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991.
A. I. Kovalev Yu. I. Lyakhovetskli M. M. Teplyakov A. L. Rusanov P. V. Petrovskii S. O. Yakushin 《Russian Chemical Bulletin》1993,42(9):1529-1535
The chemical heterogeneity of polyphenylenes obtained by trimerization poiycycio-condensation of acetylaromatic compounds has been investigated by GLC-MS analysis of the products of trimerization cyclocondensation of acetophenone. The mechanism for the formation of side products of the reaction is discussed. The presence of dypnone fragments in the polyphenylene structure results in a decrease in the thermal stability of these polymers.Deceased March, 1993.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1595–1601, September, 1993. 相似文献
992.
J. P. Doumerc J. M. Cocciantelli J. C. Grenier M. Pouchard P. Hagenmuller 《无机化学与普通化学杂志》1993,619(4):748-752
Magnetic susceptibility of V2O5 and of the α-, ?-, δ- and γ-LixV2O5 bronzes prepared either at high or at room temperature has been measured between liquid helium and ambient temperature. The results are representative of the localized character of the V4+ ion d-electron and, for high enough x-values, of the existence of antiferromagnetic interactions in a low dimensional system. The intrachain exchange integral J has been determined using the Bonner/Fischer model for Heisenberg chains with S = 1/2 spin. It is larger for the γ- than for the δ-phase. This result as well as the occurrence of long range ordering below TN ≈ 130 K in the γ-phase may be ascribed to ordering of V4+ and V5+ ions in the former bronze and to the random distribution of V4+ ions in the latter one. 相似文献
993.
The enthalpies of formation (ΔH
f
o) for 23 halosubstituted radicals were determined from the published data on bond dissociation energies. The ΔH
f
o values of the corresponding molecules necessary for the calculation of ΔH
f
o of the radicals were taken from handbooks or calculated by the additive-group method. The conjugation energies of the radicals
are calculated, and the effect of substituents at the π-system on these values was shown. Errors of determination of the ΔH
f
o values of the radicals were estimated.
For Part 1, see Ref. 1.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 643–646, April, 1998. 相似文献
994.
I.J. Galpin F.E. Hancock B.K. Handa A.G. Jackson G.W. Kenner P. McDowell P. Noble R. Ramage 《Tetrahedron》1981,37(17):3043-3050
The previously synthesised (1–37), (38–75), (76–93), (94–104), (105–117) and (118–129) fragments of the analogue were combined making extensive use of the DCCI/HONSu method. The final coupling involved the (1–75) and (76–129) sub-fragments. Aggregation of the latter fragment caused problems in purification by routine gel filtration methods employing Enzacryl K2 or Sephadex LH60. The fully protected (1–129) product was partially purified by washing, then deprotectcd and purified by gel filtration and ion exchange chromatography. Satisfactory removal of the acetamidomethyl group used for cysteine protection could not be achieved. 相似文献
995.
总结毛者提出的线型缩聚中当量系数的新定义及引入缩聚体系单体平均官能度的新方法,本文总结出了一套讲授数均聚合度计算问题的简单方法。 相似文献
996.
997.
本文研究了以正丁基锂为引发剂,四氢呋喃为添加剂,环己烷为溶剂中的α-甲基苯乙烯阴离子平衡聚合动力学。讨论了体系中的反应活性种;提出了聚合机理;得到了聚合温度为20℃时的平衡单体浓度与活性种速率常数及添加剂浓度之间的关系式。 相似文献
998.
Band broadening in capillary columns is satisfactorily described by the Golay-equation extended to situations of appreciable pressure drop by Giddings. In practice, however, several simplifications are often made. The effect of these simplifications on the calculated values of the minimum plate height and optimum carrier gas velocity are treated systematically. 相似文献
999.
R. Leboda 《Chromatographia》1980,13(9):549-554
Summary The surface properties of complex adsorbents prepared through the pyrolysis of benzyl and n-heptyl alcohols and their mixtures
on the surface of silica gel were investigated. The reactions were carried out in an autoclave at 500°C. A series of adsorbents
having different porous structure, chemical nature of the adsorption centers and their topography were obtained. The best
resolution of different mixtures was obtained by the carbon-silica adsorbent prepared through the pyrolysis of n-heptanol. 相似文献
1000.
Yatsimirskii V. K. Oleksenko L. P. Lutsenko L. V. 《Theoretical and Experimental Chemistry》2004,40(1):44-51
We have studied the kinetic behavior of oxidation of carbon monoxide on Co-containing zeolite ZSM-5. We have shown that the kinetic curves obtained for the dependence of the reaction rate on the reagent concentration can be described by an Eley–Rideal mechanism, which assumes that oxygen can be adsorbed on the surface of the catalyst in both atomic and molecular form, followed by reaction of CO from the gas phase with the adsorbed oxygen. 相似文献