·2,447,543篇论文数据，部分数据来源于NoteExpress
In this work, the questionnaire was used for collecting data. Totally 268 questionnaires were sent out while 142 valid ones were got back. The ratio of valid questionnaire is 53%.
本研究采用问卷调查方法进行了数据收集，共发出调查问卷268份，回收有效问卷142份，有效问卷率为53%。
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