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901.
902.
梭鱼人工养殖群体与自然群体的随机扩增多态DNA(RAPD)分析 总被引:54,自引:2,他引:52
利用随机扩增多态DNA(RAPD)技术,对黄河口海域棱鱼人工养殖群体与自然群体的遗传多样性进行了分析比较,以期由分子水平了解梭鱼的种群遗传多样性背景及人为干涉因素对梭鱼种群遗传多样性造成的影响.选用OPC组20个10碱基对(bp)的随机引物,对采自河北省黄骅市的24尾野生梭鱼和15尾人工养殖梭鱼进行了分析.选出11个扩增效果稳定的引物用于群体分析,扩增结果具有较好的可重复性.11个引物共检出112个位点,其中养殖群体中有94个表现多态,多态比例为83.93%;自然群体在96个位点上表现多态,多态比例为85.71%.经计算,养殖群体的遗传多样性指数为0.2124,自然群体的遗传多样性指数为0.2271;梭鱼两群体间的相似系数为92.82%,遗传距离为0.0718.研究结果表明,目前黄河口海域梭鱼群体的遗传多样性比较丰富,人工养殖过程对其未造成明显的影响,估计这与人工养殖过程中人为干涉因素少(如育苗历史短、亲鱼来源于自然群体、无定向选择和近亲繁殖等)有关.这一结果表明,梭鱼的人工养殖业在黄河口海域有很好的发展前景. 相似文献
903.
中国对虾黄、渤海沿岸地理群的RAPD分析 总被引:43,自引:1,他引:42
采用随机扩增多态DNA(random amplified polymorphic DNA,简称RAPD)技术,对中国对虾的黄、渤海地理群的32个个体遗传多样性进行了检测,使用OPI系列的20个10bp的寡核苷酸随机引物,对每个个体的基因组DNA进行扩增,结果为:17个引物获得了谱带清晰且重复性好的产物,扩增片段的分子量在2000~2000bp之间,共检测106个位点,其中多态位点数为39个,占36.8%;平均遗传距离为0.0941+0.0206,有67个标记(占63.2%)在整个群体的32个个体间表观稳定的一致性. 相似文献
904.
Climate change and human activities are driving forces of sandy desertification and the relative role of them in sandy desertification
is the hot point in related researches. A study was carried to assess the relative role of climate change and human activities
in sandy desertification of Ordos region in China. Potential NPP and the difference between potential and actual NPP were selected as indicators to assess the relative role of climate change and human activities in sandy desertification,
respectively. Assessing methods were built based on some scenarios for the reversion and expansion of sandy desertification
and the relative role of climate change and human activities in sandy desertification of Ordos region were assessed from 1981
to 2000. The results showed that although some local places experienced an expansion of sandy desertification, the change
of sandy desertification of Ordos region from 1981 to 2000 showed a stably reversing trend. The relative role of climate change
and human activities in sandy desertification of Ordos region varied at different temporal and spatial scales in the reversion
and expansion processes. In the reversion of sandy desertification, climate change was the dominant factor in the period of
1981 to 1990 and the reversed areas mainly induced by climate change including Mu Us sandy land and the transition zone between
temperate steppe and temperate deciduous scrubs in north east of Ordos region; however, human activities controlled the reversed
process during the period from 1991 to 2000 and the areas mainly induced by human activities distributed in all banners of
Ordos region. In the expansion of sandy desertification, human activities were the dominant factor in the period of 1981 to
1990 and the expanded areas mainly included the regions around common boundary of Hanggin, Dalad Banners and Dongsheng City;
however, climate change dominated the expansion of sandy desertification from 1991 to 2000, the expanded areas equably distributed
in the whole of Ordos region except the south east of Otog Qian, Uxin and Jungar Banners.
Supported by Chinese National Academic Institutional Commonweal Research Programs (Grant No. 2005DIA3J006) 相似文献
905.
探讨了六盘水市煤岩资源开发过程中产生的废弃物,煤矸石、矿区废水、废气对其环境的危害性,指出其环境治理的紧迫性,应加强综合治理。 相似文献
906.
907.
主震和余震--从大森公式到ETAS模型 总被引:5,自引:0,他引:5
介绍了从描述余震发生频次的大森公式到ETAS模型的发展过程;给出了ETAS模型的主要理论,主要内容包括条件强度函数、参数估计和模型选择;讨论了ETAS模型在地震活动性研究中的应用情况,尤其是在前兆平静和前震研究中的应用,并对该模型的优缺点进行了评价。 相似文献
908.
This paper discussed the random distribution of the loading and unloading response ratio(LURR) of different definitions(Y_1~Y_5)using the assumptions that the earthquakes occurfollowing the Poisson process and their magnitudes obey the Gutenberg-Richter law.Theresults show that Y_1~Y_5 are quite stable or concentrated when the expected number of eventsin the calculation time window is relatively large(>40);but when this occurrence ratebecomes very small,Y_2~Y_5 become quite variable or unstable.That is to say,a high value ofthe LURR can be produced not only from seismicity before a large earthquake,but also from arandom sequence of earthquakes that obeys a Poisson process when the expected number ofevents in the window is too small.To check the influence of randomness in the catalogue tothe LURR,the random distribution of the LURR under Poisson models has been calculated bysimulation.90%,95% and 99% confidence ranges of Y_1 and Y_3 are given in this paper,which is helpful to quantify the random influe 相似文献
909.
910.