共查询到20条相似文献，搜索用时 156 毫秒
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遗传的基本规律是高中生物学的重点内容之一。指导学生掌握有关遗传规律习题的解答方法,不仅有利于复习遗传知识,对促进学生智力的发展也是有益的。下面遭过两个例题,对解答遗传规律问答题的基本方法,作一简要的分析。 [例一]萝卜根有圆形、长形和卵形三种。经过一连串的杂交实验,结果如下:长形和卵形杂交产生159个长形和156个卵形后代;圆形和卵形杂交产生199个圆形和203个卵形后代;圆形和长形杂交产生576个卵形后代,卵形和卵形杂交产生121个圆形、243个卵形、119个长形后代。试问:圆形、长形和卵形三种萝卜根的基因型各是什么?并说明理由。 相似文献
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涂杰 《武汉职业技术学院学报》2013,12(1):97-99
为了减小齿轮的齿根弯曲应力,提高齿轮的传动能力,本文根据非对称渐开线齿轮研究学者提出的齿廓方程构建思路进行了建模,并用NISAⅡ进行了齿轮应力变化的有限元分析。通过分析比较得出使用非对称渐开线齿轮可以提高齿轮的弯曲强度从而提高齿轮的传动能力。 相似文献
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采用有限元分析方法对烟草包装机椭圆齿轮的静力学特性进行理论计算和研究,建立椭圆齿轮的有限元模型,通过有限元分析软件ANSYS Workbench对椭圆齿轮进行分析,得出椭圆齿轮各轮齿的应力分布,并对计算结果进行分析。该方法和所得结果为椭圆齿轮的优化设计提供了参考。 相似文献
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目的:探究非正交面齿轮与直齿圆柱齿轮组成的齿轮副在啮合传动过程中动力学特性,为基于面齿轮的传动装置提供动力学仿真分析参考.方法:首先根据啮合原理,利用包络法推导非正交面齿轮齿面的曲面族,再通过VS编写相应的计算程序,计算得到非正交面齿轮齿面上的有限个坐标点,然后使用catia曲面设计程序,得到非正交面齿轮模型,最后将非正交面齿轮与配对圆柱齿轮进行正确装配,使用动力学分析软件Adams进行啮合仿真分析.结果:通过对比分析表明,动力学仿真分析下的非正交面齿轮输出转速、法向载荷、圆周力、径向力和轴向力与理论计算基本一致.结论:验证了非正交面齿轮在啮合传动过程中有轴向力的产生,面齿轮传动具有周期性啮入啮出的特性. 相似文献
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提出椭圆齿轮的近似建模方法,将椭圆齿轮节曲线分成四段圆弧,在每段圆弧上按照普通圆齿轮的建模方法建立各轮齿模型,最后将四段圆齿轮模型拼接起来形成最终的椭圆齿轮近似模型.并分别针对齿形折算法和近似法建立的模型进行模态分析,获得了椭圆齿轮前五阶固有频率.对比分析表明,椭圆齿轮的近似建模方法建模效率较高,所得模型虽然略有误差,但对模态分析结果影响不大,同时为普通铣床加工椭圆齿轮奠定了基础. 相似文献
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基于ANSYS的高速包装机的椭圆齿轮模态分析 总被引：1，自引：1，他引：0
采用有限元法,建立了椭圆齿轮的动力学模型,通过有限元分析软件ANSYS对椭圆齿轮进行模态分析,得到了椭圆齿轮的前六阶固有频率和对应振型。该方法和所得结果为动态设计提供了参考,同时也为椭圆齿轮系统的动态响应计算和分析奠定了基础。 相似文献
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利用多媒体制作软件Authorware制作动态椭圆,方法简便,效果理想．本文介绍了动态椭圆的设计思想和制作方法． 相似文献
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讨论了椭圆及其内接、外切n边形的仿射等价问题,给出了椭圆及其内接、外切n边形与圆及其内接、外切正n边形仿射等价的必要条件和充分条件． 相似文献
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Rao CG Seshagiri SV Ramesh C Ibrahim Basha K Nagaraju H Chandrashekaraiah 《Journal of Zhejiang University. Science. B》2006,7(3):215-220
In the present study, polyvoltine germplasm stock ofAndhra Pradesh State Sericulture Research and Development, Institute （APSSRDI） was evaluated for its performance based on quantitative and qualitative traits. Twenty-one oval and 10 peanut cocoon shaped lines were reared in different seasons of the year. Since the polyvoltines are non-diapausing, six generations were reared and evaluated for various economically important traits based on evaluation index and sub-ordinate function statistical methods. Ten top ranked lines obtained by using both the methods were identified as potential parental strains. Among oval lines, APMI4, APMI 1, APMIS, APMW9, and APMI9, and among peanut lines APMD5, APMDI, APMD3, APMD9 and APMD8 were selected as base material. The identified high yielding lines will be used in various breeding programmes as initial parents for the synthesis of superior polyvoltine breeds/hybrids. 相似文献
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Silicon carbide nanotubes (SiCNTs) with special morphology synthesized by supercritical hydrothermal method at 470 ℃ and 8 MPa have been reported in this paper.SiCNTs with special morphology were characterized by transmission electron microscopy (TEM) and high-resolution TEM (HRTEM).There are two kinds of silicon carbide with special morphology:One is oval SiCNTs with small aspect ratio,the other is bamboo cone-shape structure.SiCNTs have been analyzed by fluorescence spectrometer.The results indicate that the SiCNTs have strong photoluminescence (PL) property.The SiCNTs with oval shape are one kind of intermediate state of growth process of nanotube.The growth mechanism of silicon nanotubes has been proposed based on experiment data.The investigations of growth mechanism of SiCNTs with bamboo structure show that the defect produced in the growth process play the important role in SiCNTs with special structure. 相似文献
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Silicon carbide nanotubes (SiCNTs) with special morphology synthesized by supercritical hydrothermal method at 470 °C and
8 MPa have been reported in this paper. SiCNTs with special morphology were characterized by transmission electron microscopy
(TEM) and high-resolution TEM (HRTEM). There are two kinds of silicon carbide with special morphology: One is oval SiCNTs
with small aspect ratio, the other is bamboo cone-shape structure. SiCNTs have been analyzed by fluorescence spectrometer.
The results indicate that the SiCNTs have strong photoluminescence (PL) property. The SiCNTs with oval shape are one kind
of intermediate state of growth process of nanotube. The growth mechanism of silicon nanotubes has been proposed based on
experiment data. The investigations of growth mechanism of SiCNTs with bamboo structure show that the defect produced in the
growth process play the important role in SiCNTs with special structure. 相似文献
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于丽亚 《新疆教育学院学报》2009,25(4):116-118
文章采用项目反应理论中的两参数正态双卵模型,利用MCMC的方法,给出了Gibbs抽样估计项目参数的Matlab程序,根据该程序对某校本科生的期末成绩数据进行运算得出了项目参数,并加以分析。 相似文献
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基于工作过程的课程开发是现代职业教育改革与发展的趋势;结合数控加工技术类课程项目的改革,本文在非圆曲线轮廓的回转体类零件加工中,以典型椭圆轮廓零件为案例,编制宏程序应用在数控车床中,这对职业院校课程改革和企业实际工作相结合具有一定的借鉴作用。 相似文献