definiens: shall mean a compound which [ ex vivo comprises a nitrogen containing heteroaryl base covalently coupled to a carbohydrate or a substituted carbohydrate ] . By way of example and not limitation, [ carbohydrates shall include conventional sugars, dehydro sugars and carbocyclic sugars . By way of example and not limitation, substituted carbohydrates include carbohydrates having substituent groups at their 2 ' or 3 ' positions, or having substituents in place of one or more hydrogen atoms of the sugar . By way of example and not limitation, substituent groups include alkyl, azido, alkoxide, halo, haloalkyl, alkynyl, oximinoalkyl, cyano, and sulfonyl substituents ] . shall also include compounds wherein the [ carbohydrate portion of a conventional nucleoside is acyclic or an analog of an acyclic carbohydrate ]