| http://www.w3.org/ns/prov#value | - An aryl group is the most preferred. [0039] X represents ???O???, ???S???, ???N??? or ???N???Ra, wherein Ra represents a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group. [0040] The aliphatic hydrocarbon group as represented by Ra includes a straight-chain, branched or cyclic alkyl group (preferably one having 1 to 20 carbon atoms, particularly 1 to 12 carbon at
|
