<?php
$str = <<<XML
<DATA>
<RECORD>
<STOK_NO>14</STOK_NO>
<MIKTAR>10+</MIKTAR>
</RECORD>
<RECORD>
<STOK_NO>15654</STOK_NO>
<MIKTAR>20+</MIKTAR>
</RECORD>
<RECORD>
<STOK_NO>15655</STOK_NO>
<MIKTAR>20+</MIKTAR>
</RECORD>
<RECORD>
<STOK_NO>15656</STOK_NO>
<MIKTAR>20+</MIKTAR>
</RECORD>
</DATA>
XML;

$data = new SimpleXMLElement($str);
foreach ($data->RECORD as $RECORD)
{
if ($RECORD->STOK_NO == 14)
{
echo "ID sine ait ürün miktarı: " . $RECORD->MIKTAR;
}
}