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  • 1
    Electronic Resource
    Electronic Resource
    Embryogenesis of Calliphora erythrocephala Meigen (1974)
    Springer
    Cell & tissue research 151 (1974), S. 219-228 
    Details
    ISSN: 1432-0878
    Keywords: Cell death ; Central nervous system ; Embryogenesis of Calliphora (Insecta) ; Vital staining ; Light microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary During the late embryonic period, cell death occurs in the central nervous system of Calliphora erythrocephala. The degenerating cells are small and rounded, contain a pyknotic nucleus, and selectively accumulate basic vital dyes such as nile blue sulphate and acridine orange. The number of degenerating cells is highest 13–15 hours after oviposition and decreases during the shortening of the ventral nerve cord. Nevertheless, these degenerating cells do not represent a morphogenetic phenomenon, since their number is too small to account for the 55% decrease in the length of the ventral nerve cord. In all probability the pyknoses seen in the central nervous system of this holometabolic insect are to be interpreted as phylogenetic degenerations of clearly vestigial neuroblasts that have lost functions they might have retained in the larvae of insects in lower orders, for instance the innervation of legs, wings, a larger number of abdominal segments, etc. About half of the pyknoses occur in pairs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222224
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  • 2
    Electronic Resource
    Electronic Resource
    New imidazoisoquinoline ladder polymers (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 265-272 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In previous studies on poly{(7-oxo-7, 10H-benz[de]imidazo[4′,5′:5,6]-benzimidazo-[2,1-a]isoquinoline-3,4:10,11-tetrayl)-10-carbonyl} it was observed that the polymer exhibits very unusual film-forming properties. The ladder polymer forms supermolecular aggregates in solution which translates to a high degree of interchain packing in the bulk. New ladder imidazoisoquinoline polymers have been prepared in an effort to relate the variance of molecular structure to the aggregation behavior of this class of polymers. The polymers were prepared from the solution polycondensation of 1,4,5,8-naphthalene tetracarboxylic acid or dianhydride with 1,2,5,6-tetraaminonaphthalene, 2,3,7,8-tetraaminophenazine and 2,3,7,8-tetraaminodibenzofuran. It was found that the extent of interchain packing in the bulk is dependent to a large degree on the molecular geometry of the polymer backbone.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170120202
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  • 3
    Electronic Resource
    Electronic Resource
    300 MHz 1H-NMR study of poly(propylene sulfide) (1974)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 1683-1693 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An 1H 300-MHz NMR spectroscopic study of deuterated poly(propylene sulfide) shows that methylene protons are sensitive to triad effects. It was possible to distinguish i, hi, s, and hs triads. Experimental values found for different polymers are in good agreement with theoretical amounts obtained from statistical probability calculation. The methyl groups are also slightly stereosensitive. By using optically active deuterated monomers with different R/S ratios it was possible to confirm the assignment of peaks and the tacticity. Nondeuterated polymers give very complicated spectra, and only the highly stereoregular polymer could be analyzed through its ABCX3 spin system.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1974.170120808
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