鸡传染性贫血对生产鸡群的免疫抑制影响试验研究

<正>鸡传染性贫血是我国近年来养禽生产中较为多发的一种免疫抑制性疾病,其致病原为鸡传染性贫血病毒(Chicken infections anemia virus),以鸡再生障碍性贫血和淋巴组织萎缩为主要病理特征。当鸡受到CIAV感染后,CIAV对T细胞的损害会影响细胞因子和辅助性T细胞的作用以及对体液免疫和局部黏膜免疫功能的降低,从而影响整个免疫调控系统的协调作用,引起机体的免疫抑制;在感染期间如继发其它细菌或病毒感染,会加速患病     

鸡传染性贫血病最新研究进展

<正>鸡传染性贫血病是由圆环病毒科(Circoviridae)陀螺病毒(Gyrovirus)属的鸡传染性贫血病毒(Chicken infectious anemia virus,CIAV)引起的,临床上以贫血、骨髓黄染、全身淋巴组织萎缩和免疫机能损害为主要特征。1979年Yuasa等〔1〕首次分离到鸡传染性贫血病毒(Gifu-1株)。该病呈世界性分布,广泛存在于日本、英国、瑞典、美国、巴西、     

西藏地区黄牛放线菌病的诊治

正1前言牛放线菌病(Bovine actinomycosis)又称大颌病(Lumpy jaw),是一种多发性、非接触性、化脓性、肉芽肿性的慢性传染病。该病的特征为头、颈、颌下和舌的放线菌肿。本病广泛分布于世界各地,我国也有存在。病原为牛放线菌(Actinomyces bovis),革兰氏阳性、不运动、不形成芽胞杆菌。本病呈散发性发生,尤以2~5岁牛易感。病原存在于污染的土     

涂高效抽枝宝和刻芽对苹果幼树1a生枝条萌芽和新梢生长的影响

以2013年栽植的‘2001’富士苹果幼树为试材,研究了涂高效抽枝宝和刻芽对拉枝后1a生枝条萌芽和新梢生长的影响。结果表明:涂高效抽枝宝、刻芽和自然生长的枝条萌芽率分别为89.95%、89.05%和69.13%;单株抽出新梢量分别为30.74个、18.41个和16.07个。涂高效抽枝宝与刻芽的萌芽物候期基本一致,均比自然生长的提前2d。自然生长枝条上的新梢生长量要显著高于涂高效抽枝宝和刻芽处理,涂高效抽枝宝处理的新梢生长量与刻芽处理无显著差异。     

Implications of crude oil pollution on natural regeneration of plant species in an oil-producing community in the Niger Delta Region of Nigeria

The study evaluated the impact of crude oil pollution on natural regeneration of plant species in a major oil-producing community in the Niger Delta region of Nigeria. Three sites—unpolluted site(US), polluted and untreated site(PUS), and polluted and treated site(PTS)—were purposively chosen for the study. The seedling emergence method was used to evaluate soil seed banks in the various sites at two depths, 0 to 10 cm and 10 to 20 cm. Woody-plant species richness, abundance, and diversity were higher in the US seed bank than in the PUS and PTS seed banks. The highest number of non-woody plants was observed in the US, followed by the PTS, and then the PUS. Both species richness and diversity of non-woody plants were highest at the US, followed by the PUS, and lowest in the PTS. Woody species in the US seed bank were 87.5% and 80% dissimilar with those of the PUS and PTS at 0–10 cm and 10–20 cm respectively. No variation was observed between woody species in the PUS and PTS seed banks. Non-woody species at 0-10 cm US seed bank were 73.08% dissimilar with those of PUS at the two soil depths and 81.48/88.46% dissimilar with those of the 0–10/10–20 cm of the PTS respectively. At 10–20 cm, non-woody species of the US were 69.66% dissimilar with those from each of the two soil depths in PUS; and 73.91/81.82% dissimilar with those of 0–10/10–20 cm of the PTS respectively. Non-woody species variation between the PUS and PTS was higher at 10–20 cm than 0–10 cm. The poor seed bank attributes at the polluted sites demonstrates that crude oil pollution negatively affected the natural regeneration potential of the native flora because soil seed banks serve as the building blocks for plant succession. Thorough remediation and enrichment planting are recommended to support the recovery process of vegetation in the polluted areas.     

美国红栌植株再生体系的建立

为解决美国红栌传统方法繁殖系数低的问题,以其带芽茎段为外植体进行了美国红栌组培植株再生研究。结果表明,美国红栌带芽茎段经0.1%HgCl2体表灭菌5min,在MS+30.0g/L蔗糖+6.0g/L琼脂初代培养基中可获得高质量无菌材料。经过对不同基本培养基及不同植物生长调节剂浓度配比的培养基进行筛选,确定WPM+1.0mg/L 6-BA+0.1mg/L NAA+30.0g/L蔗糖+6.0g/L琼脂为最佳不定芽分化培养基,不定芽分化率可达92%;最佳不定根分化培养基为1/2MS+0.5mg/L NAA+0.1mg/L IBA+15.0g/L蔗糖+6.0g/L琼脂,不定根分化率可达100%。该体系可直接用于美国红栌的苗木生产。     

Optimizing any-aged management of mixed boreal forest under residual basal area constraints

The current trend of forest management in many countries is reduced use of clear-felling and planting, and increased use of continuous cover management. In Finland, the new forest act of 2014 made all types of cuttings equally allowable on the condition that if the post-cutting residual stand basal area is too low, the stand must be regenerated within certain time frame. Forest landowner can freely choose between evenand uneven-aged management. This study developed a method for optimizing the timing and type of cuttings without the need to categorize the management system as either even-aged or uneven-aged. A management system that does not set any requirements on the sequence of post-cutting diameter distributions is called any-aged management. Planting or sowing was used when stand basal area fell below the required minimum basal area and the amount of advance regeneration was less than required in the regulations. When the cuttings of 200 stands managed earlier with even-aged silviculture were optimized with the developed system, final felling followed by artificial regeneration was selected for almost 50% of stands. Reduction of the minimum basal area limit greatly decreased the use of artificial regeneration but improved profitability, suggesting that the truly optimal management would be to use natural regeneration in financially mature stands. The optimal type of thinning was high thinning in 97–99 % of cases. It was calculated that the minimum basal area requirement reduced the mean net present value of the stands by 12–16 % when discount rate was 3–5 %.     

Afforestation,restoration and regeneration——Not all trees are created equal

Undulations in weather patterns have caused climate shifts of increased frequency and duration around the world. The need for additional research and model data on this pressing problem has resulted in a plethora of research groups examining a particular tree species or biome for negative effects of climate change. This review aims to （1） collect and merge recent research data on regeneration within old- and new-growth forests, （2） highlight and expand upon selected topics for additional discussion, and （3） report how shade tolerance, drought toler- ance, and inherent plasticity affect tree growth and development. Al- though shade and drought tolerance have been well studied by a number of research groups, this review reveals that in-depth analysis of a single or a few species in a given area will not generate the data required to implement a successful regeneration plan. Studies using historical accounts of previous species composition, information regarding site sea- sonality, species competition, and individual responses to drought and shade are needed to （1） develop best management plans and （2） ensure future modeling experiments are focused on a greater variety of species using more innovative methods to evaluate climate change effects.     

污水资源化是可持续利用的有效途径

正一、水资源概况1.水资源现状太康县多年平均降水量为8785毫米,折合总降水量为217173亿立方米,多年平均水资源总量为3.4911亿立方米,人均占有水资源量为320立方米,仅为全国人均占有量的15%,相当于世界人均占有量的3%。2.水资源特点地区分布不均即周口市地表水资源主要来源于大气降水。因此,年径流量的地域分布总趋势和降水基本一致,由东南沿海向西北内陆递减。年际年内变化大在1956~2000年系列中,最大年径流量为     

利用废弃杨木水泥模板生产纤维板的研究

利用废弃杨木水泥模板制造纤维板,以实现保护环境,综合利用有限资源的目的。首先对废弃水泥模板组成单元-单板的密度、强度、吸水性和微观构造进行研究,并分析其纤维得率。在此基础上,以废弃水泥模板为原料制造不同密度的纤维板,并与杨木纤维及水泥模板纤维为原料制造不同比例的混合纤维板进行性能对比分析。结果表明:废弃水泥模板的单板气干密度、弹性模量和静曲强度以及纤维得率均高于普通杨木单板,而吸水厚度膨胀率小于普通杨木单板;当用水泥模板制得的纤维板密度达到0.75 g/cm3时,板材的力学性能和TS值均优于其他目标密度的板材,各项力学性能都达到国家标准的要求,且超过了普通杨木纤维板,说明废弃杨木水泥模板完全可以作为纤维板生产的好原料。