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  • 1
    Digitale Medien
    Digitale Medien
    Rapid change in strontium isotopic composition of sea water before the Cretaceous/Tertiary boundary (1991)
    [s.l.] : Nature Publishing Group
    Nature 351 (1991), S. 644-647 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Compilations of previous studies of the evolution of the 87Sr/86Sr ratio in sea water1'4 by Macdougall5 and by Javoy and Courtillot6 emphasized a distinct positive spike of 1-2 x 1CT4 above the ambient isotope ratio before and after the K/T boundary. Macdougall inferred a sharp rise in the ratio ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/351644a0
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  • 2
    Digitale Medien
    Digitale Medien
    Radiographic observation of chamber formation in Nautilus pompilius (1983)
    [s.l.] : Nature Publishing Group
    Nature 304 (1983), S. 57-59 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Externally-shelled cephalopods, such as Nautilus, produce neutral buoyancy with the use of air and liquid-filled chambered shells. As the animal grows, it must periodically enlarge the chambered shell portions if neutral buoyancy is to be maintained. Denton and Gilpin-Brown1 outlined the major ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/304057a0
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  • 3
    Digitale Medien
    Digitale Medien
    Marine isotope evolution (1992)
    [s.l.] : Nature Publishing Group
    Nature 358 (1992), S. 378-378 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] SIR - McArthur et al.1 criticized aspects of our study of Maastrichtian seawater 87Sr/86Sr evolution2. Their primary con-tention is that our calculated rates of marine Sr isotope evolution are incorrect because of error in locating the Upper-Lower Maastrichtian boundary, and be-cause of ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/358378a0
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  • 4
    Digitale Medien
    Digitale Medien
    Cameral liquid transport and buoyancy control in chambered nautilus ( Nautilus macromphalus ) (1980)
    [s.l.] : Nature Publishing Group
    Nature 286 (1980), S. 55-56 
    Details
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] To expose the siphuncle to osmotic pressure differences tending to draw water into a chamber, we drilled a hole into a 20-ml chamber and removed any liquid. Then we added 5ml of NaCl-enriched seawater (either 1.3 or 1.9 osmolal). To give the animals an 'incentive' to empty their chambers, we ...
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1038/286055a0
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  • 5
    Digitale Medien
    Digitale Medien
    The structure of the chambered nautilus siphuncle: The siphuncular epithelium (1982)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 172 (1982), S. 5-22 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The siphuncle of the chambered nautilus (Nautilus macromphalus) is composed of a layer of columnar epithelial cells resting on a vascularized connective tissue base. The siphuncular epithelium taken from chambers that have not yet begun to be emptied of cameral liquid has a dense apical brush border. The great number of apical cell junctions (zonula adherens) compared to the number of nuclei suggests extensive interdigitation of these cells. The perinuclear cytoplasm of these preemptying cells is rich in rough endoplasmic reticulum. The siphuncular epithelium of both emptying and “old” siphuncle (which has already completed emptying its chamber) both show little rough endoplasmic reticulum but do contain extensive systems of mitochondria-lined infoldings of the basolateral plasma membranes. Active transport of NaCl into the extracellular space of this tubular system probably entrains the water transport involved in the chamber-emptying process. Both emptying and old siphuncular epithelium also show large basal infoldings (canaliculi) continuous with the hemocoel, which appear to be filled with hemocyanin. The apical cell junctions of emptying and old siphuncular epithelium contain septate desmosomes that may help to prevent back-flow of cameral liquid into the chambers.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1051720103
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