Keyword is that appeared in the literature title, abstract and text, has substantial significance to the characterization of the theme of literature words,it is important to reveal and describe the subject content, with a key, can be used as the entrance of the word or phrase retrieval.



    Including the selection principle of keywords:revealing the theme content,choose the professional terms which have a high degree of specificity.Appropriate labeling and references,clear logical relation,clear words nature（noun、gerund and noun phrase,not use adj.、adv. et al）,word accuracy and choose a number of control words.