Statistics are updated for types of substances, ring systems, and elemental composition that have been determined for the Chemical Abstracts Service Registry Structure File at different points in time. This paper reports the updated figures and in addition some new statistics and offers some comparisons to show various shifts in file characteristics.
The Chemical Abstracts Service Chemical Registry System, operating since 1965, uniquely identifies chemical substances on the basis of molecular structure. Chemical Abstracts Service is now registering chemical substances cited in indexes to Chemical Abstracts prior to 1965. This effort will result in several hundred thousand additional chemical structures,… (More)