SCI's companion SSCI[ 1] was also founded by institute for scientific information. It is a large-scale retrieval tool, which can be used to analyze the number of social science papers in different countries and regions, and is the most important index of social science journals in the world.

SCI (Scientific Citation Index) is a citation database created and published by institute for scientific information (ISI) 196 1. SCI (Science Citation Index), EI (Engineering Index) and ISTP (Science and Technology Conference Index) are three world-famous retrieval systems for scientific documents, which are internationally recognized as the main retrieval tools for scientific statistics and scientific evaluation, among which SCI is the most important.

EI retrieval, what does EI retrieval mean? In fact, it is a global database, similar to HowNet in China. However, EI does not enter all articles, and all entered articles represent authority and high quality. Therefore, EI is called the global core and is recognized by every country. Generally used for: evaluation of masters, doctors, associate professors and professors. After the papers published by the author in international conferences or magazines are included in EI, some domestic authorities can issue EI inclusion certificates to the author.

EI retrieval is the engineering index: the engineering index (EI for short) was founded in 1884, which is a famous comprehensive retrieval tool for engineering technology published by engineering information companies. EI retrieval is published every month 1 issue, from 13000 to 14000 abstract; Each issue is accompanied by a subject index.

Author index; There is also an annual volume and an annual index every year, and the annual index also increases the author unit index. The collected literature covers almost all fields of engineering technology. For example: electric power, electrician, electronics, automatic control, mining

Metallurgy, metal technology, machinery manufacturing, management, civil engineering, water conservancy, education engineering, etc. EI retrieval has the characteristics of strong comprehensiveness, wide data sources, wide geographical coverage, large amount of reports, high quality of reports and strong authority.