危险化学品的cas.nd.un号等分别是何意思？

http://www.ccebbs.com/forum/dispq.asp?lid=59320
http://emuch.net/bbs/viewthread.php?tid=185665

1。 CAS no. (number): 不是危险品而已， 而是所有的化学品都有的一个编号， 便于数据库的查找。

CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. They are also referred to as CAS numbers or CAS RNs.

Chemical Abstracts Service (CAS), a division of the American Chemical Society, assigns these identifiers to every chemical that has been described in the literature. The intention is to make database searches more convenient, as chemicals often have many names. Almost all molecule databases today allow searching by CAS number.

As of Nov 2, 2005, there were 26,901,696 substances in the CAS registry — the curre