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991.
Ibrahim M. Labouta Ahmed M. M. Hassan Omaima M. Aboulwafa Ola Kader 《Monatshefte für Chemie / Chemical Monthly》1989,120(6-7):571-574
Summary The synthesis andin vitro antimicrobial evaluation of several benzimidazole derivatives with different heterocyclic nuclei at position-2 are described.
Synthese einiger substituierter Benzimidazole mit potentieller antimikrobieller Aktivität
Zusammenfassung Die Synthese und antimikrobielle Prüfung einiger Benzimidazole mit verschiedenen heterozyklischen Substituenten in 2-Stellung wird beschrieben.相似文献
992.
Rates of solvolysis of ions [Co(3Rpy)4Cl2]+ with R = Me and Et have been measured over a range of temperatures for a series of water-rich water + methanol mixtures to investigate the effect of changes in solvent structure on the solvolysis of complexes presenting a largely hydrophobic surface to the solvent. The variation of the enthalpies and entropies of activation with solvent composition has been determined. A free energy cycle relating the free energy of activation in water to that in water + methanol is applied using free energies of transfer of individual ionic species from water into water + methanol. Data for the free energy of transfer of chloride ions ΔG(Cl?) from both the spectrophotometric solvent sorting method and the TATB method for separating ΔG(salt) into ΔG(i) for individual ions are used: irrespective of the source of ΔG(Cl?), in general, ?ΔG(Co(Rpy)4Cl2+) > ?ΔG(Co(Rpy)4Cl2+), where Rpy = py, 4Mepy, 4Etpy, 3Etpy, and 3Mepy, showing that changes in solvent structure in water-rich water + methanol mixtures generally stabilize the cation in the transition state more than the cation in the initial state for this type of complex ion. A similar result is found when the free energy cycle is applied to the solvolysis of the dichloro (2,2′,2″-triaminotriethylamine)cobalt(III) ion. The introduction of a Me or Et group on the pyridine ring in [Co(Rpy)4Cl2]+ has little influence on the difference {ΔG(Co(Rpy)4Cl2+)?ΔG(Co(Rpy)4Cl2+)} in water + methanol with the mol fraction of methanol < 0.20. 相似文献
993.
994.
Sobhy El-Sayed Ibrahim 《Czechoslovak Mathematical Journal》2004,54(1):9-29
In this paper, the general ordinary quasi-differential expression M
pof n-th order with complex coefficients and its formal adjoint M
p
+
on any finite number of intervals I
p
=(a
p
,b
p
),p= 1,...,N, are considered in the setting of the direct sums of L
wp
2
(a
p
,b
p
)-spaces of functions defined on each of the separate intervals, and a number of results concerning the location of the point spectra and the regularity fields of general differential operators generated by such expressions are obtained. Some of these are extensions or generalizations of those in a symmetric case in [1], [14], [15], [16], [17] and of a general case with one interval in [2], [11], [12], whilst others are new. 相似文献
995.
996.
Ibrahim A. Salem 《国际化学动力学杂志》1995,27(5):499-505
The kinetics of the H2O2 decomposition in presence of Fe(III)- and Cr(III)-complexes of mono-, di-, and triethanolamine supported on Dowex-50W resin have been investigated. The decomposition process proceeded with first-order kinetics for the substrate concentration. The rate of reaction increased with increasing number of the coordinated ligands in the metal complex as well as with increasing ligand basicity. The decomposition reaction involved the formation of an intermediate active species, which converts into a peroxo-metal complex of brown, green, or gray color. A mechanism describing the decomposition process is proposed. © 1995 John Wiley & Sons, Inc. 相似文献
997.
Given a fixed line L (in Rn) and a uniform distribution of points (c) on the unit sphere, L(tc), the point of intersection of L and the hyperplane P · c = 0, leads to a mapping Xn : Rn → R, which is shown to have a Cauchy distribution. 相似文献
998.
M. R. Mahmoud S. A. El-Gyar A. Shaker A. M. Abdel-Mawgoud 《Monatshefte für Chemie / Chemical Monthly》1987,118(11):1289-1296
The synthesis of nine Zn(II) salicylideneamino acid complexes is reported. The structures of the complexes have been investigated by chemical analyses, electronic and infrared spectra, as well as molar conductance measurements. The apparent complex formation constants have been determined.
Synthese und Eigenschaften von Zn(II)-Salicyliden-Aminosäure-Komplexen
Zusammenfassung Es wird die Synthese von neun Zn(II)-Salicylidenaminosäurekomplexen berichtet. Die Struktur der Komplexe wurde mittels chemischer Analyse, den Elektronen- und IR-Spektren und auch aus Leitfähigkeitsmessungen ermittelt. Die effektiven Komplexbildungskonstanten wurden ebenfalls bestimmt.相似文献
999.
Ibrahim Haddad Shaun Hurley C. S. Marvel 《Journal of polymer science. Part A, Polymer chemistry》1973,11(11):2793-2811
Poly(phenylene sulfides) were synthesized from m-benzenedithiol and aromatic dibromides in a basic medium of potassium carbonate in dimethylformamide or dimethylacetamide. The products obtained were slightly off-white with relatively low melting ranges and had inherent viscosities in the 0.2–0.4 dl/g range in hexamethylphosphoric triamide. Similar poly(phenylene sulfides) containing pendant cyano groups along the polymer chains were obtained by the use of 5 mole-% of either 2,4-dichlorobenzonitrile or 3,5-dichlorobenzonitrile. The products were similar to the pure polyphenylene sulfides, except that they showed lower melting ranges and gave insoluble products when heated alone or in the presence of zinc chloride. 相似文献
1000.
Summary In the1H-n.m.r. spectra of (acetylacetonato)chloro-(2-cyanoetheiie)platinum(II), the three protons of the ligand appear to be equivalent.13C-n.m.r., i.r. and further1H-n.m.r. studies indicate that the metal-ligand bonding is of orthodox -olefin type (as formulated in the name of the compound above). The two 2-hydrogens are made equivalent by fluxion, but there is an accidental degeneracy with 1-hydrogen atom. 相似文献