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排序方式: 共有86条查询结果,搜索用时 325 毫秒
21.
Salvatore Cabiddu Enzo Cadoni Stefana Melis Alen Ianni Angela M. Bernard Maria G. Cabiddu Stefania De Montis Claudia Fattuoni Sandra Ianelli 《Journal of heterocyclic chemistry》2003,40(6):979-987
The reaction of benzoxathiole‐3‐oxide with lithiumdiisopropylamide in tetrahydrofuran gave an anion, which was reacted with various aryl‐methyl‐ketones to give 2‐(1‐hydroxy‐1‐arylethyl)‐1,3‐benzoxathiol‐3‐oxide derivatives. The reaction was carried out in different temperature conditions: at ‐88 °C the trans addition stereoisomers to the sulfoxide oxygen atom were the main products. 相似文献
22.
There are numerous possible vectors of industrial lead poisoning in unprotected work environments and the areas surrounding industrial sites. In the Rabat-Salé region, ceramics is the industry which uses most lead. Galena (PbS) is used in the fabrication of some types of pottery, and other lead-based compounds are used as glaze. A second source of lead pollution is the production of some fuels, in which lead is used as an anti detonator. In order to evaluate the impact of lead contamination on the environment, our investigation is focused on the lead concentration in the atmosphere, soil and vegetation at five stations in the Rabat-Salé region. We found concentrations of lead higher than those published for any other country in the atmosphere and vegetation near the ceramics factories of Rabat-Salé. These concentrations decreased significantly as we moved away from urban areas. 相似文献
23.
The heavy metals contamination of the lower Sebou sediments was studied to determine the average degree of contamination and to assess the extent of anthropogenic contamination. The spatial and temporal distribution of these metals and the results of the contamination indices showed very serious metallic contamination principally of Cr, Pb and Hg. However accurate analysis of the situation in the river mouth was complicated by the fact that the metals could be moved by the tides and currents. 相似文献
24.
Pd(II) complexes of Schiff bases and their application as catalysts in Mizoroki–Heck and Suzuki–Miyaura cross‐coupling reactions
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Schiff bases of 2‐(phenylthio)aniline, (C6H5)SC6H4N?CR (R = (o‐CH3)(C6H5), (o‐OCH3)(C6H5) or (o‐CF3)(C6H5)), and their palladium complexes (PdLCl2) were synthesized. The compounds were characterized using 1H NMR and 13C NMR spectroscopy and micro analysis. Also, electrochemical properties of the ligands and Pd(II) complexes were investigated in dimethylformamide–LiClO4 solution with cyclic and square wave voltammetry techniques. The Pd(II) complexes showed both reversible and quasi‐reversible processes in the ?1.5 to 0.3 V potential range. The synthesized Pd(II) complexes were evaluated as catalysts in Mizoroki–Heck and Suzuki–Miyaura cross‐coupling reactions. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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26.
Konstanze R. Hahn Claudio Melis Luciano Colombo 《The European Physical Journal B - Condensed Matter and Complex Systems》2014,87(7):1-5
On the basis of the experimental data concerning interactions between humans the process of epidemic spreading in a social network was investigated. It was found that number of contact and average age of nearest neighbors are highly correlated with age of an individual. The influence of those correlations on the process of epidemic spreading and effectiveness of control measures like mass immunizations campaigns was investigated. It occurs that the magnitude of epidemic is decreased and the effectiveness of target vaccination is increased. 相似文献
27.
Vladimir P. Zaytsev Fedor I. Zubkov Flavien A. A. Toze Daria N. Orlova Maria N. Eliseeva Dmitry G. Grudinin Eugeniya V. Nikitina Alexey V. Varlamov 《Journal of heterocyclic chemistry》2013,50(Z1):E18-E38
The interactions between 4‐R‐substituted 2‐furyl‐1,2,3,4‐tetrahydroquinolines (synthesized by the Povarov reaction) and a number of alkenes have been investigated. Maleic, dibromomaleic, dichloromaleic, and citraconic anhydrides, as well as acryloyl, methacryloyl, crotonyl, and cynnamoyl chlorides were used as alkene components. It was shown that the initial N‐acylation of the tetrahydroquinolines was followed by a spontaneous [4+2]‐cycloaddition of an N‐acryloyl substituent to the furan ring. It was established that the intramolecular Diels–Alder reaction of furans is reversible, occurs stereoselectively as exo‐addition, and led to target epoxyisoindolo[2,1‐a]tetrahydroquinolines with moderate yields. Oxidation and aromatization of the synthesized products were carried out. 相似文献
28.
Dr. Romain Plais Guy Gouarin Amélie Bournier Olfa Zayene Vanessa Mussard Flavien Bourdreux Dr. Jérome Marrot Arnaud Brosseau Dr. Anne Gaucher Dr. Gilles Clavier Dr. Jean-Yves Salpin Prof. Dr. Damien Prim 《Chemphyschem》2023,24(2):e202200524
Modulation and fine-tuning of the strength of weak interactions to bind anions are described in a series of synthetic receptors. The general design of the receptors includes both a urea motif and a tetrazine motif. The synthetic sequence towards three receptors is detailed. Impacts of H-bond strength and linker length between urea and tetrazine on chloride complexation are studied. Binding properties of the chloride anion are examined in both the ground and excited states using a panel of analytical methods (NMR spectroscopy, mass spectrometry, UV/Visible spectroscopies, and fluorescence). A ranking of the receptors by complexation strength has been determined, allowing a better understanding of the structure-properties relationship on these compounds. 相似文献
29.
Dr. Georgian Melinte Dr. Veselina Georgieva Dr. Marie‐Anne Springuel‐Huet Dr. Andreï Nossov Prof. Ovidiu Ersen Dr. Flavien Guenneau Prof. Antoine Gedeon Dr. Ana Palčić Dr. Krassimir N. Bozhilov Dr. Cuong Pham‐Huu Prof. Shilun Qiu Dr. Svetlana Mintova Dr. Valentin Valtchev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(6):1881-1881
30.
Erdal Bedir idem Karakoyun Gamze Doan Gülten Kuru Melis Küüksolak Hasan Yusufolu 《Molecules (Basel, Switzerland)》2021,26(10)
Microbial biotransformation is an important tool in drug discovery and for metabolism studies. To expand our bioactive natural product library via modification and to identify possible mammalian metabolites, a cytotoxic cardenolide (gitoxigenin) was biotransformed using the endophytic fungus Alternaria eureka 1E1BL1. Initially, oleandrin was isolated from the dried leaves of Nerium oleander L. and subjected to an acid-catalysed hydrolysis to obtain the substrate gitoxigenin (yield; ~25%). After 21 days of incubation, five new cardenolides 1, 3, 4, 6, and 8 and three previously- identified compounds 2, 5 and 7 were isolated using chromatographic methods. Structural elucidations were accomplished through 1D/2D NMR, HR-ESI-MS and FT-IR analysis. A. eureka catalyzed oxygenation, oxidation, epimerization and dimethyl acetal formation reactions on the substrate. Cytotoxicity of the metabolites were evaluated using MTT cell viability method, whereas doxorubicin and oleandrin were used as positive controls. Biotransformation products displayed less cytotoxicity than the substrate. The new metabolite 8 exhibited the highest activity with IC50 values of 8.25, 1.95 and 3.4 µM against A549, PANC-1 and MIA PaCa-2 cells, respectively, without causing toxicity on healthy cell lines (MRC-5 and HEK-293) up to concentration of 10 µM. Our results suggest that A. eureka is an effective biocatalyst for modifying cardenolide-type secondary metabolites. 相似文献