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61.
拖拉机侧翻事故是农业生产过程中最严峻的安全问题之一,现有主、被动安全手段均未能从根本上解决该问题。在前期利用飞轮—电机加速旋转时产生的反向力矩进行姿态调节实现失稳态拖拉机姿态回稳的基础上,为进一步避免姿控飞轮卸载过程造成能量浪费,本文基于1∶16比例模型试验平台设计搭建了飞轮卸载能量回收电路,并通过模型试验对其回收效果进行了验证。试验结果表明,当模型拖拉机以0.2m/s速度行驶于路面不平度较高的G级、H级路面出现侧翻趋势并实现姿态回稳时,整机侧向姿态角降至10°后能量回收系统可介入工作,此时回收电压出现峰值0.97V(H-B轨迹),随后其数值变化趋势与姿控飞轮转速的降低趋势相似,直至飞轮卸载完成后回收电压归零。试验过程中,飞轮—电机系统在对不同的整机侧翻趋势做出响应时,能量回收系统完成的电量回收不同,但均完成了对飞轮卸载能量的部分回收,提高了整机能源的利用效率。 相似文献
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覃良军 《上海交通大学学报(农业科学版)》2015,(5):37-41
在校园足球得到空前重视和全力推动的大环境里,作为一个篮球教育者,必须去思考篮球的发展与未来。足球、篮球此时的不同待遇有着复杂的现实因素和社会因素,校园足球的发展也将影响校园篮球的发展。在这样的背景下,在对比中思考校园篮球发展的问题所在,从而提出有效的对策。 相似文献
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为优化旱作马铃薯氮素施用量,进一步提高马铃薯产量和改善薯块品质,通过盆栽种植方式,研究氮素营养对马铃薯干物质积累量、根冠比、产量及薯块品质的影响。结果表明:施氮量为190 kg/hm~2时,马铃薯各生育时期干物质积累量、根冠比和单株产量最高,根据一元二次拟合方程得出最佳施氮量为206.39 kg/hm~2,此时马铃薯单株产量为388.22 g,与实际最佳施氮量接近;马铃薯薯块淀粉和VC含量均在施氮量为190 kg/hm~2时最高,薯块蛋白质含量随氮素的增加呈递增趋势,而有机酸含量随氮素增加呈先增后降的趋势,在施氮量为350 kg/hm~2时达到最大值。在试验条件下,综合分析马铃薯产量形成特性及各品质指标,马铃薯氮素最适施用量为190~206.39 kg/hm~2。 相似文献
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CHEN Wei-qian PENG Yan-ping ZHANG Wei-xi YE Le-ping DONG Liang XIA Xiao-dong 《园艺学报》2017,33(8):1481-1486
AIM: To investigate the effect of hypercapnia on hypoxia-induced pulmonary hypertension and the changes of lysyl oxidase (LOX) and extracellular matrix collagen cross-links in the rat. METHODS: Sprague-Dawley rats were randomly divided into 4 groups:normoxia group, hypoxia group, hypercapnia group and hypoxia+hypercapnia group. LOX activity was detected by fluorescence spectrophotometry. LOX protein expression was detected by immunohistochemistry and Western blot. The mRNA expression of LOX in the pulmonary artery was detected by real-time PCR. RESULTS: The levels of mean pulmonary artery pressure (mPAP), RV/(LV+S) and WA/TA in hypoxia group were significantly higher than those in normoxia group (P<0.01). Moreover, the levels of mPAP and RV/(LV+S) in hypoxia+hypercapnia group were significantly lower than those in hypoxia group (P<0.01). However, no significant difference of mPAP and RV/(LV+S) between hypercapnia group and normoxia group was observed. In hypoxia group, the collagen cross-links in the lung tissue was significantly higher than that in normoxia group and hypercapnia group (P<0.01). Importantly, collagen cross-links in the lung tissue of hypoxia+hypercapnia group was significantly lower than that in hypoxia group (P<0.01). There was no significant difference in collagen cross-links between hypercapnia group and normoxia group. The expression of LOX at mRNA and protein levels and its activity in the pulmonary arteries of hypoxia group were significantly increased as compared with normoxia group (P<0.01). Furthermore, the expression of LOX at mRNA and protein levels and its activity in the pulmonary arteries in hypoxia+hypercapnia group were lower than those in hypoxia group (P<0.01). CONCLUSION: Hypoxia not only up-regulates LOX but also promotes collagen cross-linking in the rat lung, which contributes to the development of pulmonary hypertension. Hypercapnia inhibits hypoxia-induced LOX expression and collagen cross-linking, therefore impairing the progress in hypoxia-induced pulmonary hypertension. 相似文献
69.
贵州省黔东南地区草地贪夜蛾寄生性天敌资源调查初报 总被引:1,自引:0,他引:1
草地贪夜蛾Spodoptera frugiperda(J. E. Smith)于2019年5月入侵贵州黔东南地区,严重威胁当地农业生态。黔东南地区丰富的生物资源是挖掘草地贪夜蛾自然天敌的重要基础。为明确黔东南地区草地贪夜蛾天敌的发生情况,2019年5月至7月,采用五点取样法对选取的3个地点开展调查。结果表明,草地贪夜蛾在黔东南地区的主要寄生性天敌有5类,分别为白僵菌属、绿僵菌属、茧蜂科、姬蜂科和黑卵蜂属昆虫,寄生率最高分别为45.50%、57.00%、3.00%、20.00%和12.50%,寄生草地贪夜蛾幼虫期4种天敌综合控制力最高达96.50%。本研究可为草地贪夜蛾天敌资源挖掘与利用提供重要参考。 相似文献
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AIM: To investigate the pathogenesis of chronic obstructive disease (COPD) in mice by using nasal drip of cigarette dust particles (DSP) induced pulmonary function damage model.METHODS: BALB/c mice were randomly divided into control group, LPS 100 mg/L group, DSP 0.75 mL/L group, DSP 1.5 mL/L group and DSP 3 mL/L group for 30 days. The method of nasal drip was used for 30 days to establish the COPD model. Rrs, Ers, Crs, Est, Cst, P-3/8Rn, P-3/8G and P-3/8H were measured for evaluating lung function of the mice in each group by the method of FlexiVent. The effect on the increase of airway resistance induced by methacholine (Mach) was determined using main bronchial rings by Myograph method. The HE, Masson and Resorcinol fuchsin staining of mouse tracheas and lung tissues were conducted. RESULTS: Continuous nasal drip with DSP for 30 days increased Rrs, Ers, Est, P-3/8Rn and decreased Crs, Cst, P-3/8G and P-3/8H in the mice. DSP significantly shifted the dose-effect curve of tracheal contraction induced by Mach to the left, increased the sensitivity of the airway to Mach, and significantly increased the maximal contractile airway effect of Mach. Exposure to DSP caused fibrosis of airway subepithelial, deposition of collagen in the airway basement membrane under the reticular plate, induced reticular plate thickening, pulmonary bronchial lumen serious deformation, and the inflammatory cell infiltration in the lung of mice. Significantly increased alveolar wall muscle fibers and collagen fibers were also observed. CONCLUSION: The lung function and pathomorphological changes of COPD mice induced by 30 days nasal drip of cigarette dust particles were similar to those of human COPD. 相似文献