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排序方式: 共有566条查询结果,搜索用时 430 毫秒
1.
李靖文 《四川畜牧兽医学院学报》2006,4(3):214-217
侧踹腿是武术散打技术中最基本的腿法之一.速度快,力量大,不易防守,而且配合步法运用,变化多端,易于在不同距离上使用,既是进攻性腿法,也是防守性腿法.因此它在散打比赛中的作用非常重要.笔者结合多年的训练实践,阐述了侧踹腿的主要训练手段和在比赛中的合理运用. 相似文献
2.
研究了催化氯化的产物分布,试验了有关条件对产物分布的影响。结果表明:氯化程度是产物分布的主要影响因素;温度的提高,有利于苄叉二氯和苄川三氯的生成;铁离子、低温及水会导致环上的氯化;水引起水解的发生。 相似文献
3.
在试验和理论分析的基础上,本文提出了复合卷曲的切屑比向上卷曲的切屑、当侧卷程度较大时比例向卷曲的切屑易于折断的观点,并且讨论了切屑产生复合卷曲及侧向卷曲的条件,这些对断屑槽的设计和使用有重要意义。 相似文献
4.
M. Bertamini M. S. Grando K. Muthuchelian N. Nedunchezhian 《Physiological and Molecular Plant Pathology》2002,61(6):349
We have studied the effect of the apple proliferation phytoplasmal infection on some features of the thylakoids from field grown apple (Malus pumila) leaves. Changes in photosynthetic pigments, soluble proteins, ribulose-1,5-bisphosphate carboxylase, nitrate reductase, photosynthetic activities and thylakoid membrane proteins were investigated. The level of total chlorophyll and carotenoids were reduced in phytoplasma-infected leaves. Similar results were also observed for soluble proteins and ribulose- 1,5-bisphosphate carboxylase activity. The in vivo nitrate reductase activity was significantly reduced in infected leaves. When various photosynthetic activities were followed in isolated thylakoids, phytoplasmal infection caused marked inhibition of whole chain and photosystem II activity while the inhibition of photosystem I activity was only marginal. The artificial exogenous electron donors, diphenyl carbazide and hydroxylamine significantly restored the loss of photosystem II activity in infected leaves. The same results were obtained when Fv/Fm was evaluated by chlorophyll fluorescence measurements. The marked loss of photosystem II activity in infected leaves could be due to the loss of 47, 33, 28–25, 23 and 17 kDa polypeptides. It is concluded that phytoplasmal infection inactivates the donor side of photosystem II. This conclusion was confirmed by immunological studies showing that the content of the 33 kDa protein of the water-splitting complex was diminished significantly in infected leaves. 相似文献
5.
张丽 《农业机械化与电气化》2011,(4):56-57
PF455S插秧机的行走底盘与国产独轮驱动插秧机相比,水田机动性能和通过性较好,但也存在手柄安装夹紧不当等问题。介绍PF455S动力插秧机的系统组成、设计原理与主要参数,对发现的侧离器手柄问题进行改进,达到了设计目的。 相似文献
6.
范体强 《农业装备与车辆工程》2014,(8):5-8
根据整车侧碰模型建立了简化模型,通过B柱上、中、下部的变形速度和B柱的变形模式对比验证了简化模型的有效性。通过对简化模型的多因素正交优化设计,总结了侧面结构材料参数对侧碰性能的影响趋势,依次为:B柱材料、门槛件厚度、B柱加强件材料、门槛件材料、B柱加强件厚度,并将优组合方案应用于整车模型,仿真结果表明了材料优化方案的B柱变形速度趋势和原模型保持一致,假人胸部上肋骨峰值保持不变,中肋骨峰值得到了降低,下肋骨峰值有所升高,但在法规允许的范围内。 相似文献
7.
Influences of sand cover on erosion processes of loess slopes based on rainfall simulation experiments 总被引:1,自引:0,他引:1
Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China.Understanding the composition,distribution,and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion.In this study,based on laboratory rainfall simulation experiments,we analyzed rainfall-induced erosion processes on sand-covered loess slopes(SS)with different sand cover patterns(including length and thickness)and uncovered loess slopes(LS)to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion.The grain-size curves of eroded sediments were fitted using the Weibull function.Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS.The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed.The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS.Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes.The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage.Sand cover on loess slopes aggravates loess erosion,not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess,compared with the loess slopes without sand cover.The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount.Furthermore,given the same sand cover pattern,a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion.This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact. 相似文献
8.
随着城市地铁的飞速发展,地铁车站在条件满足的情况下大都采用明挖法施工。在施工主体侧墙时采用满堂红支架法施工,但因施工时工期较长且易存在一些质量通病,因此,近年来大块定型移动模架被得到了广泛的应用。 相似文献
9.
陈倩 《辽宁农业职业技术学院学报》2020,22(1):42-45
大学生思想政治教育获得感是衡量实效的“标尺器”、提升质量的“助推剂”和话语转换的“凭证书”,其归根到底是思想政治教育供求平衡的产物。现阶段思想政治教育供给不平衡不充分同大学生需求之间矛盾减削获得感,思想政治教育供给要在把握以情动人、以理服人、以行化人的维度基础上,力求内容既高大上又接地气、形式既含温度又设尺度、氛围既横向搭又纵向建,实现优质供给与需求恰好适配,直接精准提升获得感。 相似文献
10.
在汽车侧面碰撞中,约束系统对降低乘员的伤害起到非常重要的作用.本文采用MADYMO仿真分析软件,建立某车型侧面碰撞的约束系统仿真模型;考虑了髋部推动块的压溃力、气囊起爆时间、气体质量流量和气袋排气孔面积对乘员损伤的影响,建立了乘员损伤指标的响应面模型;基于蒙特卡罗随机模拟,进行了侧面碰撞乘员约束系统的可靠性优化.结果表明,优化后的约束系统设计方案满足可靠性目标要求. 相似文献