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在设计和研究抓具系统的功能和各种特性时,首先必须对抓具颚爪的抓取曲线进行研究。本文分析和论述了抓具的抓取轨迹曲线、影响抓取轨迹曲线的因素以及抓取曲线的绘制。 相似文献
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INTRODUCTIONAtpresent,oxygenbleachinghasbecomeanlndustrializedtechnolOgy.Uptol989,thistechnologyhadbeenusedin58paPerndlls,and50%ofthemwereinEuroPe,20%inNorthemAmencaand20%inJapan.Inrecentyears,severaloxygnbleachiofequiPmenthadbeenintroducedintoChina.Inaword,oxygenbleachinglsasuccessfulandenviron-mentallyaccePtableprocessfOrPulpbleaching.However,littleworkhadbeendevotedtounderstandingthefundamentalaspectsofthissysten1,sotherewaslittledetailedinfOrmationonthel11echanismsofoxygenbleachi… 相似文献
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AIM: To study the role of liver in immune regulation in experimental endotoxemia. METHODS: 17 castrated male goats were subjected to simultaneously installing catheters in jugular, hepatic and portal veins by surgery. Four days later, lipopolysaccharide (LPS) was infused in term of three groups as followings: In group ①, LPS of 20 EU (endotoxin unit, EU)·kg-1 was infused into portal vein; In group ②, LPS of 20 EU·kg-1 was infused into jugular vein and LPS of 1 500 EU·kg-1 infused into jugular vein in group ③. Before and after infusion, blood samples were collected from the three veins through the catheters for 8 h.The plasma levels of TNF-α were measured by RIA. RESULTS: In group ①, the plasma TNF-α levels of hepatic and portal vein rose to peak value at 5 h, but that of the jugular vein did not changed. In group ②, the plasma TNF-α levels in hepatic vein rose to peak value at 3 h. The TNF-α levels of jugular vein rose to peak value at 1 h and the one in portal vein enhanced continuously between 0-8 h. In group ③, the plasma TNF-α levels in jugular, hepatic and portal vein rose to significant peaks at 1 h simultaneously. CONCLUSION: During experimental endotoxemia,liver showed different dynamic characteristics in TNF-α secretion according to the pathway and doses of LPS delivery. 相似文献
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WANG Li-wei CHEN Li-xin MAO Jian-wen ZHU Lin-yan NIE Si-huai ZHONG Ping SUN Xue-rong CAI Bo LI Pan 《园艺学报》2004,20(8):1349-1352
AIM: To investigate the relationship between osmolarity, cell volume and cell proliferation in nasopharyngeal carcinoma cells. METHODS: MTT method was applied to detect the proliferation ability of the poorly-differentiated nasopharyngeal carcinoma cell (CNE-2Z) under various osmolarity conditions. The flow cytometry was used to analyse cell cycle distribution. Cell volume was obtained by the image analysis of living cells and cell viability was determined by the trypan blue assay. RESULTS: Cultivation of cells under the hypertonic conditions of 370 and 440 mOsmol/L increased cell volume by 8.7% and 27.8% and facilitated cell proliferation by 22.2% and 33.9%, respectively. However, hypotonic incubation of cells with osmolarity of 160 and 230 mOsmol/L decreased cell volume by 12.8% and 4.1% and inhibited cell proliferation by 34.0% and 15.6%, respectively. Cell volume was positively correlated with cell proliferation rate. Long-term cultivation of cells under anisotonic conditions did not significantly alter cell cycle distribution, but hypotonic cultivation decreased cell viability. CONCLUSION: Proliferation of nasopharyngeal carcinoma cells was closely correlated with the osmolarity of culture medium and cell volume. Hypotonic cultivation may inhibit cell proliferation by decreasing cell volume to facilitate cell death mechanisms. 相似文献
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不同播种期对高产玉米品质影响 总被引:3,自引:2,他引:1
目的 研究在自然条件下,测定不同播种时期籽粒的干重、鲜重、容重、水分变化规律以及淀粉、蛋白质、脂肪的含量变化.方法 本实验以郑单958为试验材料,分八个不同播期和四个不同的采样期.结果 结果表明:郑单958的干重、鲜重在4月30日左右播种的籽粒增加显著,容重和水分变化规律也如此.结论 综合分析后,确定4月30日左右为郑单958的最佳播种期. 相似文献
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湖南小溪国家级自然保护区生态旅游资源的SWOT分析 总被引:1,自引:0,他引:1
对湖南小溪国家级自然保护区进行了生态旅游资源的SWOT分析,其优势是:良好的原始次森林和高品位的自然资源、森林浴的理想场所、优秀独特的人文资源、丰富的植物基因库存.但是可进入性差、知名度低、接待设施及能力较差.周边存在张家界国家森林公园和栖凤湖风景区的竞争威胁.分析了发展机会. 相似文献