The main content of this dissertation includes: 1. Research on the theory of ultrasonic power supply, introduce its development process. On the basis of these, fix on the scheme of medical ultrasonic low-power supply. 2. According to the principle of modularized design, divide medical ultrasonic low-power supply into four parts. They are power amplify circuit, power control circuit, frequency automatic tracking circuit and matching circuit. Separately research on their theories and design their circuits and necessary programs, especially, effectively resolve the problem tracking the supersonic vibration system with a narrow syntony frequency bandwidth and a high swing. 3. The matching experiments gain good result, and prove that medical ultrasonic low-power supply is entirely up to the mustard on intellectualization, wide band of working frequency, steady output and high efficiency.

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Exploratory study was made on the Guanting reservoir influent treatment by using two-stage BAF at extreme low temperature.The results show that the removal of organics and ammonia nitrogen is seriously inhibited due to low temperature,and the conversion of nitrite into nitrate is no longer a limiting factor of complete nitrification.One possible hypothesis is that the activity of nitrobacter is hi gher than that of nitrosomonas at extreme low temperature.

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This paper is in view of low pressure, low production and downhole throttle characters of SuLiGe gas field, developed the research of the foam drainage technology, aim of deceling the loss of wellhole pressure and triturate a new low density foaming agent successfully, solved the welldown liquid loading issue of SuLiGe gas field.

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In recent years, with the advanced requirements for speedup and heavy load from rail transport, the advanced requirements for the property of supporting pedestal have been proposed. The inherent defectivenesses which include the low mechanical property, low fatigue ductility and low shock resistance of cast-steel product, and the avoidless gas cavity, shrinkage porosity, inclusion, crack, etc in cast-steel product, existed in the product of Cast-steel supporting pedestal, have threatened the high speed and safe running of railroad.

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The titanomagnetite is characterized by low content of chadacryst minerals, high content of iron and low content of titanium, therefore high quality vanadium-iron concentrate with high iron and low titanium could be obtained.

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The biomarkers such as the n-Alkanes, the isoprenoids, the terpane, and cholestane were detected through GC-MS analysis. Based on the study of the biomarkers, the biological evolution during Permian and Triassic can be divided as three stages, namely, the mixing source stage of low biota such as thallose and advanced plant in late Permian (below bed 63), the stage of low biota such as thallose in the boundary transitional layer (bed 63-69) and the mixing source stage of advanced plant and low biota such as thallose in early Triassic (above bed 69). What's more, the second stage near the boundary transitional layer can be subdivided into 4 stages. The stages of biota evolution is close related with sedimentary environment changing and the boundary transitional layer.

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Based on the problems of low viscosity index and the acidity increasing in the lubricating base oil,it has been found that the unstable quality of the crude oil was the root cause to effect on the quality of the base oil by analysis for long time;the low viscosity index and the higher acidity were resulted from the low paraffinicity and the high content of aromatics,cyclane.

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