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61.
Solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME) was applied for the extraction of six organophosphorous pesticides (OPPs) in water samples. The analytes considered in this study were determined by gas chromatography with mass spectrometry and included prophos, diazinon, chlorpyrifos methyl, methyl parathion, fenchlorphos and chlorpyrifos. Several extraction conditions (extraction solvent and elution/dispersion solvents nature, extraction solvent volume, elution solvent volume, water volume and sample volume) were tested for SPE-DLLME with these analytes and the best results were obtained using carbon tetrachloride as the extraction solvent and acetone as the elution/dispersion solvent. Calibration curves for the determination of OPPs in water samples were constructed in the concentration range of 10-100 ng/L. Limits of detection (LODs) ranged from 38 to 230 pg/L values that are below the maximum admissible level for drinking water (100 ng/L). Relative standard deviations (RSD) were between 8.6 and 10.4% for a fortification level of 100 ng/L. At the same fortification level, the relative recoveries (R.R.) of tap, well and irrigation water samples were in the range of 30.2-97.1%. 相似文献
62.
Jaime-Vasconcelos MÁ Frontana-Uribe BA Morales-Serna JA Salmón M Cárdenas J 《Molecules (Basel, Switzerland)》2011,16(11):9109-9115
From the aerial parts of Salvia occidentalis (Labiatae) a new diterpenoid with a rearranged neo-clerodane skeleton was isolated. This new compound was named salvioccidentalin and its structure was established by spectroscopic means. A probable biogenetic relationship with salvigenolide from S. fulgens and salvileucalin A and spiroleucantholide from Salvia leucantha is proposed. 相似文献
63.
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65.
Bernardo de la Calle Ysern 《Numerische Mathematik》2005,101(2):251-271
We study the error of rational quadrature rules when functions which are analytic on a neighborhood of the set of integration are considered. A computable upper bound of the error is presented which is valid for a broad range of rational quadrature formulae and a comparison is made with the exact error for a number of numerical examples.This work was supported by the Dirección General de Investigación (DGI), Ministerio de Ciencia y Tecnología, under grants BFM2003-06335-C03-02 and BFM2002-04315- C02-01. 相似文献
66.
Roberto Rossi Andrea Marchi Adriano Duatti Luciano Magon Plinio Di Bernardo 《Transition Metal Chemistry》1985,10(4):151-153
Summary The rhenium(V) imido-complexes [Re(NR)Cl3(PPh3)2] have been obtained by heating the rhenium(V) derivative [ReOCl3(PPh3)2] with RNHCHNR R = Ph (1a), p-MeC6H4 (1b), p-ClC6H4 (1c) andp-FC6H4 (1d) in THF under reflux. [Re(NR)Cl3(PPh3)2] (R =p-MeQ6H4) has also been obtained by heating the rhenium(III)-triazenido complex [ReCl2(RN
N
NR)(PPh3)2] in CCl4 under reflux. 相似文献
67.
Deanna De Marcano Bernardo Mndez Jeannette De Mndez Jos Monasterios Aníbal C. Rojas Thomas G. Halsall 《Magnetic resonance in chemistry : MRC》1983,21(8):524-525
The 13C NMR spectra of a series of some Δ4(20),11-taxadiene derivatives are reported. A detailed analysis of their assignments is presented. 相似文献
68.
Agustin Campos Rafael Gavara Roberto Tejero Clara Gomez Bernardo Celda 《Journal of Polymer Science.Polymer Physics》1989,27(8):1559-1597
The Flory–Huggins theory as modified by Pouchlý has been applied to calculate preferential (λ) and total (Y) sorption coefficients for a ternary polymer system. The ternary interaction function (?1?2?3GT(u1, ?3)) is described as the product of three independent binary functions. This expression allows prediction of λ and Y from binary interaction parameters χ, χ, g, g, and g12(?10). Three ternary polymer systems are used to check the validity of the expression. Moreover for polymer systems in which the parameters g and/or g are unknown, a procedure to evaluate them has been developed and verified on systems for which sufficient experimental information is available. 相似文献
69.
Bernardo Masci Pierre Thury 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(11):m584-m586
In the title compound, [UO2(C13H10O2)(C11H19N3)]·C3H6O, the U atom is in a pentagonal–bipyramidal environment, with the three N atoms of the 2,6‐bis[(dimethylamino)methyl]pyridine ligand and the two O atoms of the dianionic 2,2′‐methylenediphenolate ligand in the equatorial plane. The geometry is compared with that of previously reported 1:2 uranyl–diphenoxide complexes. 相似文献
70.
Ladislav Hlavatý Stanly Steinberg Kurt Bernardo Wolf 《Journal of Mathematical Analysis and Applications》1984,104(1):246-263
Lie series and a special matrix notation for first-order differential operators are used to show that the Lie group properties of matrix Riccati equations arise in a natural way. The Lie series notation makes it evident that the solutions of a matrix Riccati equation are curves in a group of nonlinear transformations that is a generalization of the linear fractional transformations familiar from the classical complex analysis. It is easy to obtain a linear representation of the Lie algebra of the nonlinear group of transformations and then this linearization leads directly to the standard linearization of the matrix Riccati equations. We note that the matrix Riccati equations considered here are of the general rectangular type. 相似文献