Here are some useful federated search engines. Federated search involves cross searching in a collection of websites and produces result in one format.
WorldWideScience
WorldWideScience.org is a global science search engine (Academic databases and search engines) designed to accelerate scientific discovery and progress by accelerating the sharing of scientific knowledge. Through a multilateral partnership, WorldWideScience.org enables anyone with internet access to launch a single-query search of national scientific databases and portals in more than 70 countries, covering all of the world’s inhabited continents and over three-quarters of the world’s population. From a user’s perspective, WorldWideScience.org makes the databases act as if they were a unified whole
Science.gov
Science.gov is a web portal and specialized search engine. Using federated search technology, Science.gov serves as a gateway to United States government scientific and technical information and research.
National Science Digital Library
The National Science Digital Library provides high quality online
educational resources for teaching and learning, with current emphasis
on the sciences, technology, engineering, and mathematics (STEM)
disciplines—both formal and informal, institutional and individual, in
local, state, national, and international educational settings.
Dr.Clara, Librarian, VVVC, VNR, INDIA.
