Is it possible to arrive into China by plane and leave by train and still use a transit visa?

Jack, if your layover time in PRC is less than 24 hours in total, you can enjoy the 24 hour direct transit at any city by plane or train.
Or if you transit in Shanghai, Zhejiang or Jiangsu, the layover time is within 144 hours, and your nationality is one of the 51 countries, you can enjoy the free transit.
But if you stay for more than 24 hours at any other places instead of Shanghai, Zhejiang and Jiangsu, you have to apply for a transit G type or tourist L type ahead of your journey.