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

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