Perhaps you should try some spelling variations:
"learning-based no2 imputation techniques" » "learning-based no2 implantation technique", "learning-based no2 augmentation techniques", "learning-based no2 segmentation techniques", "learning-based co imputation techniques", "learning-based _o2 imputation techniques", "learning-based ko2 imputation techniques", "learning-based 3do2 imputation techniques"
"learning-based n inhalation technique" » "learning-based n floatation technique", "learning-based n implantation technique", "learning-based n inhaler technique", "learning-based _ inhalation technique", "learning-based _ inflation technique", "learning-based k inflation technique", "learning-based k inhalation technique", "learning-based 3d inhalation technique"

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (("learning-based no2 imputation techniques") OR ("learning-based n inhalation technique"))~.
• Removing quotes may allow a broader search: (( learning-based no2 imputation techniques ) or ( learning-based n inhalation technique ))~.
• Adding a wildcard symbol may retrieve word variants: (("learning-based no2 imputation techniques") or ("learning-based n inhalation technique"))*.