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排序方式: 共有278条查询结果,搜索用时 15 毫秒
51.
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54.
H. H. Sherif M. S. Faltas E. I. Saad 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2008,59(2):293-312
The Stokes axisymmetrical flow caused by a sphere translating in a micropolar fluid perpendicular to a plane wall at an arbitrary
position from the wall is presented using a combined analytical-numerical method. A linear slip, Basset type, boundary condition
on the surface of the sphere has been used. To solve the Stokes equations for the fluid velocity field and the microrotation
vector, a general solution is constructed from fundamental solutions in both cylindrical, and spherical coordinate systems.
Boundary conditions are satisfied first at the plane wall by the Fourier transforms and then on the sphere surface by the
collocation method. The drag acting on the sphere is evaluated with good convergence. Numerical results for the hydrodynamic
drag force and wall effect with respect to the micropolarity, slip parameters and the separation distance parameter between
the sphere and the wall are presented both in tabular and graphical forms. Comparisons are made between the classical fluid
and micropolar fluid.
相似文献
55.
S. Jha Sherif Yehia C. Mitros Amer Lahamer Glenn M. Julian R. A. Dunlap 《Hyperfine Interactions》1989,51(1-4):987-991
The time differential perturbed angular correlation method has been used to measure, as a function of temperature, the hyperfine
magnetic field at Cd sites in the Heusler alloys Co2MnZ (Z=Si, Ga, Ge, Sn). The hyperfine fields, normalized to the total magnetic moment per formula unit, show an approximately
linear trend toward more positive values with increasing lattice parameter. 相似文献
56.
R. M. Awadallah M. K. Sherif A. E. Mohamed F. Grass 《Journal of Radioanalytical and Nuclear Chemistry》1986,98(1):49-64
Multielemental instrumental neutron activation (INAA), inductively coupled plasmaatomic emission spectrometric (ICP-AES) and atomic absorption spectrophotometric (AAS) analyses are utilized for the determination of Ag, Al, As, Au, Ba, Be, Br, Ca, Cd, Ce, Cl, Co, Cr, Cu, Eu, Fe, Ga, Hf, K, La, Li, Lu, Mg, Mn, Na, Nb, Ni, P. Pb, Sb, Sc, Se, Sm, Sn, Sr, Ta, Th, Ti, U, V, W and Zn in sugar cane plant, raw juice, juice in different stages, syrup, deposits, molasses, A, B and C sugar, refinery 1 and 2 sugar, and in soil samples picked up from the immediate vicinity of the cane plant roots at surface, 30 and 60 cm depth. 相似文献
57.
A. M. Hussein S. M. Sherif A. A. Atalla 《Monatshefte für Chemie / Chemical Monthly》1996,127(11):1153-1160
Summary Condensation of cyano acid hydrazide1 with cyclopentanone in refluxing ethanolic piperidine yields hydrazone2. With mixtures of aliphatic aldehydes and different active methylene reagents,2 reacts to 1,2,4-triazolo[1,5-a]pyridines (8a–f). Compound2 also reacts with arylidenes9a–g to give triazolopyridines10a–g. Reaction of2 with aromatic aldehydes affords compounds13a–c. Diazotation of2 with aryldiazonium chloride in ethanol at 0 °C leads to the azo adducts15a–d. The thieno-1,2,4-triazolopyridine16 is obtained by reaction of8a with elementary sulfur.16 undergoes cycloaddition with -nitrostyrene, maleic anhydride, N-arylmalemide, and acrylonitrile yielding the isoquinolines21–24. All new compounds have been characterized by their IR,1H NMR, and mass spectra.
Ein neuer Syntheseweg für 1,2,4-Triazolo[1,5-a]pyridine und 1,2,4-Triazolo[1,5-a]isochinoline
Zusammenfassung Kondensation des Cyanohydrazids1 mit Cyclopentanon in ethanolischem Piperidin bei Rückflußtemperatur ergibt das Hydrazon2. Mit Gemischen aus aliphatischen Aldehyden und verschiedenen Verbindungen mit aktiven Methylengruppen reagiert2 zu 1,2,4-Triazolo[1,5-a]pyridinen (8a–f). Verbindung2 reagiert außerdem mit den Arylidenen9a–g zu den Triazolopyridinen10a–g. Umsetzung von2 mit aromatischen Aldehyden führt zu den Verbindungen13a–c. Diazotierung von2 mit Aryldiazoniumchloriden in Ethanol bei 0°C ergibt die Azoaddukte15a–d. Das Thieno-1,2,4-triazolylpyridin16 erhält man durch Reaktion von8a mit elementarem Schwefel.16 geht it -Nitrostyrol, Maleinsäureanhydrid, N-Arylmaleimid und Acrylnitril eine Cycloaddition zu den Isochinolinen21–24 ein. Alle neuen Verbindungen wurden durch ihre IR-,1H-NMR- und Massenspektren charakterisiert.相似文献
58.
Bhanja R Joseph R Tuli SK Beri SB Bhatia VS Kaur G Kaur M Mittra IS Bhalla KB Bharti A Lokanathan S Gupta SK Gupta VK Kaul GL Kumar V Mangotra LK Prakash Y Rao NK Sankhydhar S Satti S Claesson G Garpman S Herrström NY Jakobsson B Lund I Norén B Oskarsson A Otterlund I Persson S Sherif MM Söderström K 《Physical review letters》1985,54(8):771-774
59.
Sherif Abdelmoez Rehab A. Abd El Azeem Ahmed A. Nada Tawfik A. Khattab 《无机化学与普通化学杂志》2016,642(3):219-221
Nowadays, encapsulated dyes in a polymeric matrix have opened up new perspectives in many applications such as filtration of subatomic particles, composite reinforcement, multifunctional membranes, tissue engineering scaffolds, wound dressing, coatings, medical purposes as well as sensors. In the presented work, we report on electrospinning neat peryelene dianhydride based thermoplastic elastomers. Perylene‐3, 4,9, 10‐tetracarboxylic dianhydride (PDA) is encapsulated into cellulose acetate (CA) electrospun fibers, which was prepared from 12 % cellulose acetate solution, at 20 kV with a distance of 10 cm. The flow rate was 0.2 ml · h–1. These water repellent nanofibrous coatings are anticipated to serve as hydrophobic coatings. Scanning electron microscope is used to study the properties of the electrospun PDA‐CA nanofibers. 相似文献
60.
Potentiometric studies on Schiff bases derived from5,7-dihydroxy-6-formyl-2-methylbenzopyran- 4-one were carried out at different
ionic strengths (0.02, 0.04, 0.06, 0.10 and 0.14 M NaCl), at different temperatures (25, 35, 45 and55°C) and in ethanol-water
media of varying compositions (60, 70, 80 and 90% v/v). The ionization constants of the Schiff bases were investigated in
the presence of different organic solvents (70% v/v), e.g. methanol, ethanol, n-propanol, isopropanol, acetone, DMSO and DMF-water
media. The thermodynamic parameters (ΔG, ΔH and ΔS) were also calculated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献