楚雄州2012～2014年6种猪繁殖障碍性疫病的血清流行病学调查

[目的]了解楚雄州猪繁殖障碍性疫病的流行情况.[方法]采用血清学方法调查了楚雄州2012～2014年6种猪繁殖障碍性疫病的感染情况.[结果]楚雄州猪圆环Ⅱ型病毒病总阳性率达到89.41％,猪伪狂犬病总阳性率达到47.00％,猪细小病毒病阳总性率达到47.46％,猪乙型脑炎病总阳性率达到49.39％,猪衣原体病总阳性率达到24.36％,猪弓形虫病总阳性率达到23.98％.[结论]6种繁殖障碍性疫病广泛存在于楚雄州,此调查结果为控制繁殖障碍性疫病的流行提供了一定的参考依据.     

毛竹种群空间格局及分株间关联性——重复空间点格局分析

随着空间调查数据的增多和有重复的空间格局试验设计的需要,重复空间点格局分析方法不断得到研究和应用。采用有重复的空间点格局分析方法研究了不同营林模式下毛竹种群的空间分布格局及其分株间的空间关联性。结果表明：I类经营模式下形成的毛竹种群空间格局呈现随机分布,II类和III类经营模式分别在1.6-2.2 m和0.4-2.6 m尺度上达到了均匀分布的显著水平,表现为随着经营干扰强度的增大,毛竹种群在小尺度（〈3 m）上趋向于均匀分布;在较大尺度（〉4 m）上,3种营林模式毛竹种群空间格局均表现为随机分布;母株与新分株的空间关联性在3种营林模式下较为一致的表现出小尺度上的正关联,并在III类经营模式下,0.6 m、0.8 m和2.2 m尺度上达到了正关联的显著水平,而在较大尺度上,3种营林模式母株与新分株空间格局均表现为无明显的关联性。     

清香木天然林物种多样性及稳定性对不同干扰强度的响应

选择清香木(Pistacia weinmannifolia)典型群落样地,划分为不同干扰类型。采用物种丰富度、Simpson指数(D)、Shannon-Wiener指教(H)和均匀度指数(E)等物种多样性指数及改进的M-Godron稳定性测定方法,对清香木天然种群的物种多样性和稳定性进行分析。结果表明:清香木群落乔木层和草本层物种多样性表现为干扰弱干扰强,而灌木层为干扰弱干扰强;在不同干扰强度下群落稳定性均靠近稳定状态,其相对的稳定性比较是干扰强干扰弱,表现出与群落物种多样性不同的趋势。     

Stocking density and artificial habitat influence stock structure and yield from intensive nursery systems for mud crabs Scylla serrata (Forsskål 1775)

Intensive nursery systems are designed to culture mud crab postlarvae through a critical phase in preparation for stocking into growout systems. This study investigated the influence of stocking density and provision of artificial habitat on the yield of a cage culture system. For each of three batches of postlarvae, survival, growth and claw loss were assessed after each of three nursery phases ending at crab instars C1/C2, C4/C5 and C7/C8. Survival through the first phase was highly variable among batches with a maximum survival of 80% from megalops to a mean crab instar of 1.5. Stocking density between 625 and 2300 m⁻² did not influence survival or growth in this first phase. Stocking densities tested in phases 2 and 3 were 62.5, 125 and 250 m⁻². At the end of phases 2 and 3, there were five instar stages present, representing a more than 20‐fold size disparity within the populations. Survival became increasingly density‐sensitive following the first phase, with higher densities resulting in significantly lower survival (phase 2: 63% vs. 79%; phase 3: 57% vs. 64%). The addition of artificial habitat in the form of pleated netting significantly improved survival at all densities. The mean instar attained by the end of phase 2 was significantly larger at a lower stocking density and without artificial habitat. No significant effect of density or habitat on harvest size was detected in phase 3. The highest incidence of claw loss was 36% but was reduced by lowering stocking densities and addition of habitat. For intensive commercial production, yield can be significantly increased by addition of a simple net structure but rapidly decreases the longer crablets remain in the nursery.     

Evidence for long‐term spatial displacement of breeding and pupping harbour seals by shellfish aquaculture over three decades

• 1. Shellfish mariculture is increasing worldwide and often occurs adjacent to marine mammal breeding and feeding habitat. To better understand breeding pinniped vulnerability to potential shellfish mariculture disturbance and displacement effects in a US National Park, potential mechanisms were explored that may affect the proportion of harbour seals (Phoca vitulina) selecting high quality haul‐out sites near shellfish aquaculture within a large colony, and overall seal utilization of that colony in relation to other regional colonies.
• 2. Seal haul‐out sites isolated from the mainland (no predator access) had higher pup:adult ratios, indicating they are generally more important for pupping. Short‐term human disturbance did not have a significant effect on spatial use, but rather spatial use was pre‐determined by general sandbar isolation. Using multiple competing hypothesis and an information‐theoretic approach, it was found that within the estuary, after removing effects of El Niño, the proportion of seals (total seals and pups only) hauled out near mariculture sites was 8 ± 2% lower during years of higher oyster harvest. Annual oyster harvest was used as a measure of aquaculture activity that could result in direct disturbance or indirect displacement of harbour seals.
• 3. At the regional scale, oyster harvest, seal counts at a nearby colony, and loss of a major haul‐out site within the estuary, best explained pup and total seal use compared with the region. Regional population size, short‐term human disturbance rate, and other factors were not important. Concurrent with higher oyster harvest, the proportion of regional seals using the estuary declined by 7 ± 2% for seal pups (–65 ± 18 total pups), and 5 ± 2% for total counts ( ? 192 ± 58 total seals). These findings (both within the estuary and at the regional scale) were essentially identical whether modelling oyster harvest as either a continuous or categorical (low/high) variable and when using either frequentist or Bayesian statistical analyses.
• 4. Marine reserves set aside for wildlife may be less effective when the highest quality breeding and pupping sites are adjacent to regular aquaculture activities. These effects may not be detectable until additional natural variation lowers the quality of nearby habitats. Published in 2011. This article is a US Government work and is in the public domain in the USA.

     

发动机液压自由活塞下止点运动机理

为实现对单活塞液压自由活塞发动机工作频率的精确控制,掌握液压自由活塞下止点运动规律是基础,基于系统基本原理,研究了活塞下止点运动规律的数学模型。通过建立数学仿真模型和试验系统,研究了液压自由活塞在下止点的运动规律及其影响因素。结果表明,活塞下止点运动过程包括反向加速和正向减速过程,活塞到达下止点后的反弹距离主要由该过程决定,活塞下止点运动过程中的反向加速力来自泵腔和压缩腔压力。系统压缩腔压力变化规律可控是工作频率精确控制的基础,压力变化规律控制要考虑活塞运动状态和单向阀的阀芯动作规律的影响。     

赤泥基质改良及种植植物的筛选研究

采用四因素三水平正交改良方案对盐分含量较高的赤泥基质进行了改良研究和植物种植试验。结果表明:4种改良剂均能降低土壤的pH值,其中磷石膏对赤泥基质的pH影响最大;赤泥基质的持水率则主要受膨润土的影响,膨润土对赤泥基质的盐分具有一定的吸附或交换作用,添加量为20%时,赤泥可溶性盐含量降低了50%;3种供试植物中黑麦草最适宜改良后的赤泥基质种植。     

关于工业墙板的节点连接问题

该文作者详细叙述墙板的节点构造问题,针对这些问题,提出了几点改进方法。     

菊花加工厂废水污染调查及生物处理的初步研究

对菊花加工厂废水中的化学污染物和物理性状进行了检测，并在实验室内采用粉末炭活性污泥法对废水进行小规模处理。在实验条件下，ＢＯＤ５去除率达９３％，ＣＯＤｃｒ去除率为８７％，总氮去除率为４７％，总磷去除率为４０％〈总硬度降低５２％，出水的色度，悬浮物，ＰＨ等均达到排放标准。