【求助】关于PMC全文抓取的问题
我现在在做有关文献挖掘的工作，需要下载大量的文献。摘要信息一般很容易得到，但全文就不是那么容易得到了，尤其是需要得到大量的全文。在PMC（PubMed Central）中搜索到需要的全文。我试过两种方法，但都失败了。
第一种方法是：
#!/usr/bin/perl -w
use strict;
use LWP::Simple qw(get);
my $content=get("http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2391278");
print $content;
但是运行结果是：
Use of uninitialized value in print at getfull.pl line 5.
第二种方法是：
#!/usr/bin/perl
use strict;
use LWP;
use CGI;
my $query=CGI->new();
my $url="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2391278";
my $agent=LWP::UserAgent->new();
my $request=HTTP::Request->new(GET=>$url);
my $response=$agent->request($request);
print $response->content();
exit;
但是返回的结果是：
<HTML>
<HEADER>
<TITLE>NCBI/ipmc3 - The requested page has restricted access [Error 403]</TITLE>
</HEADER>
<BODY BGCOLOR="WHITE">
<H1>Restricted Access</H1>
<p>You are trying to access a restricted page. If you believe that you
have permission to view the page, please send an
<A HREF="mailtoTongueubMedCentral@nih.gov?Subject=PubMedCentral%20access%20denied">email to PMC</a>
and include the following information.</p>
<UL>
<DT>URL: http://pmc.lb.ncbi.nlm.nih.gov/articlerender.fcgi?tool=pmcentrez;artid=2391278
<DT>Client: 202.127.28.201
<DT>User Agent: libwww-perl/5.806
<DT>Server: ipmc3
<DT>Time: Mon Jul 28 22:17:29 2008 EDT
</UL>
<P>
Rev. 12/21/2007
</P>
</BODY>
</HTML>
请各位高手指点迷津！
