Perhaps you should try some spelling variations:
"value h2o reaction" » "value n2o reactions", "value 16o reaction", "value o reaction", "value how reaction", "value 2 reaction", "value 12 reaction"
"value hdo reaction" » "value 16o reaction", "value o reaction", "value oxo reaction", "value how reaction", "value 1d reaction", "value h reaction"
"value co ratio" » "value co ratios", "value o ratio", "value h2o ratio"

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: (("value co ratio") OR ((("value h2o reaction") OR ("value hdo reaction")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"value co ratio\") or (((\"value h2o reaction\") OR (\"value hdo reaction\"))))".
• Removing quotes may allow a broader search: (( value co ratio ) or ((( value h2o reaction ) OR ( value hdo reaction )))).
• Adding a wildcard symbol may retrieve word variants: (("value co ratio") or ((("value h2o reaction") OR ("value hdo reaction"))))*.