Perhaps you should try some spelling variations:
"learning-based cross imputation techniques" » "learning-based cross implantation technique", "learning-based cross augmentation techniques", "learning-based cross segmentation techniques", "learning-based roms imputation techniques", "learning-based access imputation techniques", "learning-based closed imputation techniques"
"learning-based code mitigation techniques" » "learning-based anode mitigation techniques"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("learning-based code mitigation techniques") or ("learning-based cross imputation techniques"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("learning-based code mitigation techniques") OR ("learning-based cross imputation techniques"))*.
• Removing quotes may allow a broader search: (( learning-based code mitigation techniques ) or ( learning-based cross imputation techniques ))*.