国内甘薯机械移栽技术发展动态

甘薯机械化移栽技术发展严重滞后已成为制约甘薯现代化生产的主要技术瓶颈。在对国内外甘薯机械移栽技术发展现状阐述、分析基础上,初步提出国内甘薯移栽机械的技术发展方向:农机农艺融合提高移栽效率、裸苗移栽优先、重视钵苗移栽、多种栽插形式并存、先栽后浇分段作业等。     

边界滑移对螺旋槽上游泵送机械密封性能的影响

为了研究边界滑移对上游泵送机械密封性能的影响,建立液膜三维几何模型和计算模型,基于 Navier 线性滑移模型对液膜壁面边界条件进行修正,采用商用软件 Fluent 的 SIMPLEC 算法及层流模型求解三维 Navier －Stokes 方程,并分析相对滑移量对液膜静压分布、开启力、摩擦扭矩、泄漏量的影响规律。结果表明：相对于边界滑移发生的位置,滑移速度的大小对密封性能的影响更大;当相对滑移量较小时,存在边界滑移与无滑移的模拟结果无明显区别,能很好地解释宏观无滑移边界假设的应用,当相对滑移量较大时液膜动压效应随滑移的增加而减弱,开启力、摩擦扭矩、泄漏量都随边界滑移的增加而减小;相对于开启力的降低,边界滑移的减阻和降低泄漏的效果更为明显;当开启力较小,应避免边界滑移发生;当开启力足够大时,加工成超疏水表面形成边界滑移,可极大地减少摩擦扭矩,降低能耗。     

黄淮海地区大豆生产机械化现状与发展趋势

机械化在大豆全程生产中发挥着重要作用。为此,针对黄淮海地区大豆机械化生产现状,分析了目前大豆机械化生产中存在的问题,对大豆产业发展,从"种子处理技术""机械化精密平播免中耕技术""科学施肥,合理使用杀虫剂和除草剂""大力推广大豆机械化收获技术"等方面简要阐述黄淮海地区大豆生产全程机械化的发展趋势。     

农田平地机激光发射平台调平控制系统设计

为使农田平地机双源激光定位系统的激光发射平台检测数据更精确、调平实时性更好,设计了激光发射平台自动调平控制系统。该系统采用三脚支撑的平台支撑方式,利用倾角传感器检测平台的倾斜度,通过步进电机驱动平台3条支腿伸缩从而实现平台调平。通过加入倾角传感器数据处理算法和基于RBF神经网络的智能PID控制算法,激光发射平台检测的数据更精确,能满足双激光源定位系统的要求,使农田平地机平地作业更精确。     

Crop milk protein is synthesised following activation of the IRS1/Akt/TOR signalling pathway in the domestic pigeon (Columba livia)

1. The experiment was conducted to study whether insulin receptor substance 1 (IRS1) / Protein kinase B (Akt)/target of the rapamycin (TOR) signalling pathway activation stimulates crop milk protein synthesis in the domestic pigeon (Columba livia).

2. Crop milk was collected from ten 1-d-old squabs and analysed for nutrient content. During the non-breeding period and the first day of lactation, blood samples were collected from 5 pairs of breeding pigeons and the levels of prolactin and insulin were determined.

3. Crop samples were collected from 5 pairs of breeders at d 14 and 16 of the incubation period and d 1, 3 and 7 of the lactation period. Crop samples were evaluated for changes in crop weight and thickness and changes in the expression patterns of IRS1/Akt/TOR signalling pathway–related proteins.

4. The results demonstrated that prolactin induces a gradual increase in the relative weight and thickness of the crop, with crops reaching a maximum size at the third day of lactation.

5. Pigeon crop milk contains 64.1% crude protein and 29.7% crude fat based on dry weight.

6. Serum prolactin and insulin levels in the lactation period were significantly higher than those in the non-breeding period. Compared with non-breeding pigeons, the expression of the phosphorylated IRS1 phosphorylated Akt, phosphorylated TOR, phosphorylated ribosomal protein S6 kinase, phosphorylated S6, phosphorylated eukaryotic initiation factor 4E binding protein 1 and eukaryotic initiation factor 4E were significantly up-regulated in the crop of pigeons in the lactation period.

7. In conclusion, prolactin might induce changes in crop tissue and form the physiological structure for crop milk synthesis. Furthermore, the synthesis of crop milk protein is regulated by activation of the IRS1/Akt/TOR signalling pathway.

     

Two single nucleotide polymorphisms in the promoter of the ovine myostatin gene (MSTN) and their effect on growth and carcass muscle traits in New Zealand Romney sheep

Myostatin is a negative regulator of muscle growth and development in mammals, and variation in ovine myostatin gene (MSTN) has been demonstrated to be associated with variation in the muscularity of sheep. Polymerase chain reaction–single‐stranded conformational polymorphism (PCR–SSCP) was used to look for single nucleotide polymorphisms (SNPs) in a 304‐bp amplicon from the promoter region of ovine MSTN. Sequence analyses revealed two previously identified SNPs (c.?2449G/C and c. ?2379T/C) that resulted in three haplotypes (H₁ (c.[?2449G; ?2379C]), H₂ (c.[?2449C; ?2379C]) and H₃ (c.[?2449G; ?2379T]). The effect of these SNPs on growth and carcass traits was investigated in 357 NZ Romney lambs. General linear mixed‐effect models revealed that sheep with the genotype c.?2449GC had a higher loin meat yield (p = 0.032) and proportion loin yield (p = 0.028), than those with the genotype c.?2449GG. The genotype c.?2379CC was associated with an increase in three weight traits: birthweight (p = 0.003), tailing weight (p = 0.009) and weaning weight (p = 0.028), when compared with the genotype c.?2379TC, but it was not found to have an association with growth rate. This suggests that c.?2379T/C has an effect that originates at, or before birth. Haplotype H₃ was associated with a decrease in birthweight (p = 0.002), tailing weight (p = 0.003) and weaning weight (p = 0.011). Haplotype H₂ was associated with increased loin yield (p = 0.012) and proportion loin yield (p = 0.002). The SNPs may have value as genetic markers for improved Romney breeding.     

质地多方面分析三个桃品种果实采后质地的变化

以鲜食桃品种"脆保"、"艳保"和"大久保"为试材,采用质构仪质地多方面分析测试法(TPA),研究3个品种果实采后不同贮藏时间的质地变化。结果表明:在室温和低温2种贮藏温度下,3个品种桃果实的硬度随着贮藏时间的延长逐渐下降,而粘附性、弹性、咀嚼性都随贮藏时间延长呈现先上升后下降的趋势,表现为"脆保""艳保""大久保";内聚性变化相对比较平缓。相关性分析表明,桃果实咀嚼性与粘附性呈极显著正相关,二者与果实硬度间亦表现为极显著正相关(P0.01)。弹性与硬度和咀嚼性之间均呈相反的线性相关关系,果肉内聚性值与其它参数值相关性较差。硬度、粘附性、弹性和咀嚼性可用于评价采后桃果实质地的变化,内聚性则反映了果实质地的细微变化。     

壳聚糖澄清黄瓜汁的试验研究

用壳聚糖对黄瓜汁进行澄清试验,研究了壳聚糖用量、pH、温度等工艺条件对黄瓜汁澄清效果的影响,并通过正交试验确定壳聚糖澄清黄瓜汁的最适工艺条件为:壳聚糖用量0.5g/L、温度50℃、pH4.0、反应时间1.5 h.     

推进鄂伦春自治旗农牧业产业化的思考

本文结合鄂伦春自治旗农牧业的物殊现状分析,指出在推进鄂伦春农牧业产业化过程中存在的主要问题,并有针对性地提出相应的对策和建议.