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81.
BAKHERAD Mohammad BAHRAMIAN Bahram NASR-ISFAHANI Hossein KEIVANLOO Ali SANG Golnaz 《中国化学》2009,27(2):353-358
The polymer-supported palladium(II) ethylenediamine complex was used as a catalyst for the heterocyclization during Sonogashira reaction between a substituted phenyl iodide and 2-amino-3-(2-propynyl)-1,3-benzothiazolium bromide, which could readily be recovered from the reaction medium by a simple filtration, and reused without a significant loss in its activity. 相似文献
82.
Bahram Hemmateenejad Saeed Yousefinejad 《Analytical and bioanalytical chemistry》2009,394(7):1965-1975
This article describes the use of the net analyte signal (NAS) concept and rank annihilation factor analysis (RAFA) for building
two different multivariate standard addition models called “SANAS” and “SARAF.” In the former, by the definition of a new
subspace, the NAS vector of the analyte of interest in an unknown sample as well as the NAS vectors of samples spiked with
various amounts of the standard solutions are calculated and then their Euclidean norms are plotted against the concentration
of added standard. In this way, a simple linear standard addition graph similar to that in univariate calibration is obtained,
from which the concentration of the analyte in the unknown sample and the analytical figures of merit are readily calculated.
In the SARAF method, the concentration of the analyte in the unknown sample is varied iteratively until the contribution of
the analyte in the response data matrix is completely annihilated. The proposed methods were evaluated by analyzing simulated
absorbance data as well as by the analysis of two indicators in synthetic matrices as experimental data. The resultant predicted
concentrations of unknown samples showed that the SANAS and SARAF methods both produced accurate results with relative errors
of prediction lower than 5% in most cases. 相似文献
83.
Test‐separator units, as traditional methods of well surveillance, mainly suffer from their inherent constraints including the expensive instrumental, mechanical, electrical, piping and safety devices along with technical and protective inspections, repair and operation services, facilities and infrastructures. Other problems are time and cost consuming, uncertainty of well isolation in test separator and need to close the co‐line wells, which are diminished using multivariate thermal well testing. A novel approach was proposed and tested to classify the oil samples taken from individual wells by source and type. The novelties of this work were the use of the applied aspects of 1H NMR spectroscopy in petroleum upstream engineering, the replacement of traditional test methods, the improvement of the confidence of tests and the recognition of multisource streams. The weighed sum method was used to correlate the spectra information, taken from the samples of Iranian offshore oil wells. The experimental results and the field data revealed that the present approach was appropriate for precocious, quick and reliable surveillance of individual oil wells located in an oil field. The model was supported by field experiments and has predicted the accurate productivity of oil wells with respect to the current expensive techniques since 2010. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
84.
85.
The mean centering of ratio kinetic profiles method was used for the simultaneous determination of binary mixtures of Ni(II) and Zn(II) in water samples, without prior separation steps. The method is based on the difference in the rate of the reaction of Ni(II) and Zn(II) with xylenol orange at pH 5.3. The method allows rapid and accurate determination of Ni(II) and Zn(II). The analytical characteristics of the methods for the simultaneous determination of binary mixtures of Ni(II) and Zn(II) were calculated. The linear range was 0.025‐2.400 μg mL?1 and 0.025‐2.20 μg mL?1 for Zn(II) and Ni(II), respectively. Interference effects of common anions and cations were studied, and the method was successfully applied to the simultaneous determination of Zn(II) and Ni(II) in water samples. 相似文献
86.
Reza Moazzemi Abdollah Mohammadi Siamak S. Gousheh 《The European Physical Journal C - Particles and Fields》2008,56(4):585-590
We discuss the effects of non-trivial boundary conditions or backgrounds, including non-perturbative ones, on the renormalization
program for systems in two dimensions. We present an alternative renormalization procedure in which these non-perturbative
conditions can be taken into account in a self-contained and, we believe, self-consistent manner. These conditions have profound
effects on the properties of the system, in particular all of its n-point functions. To be concrete, we investigate these effects in the λ
φ
4 model in two dimensions and show that the mass counterterms turn out to be proportional to the Green’s functions which have
a non-trivial position dependence in these cases. We then compute the difference between the mass counterterms in the presence
and absence of these conditions. We find that in the case of non-trivial boundary conditions this difference is minimum between
the boundaries and infinite on them. The minimum approaches zero when the boundaries go to infinity. In the case of non-trivial
backgrounds, we consider the kink background and show that the difference is again small and localized around the kink. 相似文献
87.
Mansoureh Mohammadi Marzieh Kamankesh Zahra Hadian Amir Mohammad Mortazavian Abdorreza Mohammadi 《Chromatographia》2017,80(1):119-126
Microwave-assisted extraction and dispersive liquid–liquid microextraction followed by gas chromatography–mass spectrometry as a sensitive and efficient method was applied to extract and determine four biogenic amines (BAs) in Iranian Lighvan cheese samples. Carrez solutions were used for the sedimentation of proteins. Effective factors on the performance of microextraction were studied and optimized. The proposed method showed good linear ranges from 5 to 500 ng mL?1, with the coefficients of determination higher than 0.9929. Average recoveries were between 97 and 103%. Limits of detection for all analyzed BAs ranged from 5.9 to 14.0 ng g?1, and limits of quantitation ranged between 19.7 and 46.2 ng g?1. Compared with previous methods, the proposed method is simple, fast, accurate, and precise and gives low detection limits for investigating trace amounts of BAs in Iranian Lighvan cheese samples. The levels of four BAs were determined in five Lighvan cheese samples. Cadaverine was found as prevailing amine in the cheese samples. Putrescine, tyramine, and histamine were present at the second, third, and fourth highest levels, respectively. 相似文献
88.
Mohammad Kazem Mohammadi Shahriare Ghammamy Soroush Zarrinabadi Mohammad Hossein Farjam Behrang Sabayan 《中国化学》2010,28(11):2199-2203
New orange solid tributylammonium halochromates, (C4H9)3N+CrO3X?, TBAXC (X=F, Cl) are easily synthesized by the reaction of tributylammonium fluoride and chloride with CrO3 in a 1:1 molar ratio in the presence of HF and HCl. Tributylammonium halochromates(VI) are versatile reagent for the effective and selective oxidation of organic substrates. Silica gel supported TBAFC and TBACC are versatile reagents for the effective and selective oxidation of organic substrates, in particular, thiols, under mild conditions. Considerable improvements are observed in the presence of the absorbent, making the work‐up much more convenient. 相似文献
89.
Mohammad Zaman Kassaee Hassan Masrouri Farnaz Movahedi Reza Mohammadi 《Helvetica chimica acta》2010,93(2):261-264
An efficient solvent‐free method for the synthesis of various 3,4‐dihydropyrimidin‐2(1H)‐ones using TiO2 as a recyclable heterogeneous catalyst is described. Compared to known methods, satisfactory results are obtained with excellent yields, short reaction times, and simplicity in the experimental procedure. 相似文献
90.
Soraia Meghdadi Kurt Mereiter Ahmad Amiri Narges S. Mohammadi Fahimeh Zamani Mehdi Amirnasr 《Polyhedron》2010
A novel and highly efficient approach for the synthesis of H2Me2bqb and H2Me2bpb using ionic liquid as an environmentally benign reaction medium has been developed, eliminating the need for the pyridine as a toxic solvent. The Ni(II) complex of the dianionic ligand Me2bqb2−, [Me2bqb2− = 1,2-bis(quinoline-2-carboxamide)-4,5-dimethyl-benzene dianion], has been synthesized and characterized by elemental analyses and spectroscopic methods, and the crystal and molecular structure of [Ni(Me2bqb)] (1), has been determined by X-ray crystallography. The complex exhibits distorted square-planar NiN4 coordination geometry with two short and two long Ni–N bonds (Ni–N ∼1.85 and ∼1.96 Å, respectively). The electrochemical behavior of [Ni(Me2bqb)] (1), has been studied by cyclic voltammetry and compared with the analogous complex, [Ni(Me2bpb)] (2). 相似文献