| http://www.w3.org/ns/prov#value | - If R1 is a heterocyclic group, it is, in particular, a radical of a five-membered heterocyclic ring containing one ring member other than carbon, such as --S--, --O-- or --NH--, for example furan, thiophene, pyrrole, pyrrolidone, pyroglutamic acid, maleimide of the formula ##STR12## (in which R9 and R10, independently of one another, are hydrogen, C1 -C4 alkyl, in particular methyl, or aryl, such
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