Perhaps you should try some spelling variations:
"learning-based no2 implantation technique" » "learning-based no2 floatation technique", "learning-based no2 inhalation technique", "learning-based novel implantation technique", "learning-based co implantation technique", "learning-based n implantation technique"
"learning-based two imputation techniques" » "learning-based two augmentation techniques", "learning-based two segmentation techniques", "learning-based two floatation technique", "learning-based tool imputation techniques", "learning-based co imputation 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 no2 implantation technique") or ("learning-based two imputation techniques"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("learning-based no2 implantation technique") OR ("learning-based two imputation techniques"))*.
• Removing quotes may allow a broader search: (( learning-based no2 implantation technique ) or ( learning-based two imputation techniques ))*.