Perhaps you should try some spelling variations:
"modified objective optimization algorithms" » "modified objective optimisation algorithm", "modified objective estimation algorithms", "modified objective estimation algorithm", "modified multiobjective optimization algorithms"
"modified time approximation algorithms" » "modified one approximation algorithms", "modified _ approximation algorithms", "modified bi1 approximation algorithms", "modified male approximation algorithms"

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 objective optimization algorithms") or ("modified time approximation algorithms"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified objective optimization algorithms") OR ("modified time approximation algorithms")).
• Removing quotes may allow a broader search: (( modified objective optimization algorithms ) or ( modified time approximation algorithms )).
• Adding a wildcard symbol may retrieve word variants: (("modified objective optimization algorithms") or ("modified time approximation algorithms"))*.