About: http://webisa.webdatacommons.org/33956290

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	ydrogen or methyl when X is a direct bond, and R3 and R4 may not be hydrogen when X is a methylene radical; and for those compounds which contain a basic nitrogen atom, the pharmaceutically acceptable acid additon salts thereof.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com