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81.
On the Criteria of Instability for Electrochemical Systems 总被引:7,自引:0,他引:7
Both cyclic-voltammetry-based and impedance-based experimental criteria that have been developed recently for the oscillatory electrochemical systems are critically appraised with two typical categories of oscillators.Consistent conclusions can be drawn by the two criteria for the category of oscillators that involve the coupling of charge transfer mainly with surface steps(e.g.ad-and desorption)such as in the electrooxidation of C1 organic molecules.Whereas,impedance-based criterion is not applicable to the category of oscillators that involve the coupling of charge transfer mainly with mass transfer(e.g.diffusion and convection) such as in the Fe(CN)6^3- reduction accompanying periodic hydrogen evolution.The reason is that the negative impedance cannot include the feedback information of convection mass transfer induced by the hydrogen evolution.However,both positive and negative nonlinear feedbacks,i.e., the diffusion-limited depletion and convection-enhanced replenishment of the Fe(CN)6^3- surface concentration,that coexist between the bistability,i.e.,Fe(CN)6^3- reduction with and without hydrogen evolution at lower and higher potential sides respectively,are all reflected in the crossed cyclic voltammogram(CCV).It can be concluded that the voltammetry-based criterion(in time domain)is more intuitive,less time-consuming and has a wider range of applications than the impedancebased one (in frequency domain). 相似文献
82.
1INTRODUCTIONPolarizedketenedithioacetalshavebeenex-tensivelyusedasbuildingblocksinorganicsyn-thesis,especiallyinthesynthesisofheterocycliccompounds[1~6].Pyrazoleanditsderivativesrepre-sentoneofthemostactiveclassesofcompoundspossessingwidespectraofbiologicalactivities.Overthepastfewyears,considerableevidenceshavebeenaccumulatedtodemonstratetheefficacyofpyrazolederivatives,suchasantibacterial[7],fun-gicidal[8],herbicidal[9],insecticidal[10]andotherbiologicalactivities[11,12].Uptonow,alarg… 相似文献
83.
Homopolynuclear complexes of Cu(II) respectively Cr(III) with the glyoxylate dianion, C2H2O4
2-, have been studied in non-isothermal regime in air and nitrogen. The results of the non-isothermal analysis performed for
the synthesised complexes, Cu(C2H2O4)·0.5H2O, respectively [Cr2(OH)2(C2H2O4)2(OH2)4]·2H2O, correlated with the results of the IR and TG analysis of the compounds obtained by thermal treatment from the initial complexes
and the results of the GLC and XR analysis have led to the establishment of the thermal decomposition mechanisms for the two
studied complexes. The decomposition mechanisms confirm the stoichiometric and structural formulae proposed for the two synthesised
homopolynuclear complexes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
84.
85.
V. Yu. Rovenskiî 《Siberian Mathematical Journal》1994,35(5):1027-1035
In Riemannian geometry and its applications, the most popular is the class of Riemannian submersions (and foliations) [1–4] which are characterized by simplest mutual disposition of fibers. The purpose of the present article is to introduce other, more general, classes of submersions of Riemannian manifolds which, as well as the class of Riemannian submersions, are described by simple local properties of configuration tensors and to begin their study.Given a submersion :MM of differentiable manifolds with compact connected fibers and any metric onM, we define a metric on the base with the help of theL
2-norm of horizontal fields. In this caseT¯ M becomes a subbundle of some larger bundleM. The main class of totally geodesic submersions introduced in the article (Definition 1) corresponds to the metrics onM with simplest disposition ofT¯ M inM. In the article we obtain a criterion for such submersions (Corollary 1); existence is proved by means of the product with a metric varying along fibers (Example 2). To study totally geodesic submersions, we use ideas from the theory of Riemannian submersions and submanifolds with degenerate second form (Theorems 1 and 2 and Corollary 4).Foliations modeled by totally geodesic submersions (see equality (13)) are of interest too, but we leave them beyond the scope of the article.This work was supported by the Russian Foundation for Fundamental Research (Grant 94-01-00271).Translated fromSibirskiî Matematicheskiî Zhurnal, Vol. 35, No. 5, pp. 1154–1164, September–October, 1994. 相似文献
86.
87.
Brune M Hagley E Dreyer J Maître X Maali A Wunderlich C Raimond JM Haroche S 《Physical review letters》1996,77(24):4887-4890
88.
L. S. Maergoîz 《Journal of Mathematical Sciences》1996,80(4):1931-1940
This article is a natural supplement to Chapter 5 ofAsymptotic Characteristics of Entire Functions and Their Applications [Nauka, Novosibirsk (1991)]. Earlier, for the functions holomorphic in the closure of a (ρ,α)-convex bounded domain D, the author found a criterion of
the existence of a series expansion in a special system of entire functions. Here it is shown that the same criterion applies
to the functions holomorphic in D. Moreover, a new integral representation of entire functions is described, which enables
one to construct new representing systems for the spaces of holomorphic functions
and H(D). Bibliography: 17 titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 206, 1993, pp. 91–196.
Translated by D. V. Yakubowich. 相似文献
89.
90.
The urinary codeine-to-morphine ratios in fifteen volunteers administered codeine tablets at intervals were studied by gas chromatography (GC) and compared with one month's GC results for enzyme multiplied immunoassay technique (EMIT)-screened urine specimens in a mass-screening programme for abuse of opiate drugs, particularly heroin. It appears that when M less than 2 and C/M greater than 0 or when M greater than 2 and C/M greater than 0.5, where C and M are codeine and morphine concentrations in micrograms per 10 ml of urine, codeine consumption has to be presumed. 相似文献