https://w3id.org/framester/conceptnet5/data/en/ionic_compound <https://w3id.org/framester/conceptnet5/schema/IsA> <https://w3id.org/framester/conceptnet5/data/en/natural_substance> <https://w3id.org/framester/conceptnet5/data/en/inanimate_object> risorse dalla linked data cloud