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51.
一种基于流动注射梯度技术识别异常峰及校正的方法 总被引:1,自引:0,他引:1
基于流动注射梯度信息提出了一种利用梯度比均值进行定量的校正方法。方法具有在线自动判别和修复异常峰并自行校正的功能,和通用的标准系列定量方法相比,两者测定精度相当。但本文提出的方法抗干扰能力明显优于后者,可适用于在线过程监测。 相似文献
52.
We calculate energy barriers of atom- and proton-transfer reactions in hydrogen-bonded complexes in the gas phase. Our calculations do not involve adjustable parameters and are based on bond-dissociation energies, ionization potentials, electron affinities, bond lengths, and vibration frequencies of the reactive bonds. The calculated barriers are in agreement with experimental data and high-level ab initio calculations. We relate the height of the barrier with the molecular properties of the reactants and complexes. The structure of complexes with strong hydrogen bonds approaches that of the transition state, and substantially reduces the barrier height. We calculate the hydrogen-abstraction rates in H-bonded systems using the transition-state theory with the semiclassical correction for tunneling, and show that they are in excellent agreement with the experimental data. H-bonding leads to an increase in tunneling corrections at room temperature. 相似文献
53.
《Electroanalysis》2004,16(11):938-948
The theory for an EC mechanism in chronopotentiometric techniques – reversal chronopotentiometry, cyclic chronopotentiometry and reciprocal derivative chronopotentiometry – is developed. The equations of this article are valid for spherical electrodes of any size and present a compact and easy‐to‐manage form. Methods for determining kinetic parameters of the chemical reaction are proposed and the influence of the electrode radius is discussed. We conclude that large errors in the determination of these parameters are committed if electrode sphericity is neglected. Reciprocal derivative chronopotentiometry has been applied in its traditional form (dt/dE vs. E), and in a more recently proposed modality consisting of plotting dt1/2/dE vs. E. These techniques are very convenient for studying an EC mechanism since the response is obtained in the form of peaks which are quantitatively related to the kinetic parameters of the chemical reaction. A comparison of the chronopotentiometric methods analyzed leads us to conclude that working curves based on the dt1/2/dE vs. E curves are more suitable to obtain accurate values of the rate constants of the chemical reaction. 相似文献
54.
Single crystals of U3+:LaBr3 were grown by the Bridgman-Stockbarger technique. High-resolution polarized absorption spectra of the crystals were recorded at 4.2 K in the 4000-50,000 cm−1 range. Sixty-four experimental crystal-field energy levels of the U3+ ion were fitted to a semiempirical Hamiltonian employing free-ion, one-electron crystal-field as well as two-particle correlation crystal-field (CCF) operators with an r.m.s. deviation of 28 cm−1. The performed analysis of the spectra enabled the determination of crystal-field parameters and assignment of the observed 5f3→5f3 transitions. The effects of selected CCF operators on the splitting of some specific U3+ multiplets have been investigated and the obtained values of Hamiltonian parameters are discussed and compared with those reported in previous analyses. 相似文献
55.
As an adjunct to the regression analysis of differential capacitance curves, which allows refining the adsorption parameters, a program, which takes into account possible errors in volume concentrations of organic substances, is developed. Using this procedure, the earlier data on the differential capacitance of a mercury electrode in aqueous solutions of normal butanol (1-BuOH) containing either 0.1 M NaF or 0.05 and 0.5 M Na2SO4 as the supporting electrolyte are analyzed. This allows obtaining the most accurate values of adsorption parameters for the systems mentioned above within the framework of the model of two parallel capacitors and the Frumkin isotherm. It is shown that, when a linear dependence of the intermolecular interaction parameter on the electrode potential is taken into account, the standard deviation of experimental capacitance values from those calculated using the mentioned model is 6.8–8.8%, which points to very high accuracy of this phenomenological model. 相似文献
56.
A. F. Bykov P. P. Semyannikov I. K. Igumenov 《Journal of Thermal Analysis and Calorimetry》1992,38(6):1463-1475
The processes of thermal destruction of copper(II) bis(dipivaloylmethanate) (Cu(dpm)2) in the temperature range 150°–550°C were studied by using a two-temperature variant of a double chamber Knudsen cell, with mass spectrometric recording of the gas-phase composition. The temperature range of stability of the vapour of the complex in vacuum was determined, as were those of its mixtures with oxygen in different proportions. The temperature dependence of the rate constant of the thermolysis of (Cu(dpm)2) vapour was obtained. The thermal stability of Hdpm vapour and the influence of oxygen on the thermolysis of the ligand were studied.
Zusammenfassung Unter Verwendung einer Zweitemperaturenvariante der Knudsenschen Doppelkammerzelle wurde mittels MS-Untersuchung der Gasphasenzusammensetzung im Temperaturbereich 150°–550°C der thermische Abbau von Kupfer(II)-bis(dipivaloylmethanat) (Cu(dpm)2) untersucht. Es wurde der Temperaturbereich für die Stabilität der gasförmigen Komplexe in Vakuum sowie in Gemischen mit Sauerstoff in verschiedenen Verhältnissen bestimmt. Dabei wurde die Temperaturabhängigkeit der Geschwindigkeitskonstante für die Thermolyse von Cu(dpm)2 ermittelt. Weiterhin wurde die thermische Stabilität von Hdpm-Dampf sowie der Einfluß von Sauerstoff auf die Thermolyse der Liganden bestimmt.相似文献
57.
I. Brandariz F. Arce X. L. Armesto F. Penedo M. Sastre de Vicente 《Monatshefte für Chemie / Chemical Monthly》1993,124(3):249-257
Summary A systematic study of the dependence of acid-base stoichiometric constants on the ionic strength has been carried out for the aminoacidL-valine in ClK and BrK solutions. The observed dependence has been interpreted by using Guggenheim, Scatchard and Pitzer models for the activity coefficients of the species involved in the equilibria.
Die Abhängigkeit von Gleichgewichtskonstanten desL-Valin von der Ionenstärke entsprechend den Modellen von Guggenheim, Scatchard und Pitzer
Zusammenfassung Es wurde anL-Valin in KCl- und KBr-Lösungen eine systematische Studie der Abhängigkeit der Säure-Base-Stöchiometrie von der Ionenstärke durchgeführt. Die beobachteten Abhängigkeiten wurden aufgrund der nach den Modellen von Guggenheim, Scatchard und Pitzer erhaltenen Aktivitätskoeffizienten der an den Gleichgewichten beteiligten Spezies interpretiert.相似文献
58.
A. A. El-Asmy 《中国化学会会志》1988,35(1):29-34
The preparation and characterization of a series of new coordination compounds of Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) containing o-methyl- or o-chlorobenzoyl-4-phenyl-3-thiosemicarbazide (HMBPT, HCBPT=HL) are reported. The reaction products were investigated by analyses, electrolytic conductance, magnetic susceptibility, reflectance and IR spectral studies. The IR spectra show that HMBPT and HCBPT coordinate with the metal ions via different coordination sites (NS and/or NO). The spectral data support the suggestion that the ligands form his-chelates with Ni(II) and Cu(II) of square planar stereochemistry and of general formulae ML2·H2O, where L is the uninegatively charged bidentate ligand. The Co(II) ion forms octahedral and tetrahedral structures with HMBPT and HCBPT, respectively. The ligand field parameters (D4, B and β) for the Co(II) chelates were calculated using the averaged-ligand-field approximation. The influence of the benzene ring substituents (o-chloro or o-methyl) on the stereochemistry are discussed. Also, the formation of the complexes in solution was tested by the pH-metric method. 相似文献
59.
S. V. Galushko 《Chromatographia》1993,36(1):39-42
Summary To calculate retention in reversed-phase, high-performance liquid chromatography a method based on the molecular structure of the analyte and the characteristics of sorbents and mobile phases has been employed. Characteristics of different ODS-columns in water-methanol eluents have been determined. 相似文献
60.