SD好像电子从1998年起
http://www.sciencedirect.com/science?_ob=PublicationURL&_ctockey=%23toc%236232%232011%23999509998%232817745%23FLA%23&_cdi=6232&_pubType=J&_acct=C000050165&_version=1&_urlVersion=0&_userid=1002903&md5=5704d958ab3773c5a1ddb95f4f45fd47&jchunk=xxx