油茶叶中油脂抗氧成份研究

首次从油茶叶中分离得到三种黄酮体化合物,经UV,FT-IR,’HNMR,^(13)CNMR,EI-MS及FAB-MS等仪器分析,鉴定为槲皮素(1),槲皮素-3-0-鼠李吡喃糖甙(2)和槲皮素-3-0-葡萄吡喃糖-(6→1)-鼠李吡哺糖甙(3)。在Metrohm Rancimat中测定了它们的诱导时间,显示这三种化合物对于猪油及菜籽色拉油都是良好的抗氧剂,尤其是槲皮素对于猪油的抗氧性在相同添加量时比BHT强得多。此外还对这类化合物的抗氧活性与其结构的关系作了初步探讨。

背瘤丽蚌钩介幼虫寄生变态发育和有效积温的研究

选用黄颡鱼(Pelteobagrus fulvidraco)作为寄主鱼,研究了背瘤丽蚌(Lamprotula leai)钩介幼虫寄生变态发育的过程、生物学零度和有效积温等重要生物学特征。结果显示,背瘤丽蚌钩介幼虫在黄颡鱼的鳃丝、鳍条或须上均能完成变态发育。在水温(25±1)℃时,寄生期为8 d。钩介幼虫腹缘先与寄主鱼体表组织接触,寄生后5 h,大部分被鱼体组织包裹;第2天,内幼虫足丝消失,钩介幼虫全部被包在包囊中;随着钩介幼虫寄生变态发育的进行,其壳颜色逐渐加深;第7天,变成黑色不透明,并有少量钩介幼虫变态为稚蚌;第8天,稚蚌脱落达到高峰期;第9天,稚蚌全部脱落。在寄生阶段,钩介幼虫壳长、壳高和铰合部长未发生显著变化。钩介幼虫寄生变态发育的生物学零度为12.8℃,有效积温为100.2℃.d。

Survival analysis of a stochastic single-species population model with jumps in a polluted environment

This paper is concerned with a stochastic single-species system with Levy jumps in a polluted environment. Some sufficient conditions on extinction, non-persistence in the mean, weak persistence in the mean, strong persistence in the mean, stability in the mean and stochastic permanence are obtained. The threshold between extinction and weak persistence in the mean is established. At the same time, under a simple condition, it is proved that this threshold also is the threshold between extinction and stability in the mean. The results reveal that L@vy jumps have significant effects to the persistence and extinction results.