Perhaps you should try some spelling variations:
communities bioinformatics » computing bioinformatics, communities information, computation bioinformatics
databases optimizing » catalysis optimizing, analysis optimizing, databases mining
https directional » wimps directional, aids directional, two directional
flow oriented » block oriented, fact oriented, form oriented

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: communities bioinformatics https directional ((databases optimizing) OR (flow oriented))~.
• Adding a wildcard symbol may retrieve word variants: communities bioinformatics https directional ((databases optimizing) or (flow oriented))*.