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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 192 (1961), S. 352-353 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] All solutions were made using doubly-distilled water and L-cystine (Mann-assayed grade from Mann Research Laboratories, Inc. [a] = 216 in M hydrochloric acid). Oxygenation and deoxygenation of solutions were effected by bubbling oxygen and nitrogen respectively through the solutions during ...
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0022-328X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0022-328X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0022-328X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 42 (1973), S. 381-394 
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Summary On the basis of a generalized variational principle for elastic plates with initial stresses element stiffness matrices are derived, which permit a drastic reduction of the number of finite elements and of the magnitude of the assembled stiffness matrix. To approximate the exact solution of a given problem either the element mesh may be refined or the order of the assumed displacement function within the elements or the order of the assumed force functions at the interelement boundaries may be increased. To estimate the approximation and the computational effort a comparison is made between a rectangular hybrid displacement element and a fully compatible Hermite polynomial displacement model. The proposed hybrid model gives fast and good results provided that the solution is not disturbed by singularities.
    Notes: Übersicht Auf der Grundlage eines erweiterten Variationsprinzips für elastische Platten nach der Theorie II. Ordnung wird die Herleitung von Elementsteifigkeitsmatrizen angegeben, die es erlauben, die Anzahl der finiten Elemente und damit die Größe der Gesamtstrukturmatrizen drastisch zu vermindern. Zur Annäherung an die genaue Lösung eines gegebenen Problems kann neben der feineren Elementunterteilung der Grad der Verschiebungsansätze innerhalb der Elemente und der Grad der Kraftgrößenansätze an den Elementübergängen beliebig erhöht werden. Zur Abschätzung der Genauigkeit und des Rechenaufwands bei dieser Vorgehensweise wurde an Hand eines rechteckigen Elementes ein Vergleich mit einem vollverträglichen Deformationsmodell (Hermite-Polynom Elemente) durchgeführt. Es zeigte sich, daß das hybride Modell immer dann schnelle und gute Ergebnisse liefert, wenn die Lösung nicht durch Singularitäten gestört wird.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 51 (1981), S. 45-60 
    ISSN: 1432-0681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Summary The coupled analysis of the dynamic behavior of an overhead catenary with a pantograph moving at high speed requires the representation of the catenary natural modes up to very high frequencies. This requirement hampers the economic use of commercial finite-element-programmes, because too many degrees of freedom are necessary in the finite-element-model of a multi-span catenary to represent the highest natural frequencies with the required accuracy. The analytical solution of the string differential equation is used in the paper to derive frequency dependent element matrices, in order to combine the finite-element modeling technique with the accuracy of the analytical solution. Thus clement partitioning is only governed by geometrical and physical requirements. The paper ends with a comparative analysis of a two-span catenary which was tested by British Railways.
    Notes: Übersicht Bei der Untersuchung des dynamischen Zusammenwirkens von Fahrdraht-Kettenwerk und Stromabnehmer im Hochgeschwindigkeitsbereich ist es erforderlich, die hochfrequenten Schwingungsformen der Fahrleitung zu berücksichtigen. Diese Forderung behindert den wirtschaftlichen Einsatz der in der Praxis gebräuchlichen Finite-Elemente-Programme, da zur Modellierung einer aus mehreren Mastfeldern bestehenden Abspannlänge sehr viele Freilieitsgrade zur Darstellung der hochfrequenten Eigenformen benötigt werden. In dem Beitrag wird die analytische Lösung der Seilgleichung zur Herleitung frequenzabhängiger Elementmatrizen verwendet. Damit kann die Flexibilität der Finite-Elemente-Modellierung mit der Genauigkeit und Kürze der analytischen Lösung kombiniert werden. Die Elementteilung der Fahrleitung erfolgt nur noch nach Maßgabe geometrischer und physikalischer Erfordernisse. Den Abschluß des Beitrages bildet eine Nachrechnung der von den British Railways durchgeführten Versuche, bei denen ein mehrfeldriges Kettenwerk durch Freigabe eines angehängten Gewichts zu Schwingungen angeregt wurde.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 353 (1995), S. 39-49 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract GC/MS non target screening has been applied to water samples taken during 1992–1994 from the Elbe river and its tributaries Mulde, Saale, Weiße Elster, Schwarze Elster, and Havel. Based on full scan electron impact mass spectra and supplemented by extensive use of chemical ionisation and high resolution data as well as by synthetic reference compounds, several new classes of compounds, whose possible environmental effects are yet unknown at present, have been identified. Tetrachlorinated bis-(propyl)ethers are new among the most prominent contaminants throughout the Elbe river. The confluence with the Mulde river adds a variety of compounds, related to the chemistry of chloro- and nitroaromatics, azo dyes, benzanilides, carbamates, thiophosphates, and pesticides. The combined load of the Weiße Elster and Saale rivers carries oligoformals, oxathiamacrocycles, and dichloro- and trichloro-bis-(propyl)ethers, whereas chloropropylphosphates are introduced via the Schwarze Elster. The majority of these compounds, originating from sources at the tributaries, are still present at the mouth of the Elbe river. In addition to specific industrial emissions, a variety of more generally observed organic compounds like long chain aliphatics, sterols, phenylalkanes, and plasticizers as well as ubiquitous environmental trace pollutants like polycyclic aromatic hydrocarbons, chlorobenzenes, and hexachlorocyclohexane isomers have been encountered throughout the Elbe river drainage system.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. 59-65 
    ISSN: 0749-1581
    Keywords: Azadiphosphiridines ; 31P ; 15N/31P, 13C heteronuclear shift correlation ; Coupling sign determination ; Conformational analysis based on nJ31P,13C ; Iminophosphine cycloaddition ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2D 31P, 15N heteronuclear shift correlation, based on a non-refocused INEPT pulse sequence with 15N detection, was applied to a 15N NMR study of the azadiphosphiridines 1-5 which are formed by [2 + 1] cycloaddition of iminophosphines, RP=NR′. The pulse sequence used allowed consistent assignment of both the 31P and 15N NMR spectra in one experiment; by a slight modification, also the signs of numerous 31P-15N coupling constants across one or two bonds could be determined. Comparison of the data with those of the azatriphosphetidine 6 (obtained from ID 1H,15N and 31P,15N INEPT spectra) showed the influence of the ring size and conformational effects on the NMR parameters. 31P,13C shift-correlated 2D spectra were further used to measure (including sign determination) and assign 31P-13C coupling constants across one to three bonds in 1-5. Based on the analysis of the coupling information and the known conformation of 4a, the relative stereochemistry of the diastereomers 4a and b could be derived; further, the comparison of the 31P-13C coupling data of 1-3 with those of the 4a and b allowed the conformations of these derivatives, which were previously unknown, to be determined. The derived information of the constitution and stereochemistry of 1-5 gives insight into mechanistic details of the iminophosphine [2 + 1] cycloaddition.
    Additional Material: 2 Ill.
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  • 9
    Publication Date: 2019-07-16
    Description: A study of ether-linked moieties in macromolecular bound residues of polycyclic aromatic hydrocarbons (PAH) generated in bioremediation experiments was performed using high temperature hydrolysis degradation with subsequent analysis of the products by GC-MS. This hydrolysis reaction was specifically designed to cleave ether bonds including relatively stable diarylether structures. Among the reaction products, aromatic alcohols representing typical microbiologically derived metabolites of PAH were found in addition to natural compounds. Thus, parts of the bound residues appeared to be linked within the macromolecular material by ether bonds. Model experiments with an oxidoreductase enzyme and aromatic alcohols indicate the formation of these ether bonds to be an enzyme-catalysed process.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 10
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Thesis , notRev
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