木粉/PVC复合材料挤出流动性的影响因素

研究木粉的粒径、添加剂的种类及配比等因素,对木塑复合材料挤出流动性的影响.结果表明:木粉粒径越小,复合物料在挤出过程中的流动性能越差,所制备的木塑复合材料色差越大,且产品材色越深.综合考虑加工特性和制品材色,宜选用木粉粒径45～60目；并添加稀土热稳定剂及铝酸酯偶联剂,可以提高物料的挤出流动性.     

Nutritional value of Pavlova spp. (Prymnesiophyceae) for spat of the Cortez oyster Crassostrea corteziensis during late-nursery culturing at the hatchery

Three Pavlova species were evaluated for their nutritional value as diets for growth and survival of the Cortez oyster Crassostrea corteziensis spat during late‐nursery cultivation at a hatchery. Microalgae were provided as monospecific diets (Pavlova salina, P. sp. C50 and P. sp. C53) and in binary combinations of diets 1+2, 1+3 and 2+3 at 80–90 × 10³ cells mL^?1 for 21 days. Juveniles experienced high survival rates and grew well with all dietary treatments, but binary diets yielded greater survival and growth of spat. From the three binary treatments, Diet 6 (P. sp. C50 and P. sp. C53) promoted significantly (P<0.001) fastest growth of juveniles in shell height (0.19 mm day^?1), shell length (0.14 mm day^?1), total wet weight (0.04 g day^?1) and dry weight of meat biomass (0.024 g day^?1). For all shell dimensions, the lowest growth rates occurred with Diets 2 (P. sp. C56 alone) and 3 (P. sp. C50 alone). These results highlight the importance of testing microalgal diets for bivalve spat rather than just relying on published nutritional values.     

用于铲刀连接座凹球面的淬火感应器及配用尺寸确定方法

针对淬火感应器及配用尺寸的确定方法，通过采用方铜管制作感应圈的有效感应弧端和导磁体的驱磁作用，解决了感应加热效率提升以及圆环效应的影响问题；采取感应器冷却用水与感应淬火冷却介质合二为一的方法，解决了铲刀连接座凹球面淬火时所需冷却介质的问题；通过分析给出了淬火感应器配用尺寸的确定方法。另外，所述感应器及配用尺寸的确定方法，构思新颖，结构合理，易于制作，且方法简单可行，具有很好的使用价值，并已申报了国家专利。     

Reproductive strategies in small populations: using Atlantic salmon as a case study

Abstract –  Wild salmonid populations with only a few breeding adults may not exhibit a significant reduction in genetic variability compared with larger populations. Such an observation suggests that effective population sizes are larger than population size estimates based on direct adult counts and/or the mating strategy maximises outbreeding, contributing to increased heterozygosity. In the case of wild Atlantic salmon Salmo salar populations, stratification by age classes and sexes on the spawning grounds avoids inbreeding and increases genetic variability. We studied the breeding composition of four Spanish salmon populations. Over a 7-year period we concluded that the probability of within-cohort mating is very low: females generally reproduce after two sea-winters whereas males reproduce mostly as one sea-winter ( grilse ) and/or mature parr. Considering different levels of contribution of mature parr to spawning derived from field surveys, we developed a simple model for estimating effective population sizes and found that they doubled with 65% parr contribution expected for rivers at this latitude (43°N), and ranged from 100–800 individuals. The effect of between-cohort mating was modelled considering different ranges of differences in allele frequencies between cohorts and resulted in 28–50% increases in heterozygosity when considering a 65% parr contribution. The complex mating strategy of Atlantic salmon contributes to explain the high levels of genetic variability found for small populations of this species. This model can probably be extended to other animal species with mating strategies involving different cohorts.     

千万不可忽视良种黄牛的保种问题

阐述了良种牛保种的重要意义．基因的随机漂移、选择与杂交、近交是特定基因从群体中消失的主要原因，群体及其有效含量和系统选育的科学组织是保种的重要内容。最后介绍我国良种牛的保种方法及其存在的问题，并提出解决的办法。     

家兔发情状态与受胎率和产仔数关系的研究

本文研究了家兔的发情状态与配种后的受胎率，以及产仔数之间的关系。以家兔阴粘膜颜色作为表观指标，将家兔的发情分为５个状态，其相应的阴粘膜颜色分别为：苍白、粉色、红色、大红、黑紫。经促排２号诱发排卵后，人工授精，相应状态下的受胎率为：２９．５％、４２．９％、５６．８％、５３．８％、２５．０％；相应状态下的平均产仔数分别为：５．５４、６．６９、６．６２、７．２１、５．５２。用促排３号处理后，相应状态下的受胎率为：９．０％、４３．２％、５３．２％、７０．０％、２１．７％。结果表明：无论是用促排２号，还是用促排３号处理，当阴粘膜颜色为苍白和黑紫时的受胎率或产仔数，都显著地低于或少于阴粘膜颜色为粉色、红色、大红时的受胎率（Ｐ＜０．０１）或产仔数（Ｐ＜０．０５）。说明，家兔的发情状态与配种后的受胎率和产仔数有密切的相关     

花生种子大小和重量对生长和产量的影响

花生种仁的大小及重量对出苗速度及出苗率、幼苗的生长和发育、植株的花芽分化和成花率以及荚果产量等有很大的影响。大粒优质种仁可提高出苗速度2～5d及出苗率3％～5％，植株生长健壮，花芽分化增多，成花率高，最终获得高产。     

辽东湾北部近海海域表层沉积物类型及分布特征

对2004年采自辽东湾北部近海海域的16个表层沉积物样品作了粒度分析和粒度参数计算,并进行了沉积物分类和分布特征的研究,结果表明,辽东湾北部近海的表层沉积物粒度主要由粉砂组成,平均含量65.15%,平均粒径5.031。总的特征是在5~10 m等深线,沉积物粒度的平均粒径由东部的4.530、中部的5.050逐渐增大到西部的6.236。沉积物粒度的组成类型由东向西按粉砂质砂→砂质粉砂→粉砂→砂-粉砂-黏土→黏土质粉砂由粗至细排列。     

饵料种类、温度和规格对硬壳蛤的同化率的影响

试验结果表明,温度和规格对硬壳蛤同化率的影响不显著(P>0.05);饵料种类对硬壳蛤同化率影响显著(P<0.05).其中小球藻和湛江等鞭金藻的同化率显著高于小新月菱形藻(P<0.05),而小新月菱形藻又显著高于扁藻(P<0.05).     

Burial rates of surrogate seeds in arable fields

The probability of seed consumption by surface-dwelling predators depends on the duration of seed exposure on the soil surface. We investigated seed burial using painted ceramic beads as surrogate seeds. Fifty beads of three size classes each were applied to small arenas within crop fields and their fates were followed from August to October. New sets of beads were applied as soon as most beads had disappeared from the soil surface. Bead availability on the soil surface declined immediately after placement, and then declined steadily over time, with increased loss during rain and management practices. Smaller beads were incorporated into the soil/litter matrix more easily than larger beads. Bead burial differed considerably among crop environments, with more burial in forage crops (red clover, lucerne) than in row crops (soyabean, maize). The fact that seed availability differed among crop environments suggests that it can be manipulated to maximise predation risk.