Perhaps you should try some spelling variations:
"man changes periodicals." » "man change periodicals.", "man exchange periodicals.", "man mechanics periodicals.", "woman changes periodicals.", "brain changes periodicals.", "basin changes periodicals."
"human genes periodicals." » "human genomes periodicals.", "human games periodicals.", "human gases periodicals.", "human gene periodicals.", "human genetics periodicals.", "human genetic periodicals."
"human bees periodicals." » "human diabetes periodicals.", "human indexes periodicals.", "human devices periodicals.", "human bites periodicals.", "human beast periodicals.", "human bones periodicals."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((("human genes periodicals.") or ("human bees periodicals."))) or ("man changes periodicals."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("human genes periodicals.") OR ("human bees periodicals."))) OR ("man changes periodicals.")).
• Removing quotes may allow a broader search: (((( human genes periodicals. ) or ( human bees periodicals. ))) or ( man changes periodicals. )).
• Adding a wildcard symbol may retrieve word variants: (((("human genes periodicals.") or ("human bees periodicals."))) or ("man changes periodicals."))*.