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21.
L. V. Mikhal’chenko M. A. Syroeshkin M. Yu. Leonova A. S. Mendkovich A. I. Rusakov V. P. Gul’tyai 《Russian Journal of Electrochemistry》2011,47(11):1205-1210
The electrochemical behavior of 2-, 3-, and 4-nitrosonitrobenzenes (NNB) in DMF (with Bu4NClO4 suppoting salt) in the presence and in the absence of different proton donors (water, phenol, benzoic, acetic, chloroacetic,
and sulfuric acids) is studied by the methods of cyclic voltammetry, chronoamperometry and also by electrolysis at the controlled
potential. The electrochemical reduction of these compounds is shown to preferentially afford either monomeric (N-nitrophenylhydroxylamines)
or dimeric (azoxy compounds) products, which is determined by the interplay between reactions of protonation and dimerization
of NNB radical anions. The dimerization reactions proceed fast and reversibly to afford the corresponding dimeric dianions
with the basicity much higher as compared with NNB radical anions as the result of which the monomeric products are formed
in the presence of “strong” proton donors and the dimeric products form in the presence of “weak” proton donors. Like the
effective rate of formation of dimeric products, the basicity of radical anions increases in the row 4- < 3- < 2-NNB. 相似文献
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Y. G. Abov M. I. Bulgakov S. P. Borovlev F. S. Dzheparov A. D. Gul’ko V. M. Garochkin V. E. Shestopal S. V. Stepanov S. S. Trostin 《Hyperfine Interactions》1990,61(1-4):1319-1326
The experimental investigations of the polarization transport in the disordered spin system8Li −6Li in LiF crystal are considered. This process is initiated by one originally polarized beta-active8Li nucleus produced in a nuclear reaction. The autocorrelation function Foo(t) for the ran dom-walks-in-disordered-system
problem has been measured over the range Foo(t)≥0.1 Foo(0) by analysing the β-emission anisotropy. The influence of the resonance
process at double larmor frequency and of the thermal translational motion of8Li and6Li spins is studied. Results are in a good agre ement with the theory. 相似文献
24.
Synthesis of Spirocyclic and Tricyclic Isoxazoline via 1,3‐Dipolar Cycloaddition Reactions
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1,3‐Dipolar cycloadditions of the bicyclic monoterpenes (S)‐(?)‐camphene ( 1 ), (R)‐(+)‐a‐pinene ( 2 ), and (S)‐(?)‐b‐pinene ( 3 ) with aryl and heteroaryl nitrile oxides afforded new spirocyclic and tricyclic isoxazoline derivatives 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 whose biological activities were evaluated in bioassay studies. 相似文献
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The authors have investigated the effect of the degree of extension on the strength and shrinkage of polyisoprene chloride rubber film. It is shown that the breaking strength and shrinkage at elevated temperatures are determined only by the degree of extension in the corresponding direction and are almost independent of the extension in the other direction.Mekhanika Polimerov, Vol. 2, No. 3, pp. 350–354, 1966 相似文献
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During processing of polypropylene and alkali sulfate lignin at a temperature of 180° C, a reaction occurs resulting in the formation of a polymer which appears to have a three-dimensional structure. The observed cross-linking is accompanied by an increase in reversible deformation, a decrease in irreversible deformation, a transition from solubility to limited swelling in solvents, an increase in tensile strength, and an increase in freeze resistance. This is achieved by also adding a plasticizer to the polymer.Mekhanika Polimerov, Vol. 1, No. 6, pp. 3–9, 1965 相似文献
30.
The dynamic fatigue of composite film materials has been studied as a function of the frequency and amplitude of deformation. The tests were carried out on a vibration apparatus with a frequency range from 10 to 600 cps. The test objects consisted of foil packaging with a polyethylene backing (foil-film).The dependence of the dynamic fatigue of foil-film on amplitude, frequency, and acceleration was studied. It has been shown that in all cases failure of the material is preceded by cracking of the foil and peeling of the foil from the polyethylene backing at the site of the cracks. The material fails as a result of puncture of the polyethylene backing by the broken edge of the cracked foil.Mekhanika Polimerov, Vol. 1, No. 5, pp. 90–94, 1965 相似文献