why are URLs in records downloaded from Web of Science database not valid?

In Endnote X5 on Mac, when I download a reference from PubMed, it has a URL that can be used to find the original paper (either from Endnote or manually through a browser). But when records are downloaded from the Web of Science (TS) database, the URL field has links like this:

<Go to ISI>://000172189400018

    which are not valid URLs.  What am I missing - how come records from Web of Science don’t have valid URLs and thus can’t be used for the “Find Full text” feature?