Effects of varying densities on serum reproductive parameters in pen-reared juvenile female rainbow trout <Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis> farms

The primary goal of this study was to assess the effect of varying densities on serum reproductive parameters of immature rainbow trout Oncorhynchus mykiss. Experimental trout were maintained in intensive, pen-reared farms for 300 days in fresh water reservoirs. Initial densities were 4.6, 6.6, and 8.6 kg/m³ (40, 60, 80 ind./m³), indicated as SD1, SD2, SD3, and final densities were 31.1, 40.6, 49.3 kg/m³, respectively. A summary of the ovarian stages were observed by histological examination. Serum E₂ (estradiol), T (testosterone) were evaluated by radioimmunoassay and FSH (follicle-stimulating-hormone), LH (luteinizing-hormone), vitellogenin, 17α,20β-P (17α,20βdihydroxy4-pregnen-3-one) were measured by enzyme-linked immunosorbent assay. Our findings demonstrated that ovarian development were retarded (from stage III to stage IV) at highest rearing density (SD3) after 180 days of intensive culture (over 40.6 kg/m³). In addition, we observed an inverse relationship between serum reproductive parameters and rearing density. Furthermore, compared to serum reproductive parameters of SD1, E₂, T, FSH, vitellogenin, 17α,20β-P, GSI and LH of two higher density groups decreased firstly and significantly at 60 (over 15.9 kg/m 3 ), 180 (over 31.7 kg/m 3 ), 180 (over 40.6 kg/m³), 240 (over 36 kg/m³), 240 (over 36 kg/m³), 240 (over 45 kg/m³) and 300 (over 49.3 kg/m³) days, respectively. Comparing serum reproductive parameters within the same ovarian development stage of rainbow trout from varying densities revealed that higher population density also led to significantly lower overall serum reproductive parameters. Overall, this study presents the reproductive, endocrinological parameters of juvenile female rainbow trout at high rearing densities and indicates the need for rainbow trout (114.44±5.21 g, 19.69±0.31 cm) that are initially stocked at 6.6 or 8.6 kg/m³ should be classified and subdivided into lower density after 180 days of farming (not over 31.7 kg/m³).     

THE PROBLEMS OF WATER RESOURCES IN NORTH CHINA AND THE STRATEGY

North China, whose total area is 420,000 km2, covers 2 provinces and 2 cities (Shanxi and Hebei provinces, Beijing and Tianjin) and the territories of Henan and Shandong provinces to the north of the Huanghe (Yellow) River, and part of the Inner Mongolia Autonomous Region and Liaoning Province. Most of this region, which is situated in the semi-humid, semi-arid continental climate temperate zone, gets an annual precipitation of 500-600 mm, whereas, the perennial average amount of total water resource is 50.99 billion m3, including 33.82 billion m3 of surface water, 32.94 billion m3 of ground water and 15.77 billion m3 of their duplication. Due to the intensive exploitation of water resource caused by the deficiency of water resource in North China, key elements of water balance was changed, runoff volume reduced, evaporation increased, vertical movement of moisture strengthened, water circulation pattern transformed from open system into regionally closed system; meanwhile, due to the incompetent water     

THE POSITION AND ROLES OF PORTS AND RAILWAYS IN THE EURASIA LAND BRIDGE TRANSPORTATION IN NORTHEAST CHINA

This paper systematically analyzes and proves the favorable factors of utilizing the ports and the railways in Northeast China for the Asia-Europe land bridge transportation. It will be more beneficial to Dalian Port and HaDa (Harbin-Dalian) and Binzhou (Harbin-Manzhouli) railways in Northeast China to the Siberia railway in Russia than 1) to other ports and the corresponding railways in China, 2) to the Nakhodka Port in Russia and the corresponding railways and 3) to the Chongjin Port in North Korea and the corresponding railways. This paper also puts forward the reform measures to adopt the ports and the railways in the northeast region in China for the land bridge transportation and the problems in transportation policies and management systems.     

加强法制观念 依法落实征地批后实施工作

一、依法落实“两公告一登记”工作关于对征地方案的实施,《中华人民共和国土地管理法》第46条规定：“国家征收土地的,依照法定程序批后,由县级以上地方人民政府予以公告并组织实施”。《中华人民共和国土地管理法实施条例》第25条规定：“征收土地方案经依法批准后,由被征收土地所在地的市、县人民政府组织实施,并将批准征地机关、批准文号、征用土地的用途、范围、面积以及征收土地补偿标准、农业人员安置办法和办理征地补偿的期限等,在被征用土地所在地的乡（镇）、村予以公告。被征收土地的所有权人、使用权人应当在公告规定的期限内,持土地权属证书到公告指定的人民政府土地行政主管部门办理征地补偿登记。     

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地理信息系统（GIS）科学体验区建设

针对国内缺少面向非专业人群的GIS科普内容的状况,研究在建构主义体验学习与情境学习理论的指导下,提出了"以兴趣引导体验促科学知识发现"的GIS体验区建设理念,形成了"掌握空间分析方法、提高动手实践能力、转变思维方式和观念"的体验目标和"用半开放体验线路串联系列小案例反映GIS方法与应用"的设计思路,进而以"GIS知识学习--GIS初步应用--GIS项目选址"为体验主线,进行了GIS体验区的框架设计和分场景设计,并综合运用RIA技术和开源WebGIS技术,构建了GIS科学体验的数字互动平台.GIS体验区网站运行一年以来,访问量超过17万人次,结果表明,GIS体验区能够有效把握体验者的兴趣,有利于推动GIS的大众化发展.     

SEA LEVEL RISE OF THE ZHUJIANG RIVER DELTA AND NEOTECTONICS

A linear regression analysis of 28 selected tide-gauge stations of the Zhujiang Estuary shows that there has been a tendency of local sea level rise at a rate of 2.028 mm per year. The origin of the variation is significantly attributed to the local tectonic movement of discrepant fault-block. Based on this, four types of relative local sea level changes are classified. According to calculation, half of the fertile land, or 800 km2 of the delta plain will have been submerged by sea water by about 2040. This will yield a significant influence on the economic construction and human activities.     

河南信阳珍珠岩矿床及其脱玻化机理

珍珠岩是酸性喷出岩的一个特殊变种,它由含水火山玻璃组成,具有特殊的珍珠状构造。河南信阳珍珠岩矿床是最近刚探明的一个大型非金属矿床。珍珠岩矿床贮存于中生代晚期白垩纪的火山岩中。珍珠岩矿床的产状受成矿时古地形的控制。它与晚期流纹岩一起构成复杂的地质体,在空间上多呈囊状,豆荚状,似层状产出。组成矿石的酸性火山玻璃有性脆、裂隙较为发育、化学性质不稳定等特点。在后期构造活动中往往易于破碎,在碱性水介质和其它条件下易于水解、脱玻形成蒙脱石、沸石矿物,这些矿物在合适的条件下聚集,形成与珍珠岩伴生的膨润土、沸石矿床。本文旨在阐述珍珠岩矿床特征的基础上,探讨其脱玻化的机理。     

"缠访户"变成了"养殖户"

太康县高朗乡王庄村村民周新民老汉,从1996年以来,因宅基地和其他一些问题经常赴省、市、县上访,成了远近闻名的上访户.但最近周新民的行为却发生了天翻地覆的变化,不再早出晚归上访了,而是专心致志地养起了羊,成了名副其实的养殖户.周新民老汉为什么有如此巨大的变化呢?这还得从头说起.     

宝清县锅盔山地区地质特征及找矿潜力分析

一、地质背景 宝清县锅盔山地区地层属兴凯湖一布列亚山地层区;佳木斯一虎林分区;宝清小区;出露地层以下元古界兴东群大盘道组的黑云角闪斜长变粒岩、矽线堇青钾长变粒岩、黑云矽线片岩、石英片岩、大理岩为主。零星分布白垩系上统松木河组的流纹岩,英安岩及其凝灰角砾岩、角砾熔岩夹安山岩、珍珠岩等。