Genetic diversity and differentiation of three populations of Penaeus monodon Fabricus

Genetic diversity of two wild Penaeus monodon populations sampled from the coastal waters of Qinglan （ Hainan Province of China, HN） and Malaysia （KD）, and the F1 generation of a Thailand broodstock population （CP） were examined by vertical polyacrylamide gel electrophoresis. Of 21 loci encoded by ten enzymes, 11 were polymorphic. The mean proportions of polymorphic loci of HN, KD and CP were 36. 36%, 45.45% and 50.00% , with the average heterozygosities of 0.135, 0.181 and 0.191, and the effective numbers of alleles per loci were 1. 300, 1. 330 and 1. 329, respectively. The divergent indexes of HN, KD and CP were0.023, 0.124, and 0.117, respectively. The genetic distance between the two wild populations was 0.005, and the gene differentiation coefficient was also very low （0.014）. The results indicated that the F1 generation population had a higher genetic diversity than the two wild populations, and that the HN population had the lowest one. There was no significant differentiation between HN and KD populations and all populations existed with a slight heterozygote excess.     

Seasonal variability in free-living marine nematode community structure in a sandy beach of the Taiping Bay of Qingdao, China

Nematode assemblage composition, trophic structure and biodiversity were followed over an annual cycle in a sandy beach of the Taiping Bay of Qingdao, China. Nematode assemblage in the sandy beach maintained a high genus diversity （75 genera）. Mlero- laimus and Bathylaimus were the dominant genus of the nematode assemblage, accounting for 66% of the total nematode abundance. The nematodes＇ dominant trophic structure changed seasonally as a response to the seasonal changes in food quality. Epigrowth-feeder nematodes （2A） were the dominant trophic groups in the trophic structure with the highest abundance in spring because of phytoplankton bloom, while the feeding type （ 1 B） showed higher abundance in summer that was due to the increasing of sediment detritus after spring bloom. Furthermore, species diversity and evenness calculated on nematodes identified to the genus level displayed significant temporal changes, which was also reflected by the index of trophic diversity. According to the cluster analysis, the nematode community structure of the whole year was clearly separated into two periods （A and B）. Biota-Envlron- ment matching （BIOENV） results showed that seawater temperature, sediment Chl a and grain size were responsible for the nema- tode community structure variation in spring and summer period （Period A）. However, seawater/interstitial water temperature, interstitial water dissolved oxygen concentration,interstitial water salinity, and sediment Ph a a were more important in constructing the autumn and winter period （Period B） nematode community structure.     

Water, organic matter, nitrogen and phosphorus contents in sediment of a large-scale mariculture area in the Zhelin Bay of eastern Guangdong Province, China

The Zhelin Bay is one of the most important bays for large-scale mariculture in Guangdong Province, China. Owing to the increasing human population and the expanding mariculture in the last two decades, the ecological environment has greatly changed with frequent harmful algal blooms. A monthly survey of water content, organic matter （TOM）, and various forms of nitrogen and phosphorous in sediment from July 2002 to July 2003 in the bay was conducted. The results showed that the water content was correlated significantly with TOM and various forms of nitrogen and phosphorus and can be used as proxy for quick and rough estimate of these factors in the future surveys. TOM was also correlated significantly with various forms of nitrogen and phosphorus, indicating that it was one of the key factors affecting the concentrations and distributions of nitrogen and phosphorus in the investigated waters. Average total Kjeldhal nitrogen （TkN） content was（ 1 113.1 ± 382.5）μg/g and average total phosphorus （TP） content was（567.2± 223.3）μg/g, and both were much higher than those of similar estuaries in China and elsewhere. Average nitrogen and phosphorus tended to be higher inside than outside the bay, higher at aquaculture than non-aquaculture areas, and higher at fish-cage culture than oyster culture areas, suggesting that large-scale mariculture inside the bay played an important role in the eutrophication of the Zhelin Bay. Various forms of nitrogen and phosphorus concentrations were higher during the warm season （July--September）, which was due to the increased decomposition and concentration of organic matter resulted from the fast growth and high mortality of the cultured species. Compared with July 2002, TkN and TP contents were much higher in July 2003, in consonance with the eutrophication of the Zhelin Bay. Because exchangeable phosphorus （Ex-P）, iron-bounded phos- phorus （Fe-P） and organic phosphorus （OP） combined accounted for 34.3% of the TP and authigenic phosphorus （Au-P     

Numerical Simulation of Large Diameter Cylindrical Structure Slamming

The water entry of large diameter cylindrical structure is studied by applying numerical simulation method. The processes of different diameter cyhndrical structures impacting water with various constant velocities are calculated numerically. Thereafter, analyzed are the distribution of slamming pressure on structure during slamming course and the influence of slamming velocity and cylindrical diameter on slamming process. Furthermore, presented herein is an equation being used to forecast the peak slamming force on a large diameter cylindrical structure.     

热带风暴热力非对称结构对其运动的影响

研究了热力非对称结构对0421号热带风暴"海马(Haima)"的移动和强度变化的影响。通过物理量场诊断分析发现,热带风暴(气旋)的热力结构在垂直、水平方向均呈非对称分布。热力因子对热带风暴的影响,主要体现在低层。热带风暴朝其移向前方的风暴内部的非绝热增温中心偏折,并有向此方向加速的趋势。了解热带风暴的热力结构分布特征及其对热带风暴移动的影响,对短期预报热带风暴的移动有一定的指示意义。     

城乡建设用地利用区域差异评价——以福建省为例

考虑到城乡土地利用方式的差异,构建了城乡建设用地利用区域差异评价的指标体系,从人地关系、经济效益、与社会发展协调三方面对城乡建设用地利用的区域差异进行较全面的评价,以福建省为例进行了应用。     

影响农村居民点用地规模变化的因素分析和效验

用对比法和相关分析法验证农村居民点用地规模变化社会经济影响的区域差异,为相关理论研究和管理政策的制定提供借鉴和参考。     

长沙市土地利用变化及其相关因素分析

以长沙市2002～2006年土地变更数据为基础,采用年均土地利用动态度、变化强度指数对长沙市2002～2006年5年的土地利用结构时空变化进行了研究,并分析了影响长沙市土地利用结构变化的因素,并在此基础上提出相关的建议.     

阳光政务依法办事合力调处一线解决——温岭市城北街道涉土零上访的主要做法与体会

温岭市城北街道办事处地处温岭市区北郊。是该市工业经济发展的重点区域之一,辖区总面积12．5平方公里,下辖16个行政村,1个居委会,2007年底常住人口19万人,耕地面积513．41公顷,人均耕地仅0.4亩,农保率为75％。2007年街道实现工农业生产总值41亿元,财政收入达7296万元,分别比2006年增长19％和33％。全年街道共完成重点建设项目12个,总投资为6．5亿元,用地面积达312亩,是街道发展历史上建设项目、土地需求和各类不稳定因素最多的一年,呈现涉土矛盾多、遗留问题多的特点,仅2007年群众反映至街道的涉土矛盾和纠纷就达31件。在这样的状况下,该街道却连续两年实现了涉土零上访,并连续两年被温岭市政府表彰为“信访工作先进集体”,这实在是一件不容易的事。为何取得如此好的成绩？日前,笔者走访了城北街道办事处主任朱明连和分管副主任陈根满,经总结、分析和提炼。其做法主要体现在以下五个方面：     

征地工作要处理好四方面关系——以鄞州区为例

宁波市鄞州区地处于宁波老三区的东、南、西三面,全区行政区域面积达1380多平方公里,其中耕地面积约54万亩,总人口约76万。全区行政区域有22个镇、（乡）、街道,462个行政村（拼村后）。改革开放以来,随着城市化进程的不断推进,特别是在新城区建设开发以来的十年多时间里,据不完全统计,全区年平均征地数近万亩,累计征收集体所有土地达15万亩。由于征地行为涉及到村集体和农民的切身利益,存在着诸多历史和现实原因,加上国家征地方面法律政策的滞后和空白,征地工作日益复杂和艰难,逐渐成为社会、经济发展的瓶颈,是各地政府工作的重点难点之一。本文着重对多年来本区做好征地工作中的出台政策、合理分配职责、人性化操作、以及依法规范程序四篇文章的基本做法予以总结和反思,与从事征地工作的同仁们分享和交流,以改善我们的工作方式和手段,推进今后征地工作的顺利进行。