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排序方式: 共有467条查询结果,搜索用时 31 毫秒
101.
Ababouch L 《Marine pollution bulletin》2006,53(10-12):561-568
International trade in fishery commodities reached US 58.2 billion dollars in 2002, a 5% improvement relative to 2000 and a 45% increase over 1992 levels. Within this global trade, developing countries registered a net trade surplus of US 17.4 billion dollars in 2002 and accounted for almost 50% by value and 55% of fish exports by volume. This globalization of fish trade, coupled with technological developments in food production, handling, processing and distribution, and the increasing awareness and demand of consumers for safe and high quality food have put food safety and quality assurance high in public awareness and a priority for many governments. Consequently, many countries have tightened food safety controls, imposing additional costs and requirements on imports. As early as 1980, there was an international drive towards adopting preventative HACCP-based safety and quality systems. More recently, there has been a growing awareness of the importance of an integrated, multidisciplinary approach to food safety and quality throughout the entire food chain. Implementation of this approach requires an enabling policy and regulatory environment at national and international levels with clearly defined rules and standards, establishment of appropriate food control systems and programmes at national and local levels, and provision of appropriate training and capacity building. This paper discusses the international framework for fish safety and quality, with particular emphasis on the United Nation's Food and Agricultural Organization's (FAO) strategy to promote international harmonization and capacity building. 相似文献
102.
依据气温间的空间相关性,将地统计学中的普通克里金法(Ordinary Kriging,OK)引入地面气温资料的质量控制。考虑气温在空间上的连续性,提出一种基于高斯模型改进的普通克里金(Improved Ordinary Kriging,IOK)质量控制方法。为评估该方法的性能,运用IOK法对江苏省67个台站2008年地面日平均气温资料进行质量控制,并与OK法以及反距离加权法(Inverse Distance Weighted,IDW)进行比较。试验结果表明,IOK法的检验效果优于OK法与IDW法,且稳定性与适用性较高,能有效地标记出气温观测数据中的可疑数据。 相似文献
103.
José Luis Sánchez-Hernández Javier Aparicio-Amador José Luis Alonso-Santos 《Geoforum》2010,41(3):469-478
This article draws on the theory of conventions and the concept of worlds of production for an interpretation of the transformations of a regional production system over several decades. Wine production in the Spanish region of Castile and Leon has shifted from a world of local and interpersonal production (prevailing before 1960) to the current preferred orientation towards quality markets, having passed through an intermediate phase (1960-1980) of table and bulk wines industrial production. Recently, indications have appeared of a return to an interpersonal and neo-artisanal production on the part of prestigious winemakers who distribute their wines to selected international clients. This path is the result of a gradual modification of the dominant conventions of the business, which has experienced a spectacular development in Castile and Leon, whose wines are now appreciated in many foreign markets. This evolution of conventions may be interpreted as an innovative process maintained to challenge the trends and demands of the market. But this argument does not explain how conventions change and how these changes spread along the production chain. Therefore, this article discusses the contribution of three factors to this shift across different worlds of wine production: organization of the production chain; regulations regarding the protection of food differentiated according to its geographic origin; and the setting up of a regional innovation system which supports the wine sector. 相似文献
104.
Impacts of the forces and processes of agricultural restructuring are described in this paper through an analysis of farmers’ ‘lived experience’ in the tobacco sector of Ontario, Canada. The paper argues that the political and economic changes in the 1980s fundamentally altered tobacco farming and the broader rural community. The analysis is based upon a survey of farmers and former farmers, and includes examples of individual case histories. The results show the ways in which farmers’ well-being was affected and provides insights into coping mechanisms. 相似文献
105.
通过在35、110、220、500、800kV 5种不同电压等级的变电站开展全球卫星导航定位系统(GNSS)观测实验,从数据完整率、多路径、信噪比、观测值与周跳比4项指标对各测试站点的GNSS观测数据质量进行统计分析,研究不同电压等级下电磁环境对各GNSS系统观测数据质量的影响。结果表明:不同电压等级下电磁环境对各GNSS系统的观测数据质量无负影响,该结论为论证变电站建设GNSS连续运行参考站(CORS站)的可行性提供了一定的参考价值,促进了卫星导航定位技术在电力行业的应用。 相似文献
106.
107.
大比例尺DEM生产过程中的粗差检测与质量控制的研究 总被引:3,自引:0,他引:3
为了保证DEM的精度的可靠性,探讨了从已有矢量地形图和全数字摄影测量两个方面制作DEM的方法,同时就生产过程中对DEM的粗差检测和质量控制做了阐述。 相似文献
108.
一个用于GPS数据操作的实用软件 总被引:4,自引:0,他引:4
介绍了一个简单实用的GPS工具软件,描述了针对不同型号的接收机,可以完成数据的标准RINEX格式转换、数据质量检查和编辑工作,尤其数据质量检查的结果对了解接收机性能和数据环境等具有一定的指导作用。 相似文献
109.
Abhay Kumar Singh G. C. Mondal P. K. Singh S. Singh T. B. Singh B. K. Tewary 《Environmental Geology》2005,48(8):1014-1028
Water samples collected from the six reservoirs of Damodar River basin in pre- and post-monsoon, have been analysed, to study
the major ion chemistry and the weathering and geochemical processes controlling the water composition. Ca, Na and HCO3 dominate the chemical composition of the reservoir water. The seasonal data shows a minimum concentration of most of the
ions in post-monsoon and a maximum concentration in pre-monsoon seasons, reflecting the concentrating effects due to elevated
temperature and increased evaporation during the low water level period of the pre-monsoon season. Water chemistry of the
reservoirs strongly reflects the dominance of continental weathering aided by atmospheric and anthropogenic activities in
the catchment area. Higher concentration of SO4 and TDS in Panchet, Durgapur and Tenughat reservoirs indicate mining and anthropogenic impact on water quality. The high
contribution of (Ca+Mg) to the total cations, high concentration of dissolved silica, relatively high (Na+K)/TZ+ ratio (0.3) and low equivalent ratio of (Ca+Mg)/(Na+K) suggests combined influence of carbonate and silicate weathering.
Kaolinite is the possible mineral that is in equilibrium with the water, implying that the chemistry of reservoir water favours
kaolinite formation. The calculated values of SAR, RSC and sodium percentage indicate the ‘excellent to good quality’ of water
for irrigation uses. 相似文献
110.