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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 21 (1981), S. 57-66 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé On a comparé les techniques d'essais de pureté effectués en dynamique et en discontinu. On a établi que lors des mesures dynamiques l'échantillon, dans de nombreux cas. ne peut pas être considéré sous l'aspect thermodynamique comme étant en état d'équilibre. Les problèmes liés au temps de la mesure et à l'exactitude des résultats ont été discutés pour la méthode à deux pics qui se prête au traitement des données obtenues avec la technique discontinue. On a établi que la méthode à deux pics peut être améliorée. En se servant de plusieurs pics l'exactitude des résultats et la durée des mesures peuvent être optimalisées.
    Abstract: Zusammenfassung Dynamische und stufenweise Techniken der Reinheitsprüfung wurden verglichen und festgestellt, daß bei dynamischen Messungen die Probe in vielen Fällen vom thermodynamischen Aspekt nicht für im Gleichgewichtszustand befindlich betrachtet werden kann. Die Probleme der Meßzeit und der Genauigkeit der Ergebnisse wurden für die Zwei-Peak-Methode, welche zur Verarbeitung der mit der stufenweisen Technik erhaltenen Daten geeignet ist, erörtert. Es wurde festgestellt, daß die Zwei-Peak-Methode verbessert werden kann. Durch Anwendung mehrerer Peaks können die Genauigkeit der Ergebnisse und Messzeit optimiert werden.
    Notes: Abstract Dynamic and stepwise purity test techniques were compared, and it was established that in dynamic measurement the sample in many cases can not be considered to be in a state of equilibrium from the thermodynamic aspect. The problems of the measuring time and the accuracy of the results are discussed for the two-peak method, applicable for the processing of data obtained by the stepwise technique. It was established that the two-peak method can be improved. By using several peaks, the accuracy of the results and measuring time can be optimized.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 21 (1981), S. 49-56 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé On a examiné diverses corrélations pour décrire des systèmes eutectiques à deux composants. On a établi que la relation de van't Hoff décrit la courbe de fusion dH/dT−T avec une exactitude satisfaisante. Cependant, son application pratique exige une modification de caractère mathématique mais celle-ci ne porte pas sur le contenu physique de l'équation. On donne l'interprétation et le mode d'application de l'équation modifiée.
    Abstract: Zusammenfassung Verschiedene Zusammenhänge zur thermodynamischen Beschreibung eutektischer Zweikomponentensysteme wurden untersucht. Es wurde festgestellt, daß der van't Hoff-sche Zusammenhang die Schmelzkurve dH/dT−T mit befriedigender Genauigkeit beschreibt, daß jedoch ihre praktische Anwendung eine Abänderung mathematischen Charakters benötigt, wobei der physikalische Inhalt der Gleichung erhalten bleibt. Deutung und Anwendungsmethode der modifizierten Gleichung werden angegeben.
    Notes: Abstract Relationships of various levels for the thermodynamical description of two-component eutectic systems have been investigated. It has been established that the van't Hoff relationship describes the melting curve dH vs. T with satisfactory accuracy, but for its practical application a modification of the mathematical character, maintaining the physical content of the equation, is needed. The interpretation and the mode of application of the modified equation are given.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta mathematica hungarica 84 (1999), S. 181-188 
    ISSN: 1588-2632
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Some properties of arcs in PG(2,q) are discussed via its cyclic model. A covering number of a set χ of points in PG(2,q) is the smallest number of lines needed to cover the set -χ, where the set of points of PG(2,q) is identified with Z $$Z_{q^2 + q + 1} $$ . It is proved that the covering number of a conic is either 1 or greater than q/4. Hyperovals with covering number 2 are characterized for q even. Also, a possible method for constructing nonclassical hyperovals having small covering numbers is given.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-0662
    Keywords: tropospheric fine aerosol ; rural site ; pyrolysis-gas chromatography-mass spectrometry ; humic matter ; chemical structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The organic matter in tropospheric aerosol plays animportant, yet undetermined role in atmosphericprocesses. The bulk of organic carbon representing asignificant part of the fine aerosol mass is bound toa polymeric matter whose structure and properties areto date largely unknown. Here we use thefingerprinting technique of derivatization pyrolysis-gas chromatography-massspectrometry tosubstantiate that in terms of chemical structure partof this polymer in rural aerosol in summer can beregarded as natural humic matter. We suggest thatthese compounds are likely to be directly emitted bybiogenic sources.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polycyclic aromatic hydrocarbons ; Lake Balaton ; Water and sediment samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Concentrations of polycyclic aromatic hydrocarbons (PAHs) were determined in water and sediment samples at 15 sites in Lake Balaton during three sampling campaigns in 1996. PAHs were concentrated from water samples by solid phase extraction. Sediment samples were extracted with acetone in an ultrasonic bath then cleaned by solid phase extraction. The total concentration of PAHs ranged from 30–360 ng g−1 and from 170–720 ng L−1 in sediment and water samples, respectively. Spatial and temporal variations of the concentration of PAHs were also investigated.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Periodica mathematica Hungarica 39 (2000), S. 65-71 
    ISSN: 1588-2829
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract It is shown that if there exists a binary code C of length d and covering radius k then a zonotope in the d-dimensional Euclidean space can be illuminated by ¦C¦ affine subspaces of dimension k. Applying results from coding theory, the exact value of the illumination numbers of d-dimensional parallelotopes is determined in some special cases.
    Type of Medium: Electronic Resource
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