Objective To explore the research focus and current status of saturation diving in China by bibliometric method,so as to provide reference for the development of saturation diving.Methods With the subject term of"saturation diving",the relevant literatures were retrieved from China National Knowledge Infrastructure(CNKI),VIP,Wanfang,and Chinese biomedical literature database.NoteExpress software was used to remove repetitive literatures.Results A total of 306 literatures were included,which were published in 90 journals.The journals with more publications were Chinese Journal of Nautical Medicine and Hyperbaric Medicine,Journal of Navy Medicine,and Chinese Journal of Applied Physiology,etc.A total of 501 keywords were used 1 716 times.Visual analysis revealed that the hotspot keywords were saturation diving,simulation experiments,animal experiments,patrol diving,helium oxygen saturation diving,saturation diving systems,and ternary gas mixtures.There were 55 keywords with word frequency≥4,forming 5 meaningful clusters.Research hotspots focused on saturation diving equipment,saturation diving support system,physiological function,medical support and so on.Conclusion The development of saturation diving in China is driven by important events.Technological breakthroughs depend heavily on the contribution of military scientific research.However,experimental research achievements are far more than applied practice.In the future,saturation diving experiment chamber with larger simulation depth should be built,saturation diving system with stronger practical performance should be developed,and the training of saturation divers and medical support personnel should be increased,so as to improve the operation technique and level of saturation diving in China.

Objective To ensure the freezing quality of prepared frozen foods through the access of research on the effects of such influential factors as the refrigeration compressor, the quick-freeze temperature, freezing rate, energy conservation etc.Methods The application and performance of single-stage screw compressor and the double-stage screw compressor were compared in order to choose the proper product type.Results The double-stage screw compressor used in the R22 and R404A refrigeration systems had the obvious advantages of better refrigeration capacity, improved refrigeration efficiency and energy conservation, when evaporation tempera-ture was below-30℃.Conclusion The double-stage screw compressor had wide application in the naval refrigerated food supply chain for naval vessels.