应用事件分析法对林业企业发行绿色债券市场效应的评价     

盛春光  赵晓晴  钟凤英 《东北林业大学学报》2021,49(2):89-92,100

在系统梳理绿色债券相关理论基础上,以16个二级行业为研究对象,运用事件分析法分析林业企业上市公司发行绿色债券与股价相关性、林业企业发行绿色债券的市场价值,探索发行绿色债券的林业企业市场效应。结果表明:绿色债券融资对提升公司长短期的市场价值具有重大影响,绿色债券融资是经济实体发展绿色经济的表现,是符合经济趋势和其自身发展趋势的行为。林业企业对绿色债券的发行,持积极股价效应,提升公司市场价值;由于其项目投融资的绿色性,对市场效应有更好的显著性和持续性,对绿色债券的发行表现出积极市场效应,提升企业市场价值。依据绿色债券理论和实践,并结合林业企业自身的生态特性,从林业企业发行绿色债券的政策制度、融资优势、自身特征三个方面,在详细阐述林业企业发行绿色债券可行性基础上,提出林业企业推动绿色债券发行相关建议:构建林业企业绿色债券制度规范、增强林业企业绿色债券融资意识、提高林业企业绿色债券运营能力、加强林业企业绿色债券人才建设。  相似文献   

生态系统视角下农村失独家庭的困境应对策略研究     

赵仲杰  都天虹 《南方农机》2021,(1)

农村失独父母是我国计划生育政策实施以来产生的一个特殊弱势群体。由于农村社会经济发展的特殊性,处于失独困境的家庭亟待政府和社会的更多关注和支持。农村失独家庭面临家庭关系紧张、精神承受重压、经济水平落后、生活缺乏照顾、养老医疗困顿、人际关系贫瘠等难题。为了化解上述难题,必须尽可能发挥政府和社会的保障支持功能。基于生态系统理论,需要通过多主体协同,从宏观、外层、中层、微观四个层次构建对于农村失独家庭的社会保障、社会支持体系,形成为农村失独家庭服务的系统性支持保障网络。  相似文献   

祁连山南麓高寒灌丛GPP变化特征及对生长季积温的响应     

祝景彬  贺慧丹  李红琴  张法伟  李英年  杨永胜  张光茹  王春雨  罗方林 《草业科学》2021,(2):221-230

全球气候变化背景下气温逐渐升高,将会对陆地生态系统碳循环产生重要影响。研究利用2003?2016年的涡度相关系统观测资料,研究了祁连山南麓高寒灌丛生长季(5月?9月)总初级生产力(gross primary productivity,GPP)在不同时间尺度上对生长季有效积温(growing season degree days,GDD)的响应,对于研究气候变暖对高寒生态系统碳循环的影响有重要意义。结果表明:高寒灌丛生态系统在生长季的月GPP、GDD都表现为先增大后减小的单峰变化趋势,都在7月或8月达到峰值,在5月达到最小值。在整个生长季尺度上,GPP与GDD具有较高变异性,但整体上表现为逐渐增加的趋势(P<0.05)。2003?2016年整个生长季GPP与GDD的均值分别为507.11 g·m^?2和975.93℃。在月尺度和生长季尺度上,GPP与GDD都呈显著正相关关系(P<0.05)。但是,通过比较生长季每个月GPP与GDD的关系发现,5、9月的GPP与GDD没有显著相关性(P>0.05),而在7月相关性最为显著(P<0.01)。整体上看,高寒灌丛生态系统植被的总初级生产力与热量条件表现为正相关关系,由此说明在全球气候变暖的背景下,青藏高原高寒灌丛生态系统植被的光合生产能力将会提高。  相似文献   

绿肥影响农田土传病害的研究进展     

魏勇  高嵩涓  曹卫东  段廷玉 《草地学报》2021,29(8):1605-1614

土传病害是制约我国农业可持续发展的因素之一。绿肥作为高效清洁的有机肥源,与主作物合理搭配,可有效降低主作物土传病害的发生和危害,是减少化学药剂使用的重要措施。因此,综述绿肥对土传病害的防控效果与机制,对于绿肥推广应用和土传病害绿色防控具有重要意义。绿肥影响作物土传病害的研究主要集中于土传真菌病害和线虫病害,且大多数研究表明,绿肥可通过增强主作物整体抗病水平,对病原菌的化感抑制作用和改善土壤理化性质,增加土壤微生物中拮抗菌多样性和丰富度等,显著降低主作物土传病害发病率和严重程度。然而,绿肥影响主作物病害的作用机制研究不够深入,绿肥-主作物搭配模式和绿肥调控主作物病害的社会经济学效益仍需探究。同时,加强绿肥-主作物病害一体化防控及绿肥与根际促生菌、生防菌等其他有机改良剂或与适当的化学防控措施之间协同作用的研究,是未来需要加强的研究方向。  相似文献   

绵羊BMP15基因B2突变可视化检测技术的建立     

胡瑞瑞  刘莉  郭涛  李雅心  王小奎  胡圣伟 《中国畜牧兽医》2021,48(3):810-817

骨形态发生蛋白15（bone morphogenetic protein 15,BMP15）基因突变对绵羊排卵率、产仔数以及繁殖力有很大影响,本研究旨在建立快速可视化检测BMP15基因B2突变的技术。将改良的扩增阻滞突变系统（amplification refractory mutation system,ARMS）与核酸染料SYBR Green Ⅰ结合,针对BMP15基因B2突变设计ARMS特异性引物,使引物下游3'端的最后一个碱基为A,并在下游引物3'端的第3位碱基处设计额外的错配,以提高引物的特异性;经ARMS PCR扩增后,向产物中加入SYBR Green Ⅰ,通过肉眼观察PCR管内的颜色变化来检测BMP15基因的B2突变。经测序发现所采集的样本均为野生型,因此,利用重叠延伸PCR构建BMP15基因B2突变型模板,测序结果显示BMP15基因B2突变型模板构建成功。ARMS PCR结果显示,ARMS特异性引物能够只扩增突变型模板,而不会扩增野生型模板,且扩增效果良好。ARMS PCR扩增后加入SYBR Green Ⅰ发现已知野生型模板与阴性对照一致,呈SYBR Green Ⅰ原始颜色橙黄色,而已知突变型模板呈亮绿色,且色差明显,肉眼可辨。用建立的可视化检测BMP15基因B2突变的技术检测50个小尾寒羊基因组DNA （随机向其中20个样本中加入构建的BMP15基因B2突变型模板）,将可视化检测的突变型样本编号与混合样本时记录的编号对比,结果表明该技术能够准确检测绵羊BMP15基因的B2突变,且准确率高达100%。将构建的BMP15基因B2突变型的模板进行梯度稀释,对本试验可视化检测体系的灵敏度进行检测,发现ARMS可视化检测技术的灵敏度达到0.006 ng/μL。因此,本研究建立的技术能够可视化地检测绵羊BMP15基因B2突变,且准确率高,有望为高繁殖力绵羊的选育提供技术支持。  相似文献   

Green tea polyphenols supplementation alters immunometabolism and oxidative stress in dairy cows with hyperketonemia     

Yanfen Ma  Ying Feng  Liwen Song  Muyang Li  Hongyu Dai  Hua Bao  Guijie Zhang  Lei Zhao  Chunhua Zhang  Jing Yi  Yusheng Liang 《动物营养（英文）》2021,7(1):206

Peripartal cows often experience negative energy balance, and are therefore prone to suffering from metabolic diseases such as hyperketonemia, which causes financial losses in dairy farms. This study aimed to investigate the effect of green tea polyphenol (GTP) supplementation during the periparturient period on production performance, oxidative stress and immunometabolism in dairy cows with hyperketonemia. One hundred Holstein cows were assigned to GTP (0.2 g/kg DM; n = 50) or control (without GTP; n = 50) group based on body weight, previous milk yield, and parity on d 15 before expected parturition. Subsequently, 10 cows with hyperketonemia were selected from each group, according to blood β-hydroxybutyric acid (BHBA) concentration between 1.2 and 2.9 mmol/L from 2 to 3 d postpartum. All cows were fed a close-up diet and a lactation diet with or without GTP supply from 15 d prepartum until 30 d postpartum. Milk and blood samples were obtained from 20 cows selected with hyperketonemia on 10, 20, and 30 d postpartum. Compared with control cows, greater milk yield and lower somatic cell count were observed in GTP cows. The GTP group had lower concentrations of BHBA, free fatty acids, cholesterol, triglyceride, reactive oxygen species, malondialdehyde, and hydrogen peroxide, greater concentrations of glucose, lower activities of aspartate aminotransferase, alanine aminotransferase, and glutamyl transpeptidase, alongside greater activities of superoxide dismutase, glutathione peroxidase, and total antioxidant capacity. Additionally, GTP supplementation up-regulated concentrations of interleukin-6 and interleukin-10, but down-regulated concentrations of tumor necrosis factor-α, interleukin-1β, interleukin-2, interleukin-8, and interferon-γ in plasma. Greater concentrations of plasma immunoglobulin G were also detected in the GTP group. Overall, the data suggested that GTP supplementation from 15 d prepartum to 30 d postpartum improved the milk yield and health status in cows with hyperketonemia during early lactation.  相似文献   

甜瓜黄斑病毒SYBR Green Ⅰ实时荧光定量PCR方法     

孙晓辉  潘睿婧  刘永光  王丹  石朝鹏  乔宁  孙作文  竺晓平 《植物病理学报》2023,53(1):119-125

为建立检测甜瓜黄斑病毒(melon yellow spot virus, MYSV)的SYBR Green Ⅰ实时荧光定量PCR(qPCR)方法。基于MYSV核衣壳蛋白基因保守序列设计qPCR特异性引物对,针对引物退火温度、引物浓度、特异性和敏感性进行系列优化。结果显示,优化后的qPCR方法最适退火温度为61.3℃,最适引物浓度为0.65μmol·L^-1,特异性强,灵敏度高,比PCR高100倍。以携带目的基因片段的重组质粒为标准品,构建的qPCR标准曲线循环阈值与模板浓度呈良好的线性关系,相关系数为0.999 7。实验样品验证表明建立的qPCR方法可用于MYSV的定量检测。  相似文献   

Design of the Virtual Instrument of Frequency/Amplitude Sweep     

XIE Ting ting  TANG Bao ping  QIN Shu ren 《保鲜与加工》2002,(4):11-14

In this paper the inevitable trend of constructing open ecosystem in modern settlement environment was discussed through the history of the settlement environment and the characters of modern settlement environment.The ecological crisis,change of the modern life and the citizens' needs and the ecological system character show,that it is important for sustainable development of the settlement environment to construct open ecosystem.The construction of modern habitation and the city room embodies the concept of open ecosystem.Then,in construction and research of modern settlement,the ecological viewpoint and method should be applied.  相似文献   

蔬菜的硝酸盐污染及防控措施     

孙磊 《农机化研究》2006,(12):55-56

由于不合理的种植手段,造成了蔬菜的硝酸盐污染,影响蔬菜的品质,威胁人类的身体健康和生命安全。通过重视施用有机肥、合理施用氮肥、注意施肥时期和施肥种类、在不同季节使用正确栽培设施、使用硝化抑制剂(氮肥增效剂)等技术手段,可以明显减少硝酸盐在蔬菜中的残留,对发展绿色无公害蔬菜生产和提高人民生活水平有着十分重要的意义。  相似文献   

A Framework for Valuing Ecological Services of Irrigation Water – A Case of an Irrigation-Wetland System in Sri Lanka     

Margaretha Bakker  Yutaka Matsuno 《Irrigation and Drainage Systems》2001,15(2):99-115

In many countries, irrigation water is usedfor several purposes other than irrigatingfield crops. In Sri Lanka, irrigationwater from canals, wells, and reservoirs isused for domestic purposes, industry,livestock, and fisheries, and it alsocontributes to sustain the environment. However, policy makers and water managersin irrigation systems only take intoaccount water used for irrigating the fieldcrops and sometimes water used for domesticpurposes. Owing to the failure torecognize the different uses and users ofwater, the water in irrigation systems hasbeen undervalued. This paper presents theenvironmental impact of irrigation and aframework for valuing water for itsmultiple and often competing uses,especially focusing on water uses forecological services, in this case wetlands.The south coastal area of Sri Lanka wasselected as a site for a case study, including2,610 ha of irrigated area and adownstream wetland area of 2,250 ha whichhas five lagoons. This wetland areacombines coastal, marine and freshwaterecosystems in a tropical environment inwhich distinct plant and animal speciescoexist in a delicate balance. All users ofwater and other resources, and theirenvironmental problems were identified. Thispaper discusses the policy and managementimplications of valuing water for competinguses.  相似文献