I would try to work out a workflow to do this efficiently. The best I can think of is:
1. Put each article into a Rich Text Content Control and set the tag property of each to a static phrase such as "Delete me"
2. Run a macro which searches for each of the key terms and wherever there is a hit, change the tag property of the CC it sits in to "Keep me"
3. At the end of the macro running, delete all the CC ranges that are still tagged as "Delete me"

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Andrew Lockton
Chrysalis Design, Melbourne Australia