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Yuuko Houda Misako Sasabe Xu Bo Hideki Takagi Kimiaki Yamamura 《Journal of heterocyclic chemistry》2000,37(5):1363-1365
2‐Cycloheptatrienyl‐3‐(2‐furyl)benzothiophenes, which are prepared by Stille coupling reaction of 2‐cyclo‐heptatrienyl‐3‐bromobenzothiophene with the 5‐substituted 2‐trimethylstannylfurans, react with triphenylmethyl tetrafluoroborate to give the corresponding azuleno[1,2‐b]benzothiophenic enones in excellent yields. 相似文献
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Houda Zendah Ismail Khattech Mohamed Jemal 《Journal of Thermal Analysis and Calorimetry》2012,109(2):855-861
A series of ??B?? type carbonate fluorapatites (B?CCO3?CFap) have been synthesized and characterized by X-ray diffraction, infrared spectroscopy, and chemical analysis. The thermochemical study of phosphoric acid attack of the products was performed by a 19% w/w P2O5 solution on raw and deconvoluted curves. The calculated thermogenesis curves show one, two, or four peaks, depending on the mass of dissolved solid and the carbonate content in B?CCO3?CFap. The plot of the quantity of heat measured by integrating the raw signal as a function of the dissolved mass in the same volume solution presents three straight segments for low-carbonated and two segments for moderately carbonated ones. From the slopes of line segments, it was possible to determine the enthalpies of dissolution of ??B?? type carbonate fluorapatites and to deduce that of precipitation of CaF2 and Ca(H2PO4)2·H2O, which have been compared to directly measured or literature data. 相似文献
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Diels-Alder reaction of - 2,4 pentadienoïc acid and its methyl ester (electron with-drawing) dienes with juglone and its derivatives is described. High regioselectivity is observed, the adducts have a “head-to-tail” geometry. 相似文献
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Ammar S Mahjoub MA Abdelkader HB Liouane K Skandarani I Chekir-Ghedira L Mighri Z 《Natural product research》2008,22(8):658-665
A new polyphenolic natural substance: 2,5-dihydroxy-benzoic acid 3'-formyl-5'-hydroxy-phenyl ester (1), Anamighrinal and 3-(O-alpha-L-rhamnosyl) quercetin (2) have been isolated from the methanolic aerial part extract of the plant Anagallis monelli by chromatographic separation. Their structures have been deduced essentially by one and two NMR spectroscopic procedures and mass spectrometry. Antioxidant, mutagenic, antimutagenic activities, of the natural products were realised and positive results were recorded. 相似文献
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This study proposes a simple multiresidue liquid chromatography-diode array detector (LC-DAD) method capable of determining seven macrolide antibiotics in samples of liver and kidney animals at concentrations lower than those allowed by current legislation. Samples were prepared by homogenizing the tissue with EDTA-McIlvaine's buffer and extracted with an Oasis HLB cartridge. The consumption of organic solvent during extraction was minimum. The analytes were detected by LC-DAD and also by liquid chromatography-mass spectrometry with electrospray ionization (LC-(ESI)MS). The method was specific, stable and robust enough for the required purposes. The DAD method was validated in accordance with the European Commission Decision 657/2002. Recovery data were also satisfactory with values higher than 67% for most macrolide antibiotics extracted from liver and kidney samples spiked at 200 microg/kg, the lowest MRL established for the macrolides studied. The relative standard deviations (RSD (%), (n=3)) were lower than 13% and 15% for intra-day and inter-day assays. The method was applied to investigate the occurrence of the studied macrolides in 31 beef and kidney animal samples. The results obtained by LC-DAD for positive samples were compared to those obtained by LC-(ESI)MS. Therefore, the method with simpler instrumentation than a LC-(ESI)MS can be used as a control method and the results of the validation process demonstrate that this method is suitable for application in a European Union program for monitoring residues of veterinary drugs. 相似文献
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The structure of K0.92(2) Zn0.08(2) H1.92(2) (PO4) was determined using single-crystal X-ray diffraction. The crystal structure of the Zn-KDP belonged to the tetragonal space group $ \mathrm{I}\overline{4}2\mathrm{d} $ , with cell parameters of a?=?b?=?7.4487(5)?Å and c?=?6.9703(5)?Å, 386.73(5) Å3, Z?=?4, and R?=?0.023. Zn2+ ions were used as substitutes for K+ ions with hydrogen vacancy. The Zn-KDP single crystals were submitted to further Raman, infrared, and 1H NMR studies to investigate chemical group functionalisation, possible bonding between the organic and inorganic materials, and partial substitution of K+ by Zn2+. The latter partial substitution was confirmed by the deviation of IR frequencies for O–H stretching, the variation of IR and Raman frequencies for stretching and bending vibrations ν(PO4) of H2PO4, and the appearance of additional Raman (147, 386 and 481 cm?1) vibrational bands. Electrical conductivity measurements were performed on polycrystalline pellets of Zn-KDP and pure KDP at room temperatures (RT) of up to 473K. In both cases, a conductivity jump close to 453K was observed, and a stronger increase of conductivity was measured. 相似文献
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This work was designed to develop an electrochemical sensor based on molecular imprinted polyaniline membranes onto reduced graphene oxide (RGO) and gold nanoparticles (AuNPs) modified glassy carbon (GC) electrode for dapsone (DDS) determination. The prepared RGO/AuNPs/PANI‐MIPs nanocomposite was characterized by Ultra‐Violet‐Visible (UV‐Vis), Fourier transform infrared spectroscopy (FT‐IR) and scanning electronic microscopy (SEM) images. The feature of the imprinted electrode was evaluated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and impedance spectroscopy (IS). Throughout this study several analytical parameters, such as incubation time, pH value, concentration of monomer/template molecules and electro‐polymerization cycles were investigated. Under the optimized conditions, the experimental results showed best analytical performances for DDS detection with a sensitivity of 0.188 Ω/mol L?1, a linear range from 1.0×10?7 M to 1.0×10?3 M and a detection limit of 6.8×10?7 M. The bioanalytical sensor was applied to the determination of dapsone in real samples with high selectivity and recovery. 相似文献
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