Figures & data
Figure 1. The publication output in 1999–2018
Figure 2. Time trend over average number of authors
Table 1. Top 10 frequently journals
Table 2. Top 6 articles of high citation frequency
Table 3. Top 10 productive countries
Figure 3. The network of countries
Table 4. Top 5 productive institutions
Figure 4. The network of institutions
Table 5. Top 5 productive authors
Table 6. Top 10 wos categories
Figure 5. The main research domains map
Table 7. Top 10 frequently cited journals
Figure 6. Cited journal network
Figure 7. Cited reference map
Table 8. Ranking of high frequently cited reference
Figure 8. Keyword cluster map
Table 9. The detailed information of clusters
Table 10. Ranking of high frequency keywords
Figure 9. Top 22 keywords with the strongest citation bursts
