Perhaps you should try some spelling variations:
reduction techniques » reduction technique, imputation techniques
floatation technique » inhalation technique, implantation technique, imputation techniques
no2 reduction » h2o2 reduction, _ reduction
n floatation » _ floatation
based no2 » based co
based n » based _, based k, based 3d

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( learning-based n floatation technique ) OR ( learning-based no2 reduction techniques ))~".
• Adding a wildcard symbol may retrieve word variants: (( learning-based n floatation technique ) OR ( learning-based no2 reduction techniques ))*.