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71.
西气东输管道干线截断阀的旁通管道节流阀、放空阀,站场ESD放空管道放空阀,大量使用进口Serck Audco压力平衡式旋塞阀。针对站场ESD高压放空旋塞阀内漏故障频繁,常规处理效果不好的问题,分析了进口旋塞阀的密封及压力平衡结构特点,结合现场实践经验提出了注脂处理、解体维修、更换阀门、返厂维修等处理方法。旋塞阀频繁内漏的根本原因是旋塞表面本体磨损、划伤,导致密封失效。现场解体维修中,旋塞和阀体之间的间隙难以保证恢复至原始状态,旋塞经人工打磨很难达到原始匹配精度,多次解体后维修效果可能会更差,因此解体维修应谨慎开展。返厂维修消除了旋塞表面磨损、划伤,经现场试验验证可以解决阀门内漏问题,但国产旋塞阀及国内厂家维修后的进口旋塞阀均需增加旋塞大端泄压孔,才能消除旋塞自锁现象。大端泄压孔与介质流体直接接触,当阀门用于管道介质含杂质较多的工况时,不能避免杂质进入大端底部,旋塞阀的国产化研制应在这方面开展研究。(图4,参16) 相似文献
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AIM: To investigate the effect of microwave radiation at different intensities on the rat myocardium and its possible mechanism.METHODS: The rats were radiated by the intensity of 500, 1 000, 1 500 and 2 000 W/m2 with 2 450 MHz microwave for 6 min. The heart tissue was collected 6 h after microwave radiation. ATP and mitochondria complex Ⅳ and Ⅴ were measured. The changes of the tissue structures were observed under transmission electron microscope. The apoptosis of the myocardial cells was detected by a cell analyzer. The protein level of cleaved caspase-3 was determined by Western blotting.RESULTS: The concentration of ATP and activity of mitochondria complex Ⅳand Ⅴ signi-ficantly decreased compared with control group in the cardiac tissues. The decreased number, morphological abnormalities such as dissolved cavitation, matrix and obvious tumefaction of mitochondria were observed under transmission electron microscope. The microwave radiation induced the apoptosis of myocardial cells in the rats. The cell apoptotic rate and the protein level of cleaved caspase-3 increased with increasing intensity of microwave radiation(P<0.05).CONCLUSION: Microwave radiation has obvious injury effect on the rat heart, which can cause cardiac energy metabolism dysregulation and cardiac myocyte apoptosis. 相似文献
74.
5 male Small-tail Han sheep with the body weight of 45 kg at 1.5 years old,fitted with permanent rumen fistula,to study of the effect of the supplement of the untreated commercial lysine on the rumen microbiocoenosis,rumen metabolism and whole body metabolism by 5×5 Latin square design (5 groups:control,control with low urea (equal nitrogen),low lysine,control with high urea (equal nitrogen),high lysine).The amounts of lysine-HCl supplement were 0,4.0 and 8.0 g/kg diet (as DM basis) in each group respectively,with two urea supplement control groups of equal amount of nitrogen.The results showed that by supplement of 4.0 and 8.0 g/kg of lysine-HCl diet (as DM basis) respectively,the voluntary intake of dry matter of sheep were increased by 5.5%(P>0.05) and 11.8%(P<0.05) respectively.The total amount of rumen bacteria were increased by 18.9%(P<0.01) and 23.9%(P<0.01) respectively,as the amount of rumen Coccus was increased by 21.2%(P<0.01) and 30.1%(P<0.01) respectively.The amount of rumen big Bacillus was decreased by 16.7%(P<0.05) and 33.3%(P<0.01) respectively.The total VFA of was increased by 9.6%(P<0.05) and 12.2%(P<0.01) respectively,as the butyric acid was increased by 12.8%(P>0.05) and 20.2%(P<0.01) respectively.The apparent digestibility of organic matter was increased by 6.4%(P>0.05) and 10.0%(P<0.05) respectively,the apparent digestibility of crude protein was increased by 7.0%(P>0.05) and 18.3%(P<0.01) respectively;And nitrogen retention was increased by 46.4%(P>0.05) and 110.7%(P<0.01) respectively.However,there was no effect of lysine supplement on the amounts of the rumen protozoa and fungi,and the concentration of rumen ammonia nitrogen.It was concluded that the supplement of untreated commercial lysine to adult sheep would increase the voluntary intake,digestibility,nitrogen retention the rumen microbiocoenosis and the total amount of rumen bacteria,especially the rumen Coccus of adult sheep.The effect of lysine supplement could not be replaced by urea supplement completely. 相似文献
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湖南芷江是我国传统的虫白蜡产区,素有"白蜡之乡"的美誉,但因受病虫害及气候条件等影响,芷江虫白蜡生产上一直未能实现种虫自给自足。本文研究了芷江白蜡虫生产过程中寄生蜂发生规律及综合防治方法,结果表明:芷江白蜡虫种虫生产上受寄生蜂危害严重,寄生率最高达91.3%,平均为56.1%,大量引发白蜡虫种虫绝收,寄生蜂危害是导致芷江长期不能规模化培育白蜡虫种虫的最直接原因。跳小蜂科的白蜡虫阔柄跳小蜂、白蜡虫花翅跳小蜂、中华花翅跳小蜂是白蜡虫优势寄生蜂,种群数量占寄生蜂混合种群数量的90%以上。7月至10月是寄生蜂危害高峰期。寄生蜂的优势种类结构及发生规律与云南昆明等白蜡虫种虫传统产区相比有明显差异,建议抓住优势种群危害高峰期,开展白蜡虫寄生蜂的综合控制。 相似文献
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Fat is an essential element for animal.The paper reviewed recent research progress on fat nutrition in monogastric animal at home and abroad, combining with the fat digestion and absorbing form in animal body, and summarized biological function and application of fat in production, so as to provide theoretical basis for better utilization of fat in animal production and exploration its mechanism of action. 相似文献
78.
以广东省东莞市大岭山森林公园33个乡土树种为研究对象,使用半球面影像技术和Li-6400光合仪分别获取林木冠层结构、光分布和光合作用指标,用方差分析和粗糙集理论进行评价。结果表明,林冠开度、叶面积指数、林下直射光、林下散射光、透光率和净光合速率均在各树种间存在极显著差异(p<0.0001),各指标在树种间的变化幅度也各不相同,其中林冠开度、林下直射光、林下散射光和透光率的变化幅度均超过了20%,分别为29.95%、20.40%、23.77%和22.56%,而叶面积指数和净光合速率的变化幅度分别为3.24和7.80。林冠结构和光分布均对林木净光合速率有重要贡献,但其影响程度不同。其中林冠开度最大,重要值为1/11,其余几项指标对光合作用的重要性相同,为2/33,略小于林冠开度的重要性。在评价林木冠层结构和光分布对净光合速率的综合影响力中,林冠开度贡献的权重最大,为0.27,林下直射光、林下散射光和透光率贡献的权重均为0.18。冠层结构和光分布对林木净光合速率的综合影响力在一定程度可指示冠层结构和光分布的合理性,与林木净光合速率大小不存在线性正相关关系,它只表明冠层结构和光分布对林木净光合速率的影响程度。 相似文献
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介绍了高职数字图书馆个性化信息服务的含义、服务模式、服务方式、重要性及存在的问题,提出了高职数字图书馆开展个性化信息服务的措施。 相似文献