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排序方式: 共有143条查询结果,搜索用时 15 毫秒
1.
A.-M. M. Abdel-Rahman 《General Relativity and Gravitation》1997,29(10):1329-1343
Aspects of the modified general relativity theory of Rastall, Al-Rawaf and Taha are discussed in both the radiation- and matter-dominated flat cosmological models. A nucleosynthesis constraint on the theory's free parameter is obtained and the implication for the age of the Universe is discussed. The consistency of the modified matter-dominated model with the neoclassical cosmological tests is demonstrated. 相似文献
2.
Abdel-Rahman Farghaly Hussein El-Kashef 《Monatshefte für Chemie / Chemical Monthly》2005,292(1):217-227
The synthesis of the title compounds was achieved using 1-phenyl-5-(pyrrol-1-yl)-1H-pyrazole-3-carboxylic acid azide as starting material. The latter compound was allowed to react with alcohols and amines to afford the corresponding carbamates and urea derivatives. Alkaline hydrolysis of the carbamates gave the corresponding amine, which was acylated and/or aroylated to give amide derivatives. These and the urea derivatives were subjected to cyclodehydration to give the title compounds. Antibacterial and antifungal activities were observed for several derivatives. 相似文献
3.
Laila H. Abdel-Rahman 《Transition Metal Chemistry》2006,31(7):943-950
A new series of N-phthaloylglycineate (N-phthgly) ternary complexes of cobalt(II) and nickel(II) with imidazole (imi), N-methylimidazole
(mimi) and 2,2′-bipyridyl (bipy) have been synthesized and characterized by elementary analyses, IR spectroscopy, thermogravimetric
analysis. X-ray crystal structure analyses of the three complexes of [Co(mimi)2(N-phthgly)2] (1), [Co(bipy)(OH2)4](N-phthgly)2
(2) and [Ni(imi)2(N-phthgly)2(OHCH3)2] (3) were also carried out. In complex (1), the Co(II) exists in a distorted tetrahedral enviroment, where two nitrogen atoms of two methylimidazole molecules and two
oxygen atoms of the carboxylate group of two N-phthaloylglycinate molecules are coordinated. On the other hand, in complex
(2) the cobalt atom coordinates a 2,2′-bipyridine molecule and four water oxygen atoms forming a distorted octahedral conformation.
A molecule of N-phthaloylglycinate is connected by van der waals contact and H-bonds. For complex (3), the nickel atom is surrounded by four oxygens (two oxygens of two different N-phthaloylglycinate molecules and two of methanol
ligand) in the basal plane of octahedron along with two imidazole nitrogen atoms at the apical positions. Strong intramolecular
H-bond exists between the uncoordinated carboxylic oxygen of the N-phthaloylglycinate ligand and the O–H of the methanol group. 相似文献
4.
Farag A. El-Essawy Ahmed F. Khattab Adel A.-H. Abdel-Rahman 《Monatshefte für Chemie / Chemical Monthly》2007,47(4):777-785
1-Carbethoxymethyl-4,6-dimethyl-1H-[1,2,3]triazolo[4,5-d]pyrimidine-5,7(4H,6H)-dione was synthesized and treated with hydrazine hydrate to give the corresponding hydrazide. The latter hydrazide was treated
either with phenylisothiocyanate or with carbon disulfide/alc. KOH to afford the corresponding thiosemicarbazide and oxadiazole
derivatives. Alkylation of 2-mercapto-1,3,4-oxadiazole with dimethyl sulfate or ethyl chloroacetate gave the corresponding
2-methylthio-, and 2-ethylthioglycolate derivatives. Formation of 1,3,4-thiadiazole, 5-mercapto-1,2,4-triazole, and 1,3,4-oxadiazole
were carried out by treating of the latter thiosemicarbazide with conc. H2SO4, NaOH/HCl, and HgO. Treating of 5-mercapto-1,2,4-triazole with ethyl chloroacetate afforded the thioglycolate ester. Hydrolysis
of the latter with hydrazine hydrate afforded the hydrazide derivatives. Condensation of these hydrazides with monosaccharide
aldoses gave the corresponding sugar hydrazones. The novel compounds were tested for antiviral activity against hepatitis
B virus and showed moderate activities. 相似文献
5.
Awadallah Adel M. El-Halabi Nabil M. Ferwanah Abdel-Rahman S. Awad Boshra M. 《Transition Metal Chemistry》2004,29(3):280-283
3-Acetyl-1,2,4-triazole hydrazones (3b,c) and methylhydrazone (4d) were prepared by reacting triazoles (1b–d) with an excess of hydrazines at room temperature. Square planar nickel(II) complexes (8b,c) of (3b,c) were obtained from their reaction with Ni(OAc)2 in a 2:1 mol ratio in EtOH at room temperature. The spectral data suggest structures (8b,c) for the obtained complexes, which result from ring opening of the triazole ring followed by recyclization to give the 5-arylhydrazono-2,3-dihydro-4H-1,2,4-triazine ligand (7b,c). The reaction of triazole methylhydrazone (4d) with Ni(OAc)2 in EtOH resulted, however, in the formation of the starting triazole (1d). All new compounds were characterized by elemental analysis, i.r., 1H-n.m.r. 13C-n.m.r. and hrms. 相似文献
6.
Mostafa Mohsen M. El-Shazly Rafaat M. Rakha Tawfik H. Abdel-Rahman Mohamed H. 《Transition Metal Chemistry》2002,27(3):337-340
Tribochemical reactions of KBr, KI and CaI2 with [Cu(L)Cl2(EtOH)3/2(H2O)]1/2H2O (L = formylhydrazine) give novel CuI and CuII complexes, which have been characterized by elemental analyses, spectral (i.r., u.v.–vis., 1H-n.m.r.) and magnetic measurements. The i.r. spectra indicate that (L) behaves in a monodentate manner, coordinating via the azomethine nitrogen (C-N) group in the CuII complexes, but behaving as a bidentate ligand, via the carbonyl oxygen and NH2 groups in the CuI complexes. KI and CaI2 react with [Cu(L)Cl2(EtOH)3/2(H2O)]-1/2H2O in the solid state, accompanied by a colour change, substitution of the chloride by iodide ions, and reduction of CuII to CuI to give complexes with formulae [Cu(L)I(EtOH)1/2] and [Cu1.7(L)I1.7(EtOH)1/2]. On the other hand, the tribochemical reaction of KBr with [Cu(L)Cl2(EtOH)3/2(H2O)]1/2H2O is accompanied by a colour change; substitution of the chloride by bromide ions, but without reduction of CuII and yields a complex of formula [Cu(L)2Br2(EtOH)(H2O)]1/2EtOH. The spectral and magnetic results suggest a distorted octahedral geometry for the CuII complexes while a tetrahedral geometry around the CuI ion. The non-stoichiometric structure of [Cu1.7(L)I1.7(EtOH)1/2] is discussed. 相似文献
7.
Nareman Harpy Abdel-Rahman Mohamed A. E. Sallam Abdelsattar M. El Dabour Sameh 《Physics of Particles and Nuclei Letters》2020,17(2):253-259
Physics of Particles and Nuclei Letters - Gamma spectrometry is applied for measurement of natural radioactivity by Hyper-pure germanium (HPGe) systems during the application of bioleaching optimum... 相似文献
8.
S. M. S. Atta N. M. Fawzy F. A. Ahmed A. H. Abdel-Rahman 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):863-875
4,7-Dimethoxy ( Ia ) and 4-methoxy ( Ib ) 6-hydroxybenzofuran-5-carbohydrazide were reacted with aryl or alkyl isothiocyanates to give the corresponding thiosemicarbazides ( IIa-h ). Cyclization of the substituted thiosemicarbazides with sodium hydroxide led to the formation of 1,3,4-triazol-2-yl-benzofuran derivatives ( IIIa-d ). Desulfurization of thiosemicarbazide by mercuric oxide gave 1,3,4-oxadiazolyl-benzofuran ( IVa-c ). Treatment of thiosemicarbazide with ethyl bromo-acetate or f -bromopropionic acid yielded 4-thiazolidin-2-yl-carbonyl-benzofuran ( Va-h ). The reaction of compounds IIb , e , f with sulphuric acid or phosphorus oxychloride gave 1,3,4-thiadiazol-2-yl-benzofuran ( VIa-d , VII ). 相似文献
9.
Taha M. Abdel-Rahman 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1737-1754
A novel method for the synthesis of 1,3,4-thiadiazole and 1,3,4-thiadiazine derivatives bearing a carbazole moiety is described. Carbazole was transformed into carbazole-9-thiocarbohydrazide in two steps. This compound was allowed to react with various electrophiles to yield 1,3,4-thiadiazole derivatives. The reaction with bifunctional electrophiles led to 1,3,4-thiadiazines. 2-(Carbazol-9-yl)-5,6-dihydro-4H-1,3,4-thiadiazin-5-one reacted with piperidine and formaldehyde to yield the 4-(piperidin-1-ylmethyl) derivative. The reaction with aromatic aldehydes led to the corresponding 6-arylidene derivatives, which were transformed into pyrimidino[4,5-e]-1,3,4-thiadiazines and pyrazolo[3,4-e]-1,3,4-thiadiazines by a reaction with guanidine, acetamidine, or phenylhydrazine, respectively. Structures of the products were confirmed by 1H NMR, 13C NMR, IR, and mass spectrometric measurements. Selected examples of products were screened for anticancer activity. 相似文献
10.
Etify A. Bakhite Abdu E. Abdel-Rahman Omima. S. Mohamed Eman A. Thabet 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):1983-2006
(4-Aryl-3-cyano-6-(2-thienyl)pyridin-2-ylthio)acethydrazides (5a–c), 3-amino-4-aryl-6-(2-thienyl)thieno[2,3-b]pyridine-2-carbohydrazides (6a–c) and 3-amino-4-phenyl-6-(2-thienyl)thieno[2,3-b]pyridine-2-carboxylic acid (30) were prepared and employed as key intermediates in the synthesis of the title compounds. 相似文献