The loss of genetic diversity during captive breeding of the endangered sculpin, Trachidermus fasciatus, based on ISSR markers: implications for its conservation     

������  ������  ������  ��� 《中国海洋湖沼学报》2011,29(5):958-966

Inter-simple sequence repeat (ISSR) markers were used to determine the genetic variation and genetic differentiation of cultured and wild populations of Trachidermus fasciatus, an endangered catadromous fish species in China. Six selected primers were used to amplify DNA samples from 85 individuals, and 353 loci were detected. Relatively low genetic diversity was detected in the cultured population (the percentage of polymorphic loci PPL = 73.80%, Nei’s gene diversity h = 0.178 2, Shannon information index ...  相似文献   

Sediment transport off the Huanghe (Yellow River) delta and in the adjacent Bohai Sea in winter and seasonal comparison   总被引：5，自引：0，他引：5  

Zuosheng Yang  Youjun Ji  Naishuang Bi  Kun Lei  Houjie Wang 《Estuarine, Coastal and Shelf Science》2011

Based on the data on the current velocity, water temperature, salinity, turbidity and concentration of suspended sediment collected in November 2006 along three survey transects at three time-series, ship-based stations off the Huanghe (Yellow River) delta, and at twenty-four grid survey stations in the adjacent Bohai Sea, sediment transport off the Huanghe delta and in the adjacent Bohai Sea under winter regime were studied and compared with those from the summer season.  相似文献   

Fragmentation effects of oil wells and roads on the Yellow River Delta, North China   总被引：2，自引：0，他引：2  

Xiaoli Bi  Bin WangQingshui Lu 《Ocean & Coastal Management》2011,54(3):256-264

Oil exploitation and road development have strongly fragmented the coastal landscapes, leading to profound ecological consequences. The dynamic relationships between oil wells, roads, and landscape fragmentation indices in the Yellow River Delta, China were explored. Oil wells, roads and land cover were mapped from TM images in 1992, 2000, 2006, and 2009, respectively. Changes and relationships were compared among three selected typical sections using linear regression models. We also evaluated the fragmentation effects of oil exploitation on protected wetlands in the Yellow River Delta Natural Reserve (NR). The results showed that oil wells and roads increased greatly. Oil well density and road length density were positively related to patch number and negatively related to patch shape indices. Both drivers have cumulative effects on landscape fragmentation. Influences of old oil wells and roads were stronger than those of new ones. Current management strategies of the NR have failed to effectively prohibit the disturbances of oil activities at the regional scale. The ecological function of protected wetland systems has been damaged by the increase of oil wells. Therefore, based on the principles of landscape ecology, effective approaches were proposed to minimize the negative effects of oil exploitation on the coastal area.  相似文献   

Studies on hemolysis of hemolysin produced by Synechocystis sp. PCC 6803     

Shuai Bi  Wei Wang  Yuanyuan Zhao  Shaoguo Ru  Yunzhang Liu 《中国海洋大学学报(英文版)》2011,10(4):362-368

Hemolysin produced by various bacteria,may destroy erythrocyte membranes via a pore-forming mechanism,a deter-gent action,or a lipase activity.Previous to this experiment,the mode of action used by cyanobacterial hemolysin had not been re-ported.To characterize the action mode of hemolysin produced by the wild-type strain of Synechocystis sp.PCC6803,hemolysis of erythrocytes originating from human,mouse,sheep,rabbit and goldfish was studied.The erythrocytes of mouse,sheep and rabbit were sensitive,while those of human and fish were resistant,to this hemolysin.Using rabbit erythrocytes,it was shown that hemoly-sis occurred in two steps:a binding step within the first 10 min of treatment and a lytic step after 30 min.Both binding and lysis were highly temperature-dependent.Effects of erythrocyte density on hemolysis suggest that the hemolysin might target erythrocytes via a multiple-hit mechanism.In the osmotic protection experiment,all tested osmotic protectants,with molecular diameters ranging from 0.9 ?5.66 nm,failed to effectively inhibit hemolysis.Scanning electron micrographs showed that the hemolysin caused protuberances or echinocytes in rabbit erythrocytes,and then disrupted and ruptured the erythrocytes.Characteristics of hemolysis showed distinct differences from other pore-forming mechanisms,suggesting that this hemolysin might act through a detergent-like or lipase mecha-nism,rather than a pore-forming mechanism.  相似文献   

近30年中国天气预报业务进展   总被引：8，自引：0，他引：8  

李泽椿  毕宝贵  朱彤  王友恒  牛若芸 《气象》2004,30(12):4-10

介绍了我国天气预报技术的发展现状，指出在大气探测技术、数值预报及可视化技术发展的推动下我国传统的天气预报向定量、定时方向发展，并系统阐述了天气预报业务发展过程和存在的问题，最后提出了对我国天气预报业务发展的思路。  相似文献   

The surge-like eruption of a miniature filament     

Jia-Yan Yang  Yun-Chun Jiang  Dan Yang  Yi Bi  Bo Yang  Rui-Sheng Zheng  Jun-Chao Hong 《天体物理学报》2012,(3):300-312

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类星体3C273的多波段光变周期分析     

毕雄伟  和万全  田家金  张青友  蔡群 《天文研究与技术》2012,(4):339-347

从文献中收集了类星体3C273射电、毫米、红外、光学、紫外和高能波段1963年至2006年的观测数据,获得各波段的长期光变曲线。用Jurkevich方法和离散相关函数(Discrete Correlation Function,DCF)方法分别研究了多波段的光变周期。研究结果表明:(1)3C273在所研究波段内的辐射流量都表现出周期性变化的特征;(2)用Jurkevich方法和离散相关函数方法分析得到的多波段变化周期的结果非常一致;(3)3C273在射电和毫米波段可能存在8.0年左右的固有周期成分,在红外、光学和紫外波段可能存在2.0年和11.0年左右的固有周期成分,在高能波段可能存在1.0年左右的固有周期成分。简要探讨了引起3C273各波段周期光变的可能原因,研究结果表明用激波加速模型(shock-in-jet)能较好地解释引起3C273多波段光变的原因。  相似文献   

皖西白大山群的发现及其地质意义   总被引：7，自引：0，他引：7  

毕治国  李玉发  汤加富  侯明金 《安徽地质》1994,(Z1)

皖、豫交界的白大山－茶庵一带，出露一套碎屑岩夹碳酸盐岩地层，以往被置于青白口系八公山群。近期笔者等赴该地再次进行了调查和研究，结果发现该群地层组合内含有大量球藻类和植物碎片化石，这些微古植物分子在国内外多见于下古生代。并从岩石组合特征对比分析，认为该套地层属志留－泥盆系的可能性最大。对这套地层及微古植物的发现，具有两方面重要的地质意义：１．过去对华北地台南缘从未见有这个时代地层的报导，这就为该区地层填补了一个空白；２．从已采获的微古植物组合及岩性组合特征等分析，这有可能对华北地台南缘的岩相古地理图及地史发展等问题，进行一些必要的改写与补充。  相似文献   

Application de la méthode des simulations croisées à l’analyse de tendances dans la relation pluie-débit à partir du modèle GR2M : cas du bassin versant du N’zi-Bandama (Côte d’Ivoire)     

Amani Michel Kouassi  Tozan Michel N’guessan Bi  Koffi Fernand Kouamé  Kassi Alexis Kouamé  Jean-Claude Okaingni  Jean Biemi 《Comptes Rendus Geoscience》2012,344(5):288-296

The study area is the N’zi watershed, sub-watershed of the Bandama River (Ivory Coast). The N’zi watershed is located between longitudes 3°49′ and 5°22′ West and latitudes 6°00′ and 9°26′ North and covers an area of 35,500 km². This study aims to identify trends in the rainfall-runoff relationship by using a monthly conceptual model. The methodology has consisted on the one hand in highlighting the existence of interannual climate and hydrological variability by using the method of segmentation of Hubert, and on the other hand, in applying the crossed simulations method by using the GR2M model, over several 7-year sub-periods. The results of the application of the method of segmentation of Hubert have demonstrated the presence of a hydroclimatic variability in the N’zi watershed. The modifications of the climate and physical conditions of the flow resulted in a modification of the hydrological response of the watershed translated by a non-stationarity in the rainfall-runoff relation.  相似文献   

Statistical analysis of groundwater chemistry of the Tarim River lower reaches,Northwest China   总被引：2，自引：2，他引：0  

Jianhua Xu  Yaning Chen  Weihong Li  Lijun Zhang  Yulian Hong  Xueli Bi  Yang Yang 《Environmental Earth Sciences》2012,65(6):1807-1820

This study applied a comprehensive quantitative approach including statistical, principal component and gray relation analyses to assess the groundwater chemistry based on monitored data from 840 samples collected from the lower reaches of Tarim River from 2000 to 2009. The main findings were: (1) there were six types of groundwater chemistry in the lower reaches of Tarim River where Cl·SO₄–Na·Mg was the dominant type accounting for 73.57% in all samples. There were linear relationships among chemical parameters, where TDS had significant multiple correlations with Na⁺, K⁺, Mg²⁺, Ca²⁺ and Cl⁻, respectively. (2) Three principal components (PC1, PC2 and PC3) were extracted. They included comprehensive measurements for salinization, alkalinity and pH, respectively. Most parameters showed decreasing trends during the period of 2000–2009, as well as the scores on PC1, because the concentrations of various chemical substances were diluted due to the uplift of the groundwater table in the lower reaches and the implementation of the ecological water delivery project in 2000. (3) HCO₃ ⁻ was the most sensitive chemical parameter affected by the groundwater table followed by TA, Mg²⁺, TH, SO₄²⁻, K⁺, TDS and TS. PC2 was the most sensitive principal component to the change of the groundwater table followed by PC1 and PC3.  相似文献