广东发展"三高"农业的研究

广东发展“三高”农业具有很大的市场前景,尤其对毗邻的香港市场具有较大的互补性,通过香港的窗口作用,使广东农业走向世界成为可能。     

Evolution of king crabs from hermit crab ancestors.

King crabs (Family Lithodidae) are among the world's largest arthropods, having a crab-like morphology and a strongly calcified exoskeleton. The hermit crabs, by contrast, have depended on gastropod shells for protection for over 150 million years. Shell-living has constrained the morphological evolution of hermit crabs by requiring a decalcified asymmetrical abdomen capable of coiling into gastropod shells and by preventing crabs from growing past the size of the largest available shells. Whereas reduction in shell-living and acquisition of a crab-like morphology (carcinization) has taken place independently in several hermit crab lineages, and most dramatically in king crabs, the rate at which this process has occurred was entirely unknown. We present molecular evidence that king crabs are not only descended from hermit crabs, but are nested within the hermit crab genus Pagurus. We estimate that loss of the shell-living habit and the complete carcinization of king crabs has taken between 13 and 25 million years.     

网箱密集暂养对河蟹土池大眼幼体变态影响的初步研究

河蟹土池大眼幼体达到一定日龄后将变成幼蟹，而采用网箱密集暂养可延缓大眼幼体的变态。     

中华绒螯蟹Eriocheir sinensis两个地理种群的微卫星DNA多态性分析

为了获取中华绒螯蟹群体遗传多态性的基本数据，寻找合适的遗传标记区分不同种类及不同水系的河蟹种群，采用微卫星DNA分型技术，对江苏地区两个地理种群（本地种与荷兰种）的中华绒螯蟹共计140个样本，通过DNA提取、PCR扩增、聚丙烯酰胺凝胶电泳、银染检测的方法，进行了两个微卫星基因座（Esin 67和Esin 87）的遗传多态性分析．结果表明：中华绒螯蟹本地种与荷兰种的两个微卫星基因座均有较好的多态性；在Esin 67基因座中，本地种和荷兰种绒螯蟹均有8个等位基因，两组的最高频率等位基因均为8重复序列；在Esin 87基因座中，本地种绒螯蟹有9个等位基因，荷兰种有7个等位基因，两组的最高频率等位基因均为9重复序列．同时中华绒螯蟹荷兰种这两个基因座的杂合度和多态性信息含量均高于本地种．这些结果提示了江苏本地的绒螯蟹可能受到其它地区河蟹的种质污染，基因多态性下降，因此需要加强对种质资源遗传变异的深入研究，以便采取措施对河蟹资源进行合理的管理、保护和开发利用．     

Robust judgement of inter-object distance by an arthropod

Animals use several strategies for depth vision, reflecting the constraints imposed by body size, the structure of the visual system and the visual geometry of the environment. Arthropods in particular have restricted depth perception, because they are small and possess closely set, low-resolution compound eyes. Yet, here we show that fiddler crabs defending their burrows from conspecifics can judge how close other crabs are to their burrow. When confronted with small dummy crabs, the burrow owners assess the dummy's position and motion relative to their burrow and not relative to themselves--in other words, by using an allocentric rather than an egocentric frame of reference. Irrespective of their own distance from the dummy, the likelihood that the crabs rush back to defend their burrow increases strongly as the dummy approaches the burrow. In addition, the mean dummy-burrow distance at which the crabs respond is constant and independent of the dummy's direction of approach. We propose that to solve this sophisticated task of relative distance judgement, the crabs combine visual information on dummy position and direction with information on burrow location acquired during path integration. In doing so, the crabs, like humans, make clever use of the visual geometry of their environment.     

基于K-近邻方法的网络信息文本分类

提出了一种网络信息文本分类模型的建立方法,根据网络报文的特点,抽取其中关键词作为分类特征词条,并以报文关键词进行词频统计分析建立文本分模型,分别进行了基于最近邻决策和K-近邻决策的分类效果试验研究,结果显示,K-近邻决策的分类效果要优于最近邻决策的分类效果。     

宜春地区肺吸虫第二中间宿主：—溪蟹感染情况的调查

自1982年来,全区共采集溪蟹3208只,定性解剖1684只,阳性1258只,感染率为74.70%,其中1只雄性蟹体内检获囊蚴6599只.部体解剖,91.47%囊蚴分布在肌肉、蟹足、螯肢.用新鲜囊蚴人工感染家犬获得成功.其囊蚴、虫卵、成虫均为卫氏并殖型.     

中华绒螯蟹幼蟹对饲料中维生素B6的适宜需求量

试验以酪蛋白为蛋白源,配制了维生素B₆含量分别为0,10,30,60,100,150,200和400 mg/kg的8种等氮等能的半精制饲料,在静水系统中投喂体重为(2.12±0.56) g的幼蟹10周.结果表明,饲料中不同含量的维生素B₆对中华绒螯蟹的存活率、增重率、体水分和灰分含量等均没有显著影响,但饲料中添加维生素B6能够显著提高幼蟹蛋白利用率、体粗蛋白含量和粗脂肪含量.饲料中维生素B₆含量由0~100 mg/kg升高时,蛋白利用率随之显著提高.体粗蛋白和粗脂肪含量的变化趋势与蛋白质利用率相似,其中维生素B₆添加量为100 mg/kg的处理组,幼蟹的粗蛋白和粗脂肪含量显著高于对照组和400 mg/kg维生素B₆添加组.幼蟹肝胰腺中谷草转氨酶和谷丙转氨酶的活力先随着维生素B₆添加量升高而增强,添加100 mg/kg维生素B₆的试验组,幼蟹的谷丙转氨酶活力显著高于其它各试验组.根据各处理组中华绒螯蟹对饲料蛋白的利用率和肝胰腺谷丙转氨酶活力与饲料中维生素B₆的关系,采用折线回归法计算得出中华绒螯蟹幼蟹对饲料中维生素B6的最适需求量为81.675~85.740 mg/kg饲料.     

Ecological Relationship between Mud Crab Scylla serrata (Forskal) and Mangroves and the Pattern of Utilization

The ecological relationship between mud crab Scylla serrata(Forskal)and mangroveswas described in this paper.Mangrove swamps are important reproductive places for mud crabs,where zoeae,megalopae,juveniles from 1st to 14th instar,adult crabs and ovigerous female crabswere found.Mangrove roots and the leaf litter are the shelters of the mud crab.The zoeae andmegalopae of mud crab can normally grow and develop on the plankton and debris that are well-supplied in mangrove swamps.There are a lot of Phascolesoma,Mollusca and Crustacea whichconstitute the delicious foods of the mud crab in mangrove swamps.The larger crabs have apreference for Ostrea,Balanus and Vignadula which usually amply adhere and endanger themangroves,so the mud crab is helpful for the development of the mangrove communties.Finallya pattern of ecological culture of the mud crab in mangrove swamps was suggested.     

人工感染呼肠孤病毒对拟穴青蟹部分免疫因子的影响

采用注射和浸泡的方式人工感染拟穴青蟹呼肠孤病毒,研究了其对拟穴青蟹血细胞密度以及血清中酚氧化酶(PO)、超氧化物歧化酶(SOD)和碱性磷酸酶(AKP)活力的影响.结果表明:注射(第Ⅱ组)和浸泡(第Ⅳ组)方式均能感染健康青蟹,病发死亡时间为7～9 d,死亡率达100%,血细胞平均密度在试验36～72 h间迅速上升并达最高值,其血细胞密度最高值分别为1.4008×107cells/mL与1.8243×107cells/mL;感染病毒的青蟹PO活性均大致呈现下降的趋势,其中,第Ⅳ组感染12 h青蟹PO活性相对对照组显著升高(P<0.05),其值为(6.90±1.54),达实验所测PO活性最高值;各实验组血清SOD活性呈无规律的变化;AKP活性感染组与对照组表现不同.表明测定血细胞密度以及PO和AKP活性可用来辅助诊断青蟹疾病,而SOD活性变化不能很好地表征青蟹受病毒感染的状况.     

对虾白斑症病毒(WSSV)对蟹类的感染

在对虾白斑症病毒(WSSV)病发生期间,养殖虾池内的蟹类也往往出现异常甚至死亡．通过WSSV对三疣梭子蟹(Portumus trituberculatus)的人工感染证实了其感染性．三疣梭子蟹在注射感染后第9天全部死亡,注射后第6天死亡率最高;经口感染,三疣梭子蟹在感染后第25天全部死亡,在15～20d死亡率最高;在浸洗感染和对照组30d内无蟹子死亡．在感染死亡蟹子和发病虾池内病蟹的鳃、上皮组织的细胞核内电镜观察到的病毒粒子,其形态特征与在对虾上观察到的一样．用PCR和单克隆抗体的FAT法在注射感染和投喂感染的蟹子都得到了WSSV感染阳性结果,浸浴感染的蟹子和健康蟹子都得到了WSSV感染阴性结果．蟹类(三疣梭子蟹)对WSSV的敏感性较对虾低,为此蟹类有可能是WSSV的携带者或传播者．     

Ad Hoc网络中基于AODV的拥塞适应路由协议

该文提出邻居拥塞表概念,利用旁路、邻居拥塞表、hello消息和下一绿色节点请求技术,对自组网按需距离矢量(AODV)协议进行改进,提出自组网拥塞适应按需距离矢量(CA-AODV)路由协议.在CA-AODV协议中,主节点利用邻居拥塞表,能在第一时间感知网络拥塞.当拥塞发生时,拥塞节点的上一节点能按需建立绕过拥塞节点的旁路,当数据流到达已建立旁路的节点时,被按比例分流在主路由和旁路上,实现了拥塞适应功能.仿真结果显示,与AODV相比,CA-AODV协议的平均端到端延迟更短、数据包递交率更高、规格化路由开销更少.     

Resource availability: Ancient homes for hard-up hermit crabs

Mollusc shells are a vital but sometimes scarce resource for hermit crabs, protecting them from mechanical damage and desiccation, but they require continual replacement as the crab grows. I have discovered that Coenobita rugosus, a large, tropical, semi-terrestrial hermit crab, will resort to using fossil shells when no other suitable casing is available. These unlikely mobile homes fall out of coastal limestone as it is eroded by the sea in southwestern Madagascar, placing the occupants alongside Homo sapiens as resourceful exploiters of prehistoric animal remains.     

德夯风景区植物区系的研究(Ⅲ)与邻近区系关系的比较分析

通过区系组成和地理成份的对比分析,对德夯风景区及其邻近的8个区系进行比较研究,结果表明德夯与这8个区系间存在着程度不一的区系联系。相对而言,德夯与梵净山、佼母溪和壶瓶山的关系更为密切,区系同质性最高,表明它们共属华中地区武陵山─—巫山亚区这一整体,德夯则刚好处于这一亚区整体的南缘而与雷公山─—雪峰山亚区相衔接。     

舟山海域池塘养殖和野生三疣梭子蟹抱卵量的比较研究

系统研究和比较池塘养殖和野生三疣梭子蟹人工繁殖亲本的体重、甲壳长、甲壳宽、抱卵量、生殖力和单个卵重等指标,结果表明:1.人工育苗用野生三疣梭子蟹的体重、甲壳长、甲壳宽、抱卵量显著高于池塘养殖蟹(P<0.05);2.野生三疣梭子蟹的平均生殖力(Fecundity,粒/g)和单个卵重也大于池塘养殖梭子蟹,但是由于变异系数较大,并无统计学的差异(P>0.05);3.池塘养殖三疣梭子蟹的抱卵量与体重、甲壳长和甲壳宽相关系数高于野生梭子蟹,无论野生还是池塘养殖梭子蟹的抱卵量与体重、甲壳长和甲壳宽呈正相关,且抱卵量与甲壳长的相关系数最高。从而,总结出了利用三疣梭子蟹的甲壳长和甲壳宽来预测其抱卵量的方法。     

二维复式晶格有限集团的电子结构特性

选取二维复式晶格作为有限系统的集团模型,在紧束缚近似下,计算了最近邻及考虑到次近邻集团的态密度。讨论了不同结构参数对态密度及带宽的影响。     

蟹类生殖生理学研究进展

从生殖内分泌和生殖营养两方面综述了蟹类生殖生理学的研究进展．同时探讨了蟹类生殖调控技术．并对今后蟹类生殖生理学的深入研究提出了一些建议．     

Feeding behaviour: hydrothermal vent crabs feast on sea 'snow'

The crab Xenograpsus testudinatus lives at enormously high densities around the sulphur-rich hydrothermal vents found in shallow waters off Taiwan, even though this acidic environment is low in nutrients. Here we show that these crabs swarm out of their crevices at slack water and feed on the vast numbers of zooplankton that are killed by the vents' sulphurous plumes, and that rain down like marine 'snow'. This opportunistic feeding behaviour explains how the crabs are able to survive in the adverse toxic environment of these shallow hydrothermal vents.     

基于最佳距离度量近邻法的邻域风险最小化方法

 在邻域风险最小化原则中提出一种新的定义邻域半径的方法,即对任意训练样本点,首先利用最佳距离度量近邻法定义一个距离度量,并根据这个距离度量来寻找该样本点的最近邻,然后依据它们之间的距离来定义邻域半径,最后在原有邻域风险最小化算法的基础上建立基于最佳距离度量近邻法的邻域风险最小化算法.实例表明新提出的算法是正确的、有效的.     

自然邻接点局部Petrov-Galerkin法求解中厚板弯曲问题

将基于自然邻接点插值的无网格局部Petrov-Galerkin方法应用于分析中厚板弯曲问题.自然邻接点插值创建的形函数具有Kronecker Delta函数性质,故能够准确地直接施加本质边界条件.在板中面上的局部多边形子域上采用局部Petrov-Galerkin方法建立系统平衡方程,这些子域由Delaunay三角形创建...