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71.
Stable nitroxide radicals and ESR techniques have been used to investigate rotational and translational motions of molecules in the liquid state. It is found that for hydrocarbons and molecules with low polarity the rotational frequencies are about an order of magnitude faster than translational encounters. Arrhenius parameters are reported for the rates of both types of processes. A scheme is given for the relation of these motions to radical recombination in solution and also to reactions requiring activation energy. The consequences of this scheme are examined. Such important properties as hydrodynamic fluidity, thermal conductivity, processes of extraction and solution, occurring in the liquid phase as well as at the interface are determined by mobility of particles in the liquid. The problem of molecular mobility is of essential significance for the kinetics of chemical and chemico-physical processes in the liquid phase. Application of both ESR techniques and stable nitroxide radicals for kinetic studies of molecular motions in liquids and the correlation between molecular mobility and the kinetic parameters of liquid-phase radical reactions have been studied in the present paper. 相似文献
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Sh. A. Markaryan L. G. Plekhanova G. A. Nikiforov S. V. Rykov V. V. Ershov A. L. Buchachenko 《Russian Chemical Bulletin》1972,21(11):2557-2559
Conclusions A mechanism for the reaction of quinone diazides with primary amines was proposed on the basis of the chemical polarization of the nuclei.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2620–2622, November, 1972. 相似文献
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78.
I. V. Moskalenko S. Yu. Petrova E. M. Pliss A. I. Rusakov A. L. Buchachenko 《Russian Journal of Physical Chemistry B, Focus on Physics》2016,10(2):260-262
The kinetic results of the radical chain oxidation of methyl linoleate (LH) in micelles were given. The oxidation rate depends on the average number of substrate molecules in the micelle and is almost independent of the micelle concentration under the given conditions. The chain propagation and termination were assumed to predominantly occur inside the micelle. Possible reasons for linear chain termination during the oxidation of polyunsaturated fatty esters in microheterogeneous systems were discussed. 相似文献
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80.
Darshan C Kundaliya Reeta Vij AA Tulapurkar U Vaidya R Pinto RG Kulkarni 《Pramana》2002,58(5-6):1041-1044
Electrical resistance (R) measurements of a bulk La0.33Nd0.33Ca0.33MnO3 perovskite in magnetic fields up to 40 kOe have revealed anomalous temperature hysteretic effects both in 0 Oe and 20 kOe
magnetic fields. The sharp peak observed in the R vs. T plot indicates the occurrence of metal-to-insulator (M-I) transition at a temperature of T
MI=110 K and 140 K, for cooling and warming paths, respectively. An applied magnetic field of 20 kOe reduces the resistance
and shifts T
MI to 160 K and 185 K for cooling and warming, respectively. We have observed a much higher resistance in the cooling path than
in the warming path leading to the hysteretic resistance ratio (R
cool/R
warm) of 200 at 110 K and 1.8 at 160 K for 0 Oe and 20 kOe, respectively. Record values of colossal magnetoresistance (CMR) have
been achieved. The CMR value reaches nearly 99% in the temperature ranges of 90 K to 140 K and 90 K to 170 K for 20 kOe and
40 kOe magnetic fields in the cooling mode, respectively. The observed unusual behavior is attributed to the co-existence
of La-rich and Nd-rich domains assumed to be distributed randomly in the compound. 相似文献