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991.
Malek Taher Maghsoodlou Norollah Hazeri Sayyed Mostafa Habibi Khorassani Reza Heydari Mahmoud Nassiri Ghasem Marandi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):865-877
Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of strong NH-acids, such as benzotriazole, 5-methylbenzotriazole, 5-chlorobenzotriazole, pyrrole, 2-acetylpyrrole, pyrrole-2-carboxaldehyde, 4-nitro-acetanilide, 4-methoxyacetanilide, 4-bromoacetanilide, 4-methylacetanilide, 2-methyl-acetanilide, and 2,6-dimethylacetanilide. These stable ylides exist in a solution as a mixture of two geometrical isomers as a result of the restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group. 相似文献
992.
993.
S. Yaacoub S. Calas-Etienne J. Jabbour R. Courson R. Tauk A. Khoury A. Mehdi P. Etienne 《Journal of Sol-Gel Science and Technology》2013,67(2):384-393
We report a new ORganically MOdified SILicates (ORMOSILs) stable sol based on vinyl ether function which can be deposited as a layer and structured by mean of UV radiation through a mask or by direct laser writing. Silica matrix is synthesized by sol–gel process and organic network is formed by photopolymerization. One of the potential applications is the fabrication of integrated optical circuits. [2-(3,4 epoxycyclohexyl ethyltrimethoxysilane)] has already used for the fabrication of such devices and to develop microstructures on an organic substrate by cationic polymerization. Obtained results show some weakness such as an important contribution of OH and aliphatic CH groups to the attenuation at 1550 nm wavelength and low conversion rate of organic polymerization involving poor mechanical properties. This work treats on the design of a new generation of hybrid materials with a very high reactivity and low amount of groups involved in the attenuation. We have chosen vinyl ether function as reactive organic part for her highest polymerization rate via cationic way. The new synthesized molecule is 4-vinylether phenyltriethoxysilane. Sol–gel kinetic reactions were monitored by liquid 29Si-NMR spectroscopy. In order to obtain the highest reactive multifunctional oligomers and the lowest OH groups, hydrolysis and polycondensation reactions were followed as a function of time, temperature and pH of the water involved in the hydrolysis conditions. Finally, we show the feasibility to microstructure films deposited with this sol. 相似文献
994.
Analytical derivation of electronic band gap of Single Walled Carbon Nanotube (SWCNT) under a small percent of uniaxial and
torsional strains is in this paper. Our approach is based on a kind of π-Tight Binding (π-TB) approximation which includes interactions of the second and the third neighbors of each carbon atom in addition to the
nearest ones. Implementing the approach of this paper, yields more precise results than those of other researches. 相似文献
995.
Hojat Veisi Reza Azadbakht Mehdi Ezadifar Saba Hemmati 《Journal of heterocyclic chemistry》2013,50(Z1):E241-E246
A simple, economical, and green approach to the synthesis of N‐substituted pyrroles using sodium dodecyl sulfate as surfactant in water is described. The experiment protocol features simple operations, and the products are isolated in high to excellent yields (60–98%). 相似文献
996.
This paper deals with the α-stability for a class of linear systems with multiple delays. New sufficient conditions for exponential stability with a
convergence rate are established based on Lyapunov functionals and the linear matrix inequality technique. Two numerical examples
are provided to illustrate the effectiveness of the proposed results.
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 61, Optimal
Control, 2008. 相似文献
997.
998.
Majid M. Heravi Nasser Montazeri Mohammad Rahimizadeh Mehdi Bakavoli Mitra Ghassemzadeh 《Monatshefte für Chemie / Chemical Monthly》2001,132(10):1225-1228
Summary. A facile and regioselective synthesis of 2-substituted [1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones by action of sulfuric acid on (4H-[1,2,4]triazol-3-ylsulfanyl)-acrylic acids is described.
Received January 23, 2001. Accepted (revised) May 7, 2001 相似文献
999.
The increased global concern on environmental protection has made researchers focus their attention on new and more efficient methods of pollutant removal. In this research, novel nanocomposite adsorbents,i.e., magnetic hydroxyapatite (Fe3O4@HA) and magnetic hydroxyapatite β‐cyclodextrin (Fe3O4@HA‐CD) were synthesized and used for heavy metal removal. The adsorbents were characterized by FTIR, XRD, TGA, VSM, and SEM. In order to investigate the effect of β‐cyclodextrin (β‐CD) removal efficiency, adsorption results of nine metal ions were compared for both adsorbents. β‐CD showed the most increasing effect for Cd2+ and Cu2+ removal, so these two ions were selected for further studies. The effect of diverse parameters including pH, contact time, initial metal ion concentration and adsorbent dosage on the adsorption process was discussed. The optimum pH was 6 and adsorption equilibrium was achieved after 1 hr. Adsorption kinetic data were well fitted by pseudo‐second‐order model proposing that metal ions were adsorbed via chemical reaction. Adsorption isotherm was best described by the Langmuir model, and maximum adsorption capacity for Cd2+ and Cu2+ was 100.00 and 66.66 (mg/g), respectively. Desorption experiment was also done, and the most efficient eluent used for desorption of metal ions was EDTA (0.001 M) with 91% and 88% of Cd2+ and Cu2+ release, respectively. Recyclability studies also showed a 19% decrease in the adsorption capacity of the adsorbent after five cycles of regeneration. Therefore, the synthesized adsorbents were recognized as potential candidates for heavy metal adsorption applications. 相似文献
1000.