983 resultados para Atomic clocks.
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Carbon isotopic composition of predominantly marine kerogen in latest Oligocene mudstones of the Peru Margin ODP 682A Hole shows an about 3.5? increase with decreasing age. Py-GC and elemental (C=N ratio) analysis of the kerogen plus sulphur isotopic study together with earlier knowledge on geological setting and organic geochemistry results in a better understanding of depositionary environment and allows to separation of the influence of concentration of water dissolved carbon dioxide (ce) on kerogen delta13C from that of other factors (bacterial degradation, sea surface temperature, DIC delta13C, productivity, and admixture of land plant OM). Based on this analysis, the major part of the kerogen shift is considered as a result of the latest Oligocene decrease of marine photosynthetic carbon isotopic fractionation in the Peru Margin photic zone, which in turn possibly reflects a simultaneous drop in atmospheric CO2 level. Uncertainties in the evaluation of the factors affecting the marine photosynthetic carbon isotopic fractionation and the extent of ocean-atmosphere disequilibrium do not permit calculation of the decrease of the atmospheric CO2.
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"March 1, 1961."
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"Fallout Studies Branch, Division of Biology and Medicine, AEC."
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Focuses on progress made in private industry.
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"November 1956."
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"November 1956."
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Mode of access: Internet.
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"TID-3506 Physics."
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"September 1957."
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"TID-3507 Chemistry."
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"TID-3508 Metallurgy and Ceramics."
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"January 1974."
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Bibliographical footnotes.