What query can I use to search for a list of keyword centric domains in search engines ?

Question

Can anybody tell me what query- footprint can i use in search engines to get domains which contains the exact "keyword" in their domain names

• short urls www.topkeyword.com/ - and not
• long urls(domain.com/...../keyword/ ,

so searching for the keyword "keyword" I want to find a domains like keyword.com , bestkeyword.net , topkeyword.org and not results like wikipedia/..../keyword.html .

                   Thanks