平面二次包络环面蜗杆副的失配修形

提出平面二次包络环面蜗杆副失配啮合分析的两种新方法：齿面相切法和齿面零间隙法。失配平面二次包络环面蜗杆副啮合分析表明：Ｉ型传动对误差不十分敏感,但同时接触齿数少;标准型和Ⅱ型传动对误差十分敏感。本文提出失配修形法,用标准蜗杆与由Ⅱ型滚刀加工的蜗轮失配啮合,使蜗杆副初装时对误差不敏感,跑合后得到良好的接触质量。     

萧氏松茎象虫口密度与虫孔数的关系研究

萧氏松茎象Hylobitelus xiaoi Zhang(Coleoptera：Curculionidae)是我国近年来危害最为严重的松林钻蛀性害虫[1],主要危害湿地松(Pinus elliottii Engelmann),也危害火炬松(P.taeda L.)、马尾松(P.massoniana Lamb.)和华山松(P.armandi Franch.).     

光肩星天牛防控技术研究进展

为了研究光肩星天牛的监测技术,掌握光肩星天牛危害的基本资料,笔者综述了国内外关于光肩星的生物生态学习性和综合防治技术等近30 年的研究结果。发现光肩星天牛的防治方法中,单一技术的使用是不可取的,在光肩星天牛的防控技术中不仅要开展行为化学生态学和抗性育种方面的研究,也要积极保护和招引天敌,而且还需要利用自然调控因子的综合作用,加大防治光肩星天牛的力度和推广防治面积,以实现光肩星天牛的可持续控制。     

离散元模拟导种管高度对排种性能的影响

排种系统是免耕播种机的重要组成部分,其性能直接影响到免耕播种机整体工作质量。导种管为排种系统最后一个环节,主要作用是将排种器排出的种子导入开沟器并使种子能够顺利落入种沟内,其投种位置和速度对排种系统的排种均匀性有较大影响。本文用离散元软件,对导种管施加直线运动和正弦振动,模拟玉米种子由颗粒工厂生成后,经过导种管下落到土地的过程。同时,经离散元后处理模块得到玉米种子在土地上的分布图、种子的运动轨迹及种子在导种管内运动的最小速度和种子离开导种管时的速度;并用origin软件得到种子在导种管内运动的最小速度与导种管高度的拟合曲线、种子离开导种管时的速度与导种管高度的拟合曲线。模拟结果表明:当免耕播种机作业速度为1.389m/s时,最佳导种管高度应为500mm。     

稻草还田对免耕水稻根系生长及空间分布的影响

研究了稻草还田对免耕抛秧水稻立苗期根系生长及成熟期根系空间分布的影响。结果表明,稻草还田显著或极显著提高了立苗期免耕水稻根冠比、单株根生物量、总根数、白根数、单条根长、根毛区长、一次分枝、二次分枝根数量、根系活力和超氧化物歧化酶(SOD)活性,对根系的伸长、生长起到明显的促进作用。稻草还田明显提高了水稻产量及免耕抛秧水稻0~10cm土层根系干重和根系体积,6t/hm²稻草还田量比对照0~10cm土层根系干重和根系体积分别高29.85%、41.62%,产量提高11.18%,差异均达显著水平。     

Tubifex production using agro-industrial wastes and raw cattle dung

ABSTRACT

Tubifex (Tubifex tubifex) was cultured in captivity using three different wastes: rice mill sludge (RMS), dairy sludge (DS), and raw cattle dung (RCD). Three experiments were conducted: 10, 20, and 30 days. A total of 100 g of tubifex at 62.5 g m^?2 was inoculated in 1.6 m² fiberglass-reinforced plastic tanks. Comparing all production parameters, RMS > DS > RCD. Growth rate (g m^?2 d^?1) did not differ among durations. RMS- and DS-fed tubifex contained higher protein and fat than RCD-fed tubifex. Efficiency on production of g tubifex per kg of waste material was highest at 10 days, declining with time for all waste materials. This experiment suggests that RMS and DS are effective wastes for tubifex culture, with total production increasing with no reduction in growth rate through 30 days, but with efficiency declining after 10 days.     

猪肾虫病的诊治

近几年来猪肾虫病有日益增多的趋势,由于该病不同时期、不同日龄均可发生而且死亡率不高,防治一向被忽视。再加上农村散养户养殖条件简陋,更给肾虫病的防治带来了很大困难。笔者依据近年的实践经验,现将临床猪肾虫病的诊治情况进行报告。     

Nova Scotia's bloodworm harvest: Assessment, regulation, and governance

The Nova Scotia commercial blood worm harvest was first regulated in 2002; by 2008 regulations included limited entry, seasons, area closures, minimum legal size, and reporting of daily sales and fishing location. To aid in setting minimum legal size, size of maturity was measured in the two main harvest areas. Biologist-directed and harvester-directed methods for surveying worm densities and sizes on intertidal mud flats were found to be robust. With 16 samples tests of two survey means would detect differences of 0.5 standard deviations (type I error of 0.1). With 16 samples two means separated by 1.3 standard deviations would not be declared the same when they were actually different (type II error of 0.25). Depth of digging affected survey results; the time of air exposure of the mud, the temperature of the mud surface, and the choice of harvester-samplers did not. Mud flats should be managed individually because interchange of worms between flats is probably small. Decision rules of 0.6 and 0.8 legal sized worms/m² have been set for closing a beach and opening a closed beach, respectively. Progress in fishery governance was achieved using the above results and by involving harvesters and a citizens group in decision making.     

Parelaphostrongylus tenuis Cerebrospinal Nematodiasis in a Horse with Cervical Scoliosis and Meningomyelitis

There are reports of horses with acute onset acquired cervical scoliosis and cutaneous analgesia. The underlying dorsal gray column myelitis that produces these neurologic signs has been only presumptively attributed to migration of Parelaphostrongylus tenuis within the spinal cord. Despite previous confirmation brain by polymerase chain reaction testing, of P. tenuis within the brain of horses by polymerase chain reaction testing, genetic testing has failed to definitively identify the presence of this parasite in cases of equine myelitis. This case report provides molecular confirmation via polymerase chain reaction of P. tenuis within the cervical spinal cord of a horse with scoliosis and cutaneous analgesia.