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551.
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Doménech-Carbó MT Casas-Catalán MJ Doménech-Carbó A Mateo-Castro R Gimeno-Adelantado JV Bosch-Reig F 《Fresenius' Journal of Analytical Chemistry》2001,369(7-8):571-575
A new method, based on the combined use of scanning electron microscopy-x-ray microanalysis, Fourier transform infrared spectroscopy, gas chromatography and differential pulse voltammetry, is proposed which permits a parallel investigation of organic and inorganic materials and the characterization of the artistic technique employed in canvas painting. The proposed method has led to analyze succesfully the canvas painting collection exhibited in the Basílica de la Virgen de los Desamparados (Valencia, Spain) which includes art works from 17th to 20th century. 相似文献
553.
P Bermejo E M Pe?a D Fompedri?a R Domínguez A Bermejo J A Cocho J R Fernández J M Fraga 《Journal of AOAC International》2001,84(3):847-852
Size exclusion chromatography (SEC) and flame atomic absorption spectroscopy (FAAS) were used for the separation of metal-containing species in milk whey. After milk ultracentrifugation, the sample was injected into a TSK-Gel G2000 glass column and eluted with 0.2M NH4NO3-NH3, pH 6.7. Low molecular weight proteins were fractionated, and the fractions were characterized by molecular weight. Zinc distributions were obtained by FAAS using a high performance nebulizer. The method was very sensitive (limit of detection = 2.6 x 10(-3) microg/mL; limit of quantitation = 8.9 x 10(-3) microg/mL) and precise (RSDs < or =10%). This method was applied to the determination of Zn in binding compounds in breast milk whey and in commercial cow's milk-based formulas. Distribution patterns were different. The presence of Zn in most fractions in breast milk was most significant, whereas in infant formulas Zn was detected only in fractions of molecular weight <5 kDa and in the highest molecular weight peak. 相似文献
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(S)-9-cis-4-Oxo-13,14-dihydroretinoic acid (S)-1, a new major endogenous vitamin A metabolite that activates retinoic acid receptor signaling both in vitro and in vivo, has been synthesized stereoselectively by Horner–Wadsworth–Emmons condensation and Stille cross-coupling as bond forming reactions. 相似文献
557.
The step model is one of the most widely used models of solution–precipitation creep in polycrystalline ceramics with secondary glassy phases. However, it leads to unrealistic stress exponent values when two-dimensional step nucleation takes place at the grain boundaries. We present a modification of the original model of step nucleation that avoids such unreasonable values by considering in detail the precipitation (or solution) process. The modified model agrees with reported experimental results for ceramic systems in which it has been accepted that high-temperature plasticity occurs by solution–precipitation. 相似文献
558.
Irene Domínguez Noelia Calvar Elena Gómez Ángeles Domínguez 《The Journal of chemical thermodynamics》2011,43(5):705-710
In this paper the extraction of toluene from cyclic hydrocarbons (cyclohexane, or methylcyclohexane, or cyclooctane, or cyclohexene) was analyzed by liquid extraction with 1-butyl-3-methylimidazolium methylsulfate ionic liquid, [BMim][MSO4], as solvent. The experimental (liquid + liquid) equilibrium (LLE) data were determined at T = 298.15 K and atmospheric pressure. Solubility curves were obtained by the cloud point method and tie-line compositions were determined by density measurement. An analysis of the influence of different cyclic hydrocarbons on the extraction was performed.The effectiveness of the extraction of toluene from cyclic hydrocarbons was evaluated by means of the solute distribution ratio and selectivity values. The degree of consistency of the experimental LLE data was ascertained using the Othmer–Tobias and Hand equations. The experimental data for the (liquid + liquid) equilibria of the ternary systems were correlated with the Non-Random Two-Liquid (NRTL) and UNIversal QUAsi-Chemical (UNIQUAC) thermodynamic models. 相似文献
559.
Unusual displacements of bromides and iodides through nucleophilic aromatic substitution reactions give a direct access to the xanthone core. This sustainable process is based on the use of water as an environmentally friendly solvent. 相似文献
560.