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排序方式: 共有381条查询结果,搜索用时 15 毫秒
111.
We study the nonlinear rheological behavior and the microscopic particle dynamics for a colloidal glass, to see whether recently developed models for driven glassy systems can be applied to predict the rheology. Qualitatively, all the findings predicted by the models can be retrieved in our system. Notably, the viscosity decreases strongly with the shear rate. Since it is difficult to predict non-Newtonian viscosities of colloidal systems due to long-ranged hydrodynamic interactions, this shows the promise of this approach for predicting flow behavior. In addition, the measurements allow us to relate the microscopic diffusion dynamics to the macroscopic viscosity of the system. 相似文献
112.
Fatima Al‐Omran Osama Yousef Abd El‐Hay Adel Abou El‐Khair 《Journal of heterocyclic chemistry》2000,37(6):1617-1622
A new approach to the synthesis of pyridazinone, ethoxypyridine, pyrazole and 7‐aminopyrazolo‐[1,5‐a]pyrimidine derivatives. The structure of the newly synthesized compounds was elucidated by elemental analyses, ir, 1H nmr spectra and in some cases by 13C nmr investigations. 相似文献
113.
In this paper various cation substituted Z‐hexaferrites, prepared by the usual ceramic procedure and firing at a relatively low temperature (980○C) in a 2 atm. oxygen pressure are discussed. On these materials extensive studies were undertaken, X‐ray diffraction, IR absorption, scanning electronmicroscopy and a Mössbauer spectroscopy. Data obtained are explained, and discussed in details, leading to new information about the interaction of variant doped cation with the Z‐hexaferrite Fe sites. 相似文献
114.
F. H. Abou El-Nour 《Isotopes in environmental and health studies》2013,49(11):370-372
Binary promoted nickel – chromium oxide and ternary promoted nickel – chromium oxide – aluminium oxide mixed catalysts were prepared for use in the present study. The catalysts were prepared by co-precipitation of the corresponding metal nitrates as carbonates followed by calcination in nitrogen atmosphere at 350 °C and reduction in hydrogen atmosphere at 320 °C. To prevent spontaneous oxidation of the catalysts, bidistilled water was added followed by heating of the catalyst mixtures at about 110 °C in hydrogen atmosphere for few hours. Deactivation of catalysts was studied by measurements of the variation of their activities with the time of contact of the reacting gas mixtures with the catalyst surface in the reaction chamber. It was found that while the catalytic activity of ternary catalysts for the isotopic exchange of deuterium between hydrogen and water vapour was higher than that of the binary one, the loss in activity of the former teas faster than the latter. Reactivation of the catalysts were carried out at different temperatures between 110–160°C in hydrogen atmosphere. Catalytic activity measurements indicated that higher temperatures are better for the reactivation process. 相似文献
115.
Faten I. Abou El Fadl 《Russian Journal of Applied Chemistry》2016,89(10):1673-1680
A novel hydrogel based on chitosan–poly(acrylamide-co-acrylic acid) (CAA) with different formulations were synthesized by the effect of gamma radiation. The magnetic CAA hydrogels were also synthesized and characterized by using different techniques, e.g., TEM and XRD. The prepared hydrogels and magnetic hydrogel nanocomposite were utilized for in situ cobalt nanoparticle preparation and employed as a reaction media in catalytic reduction of 2-nitrophenol (2-NP), to 2-aminophenol (2-AP). The experimental parameters that affect the reduction rates such as temperature and amount of catalyst were also, investigated. 相似文献
116.
Sakr Mahmoud E. M. Kana Maram T. H. Abou Elwahy Ahmed H. M. El-Daly Samy A. Ebeid El-Zeiny M. 《Journal of fluorescence》2021,31(5):1547-1554
Journal of Fluorescence - This paper deals with the optical and photophysical properties of dihydrophenanthro[9,10-e][1,2,4]triazine fluorescent dyes doped in Silicate based sol–gel and... 相似文献
117.
118.
A. Zarrouk H. Zarrok R. Salghi B. Hammouti R. Touir I. Warad F. Bentiss H. Abou El Makarim N. Benchat 《Research on Chemical Intermediates》2013,39(3):1279-1289
The efficiency of 1H-1,2,4-triazol-3-amine (Tz1), 4-amino-3-hydrazino-4H-1,2,4-triazole-3-thiol (Tz2), and 1H-1,2,4-triazole-3,5-diamine (Tz3) as inhibitors of corrosion of copper in nitric acid was investigated by use of density functional theory (DFT). Quantum chemical data, for example energy of the highest occupied molecular orbital (E HOMO), energy of the lowest unoccupied molecular orbital (E LUMO), energy gap (ΔE), dipole moment (μ), electronegativity (χ), electron affinity (A), global hardness (η), softness (σ), ionization potential (I), fraction of electrons transferred from the inhibitor molecules to the metallic atom (ΔN), and total energy (TE), were calculated. All calculations were performed by use of DFT with Gaussian 03W software. A good correlation was found between theoretical data and experimental results. 相似文献
119.
Amir Reza Sadrolhosseini Mohd Maarof Moksin W. Mahmood Mat Yunus Zainal Abidin Talib Mahnaz M. Abdi 《Optical Review》2011,18(4):331-337
Copper corrosion is one of the important parameters used for evaluating the quality of biodiesel. In this work, a polypyrrole-chitosan
sensing layer was utilized for the detection of Cu2+ in biodiesel using the surface plasmon resonance technique. With the sensitivity of this sensor being about 0.1 ppm, different
corrosion levels could be recognized in samples that were classified as class 1a according to the standard copper strip test. 相似文献
120.
Magnons coherent transmission and heat transport at ultrathin insulating ferromagnetic nanojunctions
A. Khater B. Bourahla M. Abou Ghantous R. Tigrine R. Chadli 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,82(1):53-61
A model calculation is presented for the magnons coherent transmission and corresponding heat transport at insulating magnetic
nanojunctions. The system consists of a ferromagnetically ordered ultrathin insulating junction between two semi-infinite
ferromagnetically ordered leads with ideally flat crystal interfaces. The ground state of the system is depicted by an exchange
Hamiltonian neglecting smaller dipolar and anisotropy terms. The spin dynamics are analyzed using the equations of motion
for the spin precession displacements, valid in the limit of low temperatures compared to an order-disorder transition temperature
characteristic of the system. The coherent transmission and reflection spectra at the nanojunction boundary are calculated
in the Landauer-Buttiker formalism using the matching theory, for all the magnons in the lead bulk, at arbitrary angles of
incidence on the boundary, and for variable temperatures. The model calculations yield the thermal conductivity κ
m
due to the magnons coherent transmission between the two leads maintained at slightly different temperatures. The model is
general, and is applied in particular to the Fe/Gd/Fe system to calculate the coherent transmission of magnons and their thermal
conductivity at the junction boundary, for different thicknesses of the Gd junction and its corresponding magnetic order.
The calculated results elucidate the comparison between the heat transport from magnons with that in parallel channels from
electrons and phonons, at the nanojunction boundary. 相似文献