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461.
The mono- and di-imines of some diaminonaphthalenes were prepared using a solid solid reaction technique. Their structures were studied using elemental analysis, infrared and electronic spectra. The thermal behaviour of the obtained compounds and their solid solid preparation reactions have also been studied. The energies of activation as well as the reaction orders of those reactions were determined. 相似文献
462.
Rafik Gharbi Anis Romdhane Zine Mighri Marie‐Thrse Martin 《Journal of heterocyclic chemistry》2005,42(1):169-172
New tetracyclic 6H‐[1]benzopyrano[3,4‐e]pyrazolo[1,5‐a]pyrimidin‐6‐ones ( 4a‐e ) have been synthesized through the condensation under acidic conditions of [1]benzopyrano[4,3‐c][1,5]‐benzodiazepin‐7(8H)‐one ( 1 ) and a series of 3,4‐disubsituted 5‐amino‐1H‐pyrazoles 3a‐e . 相似文献
463.
Ramadan M. Ramadan Mohamed S. A. Hamza Hassan A. Mohamed Samir M. El-Medani 《Transition Metal Chemistry》2006,31(1):107-110
Interaction of the tripodal ligand N-[(2-pyridyl)methyl]-2,2′-dipyridylamine (pmdpa) with [Mo(CO)6] under reduced pressure gave two complexes [Mo(CO)4(pmdpa)] and [Mo(CO)2(pmdpa)2], depending on the mole ratio and reaction time. The i.r. spectra of the two complexes gave patterns in the metal carbonyl
region confirming the proposed structures. Reaction of [Ru3(CO)12] with pmdpa in benzene gave the mononuclear complex [Ru(CO)3(pmdpa)]. The electronic absorption spectra of the complexes exhibited visible transitions due to metal-to-ligand charge transfers.
Electrochemical investigation of the complexes showed some irreversible and quasi-reversible redox reactions due tautomeric
interconversions through electron transfer. 相似文献
464.
Hamza MS Felluga A Randaccio L Tauzher G van Eldik R 《Dalton transactions (Cambridge, England : 2003)》2004,(2):287-291
The kinetics of axial water substitution by cysteine in six different cobaloximes, viz.trans-RCo(Hdmg)(2)H(2)O, where Hdmg = dimethylglyoximate, R = cyclo-C(5)H(9) (c-P), CH(3)CH(2) (Et), CH(3) (Me), C(6)H(5)CH(2) (Bz), C(6)H(5) (Ph) and CF(3)CH(2), were studied as a function of cysteine concentration, temperature and pressure. It was found that cysteine substitutes the coordinated H(2)O molecule trans to the alkyl group with second order rate constants that follow the order of reactivity: c-P > Et > Bz > Me > Ph > CF(3)CH(2). Rate and activation parameters (Deltan H(++), Delta S(++) and Delta V(++)) enable the formulation of a reaction mechanism that can account for the substitution behaviour of the investigated alkylcobaloximes. In particular, a gradual mechanistic changeover from I(d) to I is observed along the series of R groups from c-P to CF(3)CH(2). 相似文献
465.
Isoprenylated flavonoids 5,7-dihydroxy-3'-(2-hydroxy-3-methyl-3-butenyl)-3,6,4'-trimethoxyflavone (1), 3,7-dihydroxy-3'-(2-hydroxy-3-methyl-3-butenyl)-5,6,4'-trimethoxyflavone (2) and an isoprenylated acetophenone derivative (3) have been isolated from Duranta repens along with known compounds, 5-hydroxy-3,6,7,4'-tetramethoxyflavone (4), rosenonolactone (5), 6,7-dimethoxycoumarin (6), 5alpha,8alpha-epidioxyergosta-6,22-dien-3beta-ol (7) and 5alpha,8alpha-epidioxyergosta-6,9(11),22-trien-3beta-ol (8), isolated for the first time from this species. Their structures and the relative configuration were determined by spectroscopic methods (1H- and 13C-NMR, IR, UV and MS) and two-dimensional (2D)-NMR experiments. The compounds 1-5 showed inhibitory activity against prolyl endopeptidase while 4 and 5 were also active against thrombin. 相似文献
466.
Hamza A. S. Abujabal Mahmoud M. El-Borai 《Journal of Applied Mathematics and Computing》1997,4(1):109-116
In the present paper, we consider an abstract partial differential equation of the form $\frac{{\partial ^2 u}}{{\partial t^2 }} - \frac{{\partial ^2 u}}{{\partial x^2 }} + A\left( {x,t} \right)u = f\left( {x,t} \right)$ , where $\left\{ {A\left( {x,t} \right):\left( {x,t} \right) \in \bar G} \right\}$ is a family of linear closed operators and $\bar G = G \cup \partial G,G$ is a suitable bounded region in the (x, t)-plane with boundary?G. It is assumed thatu is given on the boundary?G. The objective of this paper is to study the considered Dirichlet problem for a wide class of operatorsA(x, t). A Dirichlet problem for non-elliptic partial differential equations of higher orders is also considered. 相似文献
467.
A.A. Hamza A.E. Belal T.Z.N. Sokkar H.M. El-Dessouky K.M. Yassien 《Optics & Laser Technology》2007,39(4):681-689
A modified drawing device attached with an automated system for producing multiple-beam Fizeau fringes in transmission is used to study the mechanical deformation along polypropylene (PP) fibres at low draw ratios. Two drawing processes are used for drawing PP fibres. In the first process (fast drawing), the necking deformations are formed at draw ratios from 1.2 to 1.9 along the fibre axis. While in the other process (slow/step drawing), these deformations disappeared. The refractive indices calculated at different positions along the fibre axis during the fast- and slow-drawing processes. To overcome the formation of necking deformation along the PP fibres during fast-drawing process, the slow-drawing technique is recommended. Microinterferograms are given for illustration. 相似文献
468.
The rate of reaction of [FeIIIY] (Y = EDTA anion) with NaBO3 was studied in aqueous 0.1 M NaNO3 at various temperatures. The observed rate constant,k
obs = kKKK
1[FeEDTA(H2O)-]/{[H+] + KK
1[FeEDTA(H2O)-]}applies over the pH range studied. The monohydroxy complex, [FeEDTA (OH)]2– is the catalyst which reacts with the peroxy ion to produce a violet intermediate complex. The composition of perborate confirms to Michaelis–Menten kinetics, the rate-determining step involving breakdown of the intermediate complex. The activation enthalpy and activation entropy were calculated. 相似文献
469.
A.A. Hamza T.Z.N. Sokkar K.A. EL-Farahaty M.A.M. EL-Morsy H.M. EL-Dessouky 《Optics & Laser Technology》2005,37(7):532-540
A fibre-drawing device attached with the system for producing multiple-beam Fizeau fringes in transmission is used to optimize the optical properties during the cold drawing of polypropylene (PP) fibres. This system is automated for interference pattern analysis. Two drawing processes for the PP fibres are applied and investigated. The first one is fast drawing in which the necking deformation is predicted and the other is the slow (step) drawing in which the necking can be avoided. The refractive index profiles (n and n) of PP fibres are determined at different positions along the fibre axis during the fast and slow drawing processes. The fibre interference patterns are automatically digitized and stored in a computer storage media. The slow drawing technique for PP fibres is recommended to overcome the deformation difficulties along the fibre axis due to necking during the drawing processes. Microinterferograms in case of light vibrating parallel and perpendicular to the fibre axis are given for illustration. 相似文献
470.
The centrosymmetric [Zn2{CH3OC6H4P(OC5H9)S2}4], features an eight‐membered Zn2S4P2 ring as a result of two bidentate bridging thiolate ligands; the remaining ligands are chelating. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献