[Biopython] efetch only returns 20 records of pubmed

[ming.xue at boehringer-ingelheim.com]

Hello,

I used the biopython 1.5.9 to download some pubmed abstracts. The query from
browser showed 409580 records. But I only got the count of 20 from
record["IdList"] and they matched the records on the first page from browser.
Am I blocked by NCBI or there is a parameter for page I missed?

from Bio import Entrez
Entrez.email = 'my.email at domain.com'

query = Entrez.esearch(db="pubmed", term="publisher[sb]")
record = Entrez.read(query)
print len(record["IdList"])

Thanks for your comments,
Ming