At the moment there are no direct equivalents for these in the Web UI, though the Dashboard does provide some similar functionality to Team Central, see:
https://jazz.net/jazz/resource/itemName/com.ibm.team.workitem.WorkItem/90139

For accepting new work, our team uses work item state to track this. For example, when a new work item comes in, it starts in the New state, then we Triage it and assign to a developer. I suppose you could add another state to accept work items as well.

You can also have a look at https://jazz.net/wiki/bin/view/Main/DashboardMiniDesignGuide to see a preview of Dashboard mini, which has some similarities to team central.

Thanks,
Curt