广州市城区居住区绿化质量研究

通过对广州市城区居住区绿地绿化进行抽样调查,利用调查数据对其居住区的绿化质昔进行分析,结果表明:广州市居住区植物多样性各指标整体水平较高,但内部差异很大.新居住区绿化植物过分强调美化效益和经济效益,忽略生态效益和环境效益,这种发展趋势是不可持续的.其次,居住区绿化植物,本地物种数量过少;居住区空间绿化较少,但晕增长趋势...     

醉马草的有毒成分研究

本研究用溶剂提取法和阳离子交换树脂法首次从醉马草中提取、分离出一种生物碱成分,我们称其为醉马草毒素。动物毒性试验证明,醉马草毒素是醉马草的主要有毒成分。经元素分析及有机波谱分析确定了结构式。 马属动物按照10g/kg体重的剂量,一次灌服醉马草干粉或相当剂量的粗提物,即可引起与自然发病相同的急性中毒。症状主要表现为精神极度沉郁、翘尾,四肢无力,行走如醉,肌肉震颤,心跳加快,呼吸迫促等。     

Aeromonas salmonicida infects Atlantic salmon (Salmo salar) erythrocytes

Aeromonas salmonicida subsp. salmonicida (hereafter A. salmonicida) is the aetiological agent of furunculosis in marine and freshwater fish. Once A. salmonicida invade the fish host through skin, gut or gills, it spreads and colonizes the head kidney, liver, spleen and brain. A. salmonicida infects leucocytes and exhibits an extracellular phase in the blood of the host; however, it is unknown whether A. salmonicida have an intraerythrocytic phase. Here, we evaluate whether A. salmonicida infects Atlantic salmon (Salmo salar) erythrocytes in vitro and in vivo. A. salmonicida did not kill primary S. salar erythrocytes, even in the presence of high bacterial loads, but A. salmonicida invaded the S. salar erythrocytes in the absence of evident haemolysis. Naïve Atlantic salmon smolts intraperitoneally infected with A. salmonicida showed bacteraemia 5 days post‐infection and the presence of intraerythrocytic A. salmonicida. Our results reveal a novel intraerythrocytic phase during A. salmonicida infection.     

不同采烤方式对上部烟叶质量及效益的影响

针对安康烟区上部烟叶组织结构特点,对上部烟叶一次带茎采烤方式比较研究,结果表明：上部烟叶带茎一次采烤与不带茎采烤方式相比,上中等烟比例极显著提高18.94%,均价极显著提高18.19%,原烟外观质量明显改善,橘黄烟比例明显增加,结构更加疏松,油分增多,色度增强,但用工、用煤、用电等总成本显著增加,每千克干烟增加1.14元。     

喷洒作业下四旋翼植保无人机的轨迹跟踪控制

针对所搭载药箱内药液变化导致四旋翼植保无人机喷洒作业品质下降的问题,为实现喷洒作业下四旋翼植保无人机的轨迹跟踪控制,提出一种喷洒作业下四旋翼植保无人机的轨迹跟踪控制方法.在考虑喷洒作业下药液变化影响的前提下,建立了四旋翼植保无人机的非线性动力学模型.在原有PD控制的基础上,引入模糊控制器对控制参数进行在线自适应整定,从...     

2020年山东省牛羊疫病报告及监测数据分析

为了解山东省牛羊疫病的流行及免疫现状,汇总2020年山东省牛羊疫病报告数据以及监测数据等信息,分析牛羊疫病的时间分布、空间分布及病种分布;结合监测情况,分析牛羊疫病的免疫状况和暴发风险.2020年山东省牛病以新生犊牛腹泻、牛病毒性腹泻和牛传染性鼻气管炎为主,突发输入性牛结节性皮肤病,羊病以沙门氏菌病、绵羊疥癣和布鲁氏菌...     

安哥拉山羊级进杂交后代生活力初步观察

对安哥拉山羊及其级进杂交后代的生长发育、繁殖力、抗病性、采食习性等进行初步观察研究，结果表明：在试验场良好的饲养条件下，各代杂种羊生长发育正常，但繁殖力、抗病性、采食能力随级进杂交代数的增加有降低的趋势。据此，笔者认为，在陕北特定的生态经济条件下，培育毛用山羊新品种，级进杂交代数不宜太高，到Ｆ３代应停止级进，进行横交固定，而且在整个育种中，应始终注意饲养问题，以保证新品种培育成功。     

Modelling and mapping natural hazard regulating ecosystem services in Sapa,Lao Cai province,Vietnam

Land use change due to the development of agriculture and community-based tourism has resulted in an increase in natural hazards (e.g. erosion and landslides) that affect sustainability in the Sapa mountainous area in northern Vietnam. Natural hazard regulating ecosystem services have protected the local people from the destruction of their villages, goods and natural resources, especially in the rainy season. However, it is difficult to identify which kinds of anthropogenic constructions support a co-production of regulating services in human-influenced social–ecological systems and in which specific types of land use and land cover the supply of such services takes place, especially in heterogeneous mountainous areas. Therefore, this research attempts to (1) distinguish between the potential and actual use (flow) of natural hazard regulating ecosystem services and (2) understand how soil erosion and landslide regulating ecosystem services can contribute to a sustainable management of different ecosystems, especially in rice fields and forest areas. Two models (InVEST for soil erosion, Analytic Hierarchy Process for landslide analysis) were used to analyze and map the contributions of natural versus anthropogenic components for regulating natural hazards in Sapa. The results show the incoherent distribution of erosion regulating services and low capacities of landslide regulating services in areas that have seriously been affected by human activities, especially forestry and agricultural development. The contribution of rice ecosystems to soil erosion mitigation is higher than in the case of landslides. Nevertheless, one-third of the area of paddy fields in the case study area have “no” capacity to supply natural hazard regulating ecosystem services and should therefore be re-forested.     

Fate and Transport of Nursery-Box-Applied Tricyclazole and Imidacloprid in Paddy Fields

The fate and transport of tricyclazole and imidacloprid in paddy plots after nursery-box application was monitored. Water and surface soil samples were collected over a period of 35 days. Rates of dissipation from paddy waters and soils were also measured. Dissipation of the two pesticides from paddy water can be described by first-order kinetics. In the soil, only the dissipation of imidacloprid fitted to the simple first-order kinetics, whereas tricyclazole concentrations fluctuated until the end of the monitoring period. Mean half-life (DT₅₀) values for tricyclazole were 11.8 and 305 days, respectively, in paddy water and surface soil. The corresponding values of imidacloprid were 2.0 and 12.5 days, respectively, in water and in surface soil. Less than 0.9% of tricyclazole and 0.1% of imidacloprid were lost through runoff during the monitoring period even under 6.3 cm of rainfall. The pesticide formulation seemed to affect the environmental fate of these pesticides when these results were compared to those of other studies.     

旱地施肥对春小麦根系生长、代谢的影响及促进水分有效利用的机理

本文采用田间可微区试验的方法,研究了施肥对旱地春小麦根系生长、根系活力的影响和根系特征量与土壤含水量的关系。结果表明:不同施肥处理使小麦根系的长度、重量、体积、表面积均有不同程度的增长,并使小麦根系活力增加。尤以N、P配合施用效果更好。施肥对小麦根系生长的促进作用可持续到小麦生育后期。施肥在促进小麦根系生长和代谢活力的基础上加大了小麦对深层土壤水分的利用;而且小麦根系总长度、总体积、总表面积及总的根系活力与该期土壤含水量呈极显著负相关,揭示了“以肥调水”的机理。