2./Sample, I feel that it is not very easy to use and the content is not too much. Mainly rely on users to add websites, and the search function of search engines that provide information is poor. When you enter common keywords, you often can't find a match.
3. After clicking or jumping to, this search engine can search more than 10 million kinds of chemical information or corresponding suppliers, which is somewhat similar to Chemblink, but the physical and chemical information provided is not as detailed as Chemblink, but the difference is that this search engine can provide chemical structure search (there is a search box for drawing chemical structure information online on the homepage).
4./OJOSE, (online periodical search engine) is a powerful free scientific search engine. Through OJOSE, you can find, download or purchase the resources of nearly 60 databases. But the feeling operation is more complicated.
5. http://cite.ist.psu.edu/,is a search engine about computer and information science.
6. http://hpsearch.uni-trier.de/,expert personal homepage search engine.