Perhaps you should try some spelling variations:
communities bioinformatics » computing bioinformatics, communities information, computation bioinformatics
database optimized » databases optimizing, database optimising, database limited
https directional » wimps directional, aids directional, two directional
databases invited » databases united, databases induced, datasets invited

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

• Performing a fuzzy search may retrieve terms with similar spellings: communities bioinformatics https directional ((database optimized) or (databases invited))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: communities bioinformatics https directional ((database optimized) OR (databases invited)).
• Adding a wildcard symbol may retrieve word variants: communities bioinformatics https directional ((database optimized) or (databases invited))*.