Perhaps you should try some spelling variations:
"learning-based no2 segmentation techniques" » "learning-based no2 augmentation techniques", "learning-based no2 imputation techniques", "learning-based 3d segmentation techniques", "learning-based co segmentation techniques", "learning-based n segmentation techniques"
"learning-based code floatation technique" » "learning-based code inhalation technique", "learning-based code implantation technique", "learning-based code imputation techniques", "learning-based anode floatation technique"

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 floatation technique") or ("learning-based no2 segmentation techniques"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("learning-based code floatation technique") OR ("learning-based no2 segmentation techniques"))*.
• Removing quotes may allow a broader search: (( learning-based code floatation technique ) or ( learning-based no2 segmentation techniques ))*.