Perhaps you should try some spelling variations:
"learning-based 3d imputation techniques" » "learning-based 3d implantation technique", "learning-based 3d augmentation techniques", "learning-based 3d segmentation techniques", "learning-based 3d simulation techniques", "learning-based _ imputation techniques", "learning-based co imputation techniques", "learning-based k imputation techniques"
"learning-based mri inhalation technique" » "learning-based mri floatation technique", "learning-based mri implantation technique", "learning-based mri inhaler technique", "learning-based _ inhalation technique", "learning-based mil inhalation 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 3d imputation techniques") or ("learning-based mri inhalation technique"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("learning-based 3d imputation techniques") OR ("learning-based mri inhalation technique")).
• Removing quotes may allow a broader search: (( learning-based 3d imputation techniques ) or ( learning-based mri inhalation technique )).
• Adding a wildcard symbol may retrieve word variants: (("learning-based 3d imputation techniques") or ("learning-based mri inhalation technique"))*.