中文摘要：

简要介绍WorldCat Local、EBSCO Discovery Service、Summon、Primo四大具有集中索引仓储的Web级资源发现系统，从内容索引、系统特性、检索结果显示三个方面对它们进行比较分析。最后指出资源发现系统未来的发展趋势。

英文摘要：

This paper briefly introduces four Web-scale discovery systems that have centralized indexes such as WorldCat Local, EBSCO Discovery Service, Summon, Primo, and makes a comparison of their centralized index, property, information about retrieved resuits. Finally, the paper points out some trends of resource discovery systems.