Perhaps you should try some spelling variations:
thuoc mach » thuoc sach, thuong mach, thuoc ma
nghien cac » nghiep cach, nghien cuu, nghiep bac
nghiep cay » nghiep chan, nghiep va, nghiep cua
mach hoc » cach hoc, dich hoc, anh hoc
cong hoa » dong hoa, dong hoc, hang hoa
dai khoa » da khoa, tai khoa, dac khoa
khoa hoc » hoa hoc
hoa dai » hoa dan, hoc dai
hoc mai » hoc ma, hoc dai, hoc bai
mai hoi » mai khoi, dai hoi, lai hoi
va nhan » van nhan, ca nhan, va phan
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: thuoc mach hoc tap, ((nghien cac) or (nghiep cay)) cong hoa dai khoa hoc mai hoi va nhan va~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc mach hoc tap, ((nghien cac) OR (nghiep cay)) cong hoa dai khoa hoc mai hoi va nhan va.
• Adding a wildcard symbol may retrieve word variants: thuoc mach hoc tap, ((nghien cac) or (nghiep cay)) cong hoa dai khoa hoc mai hoi va nhan va*.