Perhaps you should try some spelling variations:
thai nghien » thai nguyen, phap nghien, phan nghien
thi nghiem » thuc nghiem
thai thai » thi thai, thai tai, thai thanh
nghien du » nghiep du, nghien cuu, nghiem dau
khac thi » khau thi, khuc thi, khuat thi
tu khac » vu khac, su khac, ta khac
ca thai » chat thai, hoa thai
de hoc » te hoc, dien hoc
du hoc » tu hoc, duoc hoc
d hoc » ad hoc, y hoc, _ hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu khac thi nghiem ((d hoc) or (de hoc)) ) or ( ca thai thai nghien du hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu khac thi nghiem ((d hoc) OR (de hoc)) ) OR ( ca thai thai nghien du hoc )).
• Adding a wildcard symbol may retrieve word variants: (( tu khac thi nghiem ((d hoc) or (de hoc)) ) or ( ca thai thai nghien du hoc ))*.