During the past 40 years, China has made remarkable progress in important scientific and technological fields, including the successful experiment on the atomic bomb, the hydrogen bomb and the guided missile launching and retrieval of man-made satellites, the launching of carrier rockets, the synthesis of bovine insulin and the ribonucleic acid transferred from fermented alanine, and the successful cultivation of hybrid rice. In recent years, research on superconduction, the positron and negatron electronic collider, new technology of petroleum water injection, the KM-4 sun imitator, emulative technologies and the research on aerodynamics have reached the world's advanced level. In 1994, China recognized 26,000 important scientific and technological achievements at or above the provincial or ministerial level. The most important included internationally advanced atomic grade control and processing, linking the national computer with the international network, cultivating 270 new crop varieties, and the development of high-speed locomotives capable of reaching 160 km per hour and the 4E-type Dongfeng heavy internal-combustion engine.