低空急流对近地表风力机械结构载荷的影响

为分析低空急流对风力机械结构载荷的影响,该研究采用谐波叠加法对低空急流谱模型进行计算以生成大气入流,并基于叶素动量理论和几何精确梁方法对一台高度为270 m的15 MW风力机进行载荷分析。结果表明,低空急流在风力机高度范围内的速度剖面呈现射流和强剪切的耦合特征;低空急流最大可使风轮功率增大约40%,风轮俯仰力矩增大50%,风轮偏航力矩增大1.5倍,塔基偏航力矩的波动强度增加60%;同时,还会造成风轮偏航和俯仰力矩功率谱特性呈双阶梯型分布特征;当急流高度低于轮毂高度时,风力机俯仰力矩促使风轮向下倾斜,会增加风力机叶片打塔风险。因此,在低空急流多发地区安装风力机等高耸结构物时,应充分考虑低空急流对风力机结构载荷特性的影响。研究可为风力机在内的大尺寸高耸结构物的载荷安全性分析提供参考。     

植被覆盖度和降雨侵蚀力变化对小流域泥沙连通性的影响

泥沙连通性可以反映泥沙源汇的潜在联系,识别流域水土流失热点区域及泥沙迁移路径。研究泥沙连通性的影响因素有助于更好地理解泥沙连通性的时空变化特征。该研究在已有泥沙连通性指数（Index of Connectivity,IC）模型基础上,考虑影响连通性的功能性因素,并采用修正泥沙连通性指数（Revised Index of Sediment Connectivity,ICr）探讨了植被覆盖度和降雨侵蚀力耦合作用下的季节与年际变化对天目湖中田舍河流域泥沙连通性特征的影响。结果表明：2019年夏冬季植被覆盖度分别为85%、57%,对应的泥沙连通性指数均值是-9.39、-6.85,植被覆盖度变化对泥沙连通性具有重要影响,利用NDVI值获取模型中的地表综合系数,可以动态反映地表植被和土地利用的区域及季节性变化;降雨影响泥沙的功能连通性,年尺度上的连通性指数均值同流域泥沙量的相关系数达0.91。说明在流域植被覆盖变化不明显时或者在林地为主的流域中,降雨因子具有主导作用;植被覆盖度升高28%,IC均值降低37%,而单独考虑降雨因子的IC-R均值则反映出雨量升高,指数值随之升高,修正连通性指数ICr综合考虑了植被与降雨因子,但在应用中要依据流域实际情况适当调整两者的权重。研究结果指出泥沙连通性指数在中国东南部区域运用中存在的问题,将对气候变化背景下我国湿润区湖泊小流域水土保持与水环境治理等提供科学参考。     

Scale-dependent seasonal habitat selection by jaguars (Panthera onca) and pumas (Puma concolor) in Panama

Landscape Ecology - Few habitat modeling studies consider multiple spatial or temporal scales; less identify the operative scale of an organism's response to predictor variables. Optimizing...     

小豆白粉病菌的鉴定与小豆品种抗白粉病评价

为明确小豆白粉病病原菌的种类以及小豆种质资源对白粉病的抗性,采用形态学和系统发育学方法对近年来在北京市发生的小豆白粉病病原菌种类进行鉴定,并采用室内苗期人工接种法评价小豆常见栽培品种（系）对白粉病的抗性。结果表明,从北京市采集的感白粉病小豆病样中培养获得病原菌BJ1,该菌能在小豆叶片和茎上产生明显的白色粉斑,分生孢子梗直立,不分枝,分生孢子单细胞,成链状着生于分生孢子梗上,呈椭圆形或卵圆形。通过rDNA-ITS序列系统发育分析,小豆白粉病菌BJ1被鉴定为白粉菌目白粉菌科的苍耳叉丝单囊壳Podosphaera xanthii。室内苗期人工接种条件下,19个供试小豆品种（系）接种小豆白粉病菌BJ1后均可发病,其中9个审定品种均表现为中度感病或高度感病,10个优良品系发病略轻。     

A vegetation reconstruction method to plant <Emphasis Type="Italic">Sedum spectabile</Emphasis> Boreau using drip-irrigation with saline water on a coastal saline soil in region around Bohai Gulf

Soil salinity and saline groundwater are major constraints to the cultivation of crops and landscape plants in coastal regions. With the rapid industrialization and urbanization in these areas, there is an urgent need to improve the landscape to meet the increasing demand of living environments for cities and districts. The aim of this study was to propose a method to plant Sedum spectabile Boreau, a common landscape flower plant, on a very heavy coastal saline soil using drip-irrigation with saline water in region around Bohai Gulf. The salinity levels of irrigation water were 0.8, 3.1, 4.7, 6.3a, nd 7.8 dS/m, respectively. The results showed that the revegetation method, which mainly included ‘ridge planting + saline water drip-irrigation’, was effective in planting Sedum spectabile Boreau for reclaiming coastal saline silt soil. An soil matric potential (SMP) higher above ?5 kPa after transplanted and ?10 kPa after growing season ended, and 6 mm of irrigation water can be used as indicators for Sedum spectabile Boreau drip-irrigation scheduling with 100 % survival rate when irrigated with saline water at <7.8 dS/m in initially saline soils with a gravel–sand layer after tillage. This method is combined with comprehensive utilization of the saline water, agronomic measures, collaborative repair of the soil and plants to offer new views and theoretical support for the protection and development of saline land in coastal regions.     

黑龙江省主栽大豆品种品质优势分析

为了解黑龙江省主栽大豆品种的品质现状,探寻黑龙江省主栽大豆品种的品质优势,扩大黑龙江省大豆加工用途,本研究将2020年黑龙江省主栽大豆品种与进口大豆(来源于巴西、美国、阿根廷、乌拉圭和俄罗斯)品质指标进行比较分析.结果表明,黑龙江省大豆主栽品种以高蛋白为主,55％以上品种粗蛋白质含量超过40％.与进口大豆比较,黑龙江省...     

稻田稗属杂草致病菌的分离与鉴定

稗草Echinochloa crus-galli作为稻田难以防除的恶性杂草,严重影响水稻产量。为发掘具有防治稻田稗草潜力的生防菌,本研究从江苏、广西、贵州三省采集感病稗草,采用组织分离法获得10株对稗草致病性较强的优势菌株。通过观察优势病原菌的形态特征,结合rDNA-ITS、GAPDH、EF-1α基因片段序列分析确定10株菌分别为新月弯孢Culvularia lunata、尖角突脐蠕孢Exserohilum monoceras、禾长蠕孢菌Setosphaeria rostrata、稻平脐蠕孢Bipolaris oryzae、梭形突脐蠕孢Exserohilum fusiforme、澳大利亚弯孢Curvularia australiensis、双色平脐蠕孢Bipolaris bicolor、高粱附球菌Epicoccum sorghinum、亚隔孢壳属Didymella americana和亚隔孢壳属Didymella pinodella。该研究丰富了稗草病原菌生物资源,为进一步开发稻田生物除草剂提供了新材料。     

微型平板凝集抑制法检测伪结核棒状杆菌

将伪结核棒状杆菌用含犊牛血清的平板培养后,刮取菌落,用营养肉汤稀释,经56℃30分钟灭活制备抗原。然后用已知标准血清、高免血清、待检阳性血清及阴性血清对比进行微型平板菌体凝集抑制试验。结果:标准血清、高免血清与待检阳性血清均抑制了菌体的凝集,呈现无圆形沉淀点,或仅有分散的絮状颗粒,即阳性反应;阴性血清不能抑制菌体的凝集,均呈现明显圆形成团的沉淀点即阴性反应,未出现非特异性即假阳性反应。本试验操作简便,敏感特异适用于山羊伪结核棒状杆菌病的诊断。     

The Influence Analysis of Failure Affected by Reducing the Consequences

With the social progress, some modern method has been used in the industry. It can reduce the failure of pressure vessel. The method includes supervision, emergency cut-off and emergency relief etc. Each method is refined and quantized in the article. And it helps exact forecast for the failure.