Perhaps you should try some spelling variations:
"human vector-5?-nucleotidase" » "human actor-5?-nucleotidase", "human ecto-5?-nucleotidase", "human effector-5?-nucleotidase"
"human factor-5?-nucleoside" » "human factors-5?-nucleoside"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("human vector-5?-nucleotidase") OR ("human factor-5?-nucleoside")).
• Removing quotes may allow a broader search: (( human vector-5?-nucleotidase ) or ( human factor-5?-nucleoside )).
• Adding a wildcard symbol may retrieve word variants: (("human vector-5?-nucleotidase") or ("human factor-5?-nucleoside"))*.