基于非接触式速度测量的排种驱动系统

介绍了一种利用非接触式速度测量装置驱动排种器的工作原理.该装置用前后两个光电传感器来探测路面的反射光信号,根据两路信号的时间差得到相对速度,并用该测速装置来驱动步进电机,步进电机带动排种器转动,以达到排种和速度同步的目的.此装置可以改善现有播种机靠地轮驱动时由于打滑造成的排种不均匀的问题,使排种更加均匀化.     

Immune responses and enhanced disease resistance in Chinese drum, Miichthys miiuy (Basilewsky), after oral administration of live or dead cells of Clostridium butyrium CB2

Clostridium butyrium CB2 isolated from chickens was tested as a potential fish probiotic in the Chinese drum, Miichthys miiuy . Fish were fed live (CB), dead CB2 (D-CB) cells (10⁸ cells g⁻¹) or spent culture supernatant (SCS), for 30 days and challenged with Vibrio anguillarum or Aeromonas hydrophila . Survival was higher in both the CB and the CB-D fed groups, but the SCS group was not significantly different from the control. After feeding live or dead CB2 cells, there was increase in phagocytic activity of the head kidney macrophages, the lysozyme activity of serum and gut mucosa and immunoglobulin (Ig) level. The SCS group showed no obvious change in immune parameters. The results suggest that live or dead Clostridium butyrium CB2 has an immunomodulatory effect on fish.     

麻竹笋用林施肥效果试验

对麻竹笋用林进行施肥试验研究,分析得知,鸡粪、复合肥、配方肥3种肥料对竹笋产量和经济纯收入有显著影响,均与竹笋产量、经济纯收入呈抛物线型关系,竹笋产量、经济纯收入随施肥量增加呈现先上升后下降的趋势;3种肥料的影响程度顺序依次为：配方施肥、鸡粪、复合肥,配方施肥的最佳施肥方案为鸡400＋复60＋硫酸锌0．9。     

花叶艳山姜叶片精油提取工艺优化

以花叶艳山姜叶片为材料,采用水蒸气蒸馏法,对其精油提取工艺进行优化。通过对蒸馏时间、浸泡时间、料液比和氯化钠浓度4个因素进行单因素试验和正交试验。结果表明,各因素对精油得率都有影响,影响大小顺序为:蒸馏时间料液比氯化钠浓度浸泡时间。同时确定了最优提取工艺条件为蒸馏时间1.5 h、料液比1∶6、浸泡时间30 min和氯化钠浓度1.5%,在此条件下精油得率为0.216%。     

莰酮对蚜虫生物活性的研究

进行了樟树(CinnamomumcamphoraL.)中的莰酮(CamphorC10H160)对蚜虫的触杀、熏蒸毒力和拒食活性研究。结果表明,处理后24h莰酮对菜缢管蚜、桃蚜和棉蚜触杀作用的LD50分别为3.12×10-3,2.04×10-3,0.68×10-3 ng/头,熏蒸作用的LC50分别为3.44,2.56,1.06mg/L,拒食作用的AFC50分别为3.34,2.98,1.32mg/L。经回归和相关分析,处理浓度与作用效果相关性均达到极显著或显著水平。莰酮在田间防治菜缢管蚜的效果显著。     

长期施肥对木薯农艺性状、鲜薯产量和淀粉质量分数的影响

1992—2003年12a间，对2个木薯品种(华南205和华南124)，进行氮、磷、钾和火烧土等4种肥料各4个不同施肥水平组成共16个施肥配方的试验，研究了长期施肥对木薯农艺性状、鲜薯产量和淀粉质量分数的影响。结果表明：淀粉质量分数与收获指数呈显著正相关，鲜薯产量与株高、茎径及单株结薯数呈极显著正相关，单株结薯数与株高、茎径呈极显著正相关，株高与茎径呈极显著正相关。并列出它们的相关回归方程。推荐木薯最佳N，P2O5，K2O的施肥质量配比为2～4：1：2～4，其中，N，P2O5，K2O的施肥质量配比在连作初期以2：1：2为佳，而连作后期则以逐渐过度为4：1：4为佳。     

Dynamical analysis of net cage structures for marine aquaculture: Numerical simulation and model testing

A numerical model for analyzing dynamic properties of a net-cage system exposed in the open sea is proposed. The model is based on a lumped-mass method. In this model, the mooring lines are divided into linear elements and the net cage divided into several plane surface elements. The interconnected points or corners are called nodes or lumped-mass centers. The external force is calculated on each element and then equally distributed to its nodes. By adding the contributed forces from the neighboring elements, a system of motion equations for nodes is formed. The volume reduction coefficient of a net cage is estimated by the ratio of minimum volume of net cage during fluid and structure interaction to the original volume. In general, the numerical results are in good agreements with the experimental data. However, the results also show that if the Reynolds number is lower than the suggested range of 1400–1800, the numerical model may underestimate the environmental forces on a net-cage system.     

Comparative Study of the Adsorption Selectivity of Cr(VI) onto Cationic Hydrogels with Different Functional Groups

Two types of hydrogels with different functional groups, trimethylamine on quaternary ammonium and dimethylethoxyamine on quaternary ammonium, were synthesized. Type 1 and type 2 hydrogels were characterized with Fourier transform infrared, X-ray photoelectron spectroscopy and zeta potential analysis. The anion selectivity of these two hydrogels was investigated. The surface charges of the type 2 hydrogel were lower than those of type 1, probably because of the presence of the hydroxyl group in the ethoxy group. The Cr(VI) removal capacity of type 2 hydrogel was, therefore, less than that of type 1 hydrogel, although their adsorption rates were similar. The anion selectivity of the hydrogels was found to have a similar order: Cr(VI) > sulphate > bromide > As(V). Under the co-presence of Cr(VI) and sulphate conditions, type 2 hydrogel shows a higher selectivity towards Cr(VI). The higher hydrophobicity was caused by the presence of the ethoxy group on the quaternary ammonium in type 2 hydrogel and thus increased in selectivity towards monovalent ions (i.e. HCrO₄⁻). In addition, the hydrogels have a high reusability. Compared with type 1 hydrogel, type 2 hydrogel has an advantage for applications in Cr(VI) removal and recovery processes.     

植物EST-SSR标记开发及其应用

随着生物科技的进步,大量的植物表达序列标签（expressed sequence tags,ESTs）已经成为开发SSR标记的重要资源。EST-SSR作为一种新型分子标记,其多态性可能与基因功能直接相关,而且在相近植物间具有良好通用性,使得EST-SSR标记在实际应用中更具价值。采用计算机方法大规模发掘EST-SSR多态性位点极大地提高了SSR标记开发效率。尤其随着新一代测序技术的成熟以及测序成本的急剧下降,利用新一代测序技术产生大量的转录组数据进行EST-SSR多态性标记的计算机大规模发掘将对SSR标记的开发带来深远影响。本文简要介绍了植物EST-SSR分布特点,并对EST-SSR标记开发现状以及相关应用作了综合评述,此外,还对EST-SSR标记的计算机开发新策略进行了展望。     

西藏农村远程教育与信息服务体系发展对策研究

西藏农村远程教育与信息服务体系是实现西藏农牧业跨越式和可持续发展、增加农牧民收入和促进农村经济、文化快速发展的重要平台。在基于西藏农牧业教育、农村信息化建设的现状的条件下,通过对农村远程教育与信息化服务所面临的主要问题的分析,提出了西藏农村远程教育与信息服务体系发展的对策。