Sounds like a perfect job for XML::Twig. 
use strict;
use warnings;

use XML::Twig qw( );


my $fqn_dat = 'mlr.dat';
my $fqn_in  = 'mlr_648.xml';
my $fqn_out = 'fixed_mlr_648.xml';



my %translations;
{
   open(my $fh, '<', $fqn_dat)
      or die("Can't open \"$fqn_dat\": $!\n");

   while (<$fh>) {
      /^(.*?)\t(.*)/ or next;
      $translations{$1} = $2;
   }
}


open(my $fh_in, '<', $fqn_in)
   or die("Can't open input file \"$fqn_in\": $!\n");

open(my $fh_out, '>', $fqn_out)
   or die("Can't create output file \"$fqn_out\": $!\n");

my $twig = XML::Twig->new(   
    twig_handlers => {
       'reference/title[@type="journal"]' => sub {
          my ($twig, $elt) = @_;
          my $text = $elt->text();
          if ( exists( $translations{$text} ) ) {
             $elt->set_text( $translations{$text} );
          } else {
             warn("No translation found for \"$text\"\n");
          }
       },

       'reference' => sub {
          my ($twig, $elt) = @_;
          # Keep at most one <reference> in memory.
          $twig->flush($fh_out);
       },
    }
);

$twig->parse($fh_in);
$twig->flush($fh_out);

[download]

In reply to Re: Modifying a Sepcifig node by ikegami
in thread Modifying a Sepcifig node by ngbabu

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.