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利用黄淮地区的12个高产夏大豆品种(系),通过NCⅡ交配设计,对12个主要农艺性状的遗传进行了分析。结果表明,所有性状的加性方差大于显性方差。主茎节数、株高、每簇荚数和主茎荚数的加性成分占绝对优势,遗传力较高。分枝荚数、单株粒数和单株粒重的显性成分比例大,遗传力较低,其中单株粒重趋于完全显性。主茎节数的显性成分很少,其它性状均为部分显性。建立了单株产量与产量因子之间的逐步回归方程。 相似文献
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本文以普通高校标枪运动员助跑节奏的测试结果,运用运动生物力学理论进行技术分析,认为助跑中的主要错误动作是稳定性差和速度利用率低。参阅有关资料,结合实践经验,提出了业余标枪运动员合理的助跑节奏,供训练时参考。 相似文献
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The natural frequencies, aerodynamic noise, whistling noise, and self-excited vibration between the common circular saw with uniform thickness and the circular saw with step thickness (thin on its outer part and thick on its inner part) were researched during idling. The natural frequencies of the circular saw with step thickness increased with an increase in the thickness and in the radius of the thick part. The frequencies of the circular saws with step thickness (thick at the inner part) were higher than that of the thin circular saw with a uniform thickness of 0.5mm. The aerodynamic sound pressure level induced from circular saw teeth increased with an increase in the tooth thickness. The whistling noise and self-excited vibration easily occurred in the thick circular saws (1.5, 2.0, and 2.5mm). The whistling sound pressure level and the vibration amplitude increased with an increase in the thickness of the saw. None of the designed circular saws with step thickness generated whistling noises or self-excited vibration during idling.Part of this report was presented at the 45th annual meeting of the Japan Wood Research Society at Tokyo, April 1995 and the 12th International Wood Machining Seminar at Kyoto, October 1995 相似文献
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分析了数种优化方法,利用Excel的特点,结合某梯级泵站具体情况并考虑了电价的波峰、波谷变化规律以及级间弃水量最小等因素,提出了一种实时优化的方案,在该泵站仿真系统上进行模拟计算,获得较好的结果,达到了经济运行的目的. 相似文献
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水泥稳定碎石骨架密实结构的合理级配 总被引:1,自引:0,他引:1
采用逐级填充方法,通过最大密实度曲线可以确定出粗集料级配和粗细集料的填充比例,得到理想的骨架密实结构.与规范中值级配进行抗压强度、劈裂强度和缩裂性质的比较结果表明:该方法确定的混合料级配具有良好的路用性能. 相似文献
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研究了由微粗糙表面与光滑平面形成的混合接触承载性能.混合接触由固体-边界膜-固体三体接触和固体-流体固体三体接触组成.两表面相对滑动时表面间形成许多个微阶梯轴承.这些微阶梯轴承的承载量之和构成两接触表面承载量.微阶梯轴承的入口区为传统流体区域,出口区为边界膜区域.给出了微阶梯轴承承载能力分析方法,研究了边界膜对混合接触承载能力和接触性能的影响. 相似文献
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