Perhaps you should try some spelling variations:
nganh khong » nganh cong, nhanh chong, nganh nong
hoc nganh » hoc nhanh
cac thoi » cac toi, cac hop, cac tro
thuoc xa » thuoc ma, thuoc va, thuoc tai
thuoc la » thuoc ma, thuoc va, thuoc tai
van nhan » van phan, van thanh, danh nhan
cuu hoa » cuu khoa, cuu hoan, cau hoa
hoi van » hoi va, hoi dan, hai van
nhan va » nhan tai, nhan dan, nhan tao

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu cac thoi gian, nghien cuu hoa hoc nganh khong ((thuoc xa) or (thuoc la)) hoi van nhan va~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu cac thoi gian, nghien cuu hoa hoc nganh khong ((thuoc xa) OR (thuoc la)) hoi van nhan va.
• Adding a wildcard symbol may retrieve word variants: tu cac thoi gian, nghien cuu hoa hoc nganh khong ((thuoc xa) or (thuoc la)) hoi van nhan va*.