鹅绒助长剂配方的筛选

配制3种不同的助长剂B,C,D拌入饲料中喂鹅,结果表明,与对照组比较,喂助长荆C组的活重、片毛与绒毛重平均分别增产16.5%,1 7.0%,58.6%;绒朵拉长和含绒朵量分别多0.5cm和2.9%;平均只鹅盈利多5.12元。     

DEM尺度变换中直方图相似度计算与应用

基于DEM尺度变换生成的不同栅格尺寸DEM分辨率确定的需求,采用直方图相似度计算方法,将不同栅格尺寸DEM同不同比例尺地形图对应分辨率的DEM进行对比,从而确定尺度变换生成DEM的分辨率。采用了4种不同的相似度计算方法,L₁距离,L₂距离,χ²距离和直方图的交,实验结果表明直方图的相似度计算可以有效地确定相似的DEM数据,从而确定DEM的分辨率。4种计算方法,L₁距离比直方图的交有更广的适用范围,比L₂距离、χ²距离更加直观。     

Mineral Composition in Corchorus depressus at Heterogeneous Environmental Conditions and Their Relationships with Bottom‐Up,Top‐Down,and Plant Metabolite Factors

Advanced technological inputs may enable profitable crop production but the agro‐ecological potential of a locality can only be maximized by a reorganization of ecological principles for special production. Selection of most suitable types, addition of water supply, and provision for adequate soil fertility are most easily optimized and utilized for improvement of plants' potential. In the work presented here, there is variation in potassium, sodium, calcium, phosphorus, iron, and zinc contents in the different compartments of Corchorus depressus under the heterogeneous environmental conditions of Indian Thar desert. The principal component analysis (PCA) was performed to synthesize the relationship and future lines of study with the help of plant biomass and community dynamics (bottom‐up factor), soil parameters (top‐down factors) and plant metabolites. The potassium, calcium, and iron were positively related with each other, but these elements inhibited the concentration of steroidal sapogenin and phenol at significant levels. Changes in soil nitrogen and soil phosphorus, however, favor these metabolites directly and alkaloid contents indirectly.     

用联合尺度检验法研究猪产仔数加性—显性遗传模型以及基因效应

对二花脸猪、大白猪、杂交１代和回交１代４个群体共计３３８窝产仔数的资料进行了加性－显性遗传模型以及基因效应的研究。联合尺度检验法的结果表明：猪总产仔数和活产仔数的群体平均值分别为１２．７８％和１２．２１,二花脸猪总产仔数和活产仔数基因加性值比大白猪分别高２．７８头和２．５３头,二花脸猪高的总产仔数和活产仔数基因对大白猪等位基因均为显性,显性度分别为０．９２和０．９５。适合性检验结果表明窝产仔数（总产仔数和活产仔数）符合加性－显性遗传模式。     

宁夏中宁县麦蚜种群空间分布与蚜茧蜂的跟踪作用

采用棋盘式五点取样法调查,应用聚集度指标和灰色关联度法,对不同景观结构下麦蚜及僵蚜田间分布型变化和时间动态进行分析与模拟。发现当地蚜茧蜂10种,蚜小蜂1种。麦长管蚜、麦二叉蚜及僵蚜在时空上呈负二项分布,聚集强度随虫口密度增加而增强。麦长管蚜聚集程度受田块景观复杂程度的影响显著,麦二叉蚜则不显著。2种蚜虫空间格局表现为扩散-聚集周期性变化,但周期性变化不尽相同。僵蚜分布与蚜虫分布有明显的相关关系,但对麦长管蚜跟踪明显高于对麦二叉蚜的跟踪。用Blackith种群聚集指数分析,结果表明蚜虫的聚集原因主要是由环境因素所引起。当麦长管蚜、麦二叉蚜平均密度分别大于5.57、8.26/株时,聚集程度取决于本身生物学特性与环境因素共同作用。对麦蚜种群数量具有显著性跟踪关系的蚜茧蜂主要有燕麦蚜茧蜂、烟蚜茧蜂及四川蚜茧蜂。     

不同虹鳟品系异速生长的比较分析

研究测量了渤海虹鳟、丹麦虹鳟、美国道氏虹鳟、美国加州虹鳟和挪威虹鳟等5个虹鳟品系4年龄148个个体体重和20个形态学性状。应用静态联合异速生长模型同时估计多个体型性状对体重、纵向性状对体长、垂直性状对体高和横向性状对体宽的异速生长指数。首先建立每个虹鳟品系相对性状的最优联合静态异速生长指数方程,采用Newman-Keuls t检验法进行虹鳟品系间每个最优异速方程中异速生长指数的多重比较。结果表明,每个虹鳟品系存在显著不同的偏异速生长指数分布,其中全长与体重、体高与体重间存在较高的异速生长关系。在5个虹鳟品系中,头长、头宽、眼径、吻长、尾柄长、臀鳍高和臀鳍基长等7个形态性状相对体重的异速生长指数都不显著。背吻距与体长和尾柄高与体高在5个虹鳟品系中都存在显著的异速生长关系,但是品系间的多重比较却完全显著。本文通过对不同虹鳟品系异速生长指数的统计比较,分析它们之间的形态变异特点,为虹鳟及其他水产动物品系的形态学鉴别提供了一种有效的理论方法。     

拉枝下垂对双季葡萄秋冬茬成花的影响

[目的]研究拉枝下垂对双季葡萄秋冬茬成花的影响。[方法]对夏黑、巨玫瑰、金手指、维多利亚4个葡萄品种春茬开花后进行拉枝下垂(拉枝角度约90°),秋冬茬于8月上中旬全部落叶后用50%单氰胺25倍液进行破眠催芽处理,研究拉枝下垂对春茬枝条老熟、果实转色成熟及秋冬茬成花的影响。[结果]拉枝下垂可促进春茬枝条提前老熟4~8 d,果实提早转色成熟5~7 d;促进花芽分化,提高花序质量,使花穗增长0.9~1.7 cm,成花率提高3.9%~10.1%、成花系数提高0.13~0.65,效果显著。[结论]拉枝下垂抑制了顶端枝条营养生长,使树体的生长势得以缓和,致使营养物质回流,促使营养生长向生殖生长转化,促进花芽分化,从而有利于早成花。     

Do albacore exert top‐down pressure on northern anchovy? Estimating anchovy mortality as a result of predation by juvenile north pacific albacore in the California current system

Quantifying the mortality of marine fishes is important for understanding spawner–recruit relationships, predicting year‐class strength, and improving fishery stock assessment models. There is increasing evidence that pelagic predators can exert a top‐down influence on prey, especially during critical early life‐history stages. The objective of this study was to quantify predation by North Pacific albacore on Northern anchovy in the California current system (CCS). I estimated the abundance of juvenile albacore in the CCS from 1966–2005 using stock assessment models and spatially explicit catch‐per‐unit‐effort time series. Anchovy abundance (1966–93), both recruitment and total biomass, was obtained from a stock assessment model. Annual rates of anchovy consumption by albacore were calculated using diet studies of albacore in the CCS, an age‐structured bioenergetics model, and regional estimates of albacore abundance. The range of estimates was large: albacore may remove from less than 1% to over 17% of anchovy pre‐recruitment biomass annually. Relationships between predation and recruitment biomass were consistent with expectations from top‐down effects, but further study is required. This is the first attempt to quantify a specific source of mortality on anchovy recruits and to demonstrate potential top‐down effects of predation on anchovy.     

东海北部鱼类组成特征分析

利用1997-2000年东海北部(29°30′～33°00′N,122°30′～128°00′E)四个季节的底拖网调查资料,选取生物量占总生物量90％的前27种鱼类,运用聚类分析和多维标度分析法,研究了东海北部鱼类组成的空间格局特征。结果显示东海北部鱼类组成可分为三个群聚类型,即近海群聚、较深海域群聚和外海群聚。近海群聚的主要种类有凤鲚(Coilia mystus)、龙头鱼(Harpadon nehereus)、黄鲫(Setipinna taty)等;较深海域群聚的主要种类有鳀(Engraulis japonicus)、带鱼(Trichiurus japonicus)、日本鲭(Scomber japonicus)、鳄齿鱼(Champsodon capensis)、细条天竺鲷(Apogon lineatus)、发光鲷(Acropoma japonicum)等;而竹(竹夹)鱼(Trachurus japonicus)、星康吉鳗(Conger myriaster)、黄鲷(Taius tumifrons)、水珍鱼(Argentina kgoshimae)、日本海鲂(Zeus fober)、绿鳍马面鲀(Thamnaconus sepremtrionalis)等为外海群聚的主要种类。同时分析了水深、底层温度、底层盐度等环境因子与鱼类群聚的关系,表明影响鱼类群聚的主要环境因子有水深、底层盐度。不同群聚间的种类分布是重叠交错的,并没有明显的群聚边界,但密集分布海域各异,不同群聚的种类组成在不同季节具有一定的持续性,其种类组成保持了相对的稳定。     

The effect of a crab predator (Cancer porteri) on secondary producers versus ecological model predictions in Tongoy Bay (south‐east Pacific coast): implications for management and fisheries

• 1. The present study compares the propagation of effects observed as a response to changes in the abundance of a top predator (top‐down cascading effect) in a benthic community within the south‐east Pacific upwelling ecosystem of northern Chile, with predictions derived from quantitative and qualitative multispecific models.
• 2. Results with Loop Analysis achieved 71.4% of predictive certainty; indicating that this technique is useful for assessment of the effects of human intervention related to the mud‐bottom ecosystem tested. On the other hand, Ecosim using bottom‐up flow control mechanism achieved only 14.3% certainty. In an intermediate range, predictions obtained using the Mixed Trophic Impacts and Ecosim models using top‐down, mixed and flow control mechanisms estimated by the program, achieved 57.1% certainty.
• 3. The results obtained have important implications for the management of communities and ecosystems since human interventions can be studied using holistic models with an end result of evaluating the eventual changes that they propagate.

Copyright © 2007 John Wiley & Sons, Ltd.