根据您现在拥有的内容，以下内容应该可以工作：

#simulate data

df1 <- data.frame(Periods=rnorm(10),y1=rnorm(10))
df2 <- data.frame(Periods=rnorm(10),y2=rnorm(10))
df3 <- data.frame(Periods=rnorm(10),y3=rnorm(10))

# list to store results

results = vector("list",3)

for(i in 1:3) {
  name1<-paste0("y",i,sep="")
  name2<-paste0("df",sep="")
  FORMULA = as.formula(paste(name1,"~ Periods"))
  COEF = as.numeric(coefficients(lm(FORMULA,data=get(name2))))
  results[[i]] <- data.frame(
         name1=name1,name2=name2,intercept=COEF[1],coefficient=COEF[2]
  )
}

do.call(rbind,results)

仍然有50个df浮动有点混乱吗？为什么不尝试这样的事情：

# do not split your dfs,or just combine them like this
DF <-data.frame(
Periods=rnorm(30),y=rnorm(30),df=paste("df",rep(1:3,each=10),sep="")
)
library(lme4)
coefficients(lmList(y ~ Periods | df,data=DF))
    (Intercept)     Periods
df1   0.2931990 -0.44942868
df2   0.1146975  0.01613812
df3  -0.3491186  0.11273944

我尝试了一种替代解决方案，使用下面的代码制作每种情况下的斜率图

x<-0
for (i in 1:6) {
  x[i]<-i
}

x<-as.numeric(x)

for (i in 1:49) {
  name1<-paste0("y",sep="")

  name4<-paste0("stats",sep="")
  name5<-paste0("slope",sep="")
  assign(name4,lm(x~get(name1),data=get(name2)))
  assign(name5,get(name4)[[1]][2])

  mypath<-file.path(path[i])
  jpeg(file = mypath,width = 1800,height = 600)
  print(ggplot(data=get(name2),aes(x=Periods,y=get(name1))) +
          geom_bar(stat="identity",width=0.5,fill="steelblue") +
          annotate("text",x=1.5,y=22,label= get(name5),size=8) +
          annotate("text",x=0.75,label= "Slope=",size=8) +
          geom_smooth(aes(x = Periods,y = get(name1),group=1),method = "lm",se= FALSE,color = "firebrick",size = 2)+
          labs(x = "Time Periods") +
          labs(y="Number of tropical nights")  +
          ylim(0,25)+
          ggtitle("Number of tropical nights per time period (Tmin > 20°C)")+ theme(plot.title = element_text(hjust = 0.5)))
  dev.off()
}

它生成了这样的图