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961.
We apply the master equation and non-linear Fokker-Planck techniques to a model with autocatalysis and (Michaelis-Menten, Langmuir-Hinshelwood) saturation law and the minimal set of reactive steps for a well posed problem is given. 相似文献
962.
A capillary zone electrophoresis (CZE) method with ultraviolet-visible detection has been established and validated for the determination of five phenothiazines: thiazinamium methylsulfate, promazine hydrochloride, chlorpromazine hydrochloride, thioridazine hydrochloride, and promethazine hydrochloride in human urine. Optimum separation was obtained on a 64.5 cm x 75 microm bubble cell capillary using a buffer containing 150 mM tris(hydroxymethyl)aminomethane and 25% acetonitrile at pH 8.2, with temperature and voltage of 25 degrees C and 20 kV, respectively. Naphazoline hydrochloride was used as an internal standard. Field-amplified sample injection (FASI) has been applied to improve the sensitivity of the detection. Considering the influence of parameters affecting the on-line preconcentration (nature of preinjection plug, sample solvent composition, injection times, and injection voltage) and due to the significant interactions among them, in this paper we propose for the first time the application of a multivariate approach to carry out the study. The optimized conditions were as follows: preinjection plug of water for 7 s at 50 mbar, electrokinetic injection for 40 s at 6.2 kV, and 32 microm of H3PO4 in the sample solvent. Also, a solid-phase extraction (SPE) procedure is developed to obtain low detection limits and an adequate selectivity for urine samples. The combination of SPE and FASI-CZE-UV allows adequate linearities and recoveries, low detection limits (from 2 to 5 ng/mL), and satisfactory precisions (3.0-7.2% for an intermediate RSD %). 相似文献
963.
Marie-Hélène Paclet Cécile F. Rousseau Campion Yannick Françoise Morel Anthony W. Coleman 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(3-4):353-357
The effects of para-Sulphonato-calix[4]arene, para-Sulphonato-calix[6]arene and para-Sulphonato-calix[8]arene on the activation of NADPH oxidase in neutrophils has been studied. All three molecules do not induce NADPH oxidase activation, and hence do not stimulate neutrophils. Measurement of cell viability demonstrates that these three water-soluble calix[n]arene derivatives are not cytotoxic. 相似文献
964.
Tomás Moya-Pizarro Roger Salmon Léopold Fournes Gilles Le Flem Barbara Wanklyn Paul Hagenmuller 《Journal of solid state chemistry》1984,53(3):387-397
Single crystals of the high-temperature form of NaFeP2O7 have been grown by a flux technique. II-NaFeP2O7 crystallizes in the monoclinic space group with lattice parameters: a = 7.298(2) Å, b = 7.874(2) Å, c = 9.536(3) Å, β = 111.85(2)°. The structure refined from 1481 independent reflections leads to R = 0.044 and confirms the work previously published by M. Gabelica-Robert, M. Goreaud, P. Labbe, and B. Raveau (J. Solid State Chem.45, 389, 1982). Magnetic Mössbauer resonance studies have shown the existence of antiferromagnetic ordering with a weak ferromagnetic component below 30 K. The FeO bond is markedly ionic in character due to the highly polarizing power of phosphorus in tetrahedral site. 相似文献
965.
A. V. Guttsait S. V. Belyakov A. F. Mishnev Ya. Ya. Bleidelis é. Yu. Gudrinietse 《Chemistry of Heterocyclic Compounds》1987,23(9):986-989
4-Trifluoromethyl-6-phenyl-2-chloro-3-cyanopyridine was synthesized, and its molecular-crystal structure was established. The chlorine atom was replaced by amino, mercapto, thiocyanato, and azido groups. The possibility of the direct amination of 4-trifluoromethyl-6-phenyl-3-cyano-2-pyridone by the action of hexamethylphosphoric triamide (HMPT) was demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1233–1237, September, 1987. 相似文献
966.
Zh. Bo J. H. Yan X. D. Li Y. Chi K. F. Cen B. G. Chéron 《Plasma Chemistry and Plasma Processing》2007,27(5):546-558
The combined effects of oxygen and water vapor on three typical volatile organic compounds, i.e. tetrachloromethane, n-butane and toluene, decomposition efficiency under gliding arc gas discharge conditions are studied. The electron density
and the density of the reactive radicals such as O and OH are modified by addition of oxygen and water vapor. Consequently,
the decomposition process can be enhanced or suppressed, depending on the involved chemical structures and reaction channels.
The addition of oxygen and water vapor suppresses the tetrachloromethane decomposition which indicates that this process is
mainly controlled by the electron dissociation reactions. By contrast, the n-butane and toluene decompositions are enhanced, which shows that they can be mainly ascribed to the radical induced reactions.
Especially, in a moist atmosphere the OH radicals are supposed to play the most important role in the n-butane decomposition process. 相似文献
967.
Development of an analytical procedure for determination of selected estrogens and progestagens in water samples 总被引:1,自引:0,他引:1
An analytical procedure has been developed for determination of eight selected natural and synthetic hormonal steroids in surface water and in effluent samples. Several methodological points have been investigated and are discussed; they include the choice of the solid-phase extraction sorbent, the influence of flow rate on recovery, the breakthrough volume for a given sorbent (Env+ and Oasis HLB), sample clean up, and sample storage. As regards the latter point, it was found that when no preservative was added to effluent from a sewage-treatment plant, severe loss of steroids occurred—85% of progesterone and about 30% of both estrone and estradiol were found to be degraded in 24 h. The procedure developed was applied to samples from the Seine river estuary. Sex steroids were not detected in surface water; estrone was the most commonly detected steroid in sewage-treatment plant effluent, with levels ranging from 1.8 to 8.3 ng L–1. Synthetic estrogens (ethynylestradiol and mestranol) and progestagens (levonorgestrel and norethindrone) were never detected, whatever the sampling season. Overall, for 162 out of 168 measurements levels were below the detection limits of the developed procedure. 相似文献
968.
Alain H. Roux Daniel Hétu Gérald Perron Jacques E. Desnoyers 《Journal of solution chemistry》1984,13(1):1-25
Mixed micelles can be formed in water between various pairs of hydrophobic solutes such as surfactants, alcohols and hydrocarbons. These systems can often be studied through the thermodynamic functions of transfer of one of the solutes, usually kept near infinite dilution, from water to an aqueous solution of the other solute. When mixed micelles are formed, these functions change significantly, and often go through extrema, in the region where the binary system micellizes or undergoes some microphase transition.Three main effects are responsible for the observed trends: pair-wise interactions between both solutes in the monomeric form, a distribution of the reference solute between the aqueous and micellar phases and a shift in the monomer-micelle equilibrium in the vicinity of the reference solute. Simple equations can be derived for these three effects which can account for the sign and magnitude of the observed trends using parameters which are derived for the most part from the two binary systems. 相似文献
969.
Ru-based catalysts can be used in E-selective cross metathesis (CM) reactions to synthesise various functionalised internal allylic monofluorides. 相似文献
970.
Petra Spitzer Bruno Rossi Yves Gaignet Stéphane Mabic Uwe Sudmeier 《Accreditation and quality assurance》2005,10(3):78-81
There is currently a major issue with the calibration of conductivity meters used for high purity water: the lack of availability of a reference material or reference methods for low conductivity ranges (conductivity below 1 S cm–1 at 25.0 °C, resistivity >1 M cm at 25.0 °C). This paper describes the current status of conductivity measurements in high purity water. A new and improved approach, currently being investigated, should allow us to make the calibration of conductivity meters used for low conductivity ranges traceable to the SI.Milipore, Milli-Q and Elix are registered trademarks of Millipore Corporation. 相似文献