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排序方式: 共有1471条查询结果,搜索用时 15 毫秒
1.
本文详细介绍了300份海岛棉种质材料的30个性状记录所建立的综合性状数据库系统的数据来源,软件设计思想,系统功能和特点,数据库管理和统计分析两个子系统间的通讯。该系统的研制对海岛棉种质资源的加工利用和育种工作提供了大量重要信息。  相似文献   
2.
Within this paper we describe an unmanned aerial vehicle (UAV) based method to estimate the spatial feed pellet distribution in salmon fish-cages and exploit it within a case study to determine the radial pellet distribution for different rotor spreaders and blower configurations. Compared to previously used methods, capturing pellets thrown from a rotary feed spreader in rows of Styrofoam boxes, the UAV based method is simpler and faster to setup and allows to cover a larger portion of the sea cage surface area. We compare results obtained with the Styrofoam box method with results we obtained by an automatic analysis of aerial videos taken by the UAV during feeding experiments. The employed method helps to gain insight into the spatial feed pellet distribution in full-scale salmon fish-cages where the feeding pipe and actual fixation of the spreader may influence the dynamic behaviour of the feeding system. This can also be seen as a step towards a continuous measuring of the feed pellet distribution, particularly in view of possible future feeding systems that may allow to adapt the feed pellet distribution to the actual fish distribution.  相似文献   
3.
Salmon louse, or sea lice, (Lepoptherius salmonis) represents practical, economical and fish welfare challenges for salmon farming (Hamre et al., 2013) and for the free-living stocks of salmon. There is an urgent need in the industry for a system that provides reliable numbers of louse on farmed salmon. Underwater hyperspectral imaging represents a potential new technique for louse counting in sea cages. In laboratory studies, the UHI technology could detect and classify pre-adults (pre-adult I and II), adult males and adult females (ovigerous) of sea lice based on the difference in their spectral characteristics. A model was built for detection of lice on the salmon and the UHI had a detection success ranging from 67 to 100 % with an average of 82%. A classification of the detected lice was performed for pre-adults, adult males and ovigerous lice and had a prediction accuracy of 85% when lice were divided into three groups (pre-adults, adult male and ovigerous lice) and 93% when lice were divided in two groups, ovigerous lice and all the other mobile lice (pre-adults and adult male). An automatic procedure for in situ measurements of louse infected salmon could deliver a data basis several times higher than the traditional counting system. The next generation of UHI louse detector should be developed with a higher spatial resolution to be able to detect also the sessile stages of lice. For succeeding with in situ classification of L. salmonis, correction algorithms to compensate for the impact of water between the UHI and lice need also to be developed.  相似文献   
4.
众所周知,21世纪是海洋的世纪,发展海洋经济将成为世界各国的重要战略目标之一。南海作为中国海域面积最大、资源最丰富的外海,也将成为我国打造海洋强国战略目标的核心海域。而因其独特的区位因素和丰富的油气资源,引起了东南亚沿岸各国间的相互争夺,从而形成了"六国七方"的混乱局面。本文从主权争议,岛屿归属,南海资源开发(渔业资源开发,油气开采)等方面出发,研究我国南海资源开发过程中所面临的具体问题,并借鉴美、英、日、韩等国经验,寻求一种综合性解决南海资源开发的办法。  相似文献   
5.
Contemporary genetic diversity is the product of both historical and contemporary forces, such as climatic and geological processes affecting range distribution and continuously moulded by evolutionary forces selection, gene flow and genetic drift. Predatory freshwater fishes, such as Northern Pike Esox lucius, commonly exhibit small population sizes, and several local populations are considered endangered. Pike inhabit diverse habitat types, including lakes, rivers and brackish marine waters, thus spanning from small isolated patches to large open marine systems. However, pike population structure from local to regional scales is relatively poorly described, in spite of its significance to developing conservation measures. We analysed microsatellite variation in a total of 1185 North European pike from 46 samples collected across both local and regional scales, as well as over time, to address two overarching questions: Is pike population structure associated with local and/or regional connectivity patterns, and which factors likely have the main influence on the contemporary distribution of genetic diversity? To answer this, we combined estimators of population diversity and structure to assess evidence of whether populations within (i) habitats, (ii) drainage systems and (iii) geographical regions are closer related than among these ranges, and whether patterns are temporally stable. Contrasting previous predictions that genetic drift obscures signals of postglacial colonisation history, we identified clear regional differences in population genetic signatures, suggesting a major effect of drainage divides on colonisation history and connectivity. However, several populations deviated from the general pattern, showing that local processes may be complex and need to be examined case‐by‐case.  相似文献   
6.
刺参生殖腺发育的生物学零度和有效积温研究   总被引:1,自引:0,他引:1  
[目的]为刺参的繁殖以及工厂化人工育苗提供理论基础。[方法]以渤海湾地区刺参为试验材料,研究渤海湾地区刺参生殖腺发育生物学零度及其性成熟的有效积温。[结果]渤海湾地区刺参生殖腺发育的生物学零度为6.14℃,而有效积温为800.19℃·d。[结论]该研究在渤海湾地区刺参育苗生产中具有重要的参考价值。  相似文献   
7.
A pioneering boat-based survey was conducted in 2019, to gather baseline information regarding the presence, composition, relative abundance, and spatial distribution of deep-diving and off-shore cetaceans in the northern South China Sea (SCS). A total of 27 sightings comprising at least 8 cetacean species were recorded during the 13-day survey, including 5 deep-diving species (i.e. Risso's dolphin [Grampus griseus], short-finned pilot whale [Globicephala macrorhynchus], sperm whale [Physeter macrocephalus], Cuvier's beaked whale [Ziphius cavirostris], and an unidentified beaked whale [either the ginkgo-toothed beaked whale, Mesoplodon ginkgodens, or Deraniyagala's beaked whale, Mesoplodon hotaula]), as well as 3 off-shore dolphins (i.e. pantropical spotted dolphin [Stenella attenuate], striped dolphin [Stenella coeruleoalba], and Fraser's dolphin [Lagenodelphis hosei]). With the exception of pantropical spotted dolphins, all other species were sighted and recorded at sea in the northern SCS for the first time. The pantropical spotted dolphin was the most frequently sighted species, comprising 30% of the total sightings. Deep-diving cetaceans were mainly sighted in the northern Xisha Archipelago, whereas off-shore dolphins were distributed across the survey area. The pantropical spotted dolphin was observed in aggregations of more than 100 individuals and nearly all encountered species included calves; these findings suggested that the survey area functions as an important feeding and calving ground for various cetacean species. This pioneering survey provides fundamental information regarding cetacean fauna in the northern SCS and highlights the need to strengthen research and conservation efforts concerning these species.  相似文献   
8.
为建立高效的海岛棉遗传转化体系,本实验以新疆海岛棉(Gossypium barbadense L.)品种新海13号、新海14号、新海16号茎尖为转化受体,采用农杆菌介导法,研究不同苗龄茎尖、菌液浓度、侵染时间及共培养时间对基因转化的影响,建立了农杆菌介导海岛棉茎尖遗传转化体系。最佳转化体系为:将生长4 d的无菌苗茎尖浸入农杆菌(Agrobacterium tumefaciens)菌液浓度OD600为0.5的菌液中,浸染10 min,共培养48~72 h后,移至卡那霉素浓度为150 mg/L的选择培养基进行筛选,25 d后转移到生根培养基培养,获得抗性苗,经嫁接或者直接移栽,获得29株抗性植株;经过PCR和RT-PCR检测,初步证明抗除草剂5-烯醇丙酮莽草酸-3-磷酸合酶基因(5-enolpyruvylshikimate-3-phosphate synthase,EPSPS)已导入海岛棉基因组中。该转化体系的建立为海岛棉的转基因育种提供了技术支持。  相似文献   
9.
海冰水灌溉对棉田水分及棉花产量的影响   总被引:4,自引:0,他引:4  
采用海冰水(全盐含量为3‰)灌溉与井水灌溉对比,结合3种施肥措施:无机肥(传统施肥)、有机肥与无机肥配施、土壤调理剂与无机肥配施和不施肥处理,研究不同施肥条件下海冰水灌溉对土壤水分、棉花产量及水分利用效率的影响。结果表明:1)棉花整个生育期海冰水灌溉处理1m土层的土壤含水率均高于井水灌溉的处理,尤其在灌溉后0—40cm土层的土壤含水率差异显著,约为12个百分点。2)海冰水灌溉条件下,有机肥与无机肥配施、土壤调理剂与无机肥配施较传统无机肥处理均可显著提高盐碱地棉花籽棉产量,分别增产约10%、27%,井水灌溉处理也有相同的趋势,分别增产约12%、22%。3)无论井水或海冰水灌溉,有机肥与无机肥配施或土壤调理剂与无机肥配施均可显著提高棉花的水分利用效率,海冰水灌溉小区的棉花水分利用效率,两种施肥处理均高于传统无机肥处理,约为8%、30%。两种灌溉水源对棉花产量和水分利用效率均无显著影响。  相似文献   
10.
  • 1. In February 2002, France, Italy and Monaco agreed to establish an international sanctuary for Mediterranean marine mammals. The resulting Pelagos Sanctuary encompasses over 87500 km2 of the north‐western Mediterranean Sea, extending between south‐eastern France, Monaco, north‐western Italy and northern Sardinia, and surrounding Corsica and the Tuscan Archipelago.
  • 2. The Pelagos Sanctuary illustrates how the tenets of Marine Protected Area (MPA) design can be reconciled with the dynamic nature of oceanic systems, because its spatial scale was defined by oceanographic and ecological considerations, specifically the location of the Ligurian permanent frontal system.
  • 3. By expanding protective measures beyond national waters, the Pelagos Sanctuary also sets a precedent for the implementation of pelagic protected areas in the high seas. The Pelagos Sanctuary will contribute to the conservation of the Mediterranean Sea at two scales: (i) locally, by protecting important cetacean foraging and breeding grounds in the Ligurian Sea, and by providing ‘umbrella’ protection to other marine predators in this area; and (ii) regionally, by empowering other conservation measures, such as the Specially Protected Areas Protocol of the Barcelona Convention and the wider goals of the Agreement on the Conservation of Cetaceans of the Black and Mediterranean Seas (ACCOBAMS).
  • 4. However, because few cetacean species are resident within the Sanctuary, their effective long‐term conservation will require large‐scale management and coordinated monitoring throughout the Mediterranean basin.
Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   
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