Use Asterisk (*) Replace zero or more characters in a search word.
查看答案
Use Question mark (?) Replace exactly one character in a search word.
PQDT global is the largest and most widely used database of doctoral and master's theses in the world.
When you use double quotes in ScienceDirect search,
AND is not automatically inserted between terms.
B. Punctuation is ignored.
C. Wildcards are searched as wildcards.
D. Plurals are included.
When you use brackets in ScienceDirect search:
A. Stop words, punctuation, and special characters are searched.
B. Stop words, punctuation, and special characters are not searched.
C. Wildcards are searched as characters.
D. Wildcards are not searched as characters.
微信支付 
支付宝支付