基于计算机视觉的大菱鲆对背景色选择习性研究

为了探讨大菱鲆幼鱼对于不同背景色的选择习性,该文首先通过9格颜色试验发现大菱鲆幼鱼偏好淡紫色,而出现在黑色和红色背景累积频率较低;同时通过计算机视觉分析发现,幼鱼在黑色和红色背景下体表明度变化速率远比在紫色和粉色背景下剧烈,证明了黑色和红色背景对幼鱼胁迫更大,其需要调动更多激素来调整生理响应,以改变体色适应新的背景环境。因此建议养殖池的颜色尽量采用浅色,不要使用黑色等深色作为养殖背景颜色,研究结果可为养殖系统设计和生产管理提供参考依据。     

基于多源数据的县域冬小麦氮肥调控管理分区

为便于对县域尺度冬小麦进行精确氮肥调控,该文以安阳县冬小麦种植区为研究对象,在3S技术的支持下,利用定性和定量相结合的分析方法,分别对影响冬小麦氮肥调控的重要因子,如地形、土壤类型、土壤养分和光谱信息等多源数据,进行聚类和综合叠加分析,以确定最终的县域氮肥调控管理分区。基于土壤养分和产量的管理分区划分结果评价表明,各级分区土壤养分和产量的变异系数均有所减低,其中三级分区的21个子区为最终分区结果,其管理分区之间的土壤理化性质差异显著,有机质、碱解氮和产量变异系数均值分别降低70%、53%、66%。基于光谱数据的管理分区划分结果评价表明,不同分区内归一化植被指数(NDVI)的集中程度明显提高。分区结果可以作为冬小麦氮肥调控的决策单元,为精确农业管理提供有效途径。     

中国农业机械化促进法实施效果研究

《中华人民共和国农业机械化促进法》不仅确立了农业机械化的地位和作用,而且还指明了农业机械化的发展方向,对促进和提高我国农业机械化水平具有重要的意义。为此,通过对《中华人民共和国农业机械化促进法》实施前后中国农业机械化状况进行了对比分析,研究了《中华人民共和国农业机械化促进法》实施后取得的主要成效,并深入分析《中华人民共和国农业机械化促进法》本身以及实施过程中出现的问题,提出了相应的对策和建议。     

基于证据理论和可变模糊集的成都市洪灾风险评估

洪灾系统的高维性和不确定性,给灾害风险评估带来较多困难,为了提高评估的准确性和合理性,实现科学灾害管理,该文将Dempster_Shafer证据理论应用到洪水灾害风险评估中,同时利用可变模糊集理论来构造证据理论基本信任分配,实现了客观合理的证据建模,最后利用经典组合原理进行证据组合。以成都市区2012年风险等级的计算为例,风险为高等级时的信任区间为[0,0.52],似然区间为[0,0.54],不确定大小为0.019,根据判断规则,确定市区2012年的洪灾风险等级为高。基于此方法采用相同处理,对研究区成都市风险等级的时空分布进行了计算分析。结果表明该方法能够较好地融合洪水灾害系统各方面信息以及处理风险评估中的不确定性,实现了洪灾风险的准确评估。     

Monitoring of artemisinin, dihydroartemisinin, and artemether in environmental matrices using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS)

The area cultivated with Artemisia annua for the extraction of the antimalarial compound artemisinin is increasing, but the environmental impact of this cultivation has not yet been studied. A sensitive and robust method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of artemisinin in soil. Dihydroartemisinin and artemether were included in the method, and performance on analytical columns of both traditional C(18) phenyl-hexyl and porous shell particles-based Kinetex types was characterized. The versatility of the method was demonstrated on surface water and groundwater samples and plant extracts. The limit of detection was 55, 30 (25 ng/g soil), and 4 ng/mL for dihydroartemisinin, artemisinin, and artemether, respectively. Method performance was demonstrated using naturally contaminated soil samples from A. annua fields in Kenya. The highest observed concentrations were above EC(10) for lettuce growth. Monitoring of artemisinin in soil with A. annua crop production seems necessary to further understand the impact in the environment.     

Genetic characterization and evolutionary analysis of 4 Newcastle disease virus isolate full genomes from waterbirds in South China during 2003-2007

Complete genomes of four Newcastle disease virus (NDV) strains, isolated from ducks and wild birds in Guangdong province of China from 2003 to 2007, were sequenced and analyzed in this study. Pathogenicity tests in chicken embryos and chickens illustrate that D3 and R8 are lentogenic, and W4 and P4 are mesogenic strains. Phylogenetic analysis using all six genes provides a high resolution profile for genotype designation as genotype I for D3 and R8 strains and genotype VI for W4 and P4 strains. In addition, molecular dating based on different genes suggests that D3 and R8 diverged from their common ancestor at around 1998; W4 and P4 diverged from their common ancestor at around 1999. Subsequent selective pressure analysis displayed specific traits of genes evolution in all 4 strains since their divergence from the recent common ancestor. Furthermore, the geographic origins of 4 strains were deduced to be from Europe via two independent introduction events by phylogeographical analysis. This provides insights to the potential influence of waterfowl migration on NDV epidemiology.     

水田泥浆对农用纸膜黏附性影响的试验研究

为探索提高农用纸膜与水田泥浆的贴合质量的方法,试验研究了水田泥浆含水率、纸膜承载正压力和加载速度等因素对泥浆纸膜间黏附力的影响规律,建立了相应的数学模型。试验结果表明,泥浆含水率为34.5%～35.5%时,随含水率增加,泥浆黏度、黏附力急剧下降;含水率超过35.5%时,含水率变化对黏度、黏附力影响不显著;黏附力随泥浆黏度的增加呈对数增长趋势。纸膜与泥浆间的黏附力随正压力的增加,呈线性增加趋势。加载速度在0.83×10-3～0.5×10-2 m/s区间,黏附力随加载速度增加而快速上升;加载速度超过0.5×10-2 m/s时,黏附力上升速度较慢;加载速度在0.67×10-2～0.83×10-2 m/s范围内时,黏附力趋于定值。因此,为了提高纸膜覆盖质量,整地、泡田过程中,应使土壤含水率最大不要超过饱和含水率的1.05倍;在满足泥浆的抗压强度的前提下应增加纸膜单位面积上的正压力;覆膜速度低于0.5×10-2 m/s时,通过加载速度的方法来提高覆膜质量。研究成果将为纸膜覆膜机构的设计提供参考。     

双汇“瘦肉精”事件对我国生猪产业的影响

3月15日．双汇“瘦肉精”事件被中央电视台曝光后．有关“瘦肉精”事件的跟踪报道就开始接连不断．畜产品质量安全问题成为当前社会各界和人民群众最为关注的焦点．给我国的生猪产业造成了极大的影响。为了更好的应对此次事件对生猪产业的影响．促进生猪产业走上健康快速发展的道路。笔者走访了部分生猪养殖企业和屠宰加工企业．根据当前生猪养殖业实际．对事件发生后的生猪产业受到的影响进行了客观分析．并提出了对策建议．供同行参考。     

影响反刍动物产品中共轭亚油酸富集因素的研究进展

共轭亚油酸(CLA)又被称为过瘤胃脂肪酸。近年来,随着CLA对人体健康的重要作用被陆续发现,通过饲养途径如何提高反刍动物产品中CLA含量成为当前动物营养研究领域的热点。本文在查阅国内外CLA最新研究进展的基础上,对影响反刍动物产品中CLA合成的因素加以综述。