path<-"C:/test/"
 files<-list.files(path=path)
 j<-1
 for (i in files){
 name<-strsplit(i,'[.]')[[1]][1]
 assign(name,read.xlsx(file=paste(path,i,collapse=NULL,sep=""),sheetIndex=1,header=TRUE,as.data.frame=TRUE))
 files[j]<-name
 j<-j+1
 }

result=xts(nasa[,-1],order.by=as.POSIXct(strptime(a[,1],'%y/%d/%m')))

colnames(result)=colnames(name)