基于ANSYS的取土器钻头参数优化设计

根据取土器钻头的结构特点,首次给出了钻头切削部分的定义.通过对钻头工作过程的受力分析,建立了钻头的力学模型.利用ANSYS软件对钻头的刃倾角、主偏角等结构参数进行了有限元分析,得出了钻头应力的分布情况和变化趋势.结果表明:钻头最大应力总是出现在前刀面上端附近的过渡地带;刃倾角在15.时钻头最大应力处于最小值;适当增加主偏角和减小副偏角可有效增加钻头强度.为提高钻头的工作效率和使用寿命提供了可靠理论依据.     

育苗播种双向气动控制系统的设计研究

在参照原有的单向穴盘育苗播种机的基础上提出了双向育苗气动作业的思路,设计了一套双向播种的气动控制系统,并完成吸投互替的双向播种过程.设计的适用双向作业的双向育苗播种机结构,是利用传感器采集和D/A转换信号,由单片机控制电磁阀动作来完成双向播种的自动控制过程.同时,对整体系统进行了仿真分析.结果表明,其系统大大提高了生产效率,并为工业化育苗播种提供了一种新的思路.     

酵母壁多糖对断奶仔猪肠道挥发性脂肪酸和微生物菌群的影响

本研究旨在探讨饲粮中添加酵母壁多糖对断奶仔猪肠道挥发性脂肪酸和微生物菌群的影响。试验采用单因素试验设计方法,选取180头遗传背景一致、健康状况良好、胎次和体重接近的21日龄断奶仔猪,随机分为4个组,每组5个重复,每个重复9头猪。4个组试验猪分别饲喂对照饲粮(未添加酵母壁多糖)、0.15%酵母壁多糖饲粮、0.30%酵母壁多糖饲粮和0.45%酵母壁多糖饲粮。试验期21 d。结果表明:1)与对照组相比,饲粮中添加0.15%、0.30%和0.45%酵母壁多糖显著提高了仔猪结肠乙酸的含量(P0.05);其中,0.30%和0.45%酵母壁多糖还显著提高了结肠丙酸、丁酸以及总挥发性脂肪酸的含量(P0.05),且二者之间差异不显著(P0.05)。2)与对照组相比,饲粮中添加0.15%、0.30%和0.45%酵母壁多糖显著降低了盲肠沙门氏菌和大肠杆菌数量(P0.05),且0.30%和0.45%酵母壁多糖组之间差异不显著(P0.05)。由此可知,酵母壁多糖可提高仔猪肠道挥发性脂肪酸含量,并改善肠道微生物菌群结构,根据回归方程预测,酵母壁多糖在仔猪饲粮中的适宜添加水平为0.31%~0.40%。     

微生物营养剂对峨眉蔷薇种子萌发的影响

以峨眉蔷薇种子为材料,低温冷藏后取出,利用不同质量浓度的微生物营养剂进行暖温催芽处理,以零添加、零处理为对照,研究探讨了不同碳、氮质量浓度的微生物营养剂对种子萌发的影响,结果显示,不同质量浓度的营养剂均可不同程度地提高种子萌发率,促进种子快速萌发;较适宜营养剂,即蔗糖、酵母膏质量浓度分别为5、1.0g· L-1;质量浓度最高的组合效果最差,较低的碳源、氮源质量浓度组合表现出较好的综合促进作用,推测可能与微生物的活动周期有关,最适的营养剂质量浓度等仍有待进一步研究.     

溢洪道高速水流边壁蚀损分析与防护

就防洪、泄洪的工具溢洪道的建设、蚀损、防护方面措施做了简要介绍。     

温度对小球藻生长量和溶氧量影响研究

采用梯度法研究温度对小球藻生长量和溶氧量的影响.结果表明:小球藻对温度的适应范围较广,5～30℃期间小球藻均可正常生长,25℃为小球藻生长的最适温度,此时小球藻的生长速度与溶氧量增长速度达到最大,结果可为小球藻生长量和溶氧量的研究提供参考依据.     

Effects of dietary carbohydrate sources on the growth performance and hepatic carbohydrate metabolic enzyme activities of juvenile cobia (Rachycentron canadum Linnaeus.)

An 8-week feeding trial was conducted to evaluate the effect of dietary carbohydrate sources on the growth performance and hepatic carbohydrate metabolic enzyme activities of juvenile cobia. Six experimental diets were formulated to contain 20% glucose, sucrose, maltose, dextrin, corn starch and wheat starch respectively. The results indicated that fish fed the wheat starch and dextrin diets showed significantly better weight gain, specific growth rate and protein efficiency ratio compared with those fed the other diets. However, fish fed the glucose diet had a significantly lower survival and condition factor than those fed the other diets. There were significant differences in the total plasma glucose and triglyceride concentration in fish fed diets with different dietary carbohydrate sources. Haematocrit, haemoglobin, red blood cell and leucocytes were significantly affected by the dietary carbohydrate sources. The activities of glucose-6-phosphate dehydrogenase (G6PD), 6-phosphofructokinase (PFK) and fructose-1,6-bisphosphatase (FBPase) were significantly affected by the dietary carbohydrate sources, while fish fed the glucose diet showed higher G6PD, PFK and FBPase activities than those fed the other diets. These data indicated that dextrin and wheat starch were the most optimal carbohydrate sources for juvenile cobia.     

生态与景观的理性融合——湖州长田漾湿地公园概念性规划

以湖州长田漾湿地公园概念性规划为例,探讨在规划中运用景观生态学相关理念构建良好的区域生态格局、采用生态技术恢复和营造湿地景观、通过生态手法恢复地方性植被和挖掘乡土素材构建乡土景观等,实现科学保护与合理利用湿地,生态与社会价值并举的规划思路。     

Comparison of physiological and yield traits between purple- and white-pericarp rice using SLs

Five physiological and eleven yield traits of two pairs of sister lines generated from a high generation with similar genetic background (SLs) for purple pericarp were investigated to explore the reasons behind low-yield production of colored rice. Of the five physiological traits examined, except grain anthocyanin content, there were generally similar trends between the P (purple-pericarp) lines and the corresponding W (white-pericarp) lines over two seasons (in the year 2009 and 2010 separately). The results demonstrated that the chlorophyll content of flag leaves, the net photosynthetic rate of flag leaves, and the grain anthocyanin content could be easily influenced by the environment. The physiological functions of the traits for the P lines were more active than those of the corresponding W lines in the year 2010. The grain anthocyanin content of the P lines was much greater in the year 2010 than in the year 2009 during the growth period. The investigation of yield traits revealed that the P lines had reduced 1000-grain weight, yield per plot and grain/brown rice thickness compared to the W lines. A difference comparison of these traits and a source-sink and transportation relationship analysis for these SLs suggested that small sink size was a key reason behind yield reduction of purple pericarp rice.     

高等院校计算机类课程教学模式的研究

通过在教学实践中不断摸索和研究,总结出大学计算机类课程的"6-U sing"教学模式,即用眼睛看、用耳朵听、用嘴说、用脑思考、用心交流、用手操作。该教学模式体现了教师和学生在教学活动中角色互动、互补和互助的特点,有助于激发学生的学习动力,培养学生解决实际问题的能力。实践证明,应用"6-U sing"教学模式,显著地提高了大学计算机课程的教学效果。