CNKI stands for National Knowledge Infrastructure. CNKI project was initiated by Tsinghua University and Tsinghua Tong fang, which was established in June 1999. Multiple databases can be retrieved on the CNKI retrieval platform, such as journal papers, doctoral theses, conference papers, newspapers, yearbooks, encyclopedias, patents, standards, etc., but only the databases ordered by the following libraries can download the full text, and the rest can only browse the abstract information:

Bureau van Dijk Editions Electroniques SA (BvD) is a well-known European electronic provider of global financial and corporate credit analysis databases. BvD provides professional data on international financial and national macroeconomic trends for government financial regulators, banks and financial institutions, securities investment companies, etc. At the same time, BvD is also Europe's largest provider of corporate credit analysis data, with more than 10 million enterprise credit analysis libraries and global mergers and acquisitions analysis libraries in Europe,   which widely for Europe and the United States and other countries of the financial and educational institutions long-term subscription use. 

American Society for Testing and Materials, established in 1898, is one of the biggest and eldest non-profit standards developing organizations. Its mission is to develop traits and performance standards, testing methods and procedure standards in the fields of materials, products, systems, and service. It also promotes the development and popularization of relevant knowledge. 

ASME (American Society of Mechanical Engineers) was founded in 1880 and now is an international non-profit organization of educational and technical with more than 125,000 members worldwide. ASME is one of the largest technical publishing organizations in the world, holding about 30 major technical conferences and 200 professional development courses each year, developing a wide range of industrial and manufacturing industry standards. ASME now has 600 standards and codes for industrial and manufacturing industries, which are adopted in more than 90 countries around the world. 

American Society of Civil Engineers was founded in 1852, a national specialized engineer society with the longest history. Now, as a global leader in the field of civil engineering, the service has covered 130 thousand specialists from 159 countries. In order to encourage information exchange, ASCE has established partnership with 65 civil engineering societies of other countries. 

American Chemical Society (ACS) was founded in 1876. As a world-renowned science and technology publishing organization, ACS has been committed to providing high-quality journals for global research institutions, companies and individuals, covering more than 20 major chemical research fields, including medicinal chemistry, chemical engineering, materials science, environmental science, Thermochemistry, etc., was rated as "the most cited journal in the field of chemistry" by the Journal Citation Report (JCR).  ACS journals can be retrieved from electronic journals from 1879 to the present, almost from the inaugural issue of each journal to the present. In 2015, the number of ACS journals will reach 46, and about 1 million articles and nearly 4 million pages of chemical literature can be viewed, including papers, investigation reports, reviews, etc.; in 2015, ACS journals launched  new journals "ACS Infectious Diseases" , "ACS Biomaterials Science & Engineering" and the first all-OA interdisciplinary journal "ACS Central Science" (no publication fee is charged to the author). 

Founded in 1947, ACM (Association for Computing Machinery) is the world's oldest and largest computer education and scientific research institution. ACM currently provides services in more than 100 countries and has more than 90,000 members in business, academia, and government. ACM is committed to developing information technology education, scientific research and application, and publishing the most authoritative and forward-looking literature, such as professional journals, conference proceedings and news bulletins, and in 1999 began to provide an online database service -ACM Digital Library. 

Founded in 1932, Annual Reviews is a non-profit organization dedicated to providing highly summarized and practical information to global scientists, focusing on publishing authoritative review journals. It is over 70 years since the first journal Annual Review of Biochemistry® was publicated in 1932. The journal Annual Reviews covers 32 disciplines in the fields of biology, medicine, physics and social sciences.       Annual Reviews invites the most authoritative and leading scientists in a variety of disciplines to write reviews of the most cutting-edge advances in the discipline and to provide directional guidance for scientific research. The half-life of the Annual Reviews article is significantly longer than that of a single document.       The Annual Reviews series is the most cited publication, with all journals ranking in the top 10 in their respective areas. Among the 6,000 journal impact factors in the latest Institute for Scientific Information, the impact factor of Annual Reviews of Immunology topped the list with 52.280, and the impact factor of Annual Reviews of Biochemistry in second place with 37.647, and more than half of impact factor of Annual Reviews series are in the top 100, regardless of discipline.       The Annual Reviews online database provides a full text of the entire article in PDF format, dating back as far as 1932, and provide a link to references, which is convenient for users to view the relevant documents. 

American Institute of Aeronautics and Astronautics (AIAA) was formed by the merger of the American Association of Rocketry and the Institute of the Aerospace Sciences in 1963. It is one of the largest aerospace publishing organizations in the world. In more than 70 years of development, AIAA Published more than 1,000 publications and 300,000 conference papers, including journals, magazines, series of books, U.S. and international standards.