Perhaps you should try some spelling variations:
"modified a approximation algorithms" » "modified _ approximation algorithms", "modified one approximation algorithms", "modified time approximation algorithms", "modified df approximation algorithms", "modified adam approximation algorithms"
"modified adamdamdaptive estimation algorithm" » "modified _damdamdaptive estimation algorithm", "modified dfdamdamdaptive estimation algorithm", "modified adamdamdamdaptive estimation 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: (("modified a approximation algorithms") or ("modified adamdamdaptive estimation algorithm"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified a approximation algorithms") OR ("modified adamdamdaptive estimation algorithm")).
• Removing quotes may allow a broader search: (( modified a approximation algorithms ) or ( modified adamdamdaptive estimation algorithm )).
• Adding a wildcard symbol may retrieve word variants: (("modified a approximation algorithms") or ("modified adamdamdaptive estimation algorithm"))*.