Perhaps you should try some spelling variations:
"central a research program synthesis." » "central a research programs synthesis.", "central a research project synthesis.", "central _ research program synthesis.", "central 2 research program synthesis.", "central tax research program synthesis.", "central s.a research program synthesis."
"central de research program stress." » "central de research programs stress.", "central de research project stress.", "central de research program success.", "central does research program stress.", "central key research program stress.", "central led research program stress.", "centrale des research program stress.", "central _ research program stress.", "centro de research program stress."

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: (("central a research program synthesis.") OR ("central de research program stress."))~.
• Removing quotes may allow a broader search: (( central a research program synthesis. ) or ( central de research program stress. ))~.
• Adding a wildcard symbol may retrieve word variants: (("central a research program synthesis.") or ("central de research program stress."))*.