I'm not getting an alert on the invitrogen.com/site/us/en/home.html link you posted. For the future when posting suspect URLs change the http to hXXp to break links and avoid accidental exposure to a suspect site.
You can check the C:\Documents and Settings\All Users\Application Data\AVAST Software\Avast\log\nshield.log file (XP location) or C:\ProgramData\AVAST Software\Avast\log\nshield.log (Vista, win7), as that should contain the network shield alerts.