Library and citation services are subscription services, for which the institute is paying (considerable) fees. Access to these services are in principle restricted to network adresses within the institute.
To gain access to these services from home, one can either use the slightly more complicated tunneling method, that does not require assistance from a computer administrator, or else the method described below, which requires (one-time) assistance from a system administrator.
To use this method from home you need to have a permanent network adress number (ADSL -- may require that you request a permanent number from your internet provider). This will not work with modem access (would make the service open to all users of that provider).
Once you know your permanent internet adress, you need to contact your local system administrator, and ask him to allow access from that network number to a local proxy server. He will tell you the name of the proxy server, and the "port number".
The preferences ("internet connection options" or whatever) of you internet browser allow you to enter the proxy server name and the port number, and typically also allows you to make exceptions for local adresses, that do not need to go throught the proxy server. See the documentation for your browser for details.
Some proxy servers and port numbers at the Institute:
proxy.fys.ku.dk:3128
proxy.tac.dk:8080
www.astro.ku.dk:80
There is brief information to system adminsitrators about how to enable proxy access for individual users.