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  • Articles  (237)
  • Analytical Chemistry and Spectroscopy  (98)
  • Organic Chemistry  (79)
  • Cell & Developmental Biology  (60)
  • Wiley-Blackwell  (237)
  • 1
    Electronic Resource
    Electronic Resource
    Electron-impact fragmentation of the bicyclo[4.1.0]heptane-2-one system: Correlations with photochemistry (1970)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1970), S. 1-11 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The low resolution and complete high resolution mass spectra of a series of methyl and deuterium substituted bicyclo[4.1.0]heptane-2-one derivatives have been measured. An attempt has been made to test the operation of a fragmentation process analogous to the known photochemical rearrangement, and to determine if the substitution effects critical to the photorearrangement also influence the electron-impact process. The fragmentation pattern of these conjugated cyclopropyl ketones is detailed and the influence of the cyclopropyl ring is discussed. It is suggested that electron-impact-induced rearrangements which are analogous to photochemical transformations will be relatively low energy processes and will remain prominent at low ionizing voltages.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210030102
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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    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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  • 8
    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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  • 9
    Electronic Resource
    Electronic Resource
    A comparison between the ultraviolet microscopy and the Feulgen staining of certain cells (1932)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 53 (1932), S. 189-199 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper describes ultraviolet (λ = 2750 A) photomicrographs of resting and dividing chicken macrophages and fibroblasts and of erythrocytes and lymphocytes. The structures found in these photographs are compared with the ones brought out in fixed material by Feulgen staining and found to be essentially similar in appearance. A preliminary series of ultraviolet pictures is also shown of a single fibroblast passing through several of its stages of division.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1050530107
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  • 10
    Electronic Resource
    Electronic Resource
    Some ultraviolet photomicrographs made with different wave lengths (1933)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 131-135 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Photomicrographs have been made of grasshopper spermatocytes using ultraviolet light of several wave lengths. For studying chromosomes this wave length should be between ca 2800 A and ca 2500 A. With higher frequencies the entire cell becomes strongly absorbing and relatively little detail is to be seen. All cell structures, including the chromosomes, are as transparent to λ = 3500 A and to longer ultraviolet waves as they are to visible light. The present experiments do not indicate the exact point between λ = 3500 A and λ = 2800 A at which the selective chromatin absorption commences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1050550108
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