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A tubular focused sonochemistry reactor 总被引:1,自引:0,他引:1
ZHOU GuangPing LIANG ZhaoFeng LI ZhengZhong ZHANG YiHui 《科学通报(英文版)》2007,52(14):1902-1905
This paper presents a new sonochemistry reactor, which consists of a cylindrical tube with a certain length and piezoelectric transducers at tube’s end with the longitudinal vibration. The tube can effectively transform the longitudinal vibration into the radial vibration and thereby generates ultrasound. Furthermore, ultrasound can be focused to form high-intensity ultrasonic field inside tube. The reactor boasts of simple structure and its whole vessel wall can radiate ultrasound so that the electroacoustic transfer efficiency is high. The focused ultrasonic field provides good condition for sonochemical reaction. The length of the reactor can be up to 2 meters, and liquids can pass through it continuously, so it can be widely applied in liquid processing such as sonochemistry. 相似文献
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邱招丰 《杭州师范大学学报(自然科学版)》2013,(6):513-516
群G的一个子群H称为在G中弱φ-可补,如果存在G的一个次正规子群K,使得G—HK且HnK≤φ(H),其中φ(H)为子群H的Frattini子群.文章利用子群的弱争可补性对有限群结构的影响,给出了有限群为超可解群的若干充分条件. 相似文献
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Huang JianGuo Han JianWei Li HongWei Cai MingHui Li XiaoYin Zhang ZhenLong Chen ZhaoFeng Wang Long Yang XuanZong Feng ChunHua 《科学通报(英文版)》2009,54(4):616-622
There is a large amount of micro debris ranging between millimeters and micrometers in space, which has significant influence on the reliability and life of spacecrafts through long-duration integrated impacts and has to be considered in designing a vehicle’s suitability to the space environment. In order to simulate the micro-impacts on exposed materials, a plasma-driven micro-particle accelerator was developed. The major processes, including the acceleration, compression and ejection of plasmas, were mode... 相似文献
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Spatiotemporal variation in alpine grassland phenology in the Qinghai-Tibetan Plateau from 1999 to 2009 总被引:3,自引:0,他引:3
DING MingJun ZHANG YiLi SUN XiaoMin LIU LinShan WANG ZhaoFeng BAI WanQi 《科学通报(英文版)》2013,58(3):396-405
Plant phenology is the most salient and sensitive indicator of terrestrial ecosystem response to climate change.Studying its change is significantly important in understanding and predicting impressively changes in terrestrial ecosystem.Based on NDVI from SPOT VGT,this paper analyzed the spatiotemporal changes in alpine grassland phenology in Qinghai-Tibetan Plateau from 1999 to 2009.The results are enumerated as follows:(1) The spatial distribution of the average alpine grassland phenology from 1999 to 2009 is closely related to water and heat conditions.Accompanying the deterioration in heat and water conditions from southeast to northwest,the start of growth season(SOG) was delayed gradually,the end of growth season(EOG) advanced slowly,and the length of growth season(LOG) shortened gradually.Elevation played an important role in the regional differentiation of phenology,but a dividing line of approximately 3500 m existed.Below this line,the phenology fluctuated irregularly with altitude change,whereas above the line,the phenology is closely related to altitude change.(2) From 1999 to 2009,SOG of the alpine grassland came earlier by six days per decade(R2=0.281,P=0.093),EOG was late by two days per decade(R2=0.031,P=0.605),and LOG lengthened by eight days per decade(R2=0.479,P=0.018).The early SOG,the late EOG,and the extended LOG mainly occurred at the center and east of the Plateau.SOG in most of the Plateau advanced significantly,especially in the eastern Plateau.(3) The inter-annual phenology changes of the alpine grassland in the Qinghai-Tibetan Plateau exhibited significant differentiation at different elevation and natural zones.The inter-annual changes at high altitude were more complicated than that at low altitude.The most significant phenology changes were found in the eastern Qinghai-Qilian montane steppe zone,and non-significant changes occurred in the Southern Tibet montane shrub-steppe zone. 相似文献
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