会计信息失真与公司治理结构

从会计信息失真的含义界定入手，分析了我国目前公司治理结构与会计信息失真之间的关系。从内部、外部治理结构两方面讨论了会计信息失真的影响因子，并提出了相应的治理对策。     

稻曲病侵染时期和流行因素研究

分期接种试验的结果表明,稻曲病对水稻的侵染时期,主要在孕穗末期至破口期,病菌侵入籽粒在水稻开花前。3a的系统调查和对比分析结果说明,水稻穗期最高气温>32℃的天数少,降雨量大,有利病菌的侵入和发展流行,品种间抗(耐)病性差异显著。近年来稻曲病发生严重的主要原因是单季晚稻的大面积种植,穗期气候条件适宜病害发生流行。     

The effect of sowing date, stale seedbed, row width and mechanical weed control on weeds and yields of organic winter wheat

Three field experiments were carried out in organically grown winter wheat in Denmark. The treatments were sowing time (normal or late sowing) and false seedbed, row width (12 and 24 cm) and weed control method [untreated; mechanical weed control (weed harrowing at 12 cm supplemented with inter‐row hoeing at 24 cm); and herbicide weed control]. Weed biomass in midsummer was greatest on plots sown at the normal sowing time (compared with delayed sowing) and was reduced by mechanical or chemical weed control (compared with untreated plots). Row width alone had no influence on weed biomass, but in the experiment with high weed pressure, the more intensive mechanical weed control used at a row width of 24 cm reduced weed biomass. Normal sowing time tended to give higher yields, but this was only statistically significant in one of the three experiments. Wide rows gave a yield decrease in the experiment with low weed pressure. The effect of weed control on yield was dependent on the weed pressure. At low weed pressure, mechanical weed control caused a yield decrease compared with untreated or herbicide treated. At intermediate weed levels there were no differences, whereas at high weed pressure, mechanical weed control and herbicide treatment caused a yield increase compared with untreated. False seedbeds were shown to contribute to a decrease in the soil seed reserve.     

不同薏苡品种黑穗病发生情况调查

为筛选出适合宁化县推广种植的抗黑穗病品种，于2013年对当地种植的5个薏苡品种黑穗病发生情况进行调查，结果表明：龙薏一号黑穗病发病率最低，表现对黑穗病的抗性强，且产量较高，每667m2产量为257．43kg，适宜在薏苡黑穗病重发区推广种植。     

长治地区玉米丝黑穗病发生原因与防治对策

2001年玉米丝黑穗病在山西省长治地区发生严重,造成发病面积约2 000hm²,玉米产量损失严重.本文对该病发生概况、症状、发生原因进行了叙述,结合当地调查结果,提出了防治对策。     

机械力催化玉米秸秆醇解合成乙酰丙酸乙酯工艺研究

利用农作物秸秆醇解合成乙酰丙酸酯近年来受到广泛关注,但秸秆的难降解结构制约了秸秆的醇解利用。机械球磨是一种新兴的机械预处理方式,机械力作用可以有效破坏生物质致密结构,提高生物质化学反应性能。以玉米秸秆为对象,首先研究了球磨工艺对乙酰丙酸乙酯及其中间产物和副产物的影响,考察了催化剂类型、催化剂浸渍球磨、球磨时间、球磨介质填充率和球料体积比等因素;球磨显著提高了乙酰丙酸乙酯的产率。在相同H+浓度的条件下,催化剂酸性越强催化效果越好;球磨时间对乙酰丙酸乙酯的影响最大,介质填充率和球料体积比对乙酰丙酸乙酯产率的影响不显著;以乙酰丙酸乙酯产率为指标优化出的球磨工艺为:不添加催化剂球磨,球磨时间为60 min、介质填充率为35%、球料体积比为2。在此球磨条件下,乙酰丙酸乙酯的摩尔产率由20.08%提高到33.34%,基于纤维素的醇解产物总产率由73.18%提高到83.03%。     

Analysis on the self-locking effect and slipping motion of balls in the screw pair

In view of self-locking and slipping phenomenon on restricting high-speed operation of ball screw, the model of ball screw is constructed and theoretical analysis of the movement feature of ball screw is made to reveal the reason of self-locking and slipping, and its influence on high-speed operation. Then the sliding speed format of ball screw is derived according to the movement rules of ball screw, and effective methods to avoid ball self-locking and slipping are put forward. Dynamics analysis is conducted with ADAMS software. Simulation results have confirmed the correctness of ball screw’ movement.     

钢球滚子弧面分度凸轮载荷分布

运用空间啮合原理和回转张量法,推导出凸轮滚道截形采用双圆弧结构时,钢球滚子弧面分度凸轮的廓面方程和啮合方程.应用赫兹接触理论和变形协调条件,推导出载荷在每个参与啮合钢球中的分配关系.通过实例计算,发现每个钢球上的载荷大小分配不同,在钢球的啮入、啮出点,钢球受力发生突变,参与啮合的钢球数目越多,每个钢球的受力越小.     

基于RAPD标记的福建省稻曲病菌遗传多样性分析

为了解福建省稻曲病菌群体的遗传多样性和遗传组成,应用随机扩增多态性RAPD (random amplified polymorphic DNA)技术分析了来自福建省不同水稻种植区的102个稻曲病菌(Ustilaginoidea virens)的遗传多样性.从100条随机引物中筛选出10条扩增带清晰、重复性好的引物进行稻曲病菌多态性扩增,共扩增出157条带,多态性条带比率为82.17％,遗传距离变化范围为0.02～0.67.遗传多样性分析表明,福建省稻曲病菌具有丰富的遗传多样性,相对于其它地区而言,福建闽西地区分离的菌株遗传多样性水平最高PPB=76.43,H=0.2212,I=0.3383),晚稻分离的菌株群体遗传多样性(PPB=91.08,H=0.2402,I=0.3655)高于早稻群体(PPB=63.06,H=0.1892,I=0.2870).聚类分析显示,在遗传距离0.349水平上,供试的所有菌株可被划分成7个遗传聚类组(R1～R7),聚类组R1为优势聚类组,包含有80个菌株,其内又存有一些亚组.这些菌株的聚类与菌株的地理来源及水稻品种无明显相关性.但是在遗传距离0.330水平上,来自宁化的10个菌株可被明显划分成早稻群体和晚稻群体.初步分析认为菌株的地理来源、水稻品种及其生长季节是影响福建省稻曲病菌遗传多样性的主要因素,在稻曲病菌的遗传变异以及该病的发生和流行中可能起重要的作用.     

球磨机齿轮传动的可靠性优化设计

本文将球磨机齿轮传动的设计变量处理成随机变量，将可靠度做为设计变量的约束条件，建立了球磨机齿轮传动的可靠性优化设计的数学模型，并以齿轮传动的体积最小为目标圆柱齿轮传动进行了优化，结果表明，模型是准确可靠的。