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991.
Cristina López Moreno Pedro Cañada Rudner José Manuel Cano García José Manuel Cano Pavón 《Mikrochimica acta》2004,148(1-2):93-98
A sequential injection analysis method is developed for the determination of the total polyphenol index in wines. The determination is based on the Folin-Ciocalteu reaction, which is monitored spectrophotometrically. Interactions between experimental variables and their optimal levels were investigated using factorial designs. The proposed system is fully computerised and is able to monitor polyphenol index in real samples of white, sweet and red wines. The calibration graph is linear from 5 to 200mg·L–1 using Tannic acid as standard, with a detection limit of 3.2mg·L–1. Interferences are studied. For validation purposes the proposed methodology was applied to the determination of the total polyphenol index in different types of wines and compared with earlier alternatives in order to assess their performance. 相似文献
992.
Jorge?CossioEmail author Sigifredo?HerrónEmail author 《Journal of Dynamics and Differential Equations》2004,16(3):795-803
In this paper we prove that a semilinear elliptic boundary value problem has at least three nontrivial solutions when the range of the derivative of the nonlinearity includes at least the first two eigenvalues of the Laplacian and all solutions are nondegenerate. A pair are of one sign (positive and negative, respectively). The one sign solutions are of Morse index less than or equal to 1 and the third solution has Morse index greater than or equal to 2. Extensive use is made of the mountain pass theorem, and Morse index arguments of the type Lazer–Solimini (see Lazer and Solimini, Nonlinear Anal. 12(8), 761–775, 1988). Our result extends and complements a theorem of Cossio and Veléz, Rev. Colombiana Mat. 37(1), 25–36, 2003.AMS Subject classification: 35J20; 35J25; 35J60.Dedicated to Professor Shui-Nee Chow on the occasion of his 60th birthday. 相似文献
993.
994.
Merijs Meri R. Jablonskis I. Zicans J. Kalnins M. Bledzki A. K. 《Mechanics of Composite Materials》2004,40(3):247-252
Considering the wide applicability of polymeric composite materials, heterogeneous blends of poly(ethylene terephtalate) (PET) and polyethylenes of high and low densities (HDPE and LDPE, respectively) were investigated. Rheological (the flow-behavior index), mechanical (the yield strength and the Charpy impact strength), and morphological (crystallinity and the melting temperature) properties were detected for individual blend components and different blend compositions. A radiation treatment (-rays) was applied to improve certain characteristics of the heterogeneous blends. The results of this investigation show that the radiation modification can be successfully used to improve some physical properties of the PET-based blends and to choose individual blend components, optimum irradiation conditions, and desirable blend compositions, which allows producing materials with a predictable set of mechanical properties. 相似文献
995.
Rostislav?E.?MaiborodaEmail author Natalia?M.?Markovich 《Computational Statistics》2004,19(4):569-592
Summary Common non-parametric estimators of a probability density function (PDF) show bad performance for heavy-tailed PDFs. Using
a parametric approximation of the true cumulative distribution function (CDF), the transformation-retransformation of the
data is explored here as a useful tool for the reliable PDF prediction. The PDF estimators are compared by their capacity
to solve a classification problem. Simulation results and an application to Web data analysis are presented, too. 相似文献
996.
We study the problem concerning the influence of indices of maximal subgroups of a simple group on the structure of a group. We obtain a characterization property of all finite simple groups. 相似文献
997.
Zi-qing Xie Chuan-miao Chen Institute of Computation Hunan Normal University Changsha Hunan China 《应用数学学报(英文版)》2004,20(2):317-322
The multiple solutions for one-dimensional cubic nonlinear problem u" u~3=0,u(0)=u(π)=0are computed,on the basis of the eigenpairs of-φ"_k=λ_(kφk),k=1,2,3....There exist two nonzero solutions±u_k corresponding to each k,and their Morse index MI(k) for 1(?)k(?)20 is to be exactly determined.It isshown by the numerical results that MI(k)(?)k. 相似文献
998.
The chemisorption and dissociation pathways of NO on the Rh(1 0 0), (1 1 0), and (1 1 1) surfaces are studied by the plane-wave density functional theory (DFT) with CASTEP program. In addition, the electronic and geometrical effects that affect the NO dissociation reactions have been investigated in detail. The calculation results are presented as following: The effective activation energies of the best NO dissociation pathways on the Rh(1 0 0), the Rh(1 1 0), and the Rh(1 1 1) are 0.63, 0.66 and 1.77 eV, respectively. The activity of the Rh planes for NO dissociation is in the order of Rh(1 0 0) ≈ Rh(1 1 0) > Rh(1 1 1). The low dissociation barrier for Rh(1 0 0) and Rh(1 1 0) is associated with the existence of a lying-down NO structure which acts as a precursor for dissociation. By Mulliken population analysis and structure analysis, both electronic and geometrical effects are found to affect the NO dissociation reactions, but the geometrical effect exceed the electronic. The energy decomposition scheme has been used to provide further insight into the NO dissociation reactions. Based on the calculations, the interaction energy between N and O in the transition state on the Rh(1 1 1) is found much larger than that on the Rh(1 0 0) and the Rh(1 1 0). The major differences of should originate from the variation of the bonding competition effect. 相似文献
999.
1000.
扭化的Atiyah-Singer算子(I) 总被引:1,自引:0,他引:1
本文证明黎曼流表上的de Rham以及Signature算子都同构于扭化的Atiyah-Singer算子。这两类算子的局部指数定理和局部Lefschetz不动点公式都可以从扭化的Atiyah-Singer算子得到。 相似文献