Perhaps you should try some spelling variations:
"atom-cloud connectivity a index" » "atom-based connectivity a index", "atom-cloud connectivity _ index", "atom-cloud connectivity based index"
"atom-bond connectivity bank index" » "atom-based connectivity bank index", "atom-broadband connectivity bank index", "atom-edge connectivity bank index", "atom-bond connectivity based index", "atom-bond connectivity brain index", "atom-bond connectivity best index", "atom-bond connectivity tank index", "atom-bond connectivity frank index", "atom-bond connectivity bande index"

Try widening your search to All Fields.

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: (("atom-bond connectivity bank index") OR ("atom-cloud connectivity a index")).
• Removing quotes may allow a broader search: (( atom-bond connectivity bank index ) or ( atom-cloud connectivity a index )).
• Adding a wildcard symbol may retrieve word variants: (("atom-bond connectivity bank index") or ("atom-cloud connectivity a index"))*.