油松建筑材密度管理图的编制及其应用

针对建筑材目的油松人工林经营措施,探讨不同生长发育阶段油松人工林密度调控下蓄积变化,为森林可持续经营提供科学依据。对河北平泉阳坡中土、阴坡中土和阴坡厚土3种主要立地类型的全生命周期油松人工林编制密度管理图,得出培育小、中、大径级建筑材措施。结果表明:河北油松建筑材林的培育,阳坡中土培育小径材、阴坡中土和阴坡厚土培育中大径材,期间经过2~3次间伐以达到高效培育的目的。阳坡中土林分,初植密度3 000~3 300株/hm2,10年生间伐强度12%,15年生强度20%,25年生强度25%,主伐时树高级为9~11 m,培育小径材。阴坡中土林分,初植密度2 700~3 000株/hm2,9年生间伐强度25%,19年生强度30%,主伐时树高级为9~11 m,培育中径材;初植密度2 200~2 500株/hm2,9年生间伐强度20%,17年生强度25%,27年生强度30%,主伐时树高级为11~13 m,培育大径材。阴坡厚土林分,初植密度2 000~2 300株/hm2,7年生间伐强度20%,15年生强度30%,主伐时树高级为11~13 m,培育中径材;初植密度1 000~1 200株/hm2,7年生间伐强度20%,13年生强度20%,23年生强度25%,主伐时树高级为13~15 m,培育大径材。     

高含硫管道氢致开裂的分形效应及扩展速率计算

氢致开裂是高含硫气田集输管网、长输管网管线钢失效的主要模式之一,为明确管道氢致开裂的机理与过程,对其开裂模式进行了研究。对氢质量浓度在金属裂尖扩展过程中的变化规律进行分析,考虑分形效应的影响,对氢致裂纹的动力学模型进行修正,提出了氢致裂纹扩展的直裂纹-剪切带分形模型:在Gerberich对氢致开裂研究的基础上,基于裂尖的氢化作用与裂纹扩展过程中存在的耦合因素,将断裂过程区的形状与裂纹的扩展长度进行结合,构建了氢致开裂裂纹扩展各阶段分形速率的表达式,得到了更为合理的基于分形效应的氢致开裂数学模型。以材质为16Mn和20钢的天然气管道为例,分别计算了母材与焊缝处的氢致裂纹扩展速率,对比得出两种材料抗H2S的性能,研究结果对于高含硫管道材料的选择具有一定指导意义。     

UPLC-MS/MS快速测定貉组织中4种硝基呋喃代谢物残留量的研究

为了解皮用貉子胴体中硝基呋喃类药物残留情况,建立貉组织中硝基呋喃代谢物残留量准确、快速测定的超高效液相-串联质谱法(UPLC-MS/MS),采用貉子肌肉样品,在酸性条件下,经60℃高温衍生1h,调节pH值7～8后用乙酸乙酯提取,水浴浓缩后,经正己烷除脂净化,由超高效液相色谱-串联质谱仪在正离子模式下检测,内标法定量.结果表明:4种硝基呋喃代谢物在0.25～50 μg/kg范围内线性良好,相关系数r＞0.999.貉肌肉组织中4种硝基呋喃代谢物检出限(LOD)均为0.1 μg/kg,定量限(LOQ)均为0.25 μg/kg.在0.25～2 μg/kg范围内的四个添加水平4种硝基呋喃代谢物的回收率为89.7％～108％,相对标准偏差为1.32％～10.5％(n=6).说明该方法操作简单,灵敏度高、准确性好,适用于貉组织中硝基呋喃类代谢物残留的检测.     

寄主种类和阿维菌素对小菜蛾产卵选择行为的影响

通过田间笼罩试验,研究了小菜蛾对7种十字花科蔬菜的产卵选择性,以及喷施阿维菌素对小菜蛾产卵选择行为的影响．结果发现,其选择顺序为小白菜〉油菜〉芥菜〉萝卜〉菜心〉甘蓝〉花椰菜;喷施阿维菌素之后,小菜蛾对寄主的产卵选择性发生了变化,其在尽可能的躲避杀虫剂后才选择喜好的寄主植物．可见,寄主种类和阿维菌素共同影响小菜蛾的产卵选择行为．     

Optimal dietary protein requirement for juvenile ivory shell, Babylonia areolate

A growth experiment was conducted to determine the optimal dietary protein requirement for juvenile ivory shell reared in indoor aerated aquaria. Six isoenergetic experimental diets using fish meal, casein and gelatin as protein sources were formulated to contain graded levels of protein (27, 33, 38, 43, 49 and 54% of dry diet, respectively). Triplicate groups of 40 shells (average weight 93.50 ± 1.70 mg) were stocked in 120-l tanks and fed to apparent satiation twice daily for 8 weeks. The results showed that the growth performance and feed utilization were significantly affected by dietary protein level (P < 0.05). Maximum weight gain, mean protein gain, specific growth rate and soft body to shell ratio occurred at 43% dietary protein level (P < 0.05). There were significant differences in protein, lipid, moisture and ash content in soft body; except that ash content in shell was not significantly affected by dietary protein level. Pepsin activity in soft body tissue significantly increased with dietary protein level up to 43%, and trypsin-like enzyme activity increased with dietary protein level up to 49%. However, lipase activity in soft body decreased with increasing dietary protein level. However, no significant differences (P < 0.05) in survival, calcium, phosphorus concentration in the shell and soft body were found among dietary treatments. Quadratic regression analysis of weight gain against dietary protein level indicated that the optimal dietary protein requirement for maximum growth and feed utilization of juvenile ivory shell is 45% of dry diet.     

海水池塘虾鱼贝蟹综合生态立体混养试验

目前,全国的对虾池综合养殖面积已发展到20万hm2以上,养殖对虾的生态环境日益改善,与海区的水交换明显减少,暴发性虾病有所控制,对虾产量逐年回升,充分显示了虾池综合养殖强大的生命力和广阔的发展前景.     

Experimental study on the effect of horizontal waves on netting panels

The effect of horizontal waves on flexible netting panels is examined in this study, to evaluate the testing method of pretensioned mooring, radial systems, and flexible netting structures. The netting was suspended at a specific hanging ratio for six polyethylene panels with different characteristics. The aim was to evaluate the calculation method for horizontal wave forces on flexible netting panels. A regular wave was used in the experiment, with wave period 0.8–2.0 s and wave height 50–250 mm. The force on the netting structure was recorded by a tension transducer and digital signal recorder, and was simulated by a cubic spline in terms of the wave experiment under different wave conditions. The horizontal wave force on the netting panel changed periodically and asymmetrically, which was similar to the surface wave elevation. The horizontal wave force was related to the netting panel height and width (l), wave height (H) and wave length (L), twine diameter (d) and bar length (a) of the mesh. Using dual series relations, least-squares approximation, and multiple stepwise regression analysis, the following formula was obtained for the horizontal wave average apex value (F) on the netting panel: F=0.13ρgl(H/2)²(d/a)(H ^0.64 L ^0.77/0.9a ^0.44).     

Association Analysis between Differences of GnRHR-Ⅱ Gene Expression with Reproduction Traits Heterosis in Duck Populations

The objective of this study was to clone the sequence of duck type Ⅱ gonadotropin releasing hormone receptor (GnRHR-Ⅱ) gene, and to analyze the association of its expression levels with reproduction trait heterosis. RT-PCR method was used to clone GnRHR-Ⅱ gene fragments, and the expression levels during early laying days and laying fastigium period in Gaoyou duck, Jinding duck and crossed populations were tested by Real-time PCR method. Sequencing and homology analysis showed that the cloned duck GnRHR cDNA was about 500 bp in length, and it belonged to the avian type Ⅱ GnRHR isoforms. It was 96% identical to the cGnRHR-Ⅱ sequence reported in domestic chicken. From the early laying days to laying fastigium period, expression levels of GnRHR-Ⅱ gene in pituitary increased for Jinding duck, Gaoyou duck and crossed populations, with the highest expression levels in Jinding×Gaoyou hybrid group (P<0.01) . The expression levels of GnRHR-Ⅱ gene in hypothalamus also increased for Jinding duck, Gaoyou duck, however, it decreased in two crossed populations. The expression levels of GnRHR-Ⅱ gene in ovary were significantly higher for Jinding duck and two crossed populations than Gaoyou duck (P<0.01), but it decreased during laying fastigium period. Compared to Jinding duck and Gaoyou duck breeds, the two crossed populations had positive heterosis in 42-week production and 42-week egg fertilization percent, and negative heterosis in the first laying age and 42-week fertilized egg hatching rate traits. It suggested that the short-lived higher expression of ovary GnRHR-Ⅱ gene before early laying days be correlated with heterosis of the first laying age and 42-week production traits, and its higher expression levels in pituitary could aid to keep laying fastigium.     

光照强度对巴西橡胶树淡绿期叶片光合特性和活性氧代谢的影响

橡胶树种苗培育过程中需要避免强光照射,但光照强度对橡胶树幼苗叶片生理活性的作用机制尚不清楚。以橡胶树品系GT1的实生苗为材料,对植株进行不同光照强度处理,测定其淡绿期叶片在不同光照强度下的光合特性和活性氧代谢情况。结果表明,随着光照强度的增加,橡胶树淡绿期叶片的光化学效率(Fv/Fm)呈现上升规律,同时过氧化物的含量也呈现上升趋势,但是由于抗氧化酶对活性氧清除的作用,1 000μmol/m2·s的高光照强度并没有对橡胶树叶片造成伤害。说明200~400μmol/(m2·s)的光照强度比较适合橡胶树苗淡绿期叶片的生长和发育。