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1.
2.
Francisco‐Javier Sayas 《Numerical Methods for Partial Differential Equations》2003,19(5):555-570
This article presents and analyzes a simple method for the exterior Laplace equation through the coupling of finite and boundary element methods. The main novelty is the use of a smooth parametric artificial boundary where boundary elements fit without effort together with a straight approximate triangulation in the bounded area, with the coupling done only in nodes. A numerically integrated version of the algorithm is also analyzed. Finally, an isoparametric variant with higher order is proposed. © 2003 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 19: 555–570, 2003 相似文献
3.
We establish the convergence of the finite difference scheme for the nonlinear equations of population dynamics proposed by Guertin and MacCamy. The applicability of the discrete equations to establish qualitative properties of the solution to the continuous problem is also illustrated. 相似文献
4.
5.
I obtain exact solutions for the quantum-mechanical harmonic oscillator with a perturbation potential which belongs to a class of polynomial functions of 1/r. I show that some of the eigenfunctions enable the calculation of expectation values in closed form and are therefore suitable trial functions for the application of the variational method to related nonsolvable problems. 相似文献
6.
We show that the racemic states of the B 2 phase of liquid crystals composed of banana-shaped molecules do not satisfy the Curie principle. Thus it is argued that these states cannot exist in bulk samples and the homochiral states constitute the only stable microscopic structures. A reinterpretation of the racemic states with the same macroscopic optical behaviour is proposed in terms of mixtures of the homochiral structures. 相似文献
7.
Francisco García-Montelongo María J. Sánchez Miguel A. Rodríguez 《Mikrochimica acta》1989,98(4-6):259-265
A spectrophotometric method for cyanide based on its inhibition of the colour formation reaction between nickel(II) and 3-(4,5-dimethyl-2-thiazolylazo)-2,6-dihydroxybenzoic acid has been developed, and allows the determination of down to 0.1 g of cyanide. Most of the interferences can be avoided by displacement of the hydrogen cyanide using an arsine generator. 相似文献
8.
Fátima Nunes Serralha José Madeira Lopes Francisco Lemos Duarte Prazeres Maria Aires-Barros Joo Rocha Joaquim Cabral Fernando Ramôa Ribeiro 《Reaction Kinetics and Catalysis Letters》2000,69(2):217-222
Novel [CrIII(amp)(bipy)(Cl)] (1) (H2amp = N-(hydroxyphenyl)salicyldimine; bipy = 2,2-bipyridyl) and [CrIII(app)(bipy)(Cl)]+ (2) (H2app = N-(hydroxyphenyl)pyridine-2-carboxaldimine; bipy = 2,2-bipyridyl) complexes have been synthesized and characterized by physico-chemical methods. Complexes 1 and 2 have been employed as catalysts in the oxidation of both saturated and unsaturated hydrocarbons using tert-butylhydroperoxide (t-BuOOH). The significance of the results with respect to oxo-functionalization of C-H bonds both in unsaturated and saturated hydrocarbons is noted. 相似文献
9.
Assessing the non-specific hydroxyl radical scavenging properties of melanoidins in a Fenton-type reaction system 总被引:1,自引:0,他引:1
Francisco J. Morales 《Analytica chimica acta》2005,534(1):171-176
Soluble high molecular weight fraction (>10 kDa, named melanoidins) was isolated from Maillard reaction model systems, coffee, beer and sweet wine by ultrafiltration. Deoxyribose method was adjusted for measuring the hydroxyl radical scavenging properties of melanoidins. The presence of competitive melanoidins with deoxyribose for OH decrease the rate of deoxyribose degradation. Possible interferences to the deoxyribose method have been evaluated. Most of isolated melanoidins exhibited a variable and measurable non-site-specific hydroxyl scavenging activity in a Fenton-type reaction system. The iron reducing properties of melanoidins at the reaction conditions were evaluated with ferrozine. It has established a kinetic approach to assess the second rate constants of hydroxyl radical scavenging reactions of melanoidins. This approach may be a valuable tool for addressing the structure-activity relationships of melanoidins in a future. There is no correlation between browning (absorbance at 420 nm) and efficiency for scavenging hydroxyl radicals in solution. 相似文献
10.
Kotel'nikov A. I. Ortega J. M. Medvedev E. S. Psikha B. L. Garcia D. Mathis P. 《Russian Journal of Electrochemistry》2002,38(1):77-87
The electron transfer from the heme of cytochrome c to the bacteriochlorophill dimer in reaction centers of photosynthetic purple bacteria Rps. sulfoviridis is studied by laser flash photolysis at 40–296 K in conditions where one, two, or three cytochrome hemes are chemically reduced. In the model used for the electron transfer kinetics, the protein relaxation is described with a temperature-independent oscillatory coordinate and a temperature-dependent diffusion coordinate, with the protein dielectric relaxation times widely distributed along the diffusion coordinate. It is found that all the protein complexes can be divided into proteins with fast (k
et = 107 to 10–4 s–1) and slow (k
et 100 s–1) electron transfer. These populations presumably differ by the protonation state of the functional group. The contribution of the oscillatory and diffusion coordinates alters, which severely affects k
et. Parameters V
ab, G, , 0, and for these reactions are determined. 相似文献