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301.
Palladium-catalyzed hydrostannation of substituted Z- and E-enynols is discussed and compared. The regioselectivity of the H-Sn bond addition was found to be controlled by the geometry of the double bond (Z- or syn-directing effect) rather than the nature of its substituents. Exclusively alpha-vinyl stannanes were obtained from Z-enynols having various substituents on the double bond regardless of their electronic, steric, or chelating natures. 相似文献
302.
Mokhles M. Abd-Elzaher Ammar A. Labib Hanan A. Mousa Samia A. Moustafa Mohamed M. Abdallah 《Research on Chemical Intermediates》2014,40(5):1923-1936
A ferrocenyl ligand 1 was prepared from condensation of 5-methyl-2-furaldehyde with l,l′-diacetylferrocene dihydrazone. This ligand forms 1:1 complexes with cobalt(II), nickel(II), copper(II) and zinc(II) 2–5 in good yield. Characterization of the ligand and complexes was carried out using infrared, nuclear magnetic resonance, mass spectra, electronic absorption, magnetic susceptibility, molar conductivity, and elemental analysis. Cytotoxic activity of the prepared ligand and its complexes were tested against different human cancer cell lines. The results suggested that the synthesized compounds were more potent than the comparative standards drugs used in most cases, whereas they had less activity in the others. 相似文献
303.
Sufyan Naji Adil Belhaj Hicham Labrim Mohamed Bhihi Abdelilah Benyoussef Abdallah El Kenz 《International journal of quantum chemistry》2014,114(7):463-467
Motivated by recent experimental and theoretical works dealing with the silicene and the graphene materials and inspired from the root systems of Lie algebras, we study the electronic and the magnetic properties of the iron adatom adsorption on the graphene. The calculations have been performed using the density functional theory method. More precisely, the system we consider here consists of a static single layer of the graphene interacting with the iron atoms which are placed at hollow (H) sites and localized at a distance Δ along the normal direction. This system, involving the G2 hexagons appearing in the classification of rank two Lie symmetries, exhibits, up some details, a nice double hexagonal symmetry required by coverage of 0.666 monolayer placed at H sites. The resulting materials behave like ferromagnetic ones having a strong spin polarization, instead of gapless‐semiconductor with the nonmagnetic features appearing in the pure graphene. The responsible mechanism for such behaviors is the interaction between the iron atoms. It has been realized that there are two interaction types. The first one is associated with the direct interaction between the iron atoms, whereas the second one corresponds to the indirect interaction via the carbon atoms. Using the molecular field approximation, the Curie temperature has been estimated around 367 K. © 2013 Wiley Periodicals, Inc. 相似文献
304.
J. Abdallah et al. 《The European Physical Journal C - Particles and Fields》2006,45(2):273-289
The production of single charged and neutral intermediate vector bosons in e + e- collisions has been studied in the data collected by the DELPHI experiment at LEP at centre-of-mass energies between 183
and 209 GeV, corresponding to an integrated luminosity of about 640 pb-1. The measured cross-sections for the reactions, determined in limited kinematic regions, are in agreement with the Standard
Model predictions.
Arrival of the final proofs: 21 November 2005 相似文献
305.
306.
C.J. Fontes J. Abdallah C. Bowen R.W. Lee Yu. Ralchenko 《High Energy Density Physics》2009,5(1-2):15-22
We review the 5th non-LTE kinetics code comparison workshop, held in November 2007. Both steady-state and time-dependent cases for elements ranging from carbon to gold were examined in detail. Calculations of radiative power losses and specific spectra were requested in addition to typical plasma quantities such as the ionization balance. Non-Maxwellian electrons, external Planckian radiation and opacity effects in spectra were also included in the comparisons. We discuss the organization of the workshop and present a set of representative results. The particular case of a tungsten plasma at tokamak operating densities was considered for the first time. Due to its importance to the ITER project, more detailed results of these comparisons will be published elsewhere. 相似文献
307.
Abd El-Aziz S. Fouda Mohamed M. Farahat Metwally Abdallah 《Research on Chemical Intermediates》2014,40(3):1249-1266
Inhibition of nickel corrosion in 1 M HCl solution in the absence and presence of some Cephalosporin antibiotics derivatives was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM) techniques. The results obtained show that the inhibition efficiency of these compounds depends on their concentrations and chemical structures. The inhibitive action of these compounds was discussed in terms of blocking the electrode surface by adsorption of the molecules through the active centers contained in their structures following the Langmuir adsorption isotherm. The polarization measurement showed that these inhibitors are acting as mixed inhibitors for both anodic and cathodic reactions. The effect of temperature on the rate of corrosion in the absence and presence of these compounds was also studied. The efficiencies obtained from the potentiodynamic polarization technique were in good agreement with those obtained from EIS and EFM techniques. This proves the validity of these tools in the measurements of the investigated inhibitors. 相似文献
308.
Prerequisites for successful flow cytometry investigations are specific antibodies labeled with appropriate fluorochromes
and negligible autofluorescence of the untreated cells at the wavelength of interest. The aim of this study was (a) to characterize
frequently used urological carcinoma cell lines with regard to their autofluorescence properties, (b) to demonstrate the autofluorescence
as a serious interfering factor on FACS analysis of urological carcinoma cell lines and (c) to suggest an alternative to avoid
interfering autofluorescence. Twenty-one cell lines originating from prostate carcinoma, renal cell carcinoma and bladder
cancer were included in this study. The various cell lines were read on a flow cytometer in comparison to human erythrocytes
as cells with low fluorescence intensity. Urological cell lines show a high autofluorescence when flow cytometry analyses
are performed at the frequently used excitation wavelengths at 405 and 488 nm. At excitation wavelength of 633 nm, this problem
was reduced and most of the cell lines (14/21) were without autofluorescence at the emission wavelength of 785 nm. In addition,
with a spectrofluorometer three exemplary cell lysates were investigated. The above observations were confirmed. The dye APC-Cy7
is one suitable fluorochrome for successful investigation under these measurement conditions. 相似文献
309.
Abdallah Hamze 《Tetrahedron》2010,66(45):8698-8706
Palladium-catalyzed hydrostannation reactions of ortho-disubstituted arylalkynes were achieved with total stereo- and regio-selectivity in THF at room temperature. The regioselectivity was found to be under the control of the ortho-substituents (ortho-directing effects, ODE) and pure α-vinylstannanes are produced in good yields and as single isomers regardless of the substituents’ nature. These hydrostannation α-products are precursors of choice for the preparation of stereo-defined triarylolefins. 相似文献
310.
Rajesh A. Shenoy Mary E. Neubert David G. Abdallah Sandra S. Keast Rolfe G. Petschek 《Liquid crystals》2013,40(6):801-812
Various substituted aminodiphenyldiacetylenes of the type with X = C3H7, C5H11, F or NO2 and R, R' = H, CH3-C6H13 were synthesized and their mesomorphic properties determined. Semi-empirical and ab initio quantum chemical calculations using AM1, 421G and 631G* suggested that the amino group would increase the dielectric anisotropy and optical birefringence as compared to the alkyl chain. Mesomorphic properties were found to be poor with the maximum nematic phase range being 44.8°C and many of the compounds having no nematic phase. Both melting temperatures and enthalpies for those having nematic phases were too high to form good eutectic mixtures. 相似文献