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991.
Summary After a brief review of the main publications dealing with air-sampling and analysis of aliphatic amines, the authors propose and investigate two sampling methods (bubbling through a sulfuric acid solution, trapping on sulfuric acid-treated silica-gel) for three tertiary aliphatic amines commonly encountered in foundries. 相似文献
992.
Bruno M Rosselli S Maggio A Piozzi F Scaglioni L Arnold NA Simmonds MS 《Chemical & pharmaceutical bulletin》2004,52(12):1497-1500
Two new neoclerodane diterpenoids, 6-deacetyl-teucrolivin A (5) and 8beta-hydroxy-teucrolivin B (6), were isolated from the aerial parts of Teucrium orientale, along with four already known neoclerodane diterpenoids, teucrolivin A (1), teucrolivin B (2), teucrolivin C (3) and teucrolivin H (4), previously isolated from Teucrium oliverianum. Their structures were elucidated on the basis of spectroscopic evidence and chemical transformations. Compounds 1-3 were assayed for antifeedant activity against Spodoptera littoralis, S. frugiperda and Heliocoverpa armigera. Teucrolivin A was the most potent of the three compounds tested. 相似文献
993.
Corrado Sarzanini Giovanni Sacchero Maurizio Aceto Ornella Abollino Edoardo Mentasti 《Journal of chromatography. A》1993,640(1-2):179-185
The ion-interaction chromatographic behaviour of Plasmocorinth B (a disulphonated azo dye) and of its complexes formed with metal ions in oxidation states + 2 and + 3 (Cu2+ Ni2+, Al3+, CO3+, Fe3+, Ga3+) was investigated. The effect of cationic ion-pairing agents (tetramethyl-, benzyltrimethyl- and tetrabutylammonium) was also evaluated in the presence of alkali metal ions competitors (Li+ and Na+). The effects of organic modifier and of pH were also considered. The remarkably different behaviour of the ligand and the complexes suggests the formation of M(II)L− and M(III)L22−. The stoichiometry of complexes was confirmed by applying the electrostatic theory derived from Gouy-Chapman and a modified Langmuir adsorption isotherm to the experimental data. 相似文献
994.
Ferrari L Seraglia R Rossi CR Bertazzo A Lise M Allegri G Traldi P 《Rapid communications in mass spectrometry : RCM》2000,14(13):1149-1154
Seventeen samples of sera from patients with malignant cutaneous melanoma at various stages and 14 samples from healthy subjects were analysed by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Results highlighted the presence of several protein species at molecular weights lower than 30000 Da, presumably originating from proteolysis, in the sera of the patients with melanoma. These species were completely absent in healthy subjects. In particular, the presence and abundance of species with molecular weights in the range 2500-3500 Da exhibit significant variations related to the different clinical stages of the disease. 相似文献
995.
Enzymatic Approach to and Odor Description of the Twelve Enantiomerically Pure Isomers of Pelargene®
Agnese Abate Maurizio Allievi Elisabetta Brenna Claudio Fuganti FrancescoG. Gatti Stefano Serra 《Helvetica chimica acta》2006,89(2):177-189
Pelargene® is a commercial fragrance sold as a mixture of three regioisomeric pyran derivatives ( 1 – 3 ). The enantiomers of each of the two possible diastereoisomers of 1 – 3 were prepared by means of a biocatalyzed approach, and the odor properties of the twelve isolated stereoisomers were evaluated. 相似文献
996.
Roberta Bernini Enrico Mincione Maurizio Barontini Fernanda Crisante Giancarlo Fabrizi 《Tetrahedron》2007,63(29):6895-6900
Environmentally friendly oxidations of various organic compounds with the hydrogen peroxide (H2O2)/methyltrioxorhenium (CH3ReO3, MTO) catalytic system have been described in dimethyl carbonate (DMC), a cheap commercially available and benign chemical having interesting solvating properties, low toxicity and high biodegradability. Oxidations proceeded with good conversions and in good yields. Spectrophotometric analysis demonstrated that the [CH3ReO(O-O)2] complex was formed in DMC and that it was stable for several days at room temperature. 相似文献
997.
Elisabetta Ranucci Laura Putelli Paolo Ferruti Vittorio Ferrari Daniele Marioli Andrea Taroni 《Mikrochimica acta》1995,120(1-4):257-270
A novel polymeric material of poly(amidoamine) [PAA] structure was used as sensor-coating for the detection of CO2 and SO2 in gaseous mixtures by means of gravimetric sensors. The PAA utilized for this work was an amorphous rubber-like material, purposely selected for the flexibility of its macromolecular structure, which favours the diffusion of analyte molecules through the polymeric layer. It was prepared and characterized in our laboratory by means of IR and NMR spectroscopy, DSC analysis, viscometric measurements and potentiometric titration with standard acids. The polymeric films were prepared by casting from dilute methanol solutions and their average thickness ranged between 0.40 and 0.80 m. The morphology of the films was studied by means of SEM. Sorption experiments in the presence of CO2 and SO2 alternately were carried out in environments at controlled temperature and relative humidity (RH) levels. The response towards both CO2 and SO2 approached linearity. The limits of sensitivity towards both gaseous analytes were determined, and the dependence of the PAA Sorption on RH was investigated. The long-term stability of the material in normal atmospheric conditions was also considered. The Sorption phenomenon was completely reversible in the case of CO2, while hysteresis was detected in the case of SO2. The response times were on the order of 5 min for CO2 and 7 min for SO2. 相似文献
998.
The photochemically generated 4-(N,N-dimethylamino)phenyl cation adds to norbornene giving a phenylnortricyclene and various 2-exo substituted phenylnorbornanes (main isomers, 3-endo-, 7-anti- and 7-syn-phenyl). Acetamides are obtained in MeCN and ethers in alcohols (MeOH, iso-PrOH, tert-BuOH, CF3CH2OH). The product distribution is closely reminiscent of that obtained in the solvolysis of 2-norbornyl derivatives, supporting that the reaction offers a novel access to a 'non classical' 2-norbornyl cation. The fate of this cation is determined by the basicity/nucleophilicity of the solvent. 相似文献
999.
A. A. Ferrari E. J. França E. A. N. Fernandes M. A. Bacchi 《Journal of Radioanalytical and Nuclear Chemistry》2006,270(1):69-73
Summary The exogenous material that adheres to the leaf surface affects the elemental composition of the plant itself, thereby constituting
one of the major error sources in plant analysis. The present work investigated the surface contamination of leaves from the
Atlantic Forest. Instrumental neutron activation analysis (INAA) was applied to assess the efficiency of leaf EDTA-washing.
Chemical element concentrations were corrected using Sc (soil tracer) since resuspended soil is the main source of contamination
in leaves. As a result, EDTA-washing should be used mainly for the evaluation of terrigenous elements, while the Sc-corrected
concentrations are considered satisfactory for the other elements. 相似文献
1000.
Benzi C Cossi M Barone V Tarroni R Zannoni C 《The journal of physical chemistry. B》2005,109(7):2584-2590
The ordering properties of an anisotropic liquid crystal can be studied by recording 13C NMR spectra at different temperatures for a number of rigid solutes. The traditional difficulty in analyzing 13C data comes from the scarcity of experimental information about the carbon shielding tensors and from their limited transferability among different solutes. We show that these obstacles can be overcome by computing high-level ab initio shielding tensors, also including the solvent effects by the polarizable continuum model. The reliability of this combined approach is carefully verified, and the order parameters of several solutes are obtained by reanalyzing previously published spectra. The quality of the results is shown to be comparable to deuterium NMR without the need of isotopic substitution. 相似文献