphology of the separating regions of
the crystal solvate fullerene phase is analyzed. 相似文献
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We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented
states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among
the spinors in the coupled state. 相似文献