Perhaps you should try some spelling variations:
"disease drug effectors." » "disease drug effects.", "disease drugs effects.", "disease rug effects.", "disease drug effectsors.", "disease drag effectors.", "disease drugs effectsors."
"disease drug effectss." » "disease drug effects.", "disease drugs effects.", "disease rug effects.", "disease drug effectsss.", "disease drag effectss.", "disease drugs effectsss."
"diseases drug effect." » "diseases drug effects.", "diseases drag effect.", "diseases drugs effects."

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: (((("disease drug effectss.") OR ("disease drug effectors."))) OR ("diseases drug effect."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"disease drug effectss.\") OR (\"disease drug effectors.\"))) or (\"diseases drug effect.\"))~".
• Removing quotes may allow a broader search: (((( disease drug effectss. ) OR ( disease drug effectors. ))) or ( diseases drug effect. ))~.
• Adding a wildcard symbol may retrieve word variants: (((("disease drug effectss.") OR ("disease drug effectors."))) or ("diseases drug effect."))*.