A Bibliometric Analysis and Visualization of Fractional Order Research in China over Two Decades (2001–2020)

Table 4

Occurrence distribution of the top 20 keywords.

No.	Keyword	Occurrence
1	Fractional order	342
2	Fractional differential equation	250
3	Fractional Fourier transform	243
4	Fractional calculus	228
5	Fractional differential	145
6	Fixed point theorem	138
7	Positive solution	135
8	Boundary value problem	123
9	Fractional derivative	119
10	Fractional order system	115
11	Stability	107
12	Chaos synchronization	72
13	Fractional chaos system	64
14	Convergence	56
15	Synchronization	52
16	Sliding mode control	52
17	Chaos	51
18	Image enhancement	51
19	Existence	47
20	Caputo derivative	45