人工湿地生态系统服务价值评价研究

阐述了人工湿地生态系统服务的定义、分类、项目及其评价方法。介绍了生态系统服务价值评价在国内外的研究现状,指出了当前研究工作的局限性,对将来的发展方向作出了研究展望。论述了人工湿地所具有的服务功能,结合前人的研究初步提出对其进行价值评价的方法及计算公式。

菖蒲对不同程度富营养化水体的适应性研究

对5种不同程度富营养化水体中的菖蒲(Acorus calamusL.)在静态培养过程中的叶片长度变化、叶片数目变化进行了观测,比较了培养后各水体中菖蒲根长、根数、鲜重、根活力、叶绿素含量、叶片可溶性总糖含量、鲜重增量和根系活力的差异。研究发现,菖蒲在5种不同程度富营养化水体中均能正常生长。在非极度富营养化的水体组中,水体富营养化程度越高,菖蒲生长越好。但在极度富营养水体中,菖蒲根系生长受到抑制,其根短且须根多,且叶片生长对此水体有一段适应期,试验前8 d,其中菖蒲叶片长度增长明显小于重度富营养,8 d后,

The vibrations of bubbles and balloons

Bubbles and balloons are two examples of structures that feature a pressure difference across the skin, a thin, tensioned membrane, and a doubly curved interface surface. While mathematical models have been formulated for bubble vibrations, no such model exists for balloon vibrations. This paper reviews a model of bubble vibrations, and compares its predicted natural frequencies and modeshapes to those of a rubber balloon. It is shown that the bubble model consistently underpredicts the balloon's natural frequencies, and it is concluded that the nonlinear elasticity present in the balloon skin accounts for this result.

汉江中下游春季浮游甲壳动物群落结构的空间差异

2002年4月,在汉江中下游从丹江口坝上至其河口沿途设17个采样点,共采集到浮游甲壳动物10科26属33种,其中桡足类4科10属11种,枝角类6科16属22种。根据各采样点的种类组成和数量分布,采用Shannon Wiener指数、Simpson指数和Pielou均匀度指数分析了不同江段浮游甲壳动物的群落多样性特征,并运用SOM人工神经网络方法对其群落结构的空间差异进行了比较。结果表明,汉江中下游江段浮游甲壳动物的密度分布呈现出中游高于下游的特征,而物种丰度和群落多样性指数则是下游高于中游;中游上段的属于

单克隆抗体技术在水生动物病毒研究中的应用

“淡水生态与生物技术”国家重点实验室开放课题(2002FB07); 国家自然科学基金(30170726); 中国科学院及中国科学院水生生物研究所创新项目(KSCX2-SW-302与220313)

快速建立鲢、鳙纯系的初步研究

运用随机扩增多态性DNA(RAPD)方法对雌核发育和人工转性鲢、鳙进行了遗传多样性的研究,并用长江天然鲢、鳙群体作为对照分析.在雌核发育鲢中,共得到187条带,其中19条为多态带,占10.16％,而对照组鲢共扩增205条带,有32个多态座位,占总带数的15.61％.在雌核发育鳙中共产生232条带,其中11条为多态带,比例为4.74％,而在对照组中共产生241条带,25条为多态带,比例为10.37％.遗传距离分析表明,雌核发育鲢和鳙的平均值分别为0.102和0.023.而对照组鲢和鳙遗传距离平均值分别为0.

草鱼仔鱼耳石的自然标记和生长轮的清晰度

将野生和人工繁殖的草鱼仔鱼的耳石取出并置于显微镜下观察微结构特征。结果表明 :草鱼耳石一般有一个圆形或卵圆形的原基和中心核 ,但有 0 4 1%～ 4 6 7%的样本具有双原基或双中心核。343尾野生仔鱼中 ,6 71%的个体在矢耳石和微耳石上具有营养转换标记 ,而 187尾人工繁殖的仔鱼中 ,在矢耳石和微耳石上出现营养转换标记的比例分别是 6 4 17%和 5 0 80 % ;在营养转换标记处 ,矢耳石和微耳石的直径分别为 5 4 12±9 4 9μm和 4 0 4 8± 7 0 2 μm (n =5

荧光原位杂交技术(FISH)及其在环境微生物学中的应用

微生物对整个生态系统具有重要的影响,了解和检测微生物的种类具有十分重要的意义。但是传统的培养方法又不能满足科学研究的需要,荧光原位杂交技术(ＦＩＳＨ)就是近年发展起来的一种快速准确检测微生物的方法。作者较全面地介绍了ＦＩＳＨ技术的优点、微生物的分离和固定方法,以及原位杂交过程,同时对ＦＩＳＨ技术在环境微生物学中的应用及其前景作了展望。

Control of bimanual rhythmic movements: Trading efficiency for robustness depending on the context

This paper investigates how the efficiency and robustness of a skilled rhythmic task compete against each other in the control of a bimanual movement. Human subjects juggled a puck in 2D through impacts with two metallic arms, requiring rhythmic bimanual actuation. The arms kinematics were only constrained by the position, velocity and time of impacts while the rest of the trajectory did not influence the movement of the puck. In order to expose the task robustness, we manipulated the task context in two distinct manners: the task tempo was assigned at four different values (hence manipulating the time available to plan and execute each impact movement individually); and vision was withdrawn during half of the trials (hence reducing the sensory inflows). We show that when the tempo was fast, the actuation was rhythmic (no pause in the trajectory) while at slow tempo, the actuation was discrete (with pause intervals between individual movements). Moreover, the withdrawal of visual information encouraged the rhythmic behavior at the four tested tempi. The discrete versus rhythmic behavior give different answers to the efficiency/robustness trade-off: discrete movements result in energy efficient movements, while rhythmic movements impact the puck with negative acceleration, a property preserving robustness. Moreover, we report that in all conditions the impact velocity of the arms was negatively correlated with the energy of the puck. This correlation tended to stabilize the task and was influenced by vision, revealing again different control strategies. In conclusion, this task involves different modes of control that balance efficiency and robustness, depending on the context. © 2008 Springer-Verlag.