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  • Articles  (177)
  • Organic Chemistry  (79)
  • Cell & Developmental Biology  (60)
  • Engineering  (38)
  • Wiley-Blackwell  (177)
  • 1
    Electronic Resource
    Electronic Resource
    Absorption and Fluorescence Studies on Neutral and Cationic Isoalloxazines (1979)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 62 (1979), S. 593-608 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic properties of a variety of methylated isoalloxazine derivatives have been investigated with absorption and fluorescece techniques (Table 1). The spectral effects of methyl substitution at different positions in the isoalloxazine ring are interpreted in terms of different bond orders between the C-atoms of the methyl groups and of the aromatic ring. Methyl groups at C(6) or C(9) induce quenching of the fluorescence and shortening of the lifetime whereas a methyl group at C(7) has an opposite effect. The quenching effect might be due to strain in the molecular framework caused by the methyl groups.The lowest energy levels of the isoalloxazine cations are shifted to higher energy as compared to the neutral isoalloxazines. Apart from these shifts the trends in spectral behaviour upon methylation are similar to those observed for the neutral isoalloxazine (cf. Table 2). The fluorescence of the isoalloxazine cations is strongly quenched in auqeous solution and their lifetime much shortened. These observations indicated that there is substantial interaction between the charged fluorophore and the water dipoles and that this interaction produces efficient radiationless deactivation of the first excited singlet state.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19790620227
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  • 2
    Electronic Resource
    Electronic Resource
    Water Relaxation Measurements on Semiquinones of Various Flavoproteins (1982)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 65 (1982), S. 2422-2430 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The water relaxation rates of several flavoproteins in the semiquinone state have been investigated by the spin echo technique. The results indicate a rather unspecific interaction between water and the protein-bound flavosemiquinones. An average interaction distance of 0.3-0.5 nm has been estimated. From the temperature dependence of the rate constants the free energy of activation for proton exchange is calculated to be about 17 kJ/mol. The rate of proton exchange is around 1011 s-1 for the flavosemiquinones investigated are accessible to water regardless of their ionic state.The large difference in relaxation rates of water protons between D- and L- amino-acid oxidases is noticeable. Oxynitrilase exhibits the highest whereas Azotobacter vinelandii flavodoxin shows the lowest water relaxation rate of the flavoproteins studied. The results are discussed in relation to the visible-light absorption properties of the flavoproteins.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19820650807
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  • 3
    Electronic Resource
    Electronic Resource
    Laser-Induced Luminescence of Flavinium Salts (1980)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 63 (1980), S. 1296-1303 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flavinium salts dissolved in an ethanolic glass exhibit blue fluorescence and orange-red phosphorescence upon excitation with a UV. line from an argon ion laser equipped with UV. optics. This arrangement enables the wavelength distribution and the time-dependence of the phosphorescence to be measured in a relatively short time. Four cationic flavins were investigated. In spite of the small difference in the chemical structure of the compounds studied, large differences in the spectral shapes and in the ratio of quantum efficiencies of phosphorescence and fluorescence became apparent. The phosphorescence lifetimes were of the same order of magnitude, which indicated a similar rate of depletion of the lowest excited triplet state for all four cations. However, the efficiency of triplet formation (intersystem crossing) is affected by slight structural modifications in the pyrimidine subnucleus of the flavinium salt. The results point to a possible role of vibronic spin-orbit coupling in the intersystem crossing.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19800630521
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  • 4
    Electronic Resource
    Electronic Resource
    Azofarbstoffe und Immunbiologie. Aufhebung anaphylaktischer Azoprotein-Überempfindlichkeit durch p-Phenyl-arsinsäure-azofarbstoffe (1937)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 20 (1937), S. 1059-1077 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1. Azoprotein (sowohl in vitro hergestelltes als in vivo entstehendes) enthält entsprechend der Annahme von Pauly die Azo-gruppierung —N=N—.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.193702001152
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  • 5
    Electronic Resource
    Electronic Resource
    Letters to the editor (1981)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 17 (1981), S. 1740-1742 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620171112
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  • 6
    Electronic Resource
    Electronic Resource
    Hydrodynamic confficients of some heaving cylinders of arbitrary shape (1978)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 13 (1978), S. 17-33 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The fluid forces acting on a uniform cylinder with an infinitely long axis, heaving in the free surface or an infinite ideal fluid, are described in terms of its ‘added mass’ and ‘damping coefficient’. The techniques of multipole expansion and multiparameter conformal transformation are adopted for such calculations and applied to shapes which cannot be adequately represented by the conventional, and more rudimentary, ‘Lewis form fit’. The shapes referred to are both relevant to ship bows, one being a ‘fine section’ and the other a ‘bulbous section’. The parameters which influence the accuracy of the solution are examined. Results for these two sections are computed and compared with results based on (a) the ‘Lewis form approximation’ and (b) the ‘Frank's close fit method’ which employs a singularity representation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620130103
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  • 7
    Electronic Resource
    Electronic Resource
    A finite element approach to subsonic aerodynamics (1979)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 14 (1979), S. 665-679 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A study of the application of the Finite Element Method to compressible potential flows, typified by the airfoil problem, is undertaken. Some novel approaches, believed to simplify solution techniques, are presented.The solutions use two pseudo-variational integrals, appropriate to subsonic flows, and possessing a physical iterative basis. With constant-derivatives triangular elements formulated for cylindrical co-ordinates, accurate solutions are easily obtained for the flow over a circular cylinder. For arbitrary airfoils a simple mapping is used to transform them into near circles. An appropriate mesh is then constructed in the mapped plane. The paper then presents two solution approaches by which this non-linear problem is solved in both the near circle plane and the airfoil plane.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620140504
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  • 8
    Electronic Resource
    Electronic Resource
    Die Krystallstruktur der kubischen Modifikation von organischen Verbindungen mit kugelförmigen Molekeln (1947)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 30 (1947), S. 1782-1783 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19470300646
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  • 9
    Electronic Resource
    Electronic Resource
    Antihistaminica I. Basische Phenoläther-Derivate (1950)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 33 (1950), S. 516-522 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es wird die Synthese von 2-[o-(β-Dimethylamino-alkoxy)-benzyl]-thiophenen und 2-[o-(β-Dimethylamino-alkoxy)-benzyl]-pyridinen und ihre Antihistaminwirkung beschrieben.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19500330312
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  • 10
    Electronic Resource
    Electronic Resource
    On the species clinostomum heterostomum (1899)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 15 (1899), S. 697-710 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1050150305
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