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排序方式: 共有486条查询结果,搜索用时 21 毫秒
121.
A numerical multiphase CFD simulation for PEMFC with parallel sinusoidal flow fields 总被引:1,自引:0,他引:1
Journal of Thermal Analysis and Calorimetry - Flow field design has an important role in proton exchange membrane fuel cell (PEMFC) due to its effect on the distribution of pressure, current... 相似文献
122.
Ahmad Shaabani Ebrahim Soleimani Ali Maleki 《Monatshefte für Chemie / Chemical Monthly》2007,138(1):73-76
Summary. The synthesis of 3-aminoimidazo[1,2-a]pyridines and 3-aminoimidazo[1,2-a]pyrazines through a condensation reaction of 2-aminopyridine or 2-aminopyrazine, aldehyde, and alkyl or aryl isocyanide in
high yields at room temperature in the presence of silica sulfuric acid is described. 相似文献
123.
Reduction of barium sulfate by methane was investigated in this work. The thermogravimetric method was used to obtain kinetic parameters of the reaction in the temperature range of 900–975 °C at atmospheric pressure. The kinetics of the reaction has been studied both in the absence and presence of zinc oxide as a catalyst. The conversion–time data have been interpreted by using the grain model, and the effect of catalyst on the kinetic parameters has been elucidated. It was found that zinc oxide acted as fairly strong catalyst for the reaction, especially at higher temperatures. At about 975 °C the reaction rate constant was increased more than 7 times by using 2% of zinc oxide. This enhancement in the rate constant is valuable for industries. 相似文献
124.
Milad Sheydaei Milad Edraki Ebrahim Alinia-Ahandani Enayat Ollah Moradi Rufchahi Pegah Ghiasvandnia 《高分子科学杂志,A辑:纯化学与应用化学》2021,58(1):52-58
Abstract In this work, two polysulfide polymers were synthesized using aromatic organic monomer (α,α′-dichloro-p-xylene) and sodium disulfide (Na2S2) and sodium tetrasulfide (Na2S4) aqueous monomers. Then, the curing process of the polymers was carried out at 170° C using a rheometer. The structural characteristics of synthesized and cured samples were identified by Raman and Fourier transform infrared (FT-IR) spectroscopies. Also, morphological and thermophysical properties of samples were studied by using the X-ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. Moreover, the molecular weight of the synthesized samples was determined by proton nuclear magnetic resonance (1H NMR). Furthermore, the mechanical properties and hardness of the samples were investigated by tensile test and Shore A. The results showed that in the noncured samples during the increase of sulfur in the polymer structure, solubility was increased whereas it decreased the hardness, melting point (Tm ) and glass transition temperature (Tg ) of polymers. But in cured samples, hardness and Tg increase by increasing sulfur and the mechanical properties also improved. This is due to the increase in crosslinks. Also, Tm and solubility are not observed due to the formation of crosslinks. 相似文献
125.
Ahmad Shaabani Ebrahim Soleimani Ali Maleki Jafar Moghimi-Rad 《Molecular diversity》2009,13(2):269-274
Bis-3-aminoimidazo[1, 2-a] pyridines, pyrimidines and pyrazines as extended pi-conjugated systems were synthesized for the first time by a novel pseudo five-component condensation of 2-aminopyridine pyrimidines
and pyrazines derivatives with terephthalaldehyde or isophthalaldehyde and isocyanides in the presence of p-toluenesulfonic acid in methanol. 相似文献
126.
Mohammad R. Setare Ebrahim Karimi 《International Journal of Theoretical Physics》2007,46(5):1381-1388
In this paper the energy eigenvalues and the corresponding eigenfunctions are calculated for Hulthen potential. Then we obtain
the ladder operators and show that these operators satisfy SU(2) commutation relation. 相似文献
127.
Approximately Local Derivations 总被引:1,自引:0,他引:1
Certain linear operators from a Banach algebra A into a BanachA-bimodule X, which are called approximately local derivations,are studied. It is shown that when A is a C*-algebra, a Banachalgebra generated by idempotents, a semisimple annihilator Banachalgebra, or the group algebra of a SIN or a totally disconnectedgroup, bounded approximately local derivations from A into Xare derivations. This, in particular, extends a result of B.E. Johnson that local derivations on C*-algebras arederivations and provides an alternative proof of it. 相似文献
128.
Gary Chartrand Elzbieta B. Jarrett Farrokh Saba Ebrahim Salehi Ping Zhang 《Czechoslovak Mathematical Journal》2001,51(2):351-361
For a nontrivial connected graph F, the F-degree of a vertex in a graph G is the number of copies of F in G containing . A graph G is F-continuous (or F-degree continuous) if the F-degrees of every two adjacent vertices of G differ by at most 1. All P3-continuous graphs are determined. It is observed that if G is a nontrivial connected graph that is F-continuous for all nontrivial connected graphs F, then either G is regular or G is a path. In the case of a 2-connected graph F, however, there always exists a regular graph that is not F-continuous. It is also shown that for every graph H and every 2-connected graph F, there exists an F-continuous graph G containing H as an induced subgraph. 相似文献
129.
Summary: pH-sensitive microgels of poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA) were prepared by dispersion polymerization of 2-dimethylamino ethyl methacrylate in a mixed solvent of water/ethanol. 1HNMR, FTIR and SEM were used to confirm the chemical structure and morphological properties of the resulting microgels. Dynamic Light Scattering (DLS) was used to measure the hydrodynamic diameter of the particles. SEM micrographs showed that the microgel particles have a diameter of about 100–200 nm in dry state. Mean hydrodynamic diameter of the particles at their collapsed state at pH = 9.5 was found to be about 150 nm. DLS measurements at various pH values showed that the prepared microgels have a volume phase transition around pH = 8 at which the hydrodynamic diameter decreased from about 470 nm to around 150 nm corresponding to a 32 fold change in the mean volume of a microgel particle. 相似文献
130.
Hang Nguyen T. V. Mordukhovich Boris S. Sarabi M. Ebrahim 《Mathematical Programming》2020,180(1-2):75-116
Mathematical Programming - The paper conducts a second-order variational analysis for an important class of nonpolyhedral conic programs generated by the so-called second-order/Lorentz/ice-cream... 相似文献