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51.
Zusammenfassung In der vorliegenden Arbeit wird eine colorimetrische Methode zur Bestimmung von Brucin, Strychnin, Chinin und Cinchonin beschrieben, die darauf beruht, daß mit Kaliumhexathiocyanatochromat(III), [Cr(SCN)6]K3, komplexe Verbindungen entstehen, die in Wasser unlöslich, in Aceton hingegen mit violetter Färbung leicht löslich sind. Die acetonischen Lösungen können mit einem Pulfrich-Spektrophotometer mit Gelbfilter colorimetriert werden. Das Maximum der Absorption liegt bei 574 nm. Die Extinktion zeigt keine Veränderungen mit der Zeit. Für die Extinktionskonstanten sind folgende Werte ermittelt worden: Chinin 220, Brucin 191, Cinchonin 189 und Strychnin 135. 相似文献
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Florin Ciuprina Traian Zaharescu Silviu Jipa Ilona Pleşa Petru V. Notingher Denis Panaitescu 《Radiation Physics and Chemistry》2010,79(3):379-382
The dielectric characteristics of polyvinyl chloride nanocomposites containing titania, silica and alumina at the concentration of 5% were investigated by dielectric spectroscopy. The sharp modification in the permittivity and dielectric loss of neat and irradiated PVC samples over the low frequency range may be explained by the interaction between external electrical field and the dipoles formed during high energy exposure. The material characterization is completed by the thermal stability assay based on the accumulation of carbonyl units in the sample matrices, which provides the differences in the molecular level contact between host polymer and fillers. 相似文献
55.
Musuc Adina Magdalena Patrinoiu Greta Budrugeac Petru Cucos Andrei Dascalu Radu Calderon-Moreno Jose Carp Oana 《Journal of Thermal Analysis and Calorimetry》2022,147(22):12805-12814
Journal of Thermal Analysis and Calorimetry - The combustion behavior of fructose-derived hydrochar was investigated using a kinetic evaluation protocol that brings about novel elements related to... 相似文献
56.
Petru Jitaru Marco Roman Carlo Barbante Sophie Vaslin-Reimann Paola Fisicaro 《Accreditation and quality assurance》2010,15(6):343-350
Se is one of the most investigated essential trace elements in the past years, mostly due to its cancer prevention properties.
Nevertheless, the accurate determination of its biologically active species, such as the selenoproteins (SeProt) in human
serum, is currently a challenging task. This is because of the lack of appropriate quantification standards, certified reference
materials (CRMs), and/or reference measurement methods. Additionally, most of the methods developed so far for the determination
of SeProt were applied to the analysis of control (volunteers) serums, which are not available to other laboratories, therefore
making methods inter-comparison virtually impossible. We present here for the first time indicative levels of SeProt in a
commercially available human serum, namely the BCR-637 CRM with certified level of total Se. The concentrations of selenium
associated with glutathione peroxidase (GPx), selenoprotein P (SelP) and selenoalbumin (SeAlb) in this serum were calculated
using the results obtained by 13 different analytical methods (literature and non-published data) on the basis of (affinity)
high-performance liquid chromatography (AF-HPLC) coupled to inductively coupled plasma-mass spectrometry (ICP-MS). The indicative
levels of SeProt in the BCR-637 serum can be used for validation of methods dealing with the determination of these proteins
in human serum. 相似文献
57.
Tania A. Lazăr Adrian Petruşel Naseer Shahzad 《Nonlinear Analysis: Theory, Methods & Applications》2009
The purpose of this paper is to discuss some basic problems of the fixed point theory for non-self (single-valued and multivalued) generalized contractions. As consequences, new open operator principles and domain invariance theorems are obtained. The results complement and extend some known results in the literature. 相似文献
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If the left side of a sealed tube (shaped like an inverted U) is filled with chloroform, after many months, the chloroform passes spontaneously to the right side of the vessel in accord with the minimum energy principle. A similar experiment with a half-filled disposable lighter can be performed successfully in a much shorter period (6–8 days). The rate of the process (spontaneous transfer of a substance from one side of the vessel to the other side) decays with time. Curve fitting reveals the existence of two independent exponential-decay processes. An explanation of the possible mechanisms for the transfer of the substance is offered in this paper. 相似文献
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Analytical and Bioanalytical Chemistry - In der vorliegenden Arbeit werden zur mikrogravimetrischen Bestimmung des Osmiums drei Methoden empfohlen: 1. Aus der salzsauren Lösung von... 相似文献