1 file_get_contents方法

<?php
$opts = [
    'http' => [
        'method' => "GET",
        'timeout' => 10,
    ]
];
$context = stream_context_create($opts);
$url = 'https://www.ebi.ac.uk/europepmc/webservices/rest/MED/1/citations///json';
$html = file_get_contents($url, false, $context);
echo $html;

2 curl方法

<?php
$url = 'https://www.ebi.ac.uk/europepmc/webservices/rest/MED/1/citations///json';
$curl  = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, 1);
$data = curl_exec($curl);
curl_close($curl);
echo $data;