Perhaps you should try some spelling variations:
"5 ng decrease" » "5 _ decrease" (Expand Search), "5 g decrease" (Expand Search), "5 μg decrease" (Expand Search)
"5 a decrease" » "5 _ decrease" (Expand Search), "5 _ decreased" (Expand Search), "5 _ decreases" (Expand Search)
"5 c decrease" » "5 _ decrease" (Expand Search), "5 _ decreased" (Expand Search), "5 _ decreases" (Expand Search)
"45 c decrease" » "45 _ decrease" (Expand Search), "45 _ decreased" (Expand Search), "45 _ decreases" (Expand Search)

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"5 ng decrease\") OR (((\"5 a decrease\") OR (((\"5 c decrease\") OR (\"45 c decrease\"))))))~".
• Removing quotes may allow a broader search: (( 5 ng decrease ) OR ((( 5 a decrease ) OR ((( 5 c decrease ) OR ( 45 c decrease ))))))~.
• Adding a wildcard symbol may retrieve word variants: (("5 ng decrease") OR ((("5 a decrease") OR ((("5 c decrease") OR ("45 c decrease"))))))*.