安装bioconductor总是遇到这个问题：
请赐教

> source("http://bioconductor.org/biocLite.R")Warning: unable to access index for repository https://bioconductor.org/packages/3.7/bioc/src/contrib:
  cannot open URL 'https://bioconductor.org/packages/3.7/bioc/src/contrib/PACKAGES'
Warning: unable to access index for repository https://bioconductor.org/package ... indows/contrib/3.5:
  cannot open URL 'https://bioconductor.org/packages/3.7/bioc/bin/windows/contrib/3.5/PACKAGES'
'biocLite.R' failed to install 'BiocInstaller', use
  'install.packages("BiocInstaller",
  repos="https://bioconductor.org/packages/3.7/bioc")' or
  'install.packages("BiocInstaller",
  repos="http://bioconductor.org/packages/3.7/bioc")'
Warning message:
package ‘BiocInstaller’ is not available (for R version 3.5.1)
> biocLite("phyloseq")
Error in biocLite("phyloseq") : could not find function "biocLite"