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71.
Hamid Reza Safaei Mohsen Shekouhy Athar Shirinfeshan Sudabeh Rahmanpur 《Molecular diversity》2012,16(4):669-683
CaCl2 is applied as an efficient reusable and eco-friendly bifunctional catalyst for the one-pot three-component synthesis of 4H-pyrans under ultrasonic irradiation. A broad range of substrates including the aromatic and heteroaromatic aldehydes, indoline-2,3-dione (isatin) derivatives, acenaphthylene-1,2-dione (acenaphthenequinone) and 2, 2-dihydroxy-2H-indene-1,3-dione (ninhydrin) were condensed with carbonyl compounds possessing a reactive ??-methylene group and alkylmalonates. All reactions are completed in short times, and the products are obtained in good to excellent yields. The catalyst could be recycled and reused several times without any loss of efficiency. 相似文献
72.
Nabil Abdo Ahmed Al-Shwafi Abdulhakim Mohsen Ahmed 《Russian Journal of General Chemistry》2011,81(13):2717-2723
Distribution of litter: ropes, netting, lamb bulbs, foot wear, plastic bags, bottles, aluminum cans, cardboard, wood loges,
rubber, polystyrene blocks and plastic sheets accumulating on Red Sea beaches of Yemen were examined. The results of the study
reflected these wastes to be varied from a region to region but they were similar in almost all-coastal areas. Most of the
litter were plastics including food bags, oil and water bottles, bait bags, and also vehicles tires. Most of pollution occurred
from the sea, due to the heavy traffic and to the fishing vessels, which fish in the area. 相似文献
73.
74.
Jaber Nasrollah Gavgani Mohsen Shahrousvand Mohammad Mohammadi Aslzadeh 《Colloid and polymer science》2013,291(10):2299-2309
The polymerization of styrene (St) was carried out with varying amounts of methanol in aqueous medium. As methanol content decreased (to 50 %), the phase of polymerization mixture (methanol/water/monomer) changed to a heterogeneous state; the homogeneous state was obtained in samples that contain 75 and 100 % methanol. In order to verify the mechanism of polymerization in heterogeneous and homogeneous mixtures, the nucleus formation rate during polymerization, the stability equilibrium of the media and seeded particles, and the size of particles and their growth in polymerization were experimentally being monitored. With the homogeneous mixture in 75 wt% methanol, dumbbell, triangle, and peanut-like particles have been formed. On the other hand, the characteristics of the polymerization products were different from those typically obtained in the emulsion polymerization and in the sample with 100 wt% methanol dispersion polymerization. In the sample with 100 % methanol and in one with 50 % methanol, monodispersed spherical particles are formed in the final conversion. Thus, homogeneity in the aqueous methanol mixture can be a critical factor in determining the polymerization modes between dispersion and emulsion polymerization. 相似文献
75.
Y. Benmimoun A. Bouhemadou R. Khenata A. H. Reshak B. Amrani M. Ameri H. Baltache 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(2):165-171
The results of first-principles theoretical study of the structural,
electronic and optical properties of SrCl2 in its cubic structure, have
been performed using the full-potential linear augmented plane-wave method
plus local orbitals (FP-APW+lo) as implemented in the WIEN2k code. In this
approach both the local density approximation (LDA) and the generalized
gradient approximation (GGA) are used for the exchange-correlation (XC)
potential. Also we have used the Engel-Vosko GGA formalism, which optimizes
the corresponding potential for band structure calculations. We performed
these calculations with and without spin-orbit interactions. Including
spin-orbit coupling cause to lifts the triple degeneracy at Γ point
and a double degeneracy at X point. Results are given for structural
properties. The pressure dependence of elastic constants and band gaps are
investigated. The dielectric function, reflectivity spectra and refractive
index are calculated up to 30 eV. Also we calculated the pressure and volume
dependence of the static optical dielectric constant. 相似文献
76.
Reza Sepahvand Mohsen Adeli Bandar Astinchap Roya Kabiri 《Journal of nanoparticle research》2008,10(8):1309-1318
Metal-carbon nanotube-graft-polymer (MCNT-g-P) nanocomposites were synthesized and characterized successfully. In this work, multiwall carbon nanotubes (MWCNT) were
opened using HNO3/H2SO4 mixture and filled by metal nanoparticles such as silver nanoparticles through wet chemistry method. Then MWCNT containing
metal nanoparticles were used as macroinitiator for ring opening polymerization of ε-caprolactone and MCNT-g-P nanocomposites were obtained. Length of grafted polymer arms onto the MWCNT was controlled using MWCNT/ε-caprolactone ratio.
Structure and properties of nanocomposites were evaluated by TEM, DSC, TGA, and spectroscopy methods. 相似文献
77.
Mohsen M. Mostafa Rafaat M. El-Shazly Tawfik H. Rakha Mohamed H. Abdel-Rahman 《Transition Metal Chemistry》2002,27(2):237-237
Other Index
Forthcoming articles 相似文献78.
Measurement and modeling of three-dimensional sound intensity variations due to shallow-water internal waves 总被引:1,自引:0,他引:1
Badiey M Katsnelson BG Lynch JF Pereselkov S Siegmann WL 《The Journal of the Acoustical Society of America》2005,117(2):613-625
Broadband acoustic data (30-160 Hz) from the SWARM'95 experiment are analyzed to investigate acoustic signal variability in the presence of ocean internal waves. Temporal variations in the intensity of the received signals were observed over periods of 10 to 15 min. These fluctuations are synchronous in depth and are dependent upon the water column variability. They can be explained by significant horizontal refraction taking place when the orientation of the acoustic track is nearly parallel to the fronts of the internal waves. Analyses based on the equations of vertical modes and horizontal rays and on a parabolic equation in the horizontal plane are carried out and show interesting frequency-dependent behavior of the intensity. Good agreement is obtained between theoretical calculations and experimental data. 相似文献
79.
80.
Rani Warsi Sullivan Mohsen Razzaghi Jutima Simsiriwong 《Mathematical Methods in the Applied Sciences》2011,34(2):140-146
The objective of this paper is to present an algorithm from which a rapidly convergent solution is obtained for Volterra integral equations of Hammerstein type. Such equations are often encountered when describing the response of viscoelastic materials where the time dependency of the material properties is often expressed in the form of a convolution integral. Frequently, singularity is encountered and often ignored when dealing with the constitutive equations of viscoelastic materials. In this paper, the singularity is incorporated in the solution and the iterative scheme used to solve the equation converges within six iterations to a typical toleration error of 10?5. The algorithm is applied to the strain response of a polymer under impulsive (constant) loading and the results show excellent correlation between the experimental and analytical solution. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献