排序方式: 共有26条查询结果,搜索用时 15 毫秒
1.
Armbruster P Agarwal YK Brüchle W Brügger M Dufour JP Gaggeler H Hessberger FP Hofmann S Lemmertz P Münzenberg G Poppensieker K Reisdorf W Schadel M Schmidt K Schneider JH Schneider WF Sümmerer K Vermeulen D Wirth aG Ghiorso A Gregorich KE Lee D Leino M Moody KJ Seaborg GT Welch RB Wilmarth P Yashita S Frink C Greulich N Herrmann G Hickmann U Hildebrand N Kratz JV Trautman N Fowler MM Hoffman DC Daniels WR von Gunten HR Dornhöfer H 《Physical review letters》1985,54(5):406-409
2.
Lan Yu Qi Wang Lu Dai Wei-Ying Li Rong Chen Mian HR Mahmood Hai-Yang Liu Chi-Kwong Chang 《中国化学快报》2013,24(6):447-449
Pseudo-first order reaction rate constants of 5,10,15-tris(pentafluorophenyl)corrole Mn(V)-oxo (F15CMn(V)-oxo),5,15-bis(pentafluorophenyl)-10-(phenyl)corrole Mn(V)-oxo(F10CMn(V)-oxo),5,15- bis(phenyl)-10-(pentafluorophenyl)corrole Mn(V)-oxo(F5CMn(V)-oxo) and 5,10,15-tris(phenyl)corrole Mn(V)-oxo(F0CMn(V)-oxo) with a series of alkene substrates in different solvents were determined by UV-vis spectroscopy.The results indicated that the oxygen atom transfer pathway between Mn(V)-oxo corrole and alkene is solvent-dependent. 相似文献
3.
Hua-Hua Wang Yi-Yu Jiang Mian HR Mahmood Hai-Yang Liu Herman H.Y. Sung Ian D. Williams Chi K. Chang 《中国化学快报》2015,26(5):529-533
Tetrakis(alloxycarbonyl)porphyrin and its β-octafluoro-substituted derivatives were synthesized via Lindsey method and transformed to their zinc complexes.Single crystal X-ray structures of corresponding Zn(Ⅱ) porphyrins revealed that β-octafluorination will give more compactness of porphyrin moieties in the crystal structure owing to the hydrogen bonding interactions involving β-fluorine atoms.An unusual six-coordinated Zn(Ⅱ) was found via intramolecular coordination of oxygen atom of meso-substituents with central Zn(Ⅱ). 相似文献
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Three phenolic compounds cosmosiin, caffeic acid, and p-coumaric acid were isolated for the first time from the leaves of Cupressus sempervirens L., together with cupressuflavone, amentoflavone, rutin, quercitrin, quercetin, myricitrin. The isolated compounds were identified using (1)H- and (13)C-NMR spectra. The hepatoprotective activity of the MeOH extract was carried out in liver homogenate of normal and CCl(4)-treated rats; a significant decrease in glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, cholesterol level, and triglycerides, while a significant increase in the total protein level, was observed after the oral administration of MeOH extract. The free radical scavenging activity against stable 2,2-diphenyl-2-picrylhydrazyl (DPPH*) was measured for MeOH extract and some of the isolated phenolic compounds in comparison with alpha-tocopherol and butylated hydroxy toluene as standard antioxidants using ESR technique, showed high antioxidant activity for quercetin, rutin, caffeic acid, and p-coumaric acid. 相似文献
6.
The essential oil of the leaves of Cupressus sempervirens L. was isolated by hydrodistillation and tested against gram positive and gram negative bacteria, showing remarkable antimicrobial
activity against Bacillus subtilis with minimum inhibitory concentration (MIC) 75%. The antiviral activity of the essential oil was tested against Herpes simplex
virus type 1 (HSV-1), showing antiviral activity with virucidal percentages of 68.0% and 53.2% at concentrations of 1:32 and
1:64, respectively. We firstly reported the isolation of two epi-betulin esters of fatty acids from the CHCl3 fraction of Cupressus sempervirens L. leaves, which were isolated and purified using HPLC, and identified using PMR and MS. The CHCl3 fraction showed significant cytotoxicity against HeLa cells.
Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 265–268, May–June, 2009. 相似文献
7.
H. R. El-Seedi 《Chemistry of Natural Compounds》2007,43(3):256-258
Tetradecyl ferulate and a new n-alkyl ester of 3-hydroxy-4-methoxy-trans-cinnamate (hexacosanylisoferulate) have been isolated from Cedrelinga catenaeformis Duke (Leguminoseae). The structures were determined by 1D- and 2D-NMR spectroscopy, mass spectrometry, chemical transformations
and finally from unambiguous synthesis. This is the first report of long chained cinnamic acid ester derivative from the genus.
Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 214–216, May–June, 2007.
Dedicated to Profs. S. El-Kousy, E. E. A. El-Khrisy, and K. B. G. Torssell on the occasion of their 60th, 65th, and 75th birthdays. 相似文献
8.
Taha A. Hussien Tarik A. Mohamed Abdelsamed I. Elshamy Mahmoud F. Moustafa Hesham R. El-Seedi Paul W. Pare Mohamed-Elamir F. Hegazy 《Molecules (Basel, Switzerland)》2021,26(7)
Centaurothamnus maximus (family Asteraceae), is a leafy shrub indigenous to the southwestern Arabian Peninsula. With a paucity of phytochemical data on this species, we set out to chemically characterize the plant. From the aerial parts, two newly identified guaianolides were isolated: 3β-hydroxy-4α(acetoxy)-4β(hydroxymethyl)-8α-(4-hydroxy methacrylate)-1αH,5αH, 6αH-gual-10(14),11(13)-dien-6,12-olide (1) and 15-descarboxy picrolide A (2). Seven previously reported compounds were also isolated: 3β, 4α, 8α-trihydroxy-4-(hydroxymethyl)-lαH, 5αH, 6βH, 7αH-guai-10(14),11(13)-dien-6,12-olide (3), chlorohyssopifolin B (4), cynaropikrin (5), hydroxyjanerin (6), chlorojanerin (7), isorhamnetin (8), and quercetagetin-3,6-dimethyl ether-4’-O-β-d-pyranoglucoside (9). Chemical structures were elucidated using spectroscopic techniques, including High Resolution Fast Atom Bombardment Mass Spectrometry (HR-FAB-MS), 1D NMR; 1H, 13C NMR, Distortionless Enhancement by Polarization Transfer (DEPT), and 2D NMR (1H-1H COSY, HMQC, HMBC) analyses. In addition, a biosynthetic pathway for compounds 1–9 is proposed. The chemotaxonomic significance of the reported sesquiterpenoids and flavonoids considering reports from other Centaurea species is examined. 相似文献
9.
The first direct synthesis of A3-type unsymmetrical porphyrin is achieved via conventional pyrrole–aldehyde condensation in a one-pot procedure in an appreciable yield. Generalization of this approach to a variety of other aldehydes revealed that it is advantageous for highly electron-rich aldehydes giving unsymmetrical porphyrin, while electron-poor aldehydes even failed to cyclize under the same experimental conditions. 相似文献
10.
Nga-Chun Ng Mian HR Mahmood Chi-K.Chang Hai-Yang Liu Fei Yam Lam-Lung Yeung Chi-K.Chang 《中国化学快报》2014,25(4):571-574
A series of N-base appended corroles and their manganese complexes were synthesized and their binding constants with three different nitrogenous ligands, triethylamine, N-methylimidazole and pyridine, were evaluated by spectroscopy. Kinetic studies indicated that the presence of appended N- donor ligands may cause a significant enhancement of the rate of oxygen atom transfers (OAT) from (oxo)manganese(V) corrole to alkene, and the stronger axial ligand binding has impact on the rate of the oxidation reaction. Turnover frequency (TOF) for the catalytic oxidation of alkenes by appended manganese corroles varies with the following ligand order: acetamido 〈 pyridyl 〈 imidazolyl. The influence of the external axial ligands on the catalytic epoxidation was investigated by using appended acetamido manganese corrole as catalyst, with the results revealing that N-methylimidazole gave the best enhancement on the yields of total oxidation products among the investigated nitrogenous ligands. 相似文献