Perhaps you should try some spelling variations:
diffusion systems » fusion system
equation system » equation systems, secretion system
systems based » system based, systems fast, systems game
based tools » based tool, coated tools
system a » system _, systems _
a tools » a tool, _ tools

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( equation system a tools ) or ( diffusion systems based tools ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( equation system a tools ) OR ( diffusion systems based tools )).
• Adding a wildcard symbol may retrieve word variants: (( equation system a tools ) or ( diffusion systems based tools ))*.