How to access Blockchain remotely for statistics study? I would like to write small paper supported by Blockchain stats.
Could you tell me how to access blocks chain remotely via GUI to make a query ?

Blockchain's size is 159GB as of today, so download is heavy.

Ok, I can study block headers only to limit overheads.

Do you know how to download or access blockchain headers as mySQL database ?

How to access Blockchain remotely for statistics study ?
As you mention in your comments, blockchain.info can provide this information.

You can get a raw block in JSON format using the /rawblock/ links, for example:
https://blockchain.info/rawblock/0000000000000000008d49f25f7dd5d3704575a348e030a1d2e5f396b3e80516

Then you can also get it as the hex-encoded raw block by adding ?format=hex to the url:
https://blockchain.info/rawblock/0000000000000000008d49f25f7dd5d3704575a348e030a1d2e5f396b3e80516?format=hex

Hope that's what you are after :)

EDIT: Oh, just re-read your comment, you want just the headers? In that case you probably can't use blockchain.info, you could try BlockCyhper instead:

For example: https://api.blockcypher.com/v1/btc/main/blocks/294322

You can find more info about their API here: https://www.blockcypher.com/dev/bitcoin/#blockchain-api