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261.
Davood Domiri Ganji Mehdi Safari Reza Ghayor 《Numerical Methods for Partial Differential Equations》2011,27(4):887-897
In this article, the Sawada–Kotera–Ito seventh‐order equation is studied. He's variational iteration method and Adomian's decomposition method (ADM) are applied to obtain solution of this equation. We compare these methods together. The study highlights the significant features of the employed methods and its capability of handling completely integrable equations. © 2010 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 27: 887–897, 2011 相似文献
262.
We study the problem of maximizing constrained non-monotone submodular functions and provide approximation algorithms that improve existing algorithms in terms of either the approximation factor or simplicity. Different constraints that we study are exact cardinality and multiple knapsack constraints for which we achieve (0.25−?)-factor algorithms.We also show, as our main contribution, how to use the continuous greedy process for non-monotone functions and, as a result, obtain a 0.13-factor approximation algorithm for maximization over any solvable down-monotone polytope. 相似文献
263.
Farzad Deyhimi Rahman Salamat-Ahangari Massood Arabieh Lida Parvin 《International journal of environmental analytical chemistry》2013,93(15):1151-1163
In this work, an initial-rate spectrophotometric method and response surface methodology (RSM) were combined for modelling and optimizing the experimental parameters of the enzymatic Emerson–Trinder reaction, for the determination of hydrogen peroxide. This spectrophotometric indicator reaction is currently used in biotechnology for the determination of phenolic compounds (e.g. in industrial samples) and also for determination of various substrates (e.g. in clinical chemistry). Using 4-iodophenol as a hydrogen donor in this reaction, the quality of the generated second-order polynomial response model equation was checked by the kinetic assay of H2O2 in real samples (e.g. cosmetic and human pooled serum samples), where their resulting satisfactory analytical characteristics were reported. 相似文献
264.
In this study, silica-supported titanium tetrachloride was prepared and used as a novel catalyst for rapid and efficient synthesis of 2,4,5-trisubstituted imidazoles by a three-component, one-pot condensation of 1,2-diketones and aryl aldehydes in excellent yield under solvent-free conditions using conventional heating or microwave irradiation.
265.
Abolghasem BakhodaNasser Safari Vahid AmaniHamid Reza Khavasi Mahin Gheidi 《Polyhedron》2011,30(17):2950-2956
Homo bi-copper complexes [Cu2{PhP(2-py)2}2(NO3)3] (1) and [Cu2{P(2-py)3}2Cl2] (2), were synthesized from the reaction of Cu(NO3)2·3H2O and CuCl2·2H2O with their corresponding 2-pyridylphosphine ligands. Compound 1 has a mixed valence Cu(I)-Cu(II) core with electron acceptor phosphine atoms and two NO3− anions coordinated in a monodentate fashion to Cu(I), giving it a distorted tetrahedral geometry. The environment of Cu(II) in 1 is composed of four nitrogen atoms from pyridyl and another NO3− anion in a square pyramidal geometry. This complex shows luminescence and a low energy absorption band at 969 nm corresponding to intermetallic electron transfer between the copper centers. Complex 2 was prepared from the treatment of copper(II) chloride with tris(2-pyridyl)phosphine, producing a binuclear copper complex which possesses a crystallographic inversion center. The copper geometry in this complex is distorted tetrahedral with coordination of one Cl−, two nitrogens from one bridging tris(2-pyridyl)phosphine ligand and one P atom from the other bridging tris(2-pyridyl)phosphine ligand, in a similar way observed in related complexes. The products have been characterized by spectroscopic methods and also by the single-crystal X-ray diffraction method. 相似文献
266.
The analysis of incurred material from animals treated with pharmacologically active substances is an efficient way to check the accuracy of a method. Tylosin A was chosen for the preparation of that material because it is highly effective in controlling active infections of American Foulbrood (AFB), a global threat to apiculture, but residues in honey are not allowed according to European legislation. For this reason an in-house reference material of honey containing the macrolide tylosin A and its degradation product desmycosin (tylosin B) was prepared. After the treatment of a beehive with the appropriate macrolide tylosin A, the honey samples were collected. The incurred honey material was diluted by mixing with blank honey. Concentrations of 25.81 μg kg(-1) for tylosin A and of 19.28 μg kg(-1) for its degradation product desmycosin (tylosin B) were reached. The homogeneity was checked by analysing 12 bottles in duplicate. The stability was tested at different defined temperatures and storage conditions. The reference material described above was homogeneous and stable. Samples of this in-house reference material were used for the realisation of a proficiency test with international participation. All participants accomplished satisfying results with the exception of one laboratory. 相似文献
267.
Mohammad Bagher Gholivand Behrooz Geravandi Mohammad Hadi Parvin 《Electroanalysis》2011,23(6):1345-1351
A differential pulse anodic stripping voltammetric procedure was developed for the determination of trace amounts of iron(II) in the presence of iron(III) at a carbon paste electrode (CPE) modified with dithiodianiline and gold nanoparticle. At the pH working of 3.0, a wide concentration range from 0.1 nM to 100 nM was observed with the detection limit of 0.05 nM. The relative standard deviation for a solution containing 50 nM of iron(II) was found to be 3.11 % (n=9). Possible interferences from the coexisting ions were also investigated. The validity of the method and applicability of the sensor were successfully tested by determining of iron(II) in lentil, wheat seed and barley seed samples. 相似文献