Perhaps you should try some spelling variations:
"endogenous estrogen sulfide" » "exogenous estrogens sulfide", "endogenous hydrogen sulfide", "endogenous pyrogen sulfide", "endogenous dinitrogen sulfide", "endogenous hydrogen sulfite"
"exogenous estrogen sulfide" » "exogenous estrogens sulfide", "exogenous hydrogen sulfide", "exogenous dinitrogen sulfide", "exogenous hydrogen sulfite"
"exogenous nitrogen sulfide" » "exogenous estrogens sulfide", "exogenous latrogenic sulfide", "exogenous androgens sulfide", "exogenous dinitrogen sulfide", "exogenous hydrogen sulfide", "exogenous nitrogen sulfur"
"exogenous nitrogen disulfide" » "exogenous estrogens disulfide", "exogenous latrogenic disulfide", "exogenous androgens disulfide", "exogenous nitrogen dioxide", "exogenous dinitrogen sulfide"

Try widening your search to All Fields.

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: (("endogenous estrogen sulfide") OR ((("exogenous estrogen sulfide") OR ((("exogenous nitrogen sulfide") OR ("exogenous nitrogen disulfide")))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"endogenous estrogen sulfide\") or (((\"exogenous estrogen sulfide\") or (((\"exogenous nitrogen sulfide\") OR (\"exogenous nitrogen disulfide\"))))))".
• Removing quotes may allow a broader search: (( endogenous estrogen sulfide ) or ((( exogenous estrogen sulfide ) or ((( exogenous nitrogen sulfide ) OR ( exogenous nitrogen disulfide )))))).
• Adding a wildcard symbol may retrieve word variants: (("endogenous estrogen sulfide") or ((("exogenous estrogen sulfide") or ((("exogenous nitrogen sulfide") OR ("exogenous nitrogen disulfide"))))))*.