Perhaps you should try some spelling variations:
"modified notion approximation algorithms" » "modified network approximation algorithms", "modified time approximation algorithms", "modified one approximation algorithms"
"active learning evolution algorithm" » "active learning solution algorithm", "active learning evolutionary algorithm", "active learning convolution algorithms", "active learning convolution algorithm", "active learning emotion algorithm", "machine learning evolution algorithm"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("active learning evolution algorithm") or ("modified notion approximation algorithms"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("active learning evolution algorithm") OR ("modified notion approximation algorithms")).
• Removing quotes may allow a broader search: (( active learning evolution algorithm ) or ( modified notion approximation algorithms )).
• Adding a wildcard symbol may retrieve word variants: (("active learning evolution algorithm") or ("modified notion approximation algorithms"))*.