两种三元杂交菲律宾蛤仔(Ruditapes philippinarum)壳色品系间的聚合杂交     

苏家齐  闫喜武  张跃环  杨鹏  张辉  杨凤  张国范 《海洋与湖沼》2013,44(2):513-518

采用完全双列杂交配组方法,以三元杂交菲律宾蛤仔(Ruditapes philippinarum)壳色品系两道红白斑马(TrWz)和红白斑马(OWz)为材料,进行了2种壳色蛤仔品系间的聚合杂交研究。结果表明,浮游期间杂交组幼虫表现出微弱的的生长优势及一定程度的存活劣势;中间育成期间稚贝表现出微弱的生长劣势及明显的存活优势。三元杂交自交组两道红白斑马子代均出现了壳色分离现象,而红白斑马子代均为白斑马,且壳面花纹颜色为红色;正反交组子代均表现为两道红白斑马,其壳色表达具有显著的母本效应;但其壳色表现呈现出非伴性遗传。  相似文献   

Crop area mapping in West Africa using landscape stratification of MODIS time series and comparison with existing global land products   总被引：6，自引：0，他引：6  

Elodie Vintrou  Annie DesbrosseAgnès Bégué  Sibiry TraoréChristian Baron  Danny Lo Seen 《International Journal of Applied Earth Observation and Geoinformation》2012,14(1):83-93

In Africa, food security early warning systems use satellite-derived data concerning crop conditions and agricultural production. Such systems can be improved if they are provided with a more reliable estimation of the cultivated area at national scale. This paper evaluates the potential of using time series from the MODerate resolution Imaging Spectroradiometer MOD13Q1 (16-day composite of normalized difference vegetation index at 250 m resolution) to extract cultivated areas in the fragmented rural landscapes of Mali. To this end, we first stratified Southern Mali into 13 rural landscapes based on the spatio-temporal variability of NDVI and textural indices, using an object-oriented classification scheme.The accuracy of the resulting map (MODIS_crop) and how it compares with existing coarse-resolution global land products (GLC2000 Africa, GLOBCOVER, MODIS V05 and ECOCLIMAP-II), was then assessed against six crop/non-crop maps derived from SPOT 2.5 m resolution images used as references. For crop areal coverage, the MODIS_crop cultivated map was successful in assessing the overall cultivated area at five out of the six validation sites (less than 6% of the absolute difference), while in terms of crop spatial distribution, the producer accuracy was between 33.1% and 80.8%. This accuracy was linearly correlated with the mean patch size index calculated on the SPOT crop maps (r² = 0.8). Using the Pareto boundary as an accuracy assessment method at the study sites, we showed that (i) 20-40% of the classification crop error was due to the spatial resolution of the MODIS sensor (250 m), and that (ii) compared to MODIS V05, which otherwise performed better than the other existing products, MODIS_crop generally minimized omission-commission errors. A spatial validation of the different products was carried out using SPOT image classifications as reference. In the corresponding error matrices, the fraction of correctly classified pixels for our product was 70%, compared to 58% for MODIS V05, while it ranged between 40% and 51% for the GLC2000, the ECOCLIMAP-II and the GLOBCOVER.  相似文献   

有机固体废物快速发酵剂的制备及其效果研究   总被引：1，自引：0，他引：1  

汪玉花  张兰英  刘娜  赵艳玲 《吉林大学学报(地球科学版)》2003,33(2):252-254

从发酵的垃圾、淀粉厂污泥、腐烂桔杆等样品中，分离、纯化、诱变、筛选出分解纤维素、淀粉能力较强的4种菌株，按不同比例混合制备出有机固体废物发酵剂。从4种菌抹中选择出有较强分解能力的一组最佳配比为快速发酵剂，对有机固体废物进行分解性能实验，有机固体废物加入发酵剂后，温度迅速升高，2—3d就可以保持在70℃，提高了对纤维素、本质素及蛋白质的分解率，大大缩短了发酵周期。  相似文献   

Modelling cyclic elastic behaviour of sands     

Atilla M. Ansal  Hacer K. Ansal  Raymond J. Krizek 《Soil Dynamics and Earthquake Engineering》1987,6(2)

The cyclic stress-strain behaviour of cohesionless soils is considered to be composed of elastic and inelastic components, and the cyclic elastic stress-strain relationships for one type of uniform sand are investigated by conducting isotropic and laterally constrained compression tests under low frequency cyclic loads. The effects of relative density, stress history, and stress state on the cyclic elastic behaviour are studied. Simple and practically applicable elastic stress-strain models are developed based on Hertzian contact theory. It was observed in both types of tests that elastic strains can accurately be modelled by a power function of stresses.  相似文献   

草鱼出血病病毒株的筛选   总被引：1，自引：0，他引：1       下载免费PDF全文

罗毅志  杨广智  叶雪平 《海洋与湖沼》1993,24(5):503-506

为筛选适用草鱼出血病细胞疫苗工厂化生产的病毒株，于１９８７－１９８９年，在浙江湖州地区采集了１２个具典型草鱼出血病症状的病鱼材料，通过比较它们的毒力，对细胞的适应性，免疫原性，研究病毒在细胞内的增殖动态，细胞病变特征，毒株保存。结果表明，筛选出的ＺＶ－８８０２和ＺＶ－８９０９两毒株，其毒力高，免疫原性强，并能在细胞中大量增殖。应用这两株毒株制备的细胞疫苗，其免疫保护率在８５％以上。  相似文献   

Past, present, and future of genetic improvement in salmon aquaculture   总被引：4，自引：4，他引：4  

Gjoen  H. M.; Bentsen  H. B. 《ICES Journal of Marine Science》1997,54(6):1009-1014

  相似文献   

沂源县耕地资源现状及保护对策分析     

姚慧敏  ;郑庆云  ;张玉亭  ;隋学艳 《山东地质》2008,(7):116-118

沂源县是典型的山区农业县,目前耕地面积日益减少,人地矛盾日趋尖锐,耕地保护面临着较大的压力。为有效保护耕地资源,在对该县耕地资源质量和耕地后备资源现状进行了分析的基础上,提出加大土地开发整理力度、加强基本农田保护和加快中低产田改造等耕地资源保护与可持续利用对策。  相似文献   

贝类浮筏养殖区内、外浮游植物生态特征研究     

郭皓  闫启仑  沈亮夫 《海洋科学进展》1999,(3)

１９９６ 年 ６ 月 ２９ 日～１０ 月 ２２ 日对大连市金州区大李家湾贝类养殖筏区及近岸海域进行了调查,对养殖区内、外浮游植物的种类组成和数量分布等生态特征进行了分析。研究结果表明：同一时期养殖区内、外浮游植物的生态特性略有差异,浮游植物的优势种及优势度无明显差别,随季节变化其种类组成有显著改变;筏区内浮游植物的数量略少于筏区外,且高峰期的出现较筏区外滞后 １ 个月;浮游植物平均量的平面分布显示离岸越远其数量逐渐上升。  相似文献   

烟台四十里湾养殖水域营养盐的分布及动态变化   总被引：13，自引：0，他引：13  

赵卫红  焦念志  赵增霞 《海洋科学》2000,24(4):31-34

1997年5、8、11月及1998年3月对烟台四十里湾养殖水域营养盐的四个航次季节调查显示该水域营养盐的时空分布主要受陆源输入、养殖和自然生物活动及海流状况的影响。氮磷硅无机营养盐结构分析表明,烟台四十里湾春夏季硅限制了硅藻的生长;秋季氮为硅藻的相对限制因子,冬末春初硅是相对限制因子。  相似文献   

烟台四十里湾养殖水域氮的存在形态研究   总被引：19，自引：2，他引：17  

赵卫红  焦念志  赵增霞 《海洋与湖沼》2000,31(1):53-59

１９９７年５、８、１１及１９９８年３月对烟劝四十里湾养殖水域的溶解无机氮、溶解有机氮及颗粒氮进行了调查,对没形态氮的分布、季节变化及在总氮中所占比例进行了分析。结果表明,春、夏季溶解态氮的分布主要受自然及养殖生物活动控制;秋、冬季主要受陆源输入及物理混合控制。颗粒氮的分布主要要受生物活动及陆源输入共同控制。全年总氮主要以溶解态氮为主,其中有机氮为主要存在形式,溶解无机氮主要以氨氮为主。溶解态氮的含  相似文献