https://mirror.tuna.tsinghua.edu.cn/help/bioconductor/
source("http://bioconductor.org/biocLite.R")
options(BioC_mirror="https://mirrors.tuna.tsinghua.edu.cn/bioconductor")
options("repos" = c(CRAN="https://mirrors.tuna.tsinghua.edu.cn/CRAN/"))
biocLite("DESeq2")