1. Open the website of China HowNet and click "Advanced Search" to enter the advanced search page.
2. On the advanced search page, you can select the subject, keywords, title, full text, author, unit, abstract, cited literature, China classification number and literature source, etc. , and then enter the search term you want.
3. Select the database and literature type to search, and then click "Search" to obtain relevant literature.
Regarding the literature retrieval formula for preventing COVID-19, you can refer to the following steps and examples:
1. Enter the subject: "Prevention of COVID-19".
2. Choose the literature type: you can choose research reports, academic papers, news reports, etc.
3. Database selection: You can select all the databases of China HowNet or select a specific database.
4. Click "Search" to obtain the relevant literature on prevention of COVID-19.
Please note that the specific search formula and the number of results will be different due to different databases and search conditions.
Related content
Three Fast Retrieval Methods of HowNet
China HowNet database is the core of this project. CNKI resource database includes several sub-databases, mainly including online publishing database of academic journals in China, full-text database of excellent doctoral (master's) papers in China, full-text database of important newspapers and periodicals in China and full-text database of important conference papers in China.
China book full-text database, China yearbook online publishing database, China economic and social development statistics database, China economic information literature database, China legal knowledge resource database, China standard database, China patent database, national scientific and technological achievements database, foreign standard database, etc.
First, quick retrieval.
Click the library homepage to enter the full-text database of CNKI journals, and click "Quick Search" above the search box to enter the quick search page, as shown in figure 1. There is only one search box for quick retrieval, and there are no restrictions on fields, word positions and word frequency. The system will search and match the full text. Enter a search term in the quick search box, and then click Quick Search.
Second, the standard retrieval
Standard retrieval is what we often call advanced retrieval, which can limit various retrieval fields and specify word frequency. To carry out effective Boolean logic combination retrieval, reduce retrieval redundancy and improve retrieval efficiency. Therefore, we generally advocate the use of standard retrieval for literature retrieval.
Third, professional retrieval.
Professional retrieval can provide a retrieval method of combining logical expressions according to the actual needs of users, which can effectively improve the precision rate.