喷杆喷雾机变量控制特性测试系统设计与试验

为精准高效地完成喷杆喷雾机变量喷雾控制系统的控制特性测试,研制一种喷杆喷雾机变量控制特性测试系统,通过网络RTK采集机具行进速度,采用高精度流量与压力传感器获取管路流量和压力,利用CAN总线和无线数传的方式完成数据和指令的传递,通过Android设备进行人机交互完成数据的实时监测,结合数据处理软件完成测试结果的统计分析等功能。数据采集精度试验表明,网络RTK测速平均偏差为-0.02 km/h,流量传感器的平均误差为0.99%,平均重复性为0.31%,瞬时流量示值的平均标准偏差为0.04 L/min;压力传感器平均偏差为0.02 MPa。测试系统验证试验表明,针对某款压力调节式喷杆喷雾机,系统记录加速和减速阶段流量调节的平均滞后时间分别为1.31 s和1.70 s,平均调节偏差时间为0.56 s和1.47 s。研发的系统各项数据能准确反映机具工作状态,满足喷杆喷雾机变量量控制特性测试需求。     

基于SWOT分析的眉山市农业职业经理人培训模式研究

该文运用SWOT分析法对眉山市农业职业经理人培训模式进行了研究,结果表明:该模式具有体系构建科学、内容组配合理、制度匹配健全等优势;存在主题不够鲜明、实训不够深入的劣势;面临培育对象涌现、培养渠道畅通、培训观念转变的机会;受到参训学员、承训机构、管理人员各方能力差异的威胁.因此,应实施专题培训、探索后续跟踪、强化能力提升等.     

三种消解方法测定天然橡胶镁含量的研究

为研究更适合于天然橡胶中镁含量检测的方法,采用干灰化法、微波消解法和石墨消解法三种消解方法研究不同消解条件对天然橡胶中镁含量检测的影响。结果表明,三种消解方法对天然橡胶镁含量的测定均可以满足要求。干灰化法对实验结果影响较小,对低镁含量的样品应适当增加样品量;微波消解法操作简便且检测耗时较短;石墨消解法操作简单,工作效率较高,适用于批量样品分析,设备以及耗材成本与前两种方法相比具有较大优势,为未来我国制定天然橡胶中镁含量的检测标准提供了理论依据。     

磷对坛紫菜孢子囊枝形成的影响

主要研究了不同浓度、不同形式的磷源（磷酸二氢钾、磷酸氢二钾和甘油磷酸钠）对坛紫菜（Porphyra haitanensis）孢子囊枝形成的影响，以及丝状体对磷的利用情况。结果表明，氮磷比在2／1左右时有利于孢子囊枝形成；无机磷酸盐比有机磷酸盐更能促进坛紫菜孢子囊枝形成；当N，P为10／1、7／1和2／1时，磷吸收速率随该比值下降而上升；磷起始浓度过高不利于丝状体的生长发育，有规律地适量添加磷盐有利于坛紫菜孢子囊枝的形成。     

Assessment of attenuated Salmonella vaccine strains in controlling experimental Salmonella Typhimurium infection in chickens

Salmonella hold considerable promise as vaccine delivery vectors for heterologous antigens in chickens. Such vaccines have the potential additional benefit of also controlling Salmonella infection in immunized birds. As a way of selecting attenuated strains with optimal immunogenic potential as antigen delivery vectors, this study screened 20 novel Salmonella Typhimurium vaccine strains, differing in mutations associated with delayed antigen synthesis and delayed attenuation, for their efficacy in controlling colonization by virulent Salmonella Typhimurium, as well as for their persistence in the intestine and the spleen. Marked differences were observed between strains in these characteristics, which provide the basis for selection for further study as vaccine vectors.     

铀尾矿库茅草植物根系发育的分形特征

研究了非线性科学中的分形几何理论,并将其应用到植物根系发育的结构上,对铀尾矿库上采集的茅草（Lemongrass）植物根系分形特征进行了研究。用FractalFox软件计算了植物根系的分形维数,结果发现：这种植物根系分维数都介于1．3305～1．5214之间,说明这种植物根系分形特征明显。实验中还发现生长在水环境旁的根系分维数明显高于在干燥环境下的根系分维数,说明湿润的环境能促进植物根系发育。     

三联疫苗预防斑点叉尾(鱼回)细菌性疾病研究

对斑点叉尾鮰致病的3株细菌,经液体培养后灭活制备三联免疫疫苗,斑点叉尾鮰鱼苗通过浸泡接种,抗感染能力大为增强.经人工感染试验,对CR79-1-1和ST78-3-3菌免疫保护率达到91％～100％，对93-Ⅲ菌免疫保护率可达64％。     

氯化钴在大菱鲆饲料中的安全性评价

通过研究饲料中的氯化钴对大菱鲆幼鱼的存活、生长性能、血清生理生化指标、抗氧化酶活力、消化酶活力、血清和肝脏中VB12含量、肌肉和肝脏中钴的残留量、肝脏和肠道组织结构的影响来评估氯化钴在海水鱼饲料中的安全性。通过在基础饲料中添加氯化钴制剂来配制4种具有不同氯化钴含量(0、8、40及80 mg/kg,不计结晶水重量)的等氮等能的实验饲料,每个饲料处理设6个重复,每个重复养殖30尾大菱鲆;养殖实验为期10周。实验结果表明:饲料中添加氯化钴对试验鱼的存活没有显著影响(P0.05),但饲料中80 mg/kg的氯化钴显著降低了大菱鲆的特定生长率、终末体重、摄食率、肝体比和脏体比(P0.05);饲料中高剂量氯化钴(40和80 mg/kg)显著降低了大菱鲆血清过氧化氢酶、谷草转氨酶和碱性磷酸酶活力以及大菱鲆胃淀粉酶和胰蛋白酶活力(P0.05);大菱鲆的血糖含量、血清和肝脏中VB12含量、肝脏和肌肉中钴的残留量均随饲料中钴的添加量增加而显著升高(P0.05);饲料中添加氯化钴对大菱鲆的肠道组织结构没有产生明显影响,但饲料中添加40和80 mg/kg的氯化钴增宽了肝脏肝血窦。研究结果表明:实验条件下,氯化钴在大菱鲆饲料中的添加量8 mg/kg是安全的。     

Hydrogen sulfide ameliorates high glucose-induced endothelial cell senescence by suppressing oxidative stress

AIM：To explore the effect of hydrogen sulfide on the senescence of human umbilical vein endothelial cells (HUVECs) induced by high glucose. METHODS：Senescence model was established by treating HUVECs with 33 mmol/L glucose for 48 h. The parameters were detected to demonstrate the effect of hydrogen sulfide on senescence and the mechanism involved was also investigated. RESULTS：In the cells treated with high glucose, the proliferation was attenuated with a higher number of senescence-associated β-galactosidase (SA-β-Gal) positive cells, and plasminogen activator inhibitor 1 (PAI-1) protein expression, malondialdehyde (MDA) production and NF-κB p65 activity were increased significantly, but the expression of superoxide dismutase 1 (SOD1) was decreased. However, the cell number and SOD1 expression were increased, and the number of SA-β-Gal positive cells, PAI-1 protein expression, MDA production and the activity of NF-κB p65 were decreased after sodium hydrosulfide (100 and 200 μmol/L) treatment.CONCLUSION：Exo-genous hydrogen sulfide prevents HUVECs against high glucose-induced senescence by suppressing oxidative stress and NF-κB p65 activity.