title: Biological probes. II. Ring labeled nicotinamide.
mesh_terms: D002247:Carbon Isotopes; D003500:Cyclization; D007553:Isotope Labeling; D008722:Methods; D009536:Niacinamide; D011725:Pyridines
chemical_list: D002247:Carbon Isotopes; D011725:Pyridines; D009536:Niacinamide