广西片形吸虫中间宿主—小土窝螺线粒体rrnL基因遗传多态性研究

为研究广西小土窝螺不同地理株线粒体大亚基（large subunit ribosomal rRNA,rrnL）基因的遗传多态性,对广西大片吸虫6个流行地区96个小土窝螺样品的rrnL基因进行PCR扩增,通过单链构象多态性（single strand conformation polymorphism,SSCP）技术筛选出具有代表性的样品进行克隆、测序,并用DNAStar 5.0及MEGA 4.0软件加以比对分析。结果显示,6个地区小土窝螺rrnL基因PCR扩增长度约500 bp,在长度为273 bp的序列中检测到15个变异位点,占核苷酸总数的5.49%。百色、南宁和桂林3个地区相同地理株间存在较大的遗传差异。种系发育分析表明,线粒体rrnL基因在一定程度上不是研究小土窝螺种群遗传变异的良好分子标记。本研究为阐明片形吸虫中间宿主—小土窝螺的种群遗传关系提供了基础数据。     

军曹鱼MHC-Ⅱα基因全长cDNA的克隆及其组织表达分析

本研究根据其他鱼类MHC-Ⅱα基因的保守序列设计兼并引物,运用同源克隆和末端快速扩增方法扩增了军曹鱼MHC-Ⅱα基因的全长cDNA序列,并对cDNA及其氨基酸序列进行了分析,比较了军曹鱼和其他物种的MHC-Ⅱα氨基酸序列的差异,分析了军曹鱼MHC-Ⅱα基因的组织分布及经LPS刺激后头肾组织中MHC-Ⅱα基因的表达变化。结果表明,军曹鱼MHC-Ⅱα cDNA全长998 bp,包括53 bp的5′末端非编码区（5′UTR）、234 bp的3′末端非编码区（3′UTR）及711 bp的开放阅读框（ORF）,编码236个氮基酸,其蛋白质分子质量约为25.94 ku,等电点为4.39;军曹鱼MHC-Ⅱα蛋白质序列具有一些重要的特征,包括前导肽、α1、α2、CP/TM/CYT区和保守的半胱氨酸等;军曹鱼MHC-Ⅱα与鼠、人及其它鱼类的氨基酸同源性在25.0%～69.5%之间。Real-time PCR检测结果显示,MHC-Ⅱα基因在正常军曹鱼组织中均有表达,但其表达量在各种组织中存在差异,其中较强表达于头肾、鳃,中等程度表达于脾脏、肠,在心脏、脑、肌肉中表达较弱;经LPS刺激后,头肾中MHC-Ⅱα基因表达下调。     

双斑截尾寄蝇卵及幼虫发育过程及形态特征观察

双斑截尾寄蝇(Nemorilla maculosa Meigen)为草地螟(Loxostege sticticalisL.)寄生蝇的优势种之一,是草地螟重要的寄生性天敌,本文首次报道了双斑截尾寄蝇卵期及幼虫期的各个虫龄的形态特征及发育过程。研究结果表明:双斑截尾寄蝇在以草地螟为寄主时的卵期约为4d,从卵孵化到离体化蛹的整个幼虫期可以分为3个虫龄,1龄虫期为1d左右,体色为白色,体长约为1.27mm;2龄虫期为4d左右,淡黄色,体长约为1.87mm;3龄虫期为2d左右,淡黄色,体长约为5.24mm。     

基于流场特性的液力缓速器叶栅角度优化设计

为了提高液力缓速器制动转矩系数,对液力缓速器内湍流流动进行了三维瞬态多相流数值模拟。通过对其内流场特性分析,发现液力缓速器工作流道的壁面脱离现象以及弦面内产生的涡旋区不利于恒定制动转矩的输出。针对这一问题,考虑到液力缓速器各结构参数之间的相关性,对多参数共同作用的内流场进行数值分析,优化叶栅参数。结果表明,通过分析多参数共同作用的流场来优化缓速器叶栅参数的方法比较合理;对液力缓速器叶片前倾角和叶片前缘倒角进行优化后,叶轮流道内存在的涡团和流动分离现象基本消失,制动转矩系数提高6%。     

Dynamic analysis and optimization of gear trains in a megawatt level wind turbine

Through coupling vibration analysis of the transmission system of a 1.5 MW wind turbine gearbox, a torsional vibration model of a gear drive system in wind turbines is established. The fourth order Runge Kutta integration method is applied to calculate the dynamic response of a gear system caused by wind loads, time varying meshing stiffness, and system damping. The harmonic balance method is used to find the analytic solution. Based on the solution, a mathematical model for optimum gear system design is established. The model aims at minimizing the vibration acceleration of the planet gear and the total mass of the gear transmission system. The optimization toolbox in MATLAB program is adopted to obtain the optimal solution. A calculated example shows that the primary natural frequency of the gear system has been raised, the dynamic properties of the gear train have been improved remarkably, and the total mass of the gear train has been decreased.     

Plastic upper bound theory reliability analysis of coal gangue hills

We established the plasticity limit analysis reliability limit state equation and the reliability calculating formula for gangue hills using the JC method. This work was based on the plasticity mechanics limit analysis upper bound theory and traditional slice methods. A reliability index of gangue hill stability was derived using this equation. It was found that the safety coefficient of gangue hills derived by the limit state equation risks failure if the variability of cohesion and internal friction angle are not considered. When the variability of the strength parameters rises, the reliability theory more consistently projects practicality than the limit state equation for gangue hill stability assessment.     

contact stress and steady thermal analysis of herringbone gears in a gas turbine

To obtain the distribution characteristic of contact stress and the bulk temperature on the surface of herringbone gears, parameter modeling of gears was carried out by parametric design language. A numerical simulation was given to calculate the contact stress field and the steady thermal field by combining heat transfer theory, tribology theory, and mesh theory. The distribution of contact stress, the bulk temperature and heat flux also were analyzed. The analysis results show that the distribution of the load along the contact line possesses regularity. The heat flux along the tooth depth direction decreases first and then increases. The effect of thermal conduction of the tooth is stronger than that of convective heat transfer. The conclusion indicates that the finite element emulation method can be used to estimate the transmission performance of herringbone gears.     

德美与中美〖HTSS〗（新疆型）〖HTH〗杂交后代体尺体重变化

德国美利奴是肉毛兼用细毛羊,原产德国,对于干旱地区有较好的适应性。该羊具有生长发育快、适应性强、产肉性能好和繁殖率高的特点。本次试验研究的主要内容是中国美利奴羊（新疆型）在导入德国肉用美利奴羊血液后,其后裔(周岁公羊)在体重体尺方面的变化情况。根据试验测得的数据,经统计分析结果表明：杂交一代与中国美利奴（新疆型）相比,在各阶段平均体重均得到提高,提高范围0.07~2.1 kg。杂交二代各阶段平均体重与中国美利奴（新疆型）相比,其提高幅度大于杂交一代。在体尺上杂交一代在胸深、胸围、胸宽、十字部宽上均表现了较高的杂交优势,在体尺大小上得到了很大提高。为体重增加、产肉性能的提高提供了良好的潜在条件。杂交二代在各体尺指标上没有增加（除前肢高）,同杂交一代相比具有降低趋势。所以杂交一代是我们需要的经济类型。引进德国美利奴有利于提高中国美利奴（新疆型）的产肉性能,它是提高新疆细毛羊毛肉综合性能较为理想的父本品种。     

Study on Intelligent Displaying Mechanism of Control Fissure of Perilous Rock

Perilous rock is a kind of typical disaster and characterized by multitudinous structural planes; when the disaster happens, only one of the planes is the control fissue and the others are secondary. In this paper, the authors have done some attempts for     

A Matlab Based Numerical Simulation Analysis of Shore Stress in Vacuum Plate Glass

A numerical simulation method, the node method, and single, multi-triangle progression were used to analyze the shore stress field of vacuum plate glass. By optimizing the shore distribution, the points of greatest and least stress in vacuum plate glass were determined. The distributions of greatest stress in vacuum plate glass were calculated using MATLAB. These calculations can provide numerical foundations for accurately analyzing the shore stress and flexibility of vacuum plate glass. The result shows that the greatest stress exists in the end surface of every shore, and the maximal stress is in the second shore at four-square sides, then follows the shore of next row. The theoretical calculations correspond to the software analysis results.