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171.
Morteza BararjanianSaeedeh Hosseinzadeh Saeed Balalaie Hamid Reza BijanzadehEckardt Wolf 《Tetrahedron letters》2011,52(26):3329-3332
An efficient palladium-catalyzed protocol for the stereoselective synthesis of 3-(aminoarylmethylene)-oxindoles has been developed. In this approach, Ugi-4-component reaction adducts were used as starting materials for carbopalladative cyclization-Buchwald reaction sequences. 相似文献
172.
Hamid Reza Memarian Asadollah Farhadi Hassan Sabzyan Mousa Soleymani 《Journal of photochemistry and photobiology. A, Chemistry》2010,209(2-3):95-103
A variety of Biginelli 5-acetyl-3,4-dihydropyrimidin-2(1H)-ones are efficiently oxidized to their corresponding pyrimidin-2(1H)-one derivatives upon UV irradiation under argon atmosphere in chloroform solution. The nature of the additional substituent on the phenyl ring located on C-4 of the heterocyclic ring influences the rate of reaction. An electron-transfer induced photoreaction is proposed based on the formation of HCl and CH2Cl2. 相似文献
173.
174.
Hamid Usefi 《Journal of Pure and Applied Algebra》2008,212(10):2182-2189
Let G be a group, S a subgroup of G, and F a field of characteristic p. We denote the augmentation ideal of the group algebra FG by ω(G). The Zassenhaus-Jennings-Lazard series of G is defined by Dn(G)=G∩(1+ωn(G)). We give a constructive proof of a theorem of Quillen stating that the graded algebra associated with FG is isomorphic as an algebra to the enveloping algebra of the restricted Lie algebra associated with the Dn(G). We then extend a theorem of Jennings that provides a basis for the quotient ωn(G)/ωn+1(G) in terms of a basis of the restricted Lie algebra associated with the Dn(G). We shall use these theorems to prove the main results of this paper. For G a finite p-group and n a positive integer, we prove that G∩(1+ω(G)ωn(S))=Dn+1(S) and G∩(1+ω2(G)ωn(S))=Dn+2(S)Dn+1(S∩D2(G)). The analogous results for integral group rings of free groups have been previously obtained by Gruenberg, Hurley, and Sehgal. 相似文献
175.
Bicyclic δ-lactones with a carbon group at the bicyclic junction C-7a, designed as pseudoiridolactones, were synthesized from α-alkyl-α-hydroxymethylcyclopentanones via an intramolecular Horner-Wadsworth-Emmons reaction. 相似文献
176.
A method is proposed to calculate the response of periodic structures subjected to moving loads. It is based on the Floquet decomposition which allows the restriction of the analysis for the overall system to a generic cell. The main contribution of the approach presented hereafter is that the response is directly deduced from transfer functions in the space-wavenumber domain calculated in an unbounded generic cell. Moreover, the equivalence of this new solution with the response of invariant structures obtained using Fourier transforms is established. To cite this article: H. Chebli et al., C. R. Mecanique 334 (2006). 相似文献
177.
S.F. Abdullah S. Radiman M.A. Abd. Hamid N.B. Ibrahim 《Colloids and surfaces. A, Physicochemical and engineering aspects》2006,280(1-3):88-94
The effect of calcination temperature on the surface morphology and crystallinity of tungsten (VI) oxide, WO3 nanorods prepared using colloidal gas aphrons (CGAs) as template was studied. The synthesized WO3 nanorods were calcined in a furnace for 4 h at four different temperatures, i.e., 400, 500, 600 and 700 °C. The morphology of the calcined WO3 nanorods have been characterized by both transmission electron microscope (TEM) and variable pressure scanning electron microscope (SEM) equipped with energy dispersive X-ray analysis (EDAX). The results showed that the calcination temperature influenced the shape and size of the WO3 nanorods produced. It is also found that the calcination at various temperature do not effect the composition and the purity of the WO3 nanorods. In order to characterize the crystalinity of WO3, X-ray diffraction (XRD) has been used. It shows that all the calcined WO3 produced are in crystalline form compared to the as-prepared WO3 nanorods, which is in amorphous form. 相似文献
178.
We consider a class of quasilinear elliptic boundary problems, including the following Modified Nonlinear Schrödinger Equation as a special case: $$\begin{cases} ∆u+ \frac{1}{2} u∆(u^2)−V(x)u+|u|^{q−2}u=0 \ \ \ in \ Ω, \\u=0 \ \ \ \ \ \ \ ~ ~ ~ on \ ∂Ω, \end{cases}$$ where $Ω$ is the entire space $\mathbb{R}^N$ or $Ω ⊂ \mathbb{R}^N$ is a bounded domain with smooth boundary, $q∈(2,22^∗]$ with $2^∗=2N/(N−2)$ being the critical Sobolev exponent and $22^∗= 4N/(N−2).$ We review the general methods developed in the last twenty years or so for the studies of existence, multiplicity, nodal property of the solutions within this range of nonlinearity up to the new critical exponent $4N/(N−2),$ which is a unique feature for this class of problems. We also discuss some related and more general problems. 相似文献
179.
Application of an Itô-based approximation method to random vibration of a pinching hysteretic system
In this paper, an extension of the Cumulant-Neglect closure scheme is utilized for the random vibration analysis of a single degree of freedom system with a general pinching hysteresis restoring force. The hysteresis element used in the system model can simulate commonly observed forms of stiffness, strength and pinching degradations. The second order statistics of the system response to a stationary Gaussian white noise input are derived using an Itô-based approximation technique. The validity of these response statistics are then verified by comparing them to Monte Carlo simulation results. The numerical studies performed for different combinations of degradation parameters and excitation levels show that the response estimates obtained by this solution method are in good agreement with Monte Carlo simulation. These studies also indicate the applicability of this technique for response analysis of complicated forms of non-linearities. 相似文献
180.
Column preconcentration and electrothermal atomic absorption spectrometric determination of rhodium in some food and standard samples
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Mohammad Ali Taher Fatemeh Pourmohammad Hamid Fazelirad 《Journal of separation science》2015,38(23):4153-4158
In the present work, an electrothermal atomic absorption spectrometric method has been developed for the determination of ultra‐trace amounts of rhodium after adsorption of its 2‐(5‐bromo‐2‐pyridylazo)‐5‐diethylaminophenol/tetraphenylborate ion associated complex at the surface of alumina. Several factors affecting the extraction efficiency such as the pH, type of eluent, sample and eluent flow rates, sorption capacity of alumina and sample volume were investigated and optimized. The relative standard deviation for eight measurements of 0.1 ng/mL of rhodium was ±6.3%. In this method, the detection limit was 0.003 ng/mL in the original solution. The sorption capacity of alumina and the linear range for Rh(III) were evaluated as 0.8 mg/g and 0.015–0.45 ng/mL in the original solution, respectively. The proposed method was successfully applied for the extraction and determination of rhodium content in some food and standard samples with high recovery values. 相似文献