Can I get a Chinese Transit Visa to get out of Beijing airport to visit the city?

Now, owing to the upcoming 18th National Congress of the Communist Party of China, I don't know whether you can get a 24 hours stay permit when you arrive in Beijing airport or not, in 2011, it was possible for Canadian to get a 24 hours stay permit in the airport, then they can leave the airport to visit Beijing. At present, the visa rule becomes strict. You'd better obtain a single-entry transit visa in advance.