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

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("modified bi1 approximation algorithms") OR ("modified objective optimization algorithm"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified bi1 approximation algorithms\") OR (\"modified objective optimization algorithm\"))*".
• Removing quotes may allow a broader search: (( modified bi1 approximation algorithms ) OR ( modified objective optimization algorithm ))*.