玉米果穗剥皮装置的参数研究

利用自制剥皮装置试验台,选择影响剥皮性能的压送器转速、剥皮辊转速、剥皮辊倾角三个主要参数作为设计变量,通过二次回归通用旋转组合试验和优化设计,得出了各参数的最优组合.为玉米果穗剥皮装置的设计提供了依据.     

Shut up or shout loudly: Predation threat and sound production in fishes

Predation is a major ecological constraint shaping behaviour and communication in animals. Several fish species are known to modify their foraging, agonistic and reproductive behaviour in the presence of predators. However, close to nothing is known about how predators affect sound production in fishes. This paper reviews how vocal fish increase their chance of survival by modifying intraspecific acoustic communication and by producing sounds directed towards predators. Field studies showed that toadfish, drums and squirrelfish reduced the number and loudness of calls when dolphin sounds were played back. These studies lack behavioural observations, leaving the question open how individual fish respond to predation threat. Croaking gouramis (Trichopsis vittata, Osphronemidae) reduced acoustic and visual signalling during dyadic contests and refrained from escalated behaviour when detecting a predator in an adjacent tank. This indicates that gouramis increase their vigilance by reducing agonistic behaviour. Vocal fish have been observed to emit sounds when predators approach or when being caught. However, none of the predators (or even conspecifics nearby) responded to these calls. Therefore, the term “predator-related” sound has been introduced in this paper to avoid implying unproven functions (alarm, startling, warning, distress and disturbance). Interestingly, the readiness of numerous taxa (e.g. catfishes) to vocalize when hand-held or netted was frequently exploited to investigate sound production in fish in relation to weight, sex, sonic organs, temperature or phylogeny. Increasing levels of noise in aquatic habitats call for more research on predator–prey interactions because of potential negative effects on detection of sounds produced by predators or prey.     

含水率对原木孔洞缺陷应力波检测效果的影响

应用微单元分析模型,在实验室条件下研究含水率对原禾内部孔洞缺陷检测效果的影响。在不同含水率状态下测试原木内应力波传播速度,分析应力波传播速度与含水率的相关性,得出原木孔洞缺陷识别质量系数。结果表明,在较低的含水率状态下原木孔洞缺滔检测效果较好。     

Drought stress impact on the performance of deep convolutional neural networks for weed detection in Bahiagrass

Machine vision-based weed detection relies on features such as plant colour, leaf texture, shape, and patterns. Drought stress in plants can alter leaf colour and morphological features, which may in turn affect the reliability of machine vision-based weed detection. The objective of this research was to evaluate the feasibility of using deep convolutional neural networks for the detection of Florida pusley (Richardia scabra L.) growing in drought stressed and unstressed bahiagrass (Paspalum natatum Flugge). The object detection neural networks you only look once (YOLO)v3, faster region-based convolutional network (Faster R-CNN), and variable filter net (VFNet) failed to effectively detect Florida pusley growing in drought stressed or unstressed bahiagrass, with F1 scores ≤0.54 in the testing dataset. Nevertheless, the use of the image classification neural networks AlexNet, GoogLeNet, and Visual Geometry Group-Network (VGGNet) was highly effective and achieved high (≥0.97) F1 scores and recall values (≥0.98) in detecting images containing Florida pusley growing in drought stressed or unstressed bahiagrass. Overall, these results demonstrated the effectiveness of using an image classification convolutional neural network for detecting Florida pusley in drought stressed or unstressed bahiagrass. These findings illustrate the broad applicability of these neural networks for weed detection.     

农杆菌介导大豆未成熟子叶的遗传转化

用农杆菌LBA4404(pGBI121S4ABC)转化5个大豆品种的未成熟子叶,经卡那霉素筛选得到抗性植株,进一步用PCR检测,获得10株PCR阳性植株.同时发现,不同大豆品种农杆菌转化的效率是不同的,吉林43较易于转化;共培养时间是影响转化效率的主要因子.     

胶体金免疫层析技术在动物病毒性传染病诊断中的应用

自胶体金标记技术问世以来,已在妊娠检测、传染病、毒品、食品安全和兽医等领域得到了广泛的应用.就兽医领域而言,已应用在动物寄生虫、细菌、病毒以及兽药残留检测等方面.论文总结了胶体金免疫层析技术的基本原理和常见的检测抗原、抗体的方法,对胶体金免疫层析技术在动物病毒抗原和抗体检测中的应用进行了详细的介绍,并对该技术在动物病毒...     

畜产品中沙门氏菌的快速检测

以热裂解法快速提取DNA模板,应用PCR技术检测沙门氏菌,22种沙门氏菌的基因均获得特异性扩增(496bp),5种非沙门氏菌检测结果为阴性。试验结果表明,PCR是一种快速、敏感和高度特异性的沙门氏菌检测方法,值得在畜产品沙门氏菌的检测中推广应用。     

肠炎沙门氏菌特异性诊断方法的建立

用传统的分离鉴定方法从临床采集的12例不同蛋鸡样本中分离到1株肠炎沙门氏菌。为避免传统鉴定技术中可能出现的假阳性等问题,依据SEF 14菌毛是肠炎沙门氏菌的特异性粘附素这一特性,设计编码该粘附素基因中相对保守片段的1对引物,对上述可疑菌株进行PCR扩增,以含有编码SEF 14菌毛操纵子全基因的质粒DNA、标准株SD-2染色体DNA作为阳性对照,鸡白痢国内分离株SP染色体DNA作为阴性对照。PCR扩增结果显示分离株出现1条与预期大小498 bp一致的特异性扩增条带,阳性对照也出现相同大小的条带,而阴性对照则未出现。结合传统的细菌学分离鉴定和特定的分子生物学鉴定,将此可疑分离株确定为肠炎沙门氏菌。该方法可快速、准确、敏感地检测肠炎沙门氏菌。     

食品有害微生物快速检验方法

食品有害微生物检验在食品卫生检验中具有十分重要的作用。综述食品有害微生物快速检验方法,涉及分子生物学技术、抗原抗体免疫检测技术、载体仪器技术、代谢学技术、生物传感器、色谱技术等方面内容,介绍各种检测方法的原理、应用、结果判断等,可为食品有害微生物的准确检测提供参考和指导。