Dietary nucleotide‐rich yeast supplementation improves growth,innate immunity and intestinal morphology of Pacific white shrimp (Litopenaeus vannamei)

An 8‐week feeding trial was conducted to evaluate the effects of dietary nucleotide (NT)‐rich yeast supplementation on growth, innate immunity and intestinal morphology in Pacific white shrimp (Litopenaeus vannamei). Four isonitrogenous and isolipidic practical diets were formulated to contain 0 (control), 10, 30 and 50 g/kg of NT‐rich yeast, respectively. A total of 480 shrimp with an average initial body weight of 1.86 ± 0.02 g were randomly allocated into four groups, with four replicates per group and 30 shrimp each replicate. The results indicated that shrimp fed the diet containing 50 g/kg NT‐rich yeast had significantly higher weight gain (WG), specific growth rate (SGR) and protein efficiency ratio (PER) than those fed the control diet, and the lowest feed conversion ratio (FCR) was observed in the shrimp fed the 50 g/kg NT‐rich yeast supplemental diet. However, there was no significant difference in survival among all treatments. The crude protein of whole shrimp in the 50 g/kg NT‐rich yeast group was higher than that in the control group. Total protein, triglyceride concentrations, the activities of aspartate aminotransferase and alanine aminotransferase in serum were significantly influenced by the dietary NT‐rich yeast supplementation. The activities of serum phenoloxidase (PO) and lysozyme (LZM) of shrimp fed the diet containing 50 g/kg NT‐rich yeast were higher than those in shrimp fed the other diets. Relative expressions of alp and lzm significantly upregulated in the 30 g/kg NT‐rich yeast group compared to the control group. The intestinal fold height and fold width in the 30 g/kg NT‐rich yeast group were significantly higher than those fed the control diet; and the highest microvillus height occurred in the shrimp fed the 50 g/kg NT‐rich yeast diet. In summary, dietary 30–50 g/kg NT‐rich yeast supplementation promotes growth performance, enhances innate immunity and improves intestinal morphology of Litopenaeus vannamei.     

室内三种富营养模拟条件下水流调控对羊栖菜和石莼生长及生物质合成的影响

大型海藻养殖是一种低成本、高效、环保的水体富营养化生物修复方法,而水流则是影响大型海藻生长的一个重要因素。研究结果表明,水流交换率为200 vol·d^-1时,羊栖菜(Sargassum fusiforme)比生长率最高达(4.34±0.11) %·d^-1,而水流交换率为100 vol·d^-1、中高浓度营养盐条件下石莼(Ulva pertusa)比生长率最大值分别可达(6.31±1.42) %·d^-1、(8.00±0.79) %·d^-1,营养盐浓度决定了两种大型海藻的生长率,石莼更适宜在高营养盐环境中生长。石莼体内叶绿素a、可溶性蛋白和可溶性碳水化合物在不同应用情境间均存在明显差异,而羊栖菜体内仅可溶性蛋白表现出明显变化。水流交换的增强明显改变了石莼的生长和羊栖菜可溶性碳水化合物含量。陆基中试实验表明,与低水流速度相比,中、高流速条件下羊栖菜的比生长率分别增加80%、14%,石莼则分别增加41.3%、33.3%。     

多自由度自锁式香蕉收割机的设计与仿真

针对大规模香蕉种植基地香蕉收割机具的研发比较缺乏的现状,设计了一种多自由度自锁式香蕉收割机。该机主要由动力系统、进给系统及收割系统等组成,手动与电动混合操作方式,既可作为收割机,同时又可作为小型运输机及牵引机使用。采用三维造型软件Solid Works对其建立模型,并对关键结构进行相应的运动仿真。结果表明:该机设计满足工作要求,可为其他类似农作物收割机具的设计提供参考。     

对“富人治村”现象的分析探讨

“富人治村”是近几年我国农村出现的一种新现象,它的出现有着多种原因,其产生的影响也是多方面的。如何规范富人治村,取其有利去其不利是笔者探讨的关键。     

那曲地区不同退化程度的草地土壤养分特征分析

在对那曲地区退化草地进行多个点采样和室内分析的基础上,应用统计学方法对土壤养分数据进行标准化处理后,研究了那曲地区不同退化程度草地土壤的养分特征及养分之间的相关性。结果表明：（1）随着退化程度的增加,那曲地区草地土壤的有效氮、有效磷、全氮、有机质含量逐渐降低,有效钾含量先升后降。（2）在那曲地区不同退化程度的草地土壤中,有效氮、全氮与有机质间均存在显著的相关关系。（3）土壤全氮、有效氮和有机质含量可作为衡量藏北高原草地退化程度的重要指标。有效磷可作为评价草地退化程度的参考指标。有效钾不宜作为草地退化程度评价的指标。最后,对藏北高原草地生态系统的恢复重建提出了建议。     

3—CRPa移动并联机构运动学分析与仿真

提出一种新型3自由度纯移动并联机构,该机构由动平台、静平台以及联接两平台的3条相同的分支运动链组成。基于单开链单元理论分析,计算出机构的自由度,分别讨论了以角位移和线性位移为主动输入形式的机构运动学问题,推导出位置、速度、加速度的解析解。利用Matlab和Pro/E软件分别绘制出机构的位移、速度、加速度理论曲线和虚拟样机仿真曲线,仿真结果证明了理论分析的正确性。尤其是当以线性输入为主动输入时,机构的运动雅可比矩阵为单位阵且条件数恒等于1,所以此时机构在整个工作空间内表现为完全各向同性。     

优质富硒玉米新品种晋糯8号的开发利用

优质富硒玉米晋糯8号,种子黄色,F1果穗黑色;生育期短,抗多种病害,适应性广;花丝、穗轴紫红色,穗型美观;糯中带甜,营养丰富,粗蛋白12.43%,粗脂肪3.76%,硒(Se)0.473mg/kg。其用途较广,鲜穗可直接出售,整穗速冻、真空包装保鲜加工,干籽粒加工利用,花丝、穗轴、秸秆等都有很高的利用价值。     

烟台市土地利用结构与能源消费碳排放关联测度

[目的]分析山东省烟台市各区县土地利用结构与能源消耗碳排放的关联测度及其变化规律,为合理利用土地资源与低碳城市的建设提供科学建议。[方法]基于烟台市1986—2012年各区县的土地利用结构和能源消耗数据,采用碳排放量计算模型,测算出其能源消耗碳排放总量、碳排放强度和人均碳排放量,并运用灰色关联分析法,测度烟台市各区县土地利用结构与能源消耗碳排放的关联度。[结果]1 1986—2012年烟台市能源消费碳排放总量由3.05×106 t上升到1.494×107 t,增加了3.9倍;2 2012年烟台市各区县土地利用结构与能源消耗碳排放量、碳排放强度之间关联度最高的土地利用类型为园地,与人均碳排放量关联度最高的用地为交通运输用地;3烟台市各区县土地利用结构与能源消耗关联度较高的分别是园地(0.812 8)、城镇村及工矿用地(0.812 0)、水域及水利设施用地(0.805 9);4 1986—2012年烟台市各区县土地利用结构与能源消耗碳排放关联度较大的地区依次是长岛县(0.980 4)、芝罘区(0.962 4)和莱山区(0.948 0)。[结论]烟台市土地利用结构与能源消耗碳排放存在着密切的关联性,土地利用结构与能源消耗碳排放的关联度在空间上存在着差异性。     

Is risk consistent across tier‐based harvest control rule management systems? A comparison of four case‐studies

There can be substantial differences in data quality and quantity among fished species. Consequently, the quality and type of assessments can also vary substantially. However, all species, especially those that are targeted, need to be managed. Several jurisdictions have developed hierarchical tier systems that categorize stocks based on, for example, the data available for assessment purposes and/or the extent to which quantities on which management advice is based can be estimated. Four case‐studies (Australia's Southern and Eastern Scalefish and Shark Fishery, the USA west coast groundfishery, the USA Alaskan crab fishery and EU fisheries) are used to contrast the types of hierarchical tier systems available, and to assess the extent to which each system constrains risk to be equivalent among the tiers (termed risk equivalency). Only the Australian system explicitly aims to achieve risk equivalency. However, this intent has not been fully operationalized. Our review reveals that best practice is not to define tiers simply on data availability, but also on what the assessments based on those data are capable of estimating. In addition, clearly differentiating the quantification of uncertainty from how decision‐makers wish to address that uncertainty would simplify justification of buffers (the gap between the assessment‐produced target catch or effort and the final management decision that accounts for uncertainty and risk). Risk equivalency can be achieved using management strategy evaluation to select the values for control variables, which determine the buffer given the uncertainty associated with the assessment.     

马铃薯抗旱资源评价与抗旱指标探讨

1990～1992年,在山西省北部旱作条件下,对从国际马铃薯中心(CIP)引入的44份材料和国内10个抗旱品种进行了抗旱鉴定和评价。结果表明,经济性状表现好、高产抗旱的品种为乌盟851、系薯1号、紫花白。CIP385373·1、CIP87001、CIP86027、CIP385372·1等品种为短日照类型,生育期间植株冠层生长繁茂,块茎产量低,块茎形成晚,不适宜长日照地区种植;CIPI—1039抗病性较强,CIP24—16、CIPI—1035、CIPLT—6在干旱条件下块茎产量较高,可作为马铃薯抗旱资源进行利用。单株产量与根系拉力、冠层覆盖度、商品薯率、单株块茎数、茎叶干鲜重、根干鲜重呈直线正相关,与出苗日数、块茎形成日数呈直线负相关。根系拉力与株高、根数、茎叶干鲜重、根干鲜重、块茎数呈直线正相关,与出苗日数、块茎形成日数呈直线负相关。冠层覆盖度与根系拉力、块茎数、茎叶鲜重、根鲜重呈直线正相关,与其他性状相关不密切。因此,根据冠层覆盖度和根系拉力的大小可预测旱作马铃薯块茎产量的高低,并可作为干旱地区评价马铃薯品种抗旱性的两个重要参数。