Perhaps you should try some spelling variations:
"plant genetic resources." » "plant genetics resources."
"player cancer research." » "player anger research.", "bladder cancer research.", "player chapter research."
"plant zone research." » "plant gene research.", "plant care research.", "plant case research.", "plain zone research.", "plants one research.", "play zone research."
"plant energy resources." » "plants energy resources.", "smart energy resources.", "heat energy resources."

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((((("plant genetic resources.") OR ("plant energy resources."))) or ("player cancer research."))) or ("plant zone research."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((((("plant genetic resources.") OR ("plant energy resources."))) OR ("player cancer research."))) OR ("plant zone research.")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((\"plant genetic resources.\") OR (\"plant energy resources.\"))) or (\"player cancer research.\"))) or (\"plant zone research.\"))".
• Removing quotes may allow a broader search: (((((( plant genetic resources. ) OR ( plant energy resources. ))) or ( player cancer research. ))) or ( plant zone research. )).
• Adding a wildcard symbol may retrieve word variants: (((((("plant genetic resources.") OR ("plant energy resources."))) or ("player cancer research."))) or ("plant zone research."))*.