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41.
Naila Raziq Muhammad Shaiq Ali Salman Zafar Muhammad Imran Ali 《Natural product research》2015,29(24):2265-2270
Phytochemical investigations on Hypericum oblongifolium led to the isolation of a flavone named folicitin (1) and a bicyclic conjugated lactone, folenolide (2) from the ethyl acetate fraction of methanolic extract. Both metabolites were characterised as new compounds based on detailed spectroscopic analyses. In vitro anti-oxidant potential of both the compounds was evaluated by the DPPH radical scavenging assay. Compound 1 exhibited significant antioxidant activity while compound 2 was found inactive. 相似文献
42.
Salman H. Abbas 《应用数学和力学(英文版)》1996,17(12):1141-1146
THE THEORETICAL COST OF SEQUENTIAL AND PARALLEL ALGORITHMS FOR SOLVING LINEAR SYSTEMS OF EQUATIONSSalmanH.Abbas(ReceivedMay24... 相似文献
43.
Abraham Y Salman H Suwinska K Eichen Y 《Chemical communications (Cambridge, England)》2011,47(21):6087-6089
Cyclo[2]benzimidazole is a new host for anions that turns on its luminescence up to 150 fold upon binding. Photoexcited cyclo[2]benzimidazole undergoes an efficient non-radiative deactivation through an excited-state intramolecular proton-transfer (ESIPT) mechanism. Upon binding an anion, the ESIPT pathway is blocked, resulting in an increase in the luminescence efficiency. 相似文献
44.
Abstract The uv-vis spectra of eight ortho-hydroxy- andpara-hydroxy schiff bases were recorded in different solvents. Inductive and resonance effect of the substituents affect the electronic spectra of those molecules, while, intra-molecular hydrogen bond formation or breakage have little effect on the uv-visible spectra. 相似文献
45.
The UV spectra of some chlorinated o-hydroxyschiff bases were studied in different solvents. It was found that schiff bases derived from condensation of 2-hydroxybenzaldehyde or 5-chloro-2-hydroxy benzaldehyde with substituted aniline exist as enol form, whereas schiff bases derived from the condensation of 3,5-dichloro-2-hydroxybenzaldehyde with substituted aniline exist as enol form, whereas schiff bases derived from the condensation of 3,5-dichloro-2-hydroxybenzaldehyde with aniline exist as keto form especially in dimethyl sulfoxide. The ratio of enol/keto isomers were calculated for these schiff bases. 相似文献
46.
The carbon-13 chemical shift of seventeen N-substituted 2,4,6-triphenyl pyridinium salts (TPP) and N-substituted 2,4,6-triaryl pyridinium (TsPP) salts have been determined. 相似文献
47.
Summary We prove a Schur test for mixed-norm spaces Lp,q, 1 < p,q < ∞. Also we prove another version of the Schur test for discrete weighted mixed-norm spaces lp,q w, 1 < p,q < ∞, and wis a weight. We show that if w 1, and w 2are two weight functions on the index sets Jx Iand K x Lrespectively, and A =(a ji, kl ) j∈J, i∈I, k∈K, l∈L is an infinite matrix, then under certain conditions, Ais a bounded operator from lp,q w1, 1 < p,q < ∞ to lp,q w2. This will be a key result in proving boundedness of important operators in our work in time-frequency analysis.</o:p> 相似文献
48.
本文讨论了求解密集型线性方程组的两种并行算法。这两种算法都在下上单元(LU)分解。法的基础上使用了前向和后向置换进行的。这些算法在数值上是稳定的,并在顺序平衡机上用各种处理程序进行试验,都得到良好效果。 相似文献
49.
Salman R. Salman 《Magnetic resonance in chemistry : MRC》1984,22(6):385-387
Long-range proton–proton coupling constants between the hydroxy proton and ring protons were employed to deduce the conformational preferences of 1- and 2-hydroxynaphthalene. 2,6-Dibromo-1,5-dihydroxy-naphthalene, 2-acetyl-1-hydroxynaphthalene, 1,6-dibromo-2-hydroxynaphthalene and 2-hydroxy-1-naphthaldehyde were used as model compounds. Molecular orbital calculations at the CNDO/2 and INDO level were used to calculate the energy and the long-range proton–proton coupling of different conformers of 1- and 2-hydroxynaphthalene. 相似文献
50.
S. R. Salman 《Magnetic resonance in chemistry : MRC》1982,19(4):181-184
The spectra of several 2-methyl-6-R-disubstituted naphthalenes (R=H, Me, I, NO2, Cl, SO2Cl, OH, OMe, COMe, Br, F and NHCOMe), have been analysed. Chemical shift and coupling constant values of these compounds are presented. The proton chemical shifts have been found to correlate with the ortho parameter, Q. 相似文献