Perhaps you should try some spelling variations:
"support trade integration theories." » "support trade integration theorems.", "support trade integrationstheorie 2.", "support trade integration theory.", "support trainer integration theories.", "export trade integration theories.", "import trade integration theories."
"support syria irrigation schemes." » "support syria irrigation scheme.", "support syria irrigation systems.", "support africa irrigation schemes.", "support drip irrigation schemes.", "support surge irrigation schemes.", "support social irrigation schemes.", "support agri irrigation schemes."

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("support syria irrigation schemes.") or ("support trade integration theories."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("support syria irrigation schemes.") OR ("support trade integration theories.")).
• Removing quotes may allow a broader search: (( support syria irrigation schemes. ) or ( support trade integration theories. )).
• Adding a wildcard symbol may retrieve word variants: (("support syria irrigation schemes.") or ("support trade integration theories."))*.