如何在R语言中将不等大小的列表输出到文件中

data like this:

像这样的数据：

b <- list(
structure(c(2L, 11L, 52L, 63L, 123L), .Names = c("danazol",
"methyltestosterone", "ethinylestradiol", "methimazole", "ethionamide"
)), 
structure(c(6L, 9L, 16L, 49L, 66L, 67L), .Names = c("naproxen", "indomethacin",
"lornoxicam", "triazolam", "carbon tetrachloride", "allyl alcohol"))
)
b <- list(
structur