马铃薯中耕前期圆盘式中耕机设计与试验

针对现有马铃薯中耕机在第1次中耕作业时存在作业效果不佳、易伤苗的问题,对圆盘式马铃薯中耕机进行设计与试验。阐述了该机的工作原理,通过理论计算对其关键部件进行设计,根据农艺培土、除草等作业要求,确定了圆盘式马铃薯中耕机主要结构参数和作业参数;采用单因素和二次旋转正交组合试验,以耕作深度、机车前进速度、调节角为试验因素,以除草率及伤苗率为试验指标进行了样机试验。试验结果表明,当耕作深度为0.13 m、机车前进速度为4.6 km/h、调节角为52°时,除草率为95.2%,伤苗率为3.9%,满足国家标准伤苗率不大于5%、除草率不小于90%的要求。     

EoNPV对茶尺蠖两近缘种的毒力差异

茶尺蠖核型多角体病毒(Ectropis obliqua nucleopolyhedrosis virus,EoNPV)是一种重要的病原微生物,为进一步明确该病毒对茶尺蠖两近缘种的毒力差异,采用叶盘法对3龄茶尺蠖和灰茶尺蠖幼虫进行了EoNPV的毒力测定。研究显示,EoNPV对灰茶尺蠖的半致死剂量LD₅₀(median lethal dose)为茶尺蠖的28.9倍,EoNPV对灰茶尺蠖的致死中时间LT₅₀(median lethal time)大于茶尺蠖。结果表明,EoNPV对茶尺蠖两近缘种间的毒力存在差异,EoNPV对茶尺蠖具有更高的致病力,研究结果对EoNPV田间防治茶尺蠖两近缘种具有现实指导意义。     

Combination of serum phosphorylated neurofilament heavy subunit and hyperintensity of intramedullary T2W on magnetic resonance imaging provides better prognostic value of canine thoracolumbar intervertebral disc herniation

The aim of this study was to evaluate the prognostic value of concurrent measurement of serum phosphorylated neurofilament heavy subunit (pNF-H) concentration and intramedullary T2W hyperintensity in paraplegic to paraplegic dogs. Our hypothesis was that concurrent measurement of these would provide a more accurate prediction of functional outcome in dogs with thoracolumbar intervertebral disc herniation (IVDH). A prospective case-control clinical study was designed using 94 dogs with acute onset of thoracolumbar IVDH. The association of serum pNF-H concentration, T2W hyperintensity on sagittal MRI (T2H/L2), deep pain perception and surgical outcome were evaluated with logistic regression analysis after three months for all 94 surgically treated dogs. Sensitivity to predict non-ambulatory outcome was compared among pNF-H and T2H/L2 and combination of both. Logistic regression analysis indicated that serum pNF-H concentration and T2H/L2 were significantly correlated with surgical outcome (P<0.05); however, deep pain perception was not (P=0.41). The results of logistic regression analysis indicated that the odds ratios of unsuccessful long-term outcome were 2.6 for serum pNF-H concentration, 1.9 for T2H/L2 and 2.3 for deep pain sensation. The sensitivity and specificity to predict non-ambulatory outcome for using serum parameter pNF-H>2.6 ng/ml, using T2H/L2 value of>0.84 and using both serum pNF-H and T2H/L2, were 95% and 75.7%, 65% and 86.5%, and 90.0% and 97.5%, respectively. Therefore, combined measurements of serum pNF-H and T2H/L2 might be useful for predicting long-term outcome in dogs with thoracolumbar IVDH.     

Using Static and Dynamic Indicators to Evaluate Soil Physical Quality in a Sicilian Area

Both capacitive indicators derived from the water retention curve and dynamic measurements of the flow‐weighted mean pore radius, R₀, were used to assess the soil physical quality of two agricultural areas (cropland and olive orchard) and two natural areas (grassland and managed woodlot plantation) potentially subject to soil degradation. The overall idea of the study was to investigate whether a dynamic indicator quantitatively derived from hydraulic conductivity measurements could be used to supplement the traditionally applied capacitive indicators retrieved from water retention measurements. According to the available criteria, only the surface layer of the cropland site showed optimal soil physical quality. In the grassland and woodlot sites, the physical quality was deteriorated also as a consequence of compaction because of grazing. Overall, the physical quality was better in tilled than nontilled soils. The optimal soil in terms of capacitive indicators had hydraulic conductivity close to saturation that was intermediate among the different land uses, and it remained 1·3–1·9 times higher than that observed in the natural sites even when the largest pores emptied. A depth effect on R₀ was observed only when larger macropores were activated. It was suggested that water transmission parameters are more affected by changes in large pore domain. The plant available water content and Dexter's S‐index showed inverse statistically significant regressions with R₀. The empirical relationships were physically convincing given that, at increasing R₀, the contribution of macropores increases, water is transmitted faster below the root zone and the soil's ability to store water is reduced. Copyright © 2013 John Wiley & Sons, Ltd.     

牛角瓜根的抑菌活性研究

以牛角瓜根为实验材料,采用索氏提取法,以4种不同溶剂(石油醚、氯仿、乙酸乙酯、甲醇)对牛角瓜的根进行提取,并采用纸片琼脂扩散法对粗提物的抑菌活性进行了评价,供试菌包括白色念珠菌等6种真菌和金黄色葡萄球菌等7种细菌。结果表明:石油醚粗提物对枯草芽孢杆菌、白色念珠菌、黑曲霉菌、大肠埃希氏菌都表现出良好的抑菌活性,且抑菌效果接近或优于阳性对照氟康唑,对尖孢镰刀菌和鲍曼不动杆菌也表现出良好的抑菌活性;氯仿粗提物对白色念珠菌及粪链球菌表现出良好的抑菌活性;乙酸乙酯粗提物对粪链球菌表现出最好的抑菌活性;甲醇粗提物的抑菌活性较弱。     

胡萝卜联合收获机单圆盘对顶切割装置设计与试验

针对胡萝卜联合收获过程中对顶切割装置作业后胡萝卜损伤率高、切净率低等问题,设计了一种单圆盘对顶切割装置,并阐述了其主要结构及工作原理。在统计分析胡萝卜基本物理特性的基础上,通过理论计算确定了斜拉式导向齐平对顶机构的两对齐基板间距、拉齐区长度和对齐基板斜边角度等主要结构参数,达到胡萝卜茎叶精准拉齐的目的。以螳螂前肢胫节曲线为原型,将拟合优化后的曲线形状应用至圆盘动割刀和直割刀刃口上,构建切割机构-胡萝卜茎叶力学模型,分析其满足胡萝卜被高效切断的条件。对圆盘割刀进行运动学分析,建立圆盘割刀前进方向的运动学模型,确定影响装置工作性能的因素为胡萝卜输送速度和圆盘割刀转速。以胡萝卜收获机夹持输送皮带轮转速(胡萝卜输送速度)和圆盘割刀转速为试验因素,以胡萝卜根茎损伤率、茎叶切净率、切割平整度为试验指标,进行了二因素五水平二次正交旋转组合试验,通过对试验结果进行分析优化,确定最佳参数组合。结果表明,当胡萝卜收获机夹持输送皮带轮转速为113 r/min、圆盘割刀转速为156 r/min时,对顶切割装置性能最优,此时胡萝卜损伤率均值为0.53%、切净率均值为95.41%、平整度均值为94.10%。对优化结果进行田间试验验证,验证结果与优化结果基本一致,作业过程中装置工作平稳。     

利用盘式吸渗仪确定土壤水力学参数研究进展

各种农业措施显著影响土壤的物理性质,特别是土壤水力学参数。随着计算机模型广泛用于土壤物质迁移的预测预报,准确确定土壤水力学参数成为一项重要的研究任务。盘式吸渗仪作为一种简便实用的仪器正被广泛用于田间土壤水力学参数的测定。国内外学者研究了稳态、瞬态和反推等方法,利用盘式吸渗仪来确定土壤近饱和导水率、吸渗率和水分特征曲线。同时该仪器可以用于田间测定土壤孔隙分布状况,以及两区模型中的参数。笔者对国内外有关盘式吸渗仪研究从相关理论和应用方面进展进行了综述,并对田间测定操作中注意的问题进行评述,指导田间试验以获得准确的测定数据。盘式吸渗仪在田间测定土壤孔隙,特别是大孔隙流方面有独特的优点,但是其并未在中国不同质地土壤上得以广泛应用。     

YWS-1型烟田挖坑施肥机的研究设计与应用

为了更好地解决“烟草三农”问题，针对我国烟草种植落后的现状和发展趋势，研究和应用具有稳定挖坑和精量施肥等功能YWS-1型烟田挖坑施肥机。通过性能和生产试验测定和效益分析证明，该机具各项技术、性能指标符合设计要求，解决了烟草种植的问题，具有一定的创新特点和较好的推广和应用价值。     

独立圆盘耙单体排列参数对秸秆堵塞影响研究

为对秸秆覆盖混埋还田耕整地技术模式进行深入研究,需要研发配套圆盘耙联合整地机具,机具研发过程中首先要解决受秸秆影响的堵塞问题。通过进行影响因素的单因素试验和3因素3水平正交试验,探索独立连接圆盘耙单体排列参数对秸秆堵塞问题的影响规律。通过单因素试验确定对应机具通过性评分为3分的三个因素临界值:耙片间距为275 mm,横梁间距为900 mm,错位间距取值全部满足试验要求。正交试验极差分析结果表明:耙片排列参数对机具堵塞影响主次顺序为耙片间距B,横梁间距L,错位间距S;机具通过性的较优组合为耙片间距325 mm,横梁间距1 100 mm,错位间距0 mm。正交试验方差分析结果表明机具排列参数耙片间距和横梁间距对机具堵塞影响显著,错位间距对机具堵塞影响不显著。正交试验回归分析结果得到拟合度较高的机具通过性回归方程:T=0.833B+0.667L。本文试验结果为圆盘耙联合整地机的开发与设计提供数据参考。