title: Determination of carbon-12, carbon-13 isotopic abundances and nitrogen-carbon ratios in biological substances by proton-reaction analysis.
mesh_terms: D001923:Brain Chemistry; D002247:Carbon Isotopes / Q000032:analysis*; D004926:Escherichia coli / Q000032:analysis; D006801:Humans; D008168:Lung / Q000032:analysis; D013051:Spectrometry, Gamma
chemical_list: D002247:Carbon Isotopes