Results 301 to 310 of about 196,509 (340)

Carbon isotopic variations of kerogen pyrolyzates

Organic Geochemistry, 1988
Abstract A method has been developed for isotopic analysis of pyrolyzates from temperature-programmed pyrolysis of small quantities of immature to early mature kerogen concentrates. A C5+ pyrolyzate is collected and oxidized on-line to carbon dioxide for stable carbon isotopic measurement.
R. Burwood, R.J. Drozd, H.I. Halpern, R.A. Sedivy   +3 more
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Carbon isotope composition of birch syrup

Journal of Food Composition and Analysis, 2018
Abstract Birch syrup is a forest product produced from tree sap using methods similar to those used in maple syrup production. This study presents the first measurements of the carbon isotope ratio of birch syrup, which is ultimately a function of tree physiology and environmental variables. Birch syrup has an average δ13C value = −25.31 ± 0.62‰ VPDB
William H. Peck, Erin E. Cummings, Ellis Van Slyke   +2 more
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Vapour Pressure of Isotopic Carbon Tetrachlorides

Nature, 1951
A THEORY of the vapour pressure relationship for isotopic molecules has been given by Topley and Eyring1. It is, however, difficult to see a priori how to apply the theory in calculating vapour pressures for a particular case, in view of our lack of knowledge of the liquid state.
D. H. RANK, R. E. KAGARISE
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Carbon isotope composition of Antarctic plants

Geochimica et Cosmochimica Acta, 2000
Abstract Carbon isotope compositions of Antarctic land plants are first reported. The most interesting feature is the isotope specificity of the species. For example Usnea antarctica from different locations shows relatively narrow range of the δ 13 C-values from −22.44 to −21.29‰ (7 samples), Drepanocladus sp . from −24.86 to −23.49‰ (8 samples),
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Total Organic Carbon and Carbon Isotopes of Sediments

1981
This research project addresses the question: do the isotopes of carbon in the organic matter of the sediments within and around the Buccaneer Field indicate that any alteration of the sedimentary organic matter has resulted from drilling and producing operations?
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Isotopic Biogeochemistry of Marine Organic Carbon

Reviews in Mineralogy and Geochemistry, 2001
The ocean accounts for over 90% of the active pools of carbon on the Earth’s surface, with over 95% of marine carbon in the form of dissolved inorganic carbon (DIC) (Hedges and Keil 1995). Organic carbon dissolved in the ocean, suspended as particles or cells, and accumulating in sediments together constitute the other significant fractions of marine ...
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Fractionation of carbon isotopes

Journal of Inorganic and Nuclear Chemistry, 1973
L.L. Brown, J.S. Drury
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Nuclear Spins of the Carbon Isotopes

Physical Review, 1948
High dispersion spectrograms of the Swan bands of diatomic carbon are obtained from samples enriched to 50 percent and 40 percent, respectively, in ${\mathrm{C}}^{13}$ and ${\mathrm{C}}^{14}$. The method of exciting an intense spectrum with microgram samples is described.
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Elementary Isotopic Analysis: Determination of Carbon

Science, 1947
A V, Grosse, A D, Kirshenbaum, S G, Hindin   +2 more
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Carbon Isotope Geochemistry of Petroleum: ABSTRACT

AAPG Bulletin, 1964
Carbon isotope studies of ancient and modern natural organic materials have helped reconstruct the geochemical history of petroleum and gas accumulations. Similarity of C13/C12 ratios of petroleums, and of the lipid fraction of plants, suggests that petroleum is derived from lipids, which are the most stable organic constituents of organisms.
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