See also:

易易工作室 - 各种在线工具，站长网志，以及多个应用项目。
CiteSeer - Search engine for computer science and related matters. For all results number of citations are given which allows to estimate the importance of a paper in a given context. Most of the papers are cached and available for direct download as postscript or PDF.
ISI Highly Cited - A search tool to identify individuals, departments and laboratories that have made fundamental contributions to the advancement of science and technology in recent decades.
iSpecies - A species search engine from Rod Page of Glasgow University. Search on either the common or Latin name of a species. Results are generated by querying other data sources.
Online Journals Search Engine - A multi-search tool that permits queries of a number of scientific journals.
Scirus - Search engine that fetches only scientific websites.
SciSeek - Science search engine and directory. Also provides forums, tools and related news.