Here I have attached my code.

use warnings;
use XML::Simple;
use LWP::UserAgent;
use HTTP::Request::Common;
use URI::Escape;
use Data::Dumper;
use Text::CSV;

my @keywords;
my $file ="proteinlist.csv";
my $ua = LWP::UserAgent->new;
my $csv = Text::CSV->new({ sep_char => ',' });

#Open result CSV file.
open(my $fh, ">", "result1.csv");
print $fh "Pubmed ID, Drug name, Keyword(s) that matches, List of prot
+eins in the abstract\n";

#Open the CSV file containing list of PubMed IDs
open(my $data, '<', "pmid.csv");
while (my $line = <$data>) {
chomp $line;

if ($csv->parse($line)) {
    #Skip first line
    next if ($. == 1);
    
    my @fields = $csv->fields();
    #Replace (-) with (,)
    $fields[0] =~ tr/-/,/;
    $fields[1] =~ tr/-/,/;
    
    #Split alt name
    my @id = split /[+]/, $fields[1];
    
    for (my $i = 0; $i < scalar @id; $i++){
    #Initialize http request
    my $args = "db=pubmed&id=$id[$i]&retmode=text&rettype=abstract";
    my $req = new HTTP::Request POST => 'https://eutils.ncbi.nlm.nih.g
+ov/entrez/eutils/efetch.fcgi';
    $req->content_type('application/x-www-form-urlencoded');
    $req->content($args);
    
    #Get response
    my $response = $ua->request($req);
    my $content = $response->content;
    
    $fields[0] =~ tr/,/-/;
    
    my $keystr = "";


    #open csv file containing the protein list and compare with the co
+ntent of abstract
    open(my $data, "<", $file) or die "Could not open '$file' $!\n";
 
    while (my $readinline = <$data>) {
         chomp $readinline;
         #initialize the first data of csv as the first keyword
          my @fields = split "," , $readinline;
          $keywords[$i] = $fields[0];
    
    
        if (regex(lc $content,lc $keywords[$i]) != -1) {
            if ($keystr eq ""){
                $keystr = $keywords[$i];
            }else{
                $keystr = $keystr . "+$keywords[$i]";
            }
        }
    }
    
    if ($keystr ne ""){
        print $fh "$id[$i],$fields[0],$keystr,Yes\n";
        print "$id[$i],$fields[0],$keystr,Yes\n";
    }else{
        print $fh "$id[$i],$fields[0],No keyword matches,No\n";
        print "$id[$i],$fields[0],No keyword matches,No\n";
        }
    
    }
    }

}
close($fh);
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