Figure 6.
Yearly distribution of the 23 articles (Dai et al. [84] has been excluded because the carrier gas was not specified in the articles) in the present systematic review according to the type of carrier gas.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.