Perhaps you should try some spelling variations:
"learning-based two imputation techniques" » "learning-based two implantation technique", "learning-based two augmentation techniques", "learning-based two segmentation techniques", "learning-based tool imputation techniques", "learning-based co 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 two imputation techniques") or ("learning-based code mitigation techniques"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("learning-based two imputation techniques") OR ("learning-based code mitigation techniques"))*.
• Removing quotes may allow a broader search: (( learning-based two imputation techniques ) or ( learning-based code mitigation techniques ))*.