排序方式: 共有13条查询结果,搜索用时 31 毫秒
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Khaled M. Elsabawy Morsy M. Abou Sekkina Mohamed A. Asker Mohamed H. El-Newehy 《Solid State Sciences》2010,12(7):1094-1097
The sample with in the general formula Bi2-xPbxSrV2O9, where x = 0.0, 0.05, 0.1, 0.2, 0.3, and 0.6 mol were synthesized by the high temperature solid state reaction and firing method. The X-ray diffractograms confirmed the formation of single phased layered perovskite in all samples. TGA and DTA thermal analyses on the green samples included steps of thermal analysis of strontium carbonate, bismuth carbonate, ammonium vanadate, lead oxide and finally on the high temperature solid state formation. The effect of lead dopings on the sintering, structural and micro-structure, properties of 212BiSrV-ceramics were investigated. The infrared absorption spectra show a series of vibrational modes within the range of 400–1600 cm?1. 相似文献
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Asker E Masnovi J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,71(5):1973-1978
1,n-Di(9-ethylcarbazol-3-yl)alkanes, where n=1-5, as the dichromophoric model compounds of poly-3-vinylcarbazoles were synthesized to examine their complexation behaviors with the electron acceptors tetracyanoethylene (TCNE) and tetranitromethane (TNM). 9,9'-Diethyl-3,3'-dicarbazolyl, di(3-ethylcarbazol-9-yl)methane, and three monomeric analogues were also included for comparison. In dichloromethane solution, the dicarbazoles formed stable 1:1 electron donor-acceptor complexes with TCNE having formation enthalpies around -3.5kcal/mol. With TNM they formed more weakly bound complexes that showed little dependence on concentration and almost zero dependence on temperature changes having nearly 0kcal/mol enthalpies of formation. The smaller gap between the two carbazole groups in 1,n-di(9-ethylcarbazol-3-yl)alkanes with nor=3. 相似文献
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Bengt Asker 《BIT Numerical Mathematics》1962,2(2):76-82
It has been found that a numerical approximation of a ship-designer's spline results in a smooth interpolating function. An algorithm which computes the function coefficients is presented in Algol. Methods to vary the stiffnes of the spline are included. A test of fairness is described and finally a more elaborate algorithm which leads to a closer approximation is outlined. 相似文献
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Mattias Kalén Elisabet Wallgard Noomi Asker Aidas Nasevicius Elisabet Athley Erik Billgren Jon D. Larson Shannon A. Wadman Elizabeth Norseng Karl J. Clark Liqun He Linda Karlsson-Lindahl Ann-Katrin Häger Holger Weber Hellmut Augustin Tore Samuelsson Chelsy K. Kemmet Carly M. Utesch Jeffrey J. Essner Perry B. Hackett Mats Hellström 《Chemistry & biology》2009,16(4):432-441
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Sahera F. Mohamed Fatimah Agili Mohsen M. Asker Khaled El Shebawy 《Monatshefte für Chemie / Chemical Monthly》2011,143(2):225-232
Abstract
Turbinaria decurrens immobilized in sodium alginate showed increasing intraparticular diffusion of lead, stability of the metal binding, and affinity for lead. Equilibrium lead concentrations were attained after 9 h. The maximum lead uptakes were 1.14, 1.35, and 1.79 mmol g−1, respectively, for alginate xerogels, free alga, and immobilized alga. The order of maximum lead uptake for different biosorbents was immobilized alga > free alga > alginate xerogels. Scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis showed a uniform distribution of lead on the alginate surface. Fourier transform infrared spectroscopy (FTIR) showed that the main bands modified after lead uptake were those corresponding to hydroxyl and carboxyl stretching. The immobilized beads could be repeatedly used with high efficiency. T. decurrens immobilized in alginate xerogels constitutes an excellent biosorbent for lead, sometimes surpassing the biosorption performance of alginate alone and even the free alga. 相似文献7.
Gaballa AS Asker MS Barakat AS Teleb SM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,67(1):114-121
Four platinum(II) complexes of Schiff bases derived from salicylaldehyde and 2-furaldehyde with o- and p-phenylenediamine were reported and characterized based on their elemental analyses, IR and UV-vis spectroscopy and thermal analyses (TGA). The complexes were found to have the general formula [Pt(L)(H(2)O)(2)]Cl(2) x nH(2)O (where n=0 for complexes 1, 3, 4; n=1 for complex 2. The data obtained show that Schiff bases were interacted with Pt(II) ions in the neutral form as a bidentate ligand and the oxygens rather than the nitrogens are the most probable coordination sites. Square planar geometrical structure with two coordinated water molecules were proposed for all complexes The free ligands, and their metal complexes were screened for their antimicrobial activities against the following bacterial species: E. coli, B. subtilis, P. aereuguinosa, S. aureus; fungus A. niger, A. fluves; and the yeasts C. albican, S. cervisiea. The activity data show that the platinum(II) complexes are more potent antimicrobials than the parent Schiff base ligands against one or more microorganisms. 相似文献
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Asker E Uzkara E Zeybek O 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(5):1731-1738
Series of 1,n-dicarbazolylalkanes and 1,n-di(3-methylcarbazolyl)alkanes (where n=1-5) were synthesized and the molar extinction coefficients, equilibrium constants, enthalpies, and entropies of their charge-transfer (CT) complexes with the π-acceptors p-chloranil, tetracyanoethylene, and tetracyanoquinodimethane were investigated. 1,n-Di(3-methylcarbazolyl)alkanes formed CT complexes with higher equilibrium constants, more negative enthalpies and entropies than 1,n-dicarbazolylalkanes. Vibrational spectra of CT complexes of one of the donor molecules (1,4-dicarbazolylbutane) with all three acceptors were compared. 相似文献
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