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81.
Adel A. Shaheen Mousa M.A. Imran Omar A. Lafi Moh'd I. Awadallah Ma'rouf K. Abdullah 《Radiation Physics and Chemistry》2010,79(9):923-928
Amorphous Se90In10?xSnx (x=2, 4, 6, and 8) thin films of thickness 1000 Å were prepared on glass substrates by the thermal evaporation technique. Optical parameters of the films were investigated, in the wavelength range 400–700 nm, before and after irradiation by 4, 8, and 12 kGy doses of γ-ray. The optical absorption coefficient α for as-deposited and gamma irradiated films was calculated from the reflectance R and transmittance T measurements, which were recorded at room temperature. From the knowledge of α, at different wavelengths, the optical band gap Eg was calculated for all compositions of Se–In–Sn thin films before and after gamma irradiation. Results indicate that allowed indirect optical transition is predominated in as-deposited and irradiated films. Besides, it is found that the band gap decreases with increasing Sn concentration and this is attributed to the corresponding decrease in the average single bond energy of the films. The band gap, after irradiation at different doses of γ-ray, was found to decrease for all compositions of the studied films. This post-irradiation decrease in the band gap was interpreted in terms of a bond distribution model. 相似文献
82.
83.
Preparation, structure and spasmolytic activities of some derivatives of harmine series of alkaloids
Begum S Imran Hassan S Siddiqui BS Ifzal R Perwaiz S Kiran T Shaheen F Ghayur MN Gilani AH 《Natural product research》2006,20(3):213-227
Keeping in view the interesting chemistry and pharmacological importance of harmine series of bases -- the beta-carboline alkaloids, a number of new derivatives of tetrahydroharmine and harmalol have been prepared and characterized through spectral studies. Some of these derivatives showed spasmolytic activity. It was observed that all the N-acyl tetrahydroharmine derivatives are stable, not labile and no ring opening occurs in these compounds, as reported recently. 相似文献
84.
Farkhanda Shaheen Amin Badshah Marcel Gielen Christine Gieck Dick de Vos 《应用有机金属化学》2007,21(8):633-640
Pd(II) complexes with organophosphines and dithiocarbamates derivatives of α‐amino acids were synthesized by reacting N,N‐dicyclohexyldithiocarbamate (DCHDTC, compounds 1 – 3 ) and N‐methylcyclohexyldithiocarbamate (MCHDTC, compounds 4 – 6 ) with (R3P)2PdCl2 (R = Ph, o‐tolyl, Ph2Cl) in a 1:1 molar ratio. The complexes were characterized by elemental analyses, FT‐IR, multinuclear (1H, 13C and 31P) NMR and single X‐ray crystallography, showing that the dithiocarbamate acts as a bidentate ligand and binds to Pd(II) via two sulfur atoms, resulting in a square planar geometry around Pd(II). The cytotoxicity of compounds 2, 3 and 4 was determined in vitro against six human tumour cell lines, MCF7, EVSA‐T, WIDR, IGROV, M19 MEL, A498 and H226. Compounds 3 and 4 showed a moderate to low cytotoxicity, whereas compound 2 exhibited a very low cytotoxicity. The results of antifungal assays showed that compounds 1 – 6 possess antifungal activity against Fusarium moniliformes, Fusarium saolani, Mucor sp., Aspergillus niger and Aspergillus fumigatus. The anti‐inflammatory screening results of 1–6 are quite similar to those observed for the standard drug Declofenac at 10 mg kg?1, which inhibited the odema by 74% after 4 h. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
85.
Azhar Mahmood Itrat Fatima Shaheen Kosar Rehana Ahmed Abdul Malik 《Magnetic resonance in chemistry : MRC》2010,48(2):151-154
Prunusins A (1) and B (2), the new C‐alkylated flavonoids, have been isolated from the seed kernels of Prunus domestica. Their structures were assigned from 1H and 13C nuclear magnetic resonating spectra, DEPT and by correlation spectroscopy, HMQC and HMBC experiments. 3, 5, 7, 4′‐Tetrahydroxyflavone (3) and 3, 5, 7‐trihydroxy‐8, 4′‐dimethoxyflavone (4) have also been reported from this species. Both compounds (1) and (2) showed significant antifungal activity against pathogenic fungus Trichophyton simmi. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
86.
87.
Six oleanane‐type triterpenoid esters were isolated from the golden flowers of Tagetes erecta. Spectral studies characterized their structures as 3‐O‐[(9Z)‐hexadec‐9‐enoyl]erythrodiol ( 1 ), 11α,12α:13β,28‐diepoxyoleanan‐3β‐yl (9Z)‐hexadec‐9‐enoate ( 2 ), 13β,28‐epoxyolean‐11‐en‐3β‐yl (9Z)‐hexadec‐9‐enoate ( 3 ), 28‐hydroxy‐11‐oxoolean‐12‐en‐3β‐yl (9Z)‐hexadec‐9‐enoate ( 4 ), 3‐O‐[(9Z‐hexadec‐9‐enoyl]‐β‐amyrin ( 5 ), and 11‐oxoolean‐12‐en‐3β‐yl (9Z)‐hexadec‐9‐enoate ( 6 ). Compounds 1 – 4 and 6 are new natural products, while the known 5 was isolated for the first time from the genus Tagetes, from which only one triterpenoid has earlier been obtained. Aerial oxidation (autoxidation) converted amyrin 1 into 2 – 4 and transformed amyrin 5 into 6 . The configuration of 1 – 6 and an autoxidation mechanism (Scheme) involving the formation of the intermediate 11α‐hydroxyolean‐12‐ene derivatives 1b and 5b on thermal decomposition of the labile 11α‐OOH derivatives 1a and 5a , respectively, under neutral conditions are discussed. For the first time, the reactivity of the allylic H? C(11) bond of triterpenoids of type 1 and 5 toward aerial oxidation was observed. The long‐chain ester group at C(3) of 1 and 5 may be responsible for their labile nature, as β‐amyrin ( 7 ), erythrodiol ( 8 ), and ursolic acid were found to be inert toward autoxidation. 相似文献
88.
Ahmed M Seayad AM Jackstell R Beller M 《Journal of the American Chemical Society》2003,125(34):10311-10318
A highly chemo- and regioselective hydroaminomethylation of simple as well as functionalized alpha-olefins using a cationic rhodium precatalyst together with Xantphos as ligand is reported. Studies of the influence of ligands and reaction conditions led to an unprecedented selective hydroaminomethylation procedure. The novel procedure constitutes an economically attractive and environmentally favorable synthesis of secondary and tertiary aliphatic amines. 相似文献
89.
Choudhary MI Shah SA Musharraf SG Shaheen F Atta-Ur-Rahman 《Natural product research》2003,17(3):215-220
Transformation of dehydroepiandrosterone (DHEA) (1) was carried out by a plant pathogen Rhizopus stolonifer, which resulted in the production of seven metabolites. These metabolites were identified as 3beta,17beta-dihydroxyanandrost-5-ene (2), 3beta,17beta-dihydroxyandrost-4ene (3), 17beta-hydroxyandrost-4-ene-3-one (4), 3beta,11-dihydroxyandrost-4-ene-17-one (5), 3beta,7alpha-dihydroandrost-5-ene-17-one (6), 3A,7alpha,17beta-trihydroxyandrost-5-ene (7) and 11beta-hydroxyandrost-4,6-diene-3,17-dione (8). The structures of the transformed products were determined by the spectroscopic techniques. 相似文献
90.
Sattar R. Majeed Mina A. Amin Fawzy A. Attaby Marta E. Alberto Ahmed A. Soliman 《Molecules (Basel, Switzerland)》2022,27(3)
Three new palladium complexes ([Pd(DABA)Cl2], [Pd(CPDA)Cl2], and [Pd(HZPY)Cl2]) bearing dinitrogen ligands (DABA: 3,4-diaminobenzoic acid; CPDA: 4-chloro–o-phenylenediamine; HZPY: 2-hydraziniopyridine) were synthesized, characterized, and tested against breast cancer (MCF-7), prostate carcinoma cell line (PC3) and liver carcinoma cell line (HEPG2). [Pd(DABA)Cl2] complex exhibited the highest inhibition percentage, lying between 68–71%. The hydrolysis mechanism of each palladium complex, the key step preceding the binding to the biological target, as well as their photophysical properties were explored by means of DFT and TDDFT computations. Results indicate a faster hydrolysis process for the Pd(DABA)Cl2 complex. The computed activation energies for the first and second hydrolysis processes suggest that all the compounds could reach DNA in their monohydrated form. 相似文献