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排序方式: 共有182条查询结果,搜索用时 15 毫秒
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Cecilia Sáenz Barrio Elena Romero Melgosa Jesús Sanz Asensio Javier Galbán Bernal 《Mikrochimica acta》1996,122(3-4):267-277
Three different extraction procedures for eight pesticides (chlorfenvinphos, diazinon, ethyl parathion, ethiofencarb, fenitrothion, malathion, metalaxyl, pirimicarb) in water samples are compared. The extraction procedures are: liquid-liquid extraction (LLE), solid-phase extraction (SPE) and microextraction (ME). For each procedure the most suitable conditions were obtained experimentally, with special remarks on ME, in which the effects of different mixtures of Kaltron with other solvents were tested. A preconcentration factor (PF) was used to rank the methods; the best results were observed for ME, (PF 15–45, whereas PF < 10 for SPE, and PF 13 for LLE). In all cases, the determination was performed by gas chromatography, using a nitrogen phosphorus detector and the internal standard method (methyl parathion) as the quantification procedure. 相似文献
33.
Ramon J.Barrio Diez-Caballero Juan F.Arranz Valentin Adela Arranz Garcia Rafael Pardo Almudi Pedro Sanchez Batanero 《Journal of Electroanalytical Chemistry》1985,196(1):43-51
The stability constants of complexes of different stoichiometries, formed by Pb(II) with oxalate, maleate, tartrate and citrate anions, have been determined. The polarographic methods originally used by DeFord and Hume were used for the binary complexes and those of Schaap and McMasters for the mixed complexes. The reliability of the results obtained was verified by applying the POLAG program. Finally, different statistical considerations were undertaken which confirm the results. 相似文献
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Barluenga J Vicente R Barrio P López LA Tomás M Borge J 《Journal of the American Chemical Society》2004,126(44):14354-14355
The 1,2- and 1,3-dialkylidenecycloheptane rings are specifically assembled from chromium alkenyl Fischer carbene complexes and allenes via [3+2+2] cyclization reactions. The former cycloadducts are obtained when the cyclization is performed in the presence of 1 equiv of [Ni(cod)2], while the [Rh(cod)Cl]2-catalyzed cyclization leads to the latter cycloadducts. 相似文献
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José Barluenga Pablo Barrio Lorena Riesgo Luis A. López Miguel Tomás 《Tetrahedron》2006,62(32):7547-7551
Alkyl, aryl, and heteroaryl chromium Fischer carbene complexes undergo Ni(0)-mediated [2+2+1] cyclization reaction with internal unactivated and electron-poor internal alkynes to yield highly substituted cyclopentadienes with complete regioselectivity in most cases. The intramolecular version of this cyclization has been accomplished with 1,8-diphenyl-1,7-octadiyne to produce indene derivatives. This three-component [2+2+1] cyclization represents a very uncommon process in the chemistry of Fischer carbene complexes. 相似文献
40.
S. SerranoR. Barrio A. DenaM. Rodríguez 《Communications in Nonlinear Science & Numerical Simulation》2012,17(2):788-794
Intermittent behavior of economic dynamics is studied by a nonlinear model of business cycles when two of its control parameters, amplitude and frequency of a periodic exogenous driving force, are changed. This study points out how similar wanted situations may be reached by changing any of both parameters, and it gives a deeper understanding of what happens in actual economic data when some control parameters are changed at the same time. 相似文献