Hi,
We just received the message below from the CRC Press. 
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Dear Chemnetbase customer,

I'm sorry to announce that due to urgent and essential maintenance the Chemnetbase portal will be down today and you will not be able to access Combined Chemical Dictionary (or its constituent dictionaries), nor Properties of Organic Compounds. Access to 'CRC Handbook of Chemistry and Physics' and 'Polymers A Property Database' is still available but you may need to redirect your browser as indicated below.

For Handbook of Chemistry and Physics subscribers:
Access to this product is available by visiting www.hbcpnetbase.com

For Polymers Database subscribers:
Access to this product is available by visiting www.polymersdatabase.com

Please accept our apologies for this inconvenience. We are doing our best to restore normal service and will notify you when this happens.
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We will keep you updated as we receive more news from the vendor.
Thanks
Sherry

Sherry Willhite
Information Resources Analyst
Digital Library Services
California Digital Library