Perhaps you should try some spelling variations:
significantly observed » significantly altered (Expand Search), significantly clustered (Expand Search), significantly preferred (Expand Search)
significantly impaired » significantly improved (Expand Search), significantly improve (Expand Search), significantly improves (Expand Search)
observed decrease » observed decreased (Expand Search)
impaired decrease » marked decrease (Expand Search)

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

• Removing quotes may allow a broader search: (( significantly observed decrease ) OR ( significantly impaired decrease ))~.