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141.
The photopolymerization of acrylonitrile (AN) initiated with phenyl hydrazine (PHZ) and its derivatives has been studied. The initiator exponent and monomer exponent were determined from the kinetic investigation to be 0.66th and 2.1th respectively and the overall activation energy was 33.4KJ/mol for the PHZ-AN system. Spectral analysis and other data indicate that a charge transfer complex between PHZ as a donor and AN as an aceeptor is formed. The initiation mechanism was proposed.  相似文献   
142.
We have obtained four new bispirane systems in which both spiroatoms are vicinal atoms in cyclopropane or cyclobutane rings and in which the heterocyclic component has the basic structure of 1,4-dioxep-2-ene. We have shown that from two possibilities (bispiran, propellan) the general reaction leads only to a bispiran system. To the bispiran2 exhibiting the highest hyperchromism we ascribed the bispirocoplanar conformation (Fig. 1).

Mit 3 Abbildungen  相似文献   
143.
The kinetics of the system O2/HO2 ?, OH? were studied at pyrolytic carbon in alkaline electrolytes. The rest potentials are close to the reversible values. They decrease by 30 mV when the HO2 ?-concentration is increased by a factor 10. CathodicTafel lines displayb-values between 70 and 95 mV. The exchange current densities are evaluated by extrapolation ofTafel lines to zero overvoltage and from the charge transfer resistance. Two different succeeding charge transfer reactions occur in course of the overall process, the first of which is the rate-determining step. A cathodic reaction order of zero is obtained with respect to HO2 ?. Theb values of anodicTafel lines are between 60 and 80 mV, the corresponding reaction order concerning the HO2 ? concentration is found to be +0.5. The kinetic studies prove the reversibility of the system O2/HO2 ?, OH? at carbon electrodes. The reaction mechanism is: $$\begin{array}{*{20}c} {O_2 + e^ - \rightleftarrows O_2 } \\ {O_{2^ - } + H_2 O \rightleftarrows HO_2 + OH - } \\ {HO_2 + e^ - \rightleftarrows HO_{2^ - } } \\ \end{array} $$ .  相似文献   
144.
The combination of matrix isolation infrared spectroscopic and density functional calculation results provides strong evidence that the transition metal monoxide cation, ScO+, coordinates five noble gas atoms in forming the [ScO(Ng)5]+ (Ng = Ar, Kr, or Xe) complexes in noble gas matrixes.  相似文献   
145.
Zusammenfassung Das Verhalten des Wollkeratins ist im kochenden Wasser nach Behandlung mit Kupfer-, Kadmium-, Silber- und Quecksilbersalzen unnormal, nicht nur verglichen mit dem Verhalten des metallfreien Proteins, sondern auch gegenüber des unter gleichen Bedingungen mit anderen Metallen behandelten Keratins. Die beobachteten Phänomene werden in einigen Fällen entweder mit der Annahme der Bildung von Vernetzungen zwischen benachbarten Polypeptidketten durch Komplexbildung des Metalls mit einigen Gruppen des Keratins oder durch Blockieren des Cysteins und der Verhinderung des Disulfidaustausches erklärt. In anderen Fällen jedoch, besonders bei Silber, ist die Erklärung der eintretenden Veränderung mit Hilfe dieser zwei Mechanismen nicht möglich, und es wird die direkte Reaktion des Metalls mit dem Schwefel des Cystins vorgeschlagen. Hierbei wird das Cystin und damit die Disulfidbindung gespalten. Die Spaltung dieser Bindung und die Verhinderung ihrer Rückbildung, entweder in derselben oder in anderer Lage, senkt die Zahl der Quervernetzungen im Keratin herab und damit die Fixierung der Polypeptidketten in ihrer ursprünglichen Lage. Hieraus resultiert eine Schrumpfung der Ketten und die Kontraktion der Faser.
Summary Wool fibres containing cadmium, copper, mercury or silver set in a different way than the untreated ones or the fibres which contain other metals. This behaviour is explained in some cases by assuming the formation of complexes between the metal and the protein or by the disulphide exchange mechanism. In other cases, however, and particularly with silver this is not possible, and therefore the direct reaction between the metal and the sulphur of cystine is proposed. According to this mechanism the contraction of the fibre is due to the breakdown of the disulphide bond and the inability of its reformation.


Mit 10 Abbildungen und 2 Tabellen  相似文献   
146.
Unlabeled fluoroimmunoassay with a europium chelate is described. The recommended method is simple because the complicated labeling process is omitted. The recovery of some samples ranges from 91 to 111%. The relative standard deviation of the method is less than 10%. The detection limit is about 10−10mol liter−1antigen.  相似文献   
147.
Study of europium(III)-l-histidine complex has been made in sodium perchlorate at μ=0.1 by tast polarography. The reduction process appears to be quasi irreversible. The apparent rate constants have been determined byGellings method1. With the knowledge ofE 1 2/r and use ofLingane's method, one complex Eu(Histd)2+ with the instability constant 6.77×10?5 is reported.  相似文献   
148.
3,5-diBr-PADAP作锆(Ⅳ)显色剂的分光光度法研究与应用   总被引:2,自引:0,他引:2  
本文研究了在非离子表面活性剂存在下,用3,5-diBr-PADAP作锆显色剂的胶束增溶分光光度法。在pH1.0~2.0的HCl介质中,配合物吸光度最大且稳定,最大吸收值在610nm处。Zr(Ⅳ)与试剂形成1:2的配合物,摩尔吸光系数为1.10×10~5L·mol~(-1)·cm~(-1),zr(Ⅳ)量在0~30μg/25mL范围内遵守比尔定律。采用钽试剂一苯苹取分离法,适合于钽铌矿中微量锆的测定。  相似文献   
149.
The kinetics of the diazotization of o-, m-, p-chloroaniline in 0.005n- to 0.4n-methanolic HCl-solution at 25, 15, 0, ?10 ?20, and ?30°C was invertigated. It was found that the nitrosation reaction (the same as in1) $$C_6 H_4 ClNH_2 + NOCl \mathop \rightleftharpoons \limits^k C_6 H_4 ClNH_2 NO^ + + Cl^ - $$ is a proceeding advance-back-reaction. The decomposition of C6H4ClNH2NO+ by splitting off a proton is the rate determining step. The free activation enthalpies ΔG * for the nitrosation reaction, the activation entropies ΔS *, the activation enthalpies ΔH * and the activation energiesE a at the given temperatures are calculated. The experimentally found and the calculated velocities are given in Tables 1–6. The equilibrium constants of the o-, m-, p-chloroanilinium ions, and nitrosyl-chloride in methanol are indicated in Table 7, diagram 1. TheK M values (the ionic products of methanol, extrapolated at infinite dilution) together with theK A values of Table 7 give theK B values (p. 2) using the table10. The ΔG B values can be calculated using equation ΔG B = ?RTlnK B Fig 2 shows the linear dependance of the logarithmus of the ΔG * values from the logarithmus of theK B values.  相似文献   
150.
The model of Onsager in which a polar molecule undergoes a reaction field due to the polarization of the molecular surroundings is used to evaluate by a S.C.F. calculation (CNDO/2 approximation) the modifications of a molecular structure in the liquid state.Application to water molecule and to three polar dimers for values of the dielectric constant varying between 3 and 78, shows that most of geometric parameters and dipoles moments vary of few per cent when the molecule is inserted in a liquid. In the liquid state dipole moments do not depend very much on the dielectric constant but energies and relative stabilities of isomers are strongly dependent on the medium.[/p]
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