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651.
在水质检测工作中,质量控制方法是确保检测数据准确的一种重要手段。当前水质检测实验室中常用的质控手段有盲样考核、平行测定、加标回收、比对试验、期间核查、相关性分析与质量监督六类,通过分析比较这些质控手段在分析检测中的差异及其对检测结果的影响,为提升水质检测工作质量,出具科学、公正的检测报告提供保障。  相似文献   
652.
It is increasingly clear that a wide range of stakeholders should be included in the problem formulation phase of research aimed at solving environmental problems; indeed the inclusion of stakeholders at this stage has been formalized as an integral part of ecological risk assessment. In this paper, we advocate the additional inclusion of stakeholders in the refinement of research methods and protocols and in the execution of the research, rather than just at the final communication and reporting phase. We use a large study of potential radionuclide levels in marine biota around Amchitka Island as a case study. Amchitka Island, in the Aleutian Island Chain of Alaska, was the site of three underground nuclear tests (1965-1971). The overall objective of the biological component of the study was to collect a range of marine biota for radionuclide analysis that could provide data for assessing current food safety and provide a baseline for developing a plan to monitor human and ecosystem health in perpetuity. Stakeholders, including regulators (State of Alaska), resource trustees (US Fish and Wildlife Service, State of Alaska), representatives of the Aleut and Pribilof Island communities, the Department of Energy (DOE), and others, were essential for plan development. While these stakeholders were included in the initial problem formulation and approved science plan, we also included them in the refinement of protocols, selection of bioindicators, selection of a reference site, choice of methods of collection, and in the execution of the study itself. Meetings with stakeholders resulted in adding (or deleting) bioindicator species and tissues, prioritizing target species, refining sampling methods, and recruiting collection personnel. Some species were added because they were important subsistence foods for the Aleuts, and others were added because they were ecological equivalents to replace species deleted because of low population numbers. Two major refinements that changed the research thrust were (1) the inclusion of Aleut hunters and fishers on the biological expedition itself to ensure that subsistence foods and methods were represented, and (2) the addition of a fisheries biologist on a NOAA research trawler to allow sampling of commercial fishes. Although the original research design called for the collection of biota by Aleut subsistence fishermen, and by a commercial fishing boat, the research was modified with continued stakeholder input to actually include Aleuts and a fisheries biologist on the expeditions to ensure their representation. The inclusion of stakeholders during the development of protocols and the research itself improved the overall quality of the investigation, while making it more relevant to the interested and affected parties. Final responsibility for the design and execution of the research and radionuclide analysis rested with the researchers, but the process of stakeholder inclusion made the research more valuable as a source of credible information and for public policy decisions.  相似文献   
653.
Multiple paternity in single litters conceived in the wild was recently demonstrated in meadow voles (Microtuspennsylvanicus). In this study, we used an experimental approach (males tethered and females allowed to mate freely with one or several males) to investigate the role of female meadow voles in multiple paternity. We found that among 29 (of 39) females that copulated during our experiment, 79.3% chose to mate with more than one male. Female behavior in meadow voles thus clearly promotes multiple paternity and their role is an active one. Some of the hypotheses explaining promiscuity in meadow voles should be reconsidered in light of this result. We do not know the primary determinant of female mate choice, but male body mass played a secondary role in driving female preferences. The partial dependence between male body mass and female choice, coupled with the active role played by females, indicates that intersexual selection has the potential for reinforcing the effects of intrasexual selection (male-male dominance relationships) in this species. Finally, we demonstrate that the time period over which tests are conducted is an important part of the design of experiments aimed at understanding the role of females in multiple paternity. Received: 14 April 1998 / Accepted after revision: 12 September 1998  相似文献   
654.
铜铝复合式CPU风冷散热器的实验研究   总被引:1,自引:0,他引:1  
随着计算机的迅猛发展,CPU芯片的集成度、封装密度以及工作频率的不断提高,其发热量也不断增大,从而对CPU散热器的散热性能的要求也提高了.通过分析散热器的散热性能及性能评价方法,对放射状铜铝复合式CPU散热器进行了测试,建立不同风速下功率与CPU表面平衡温度关系曲线和不同风速下功率与热阻关系曲线,为改进散热器提供了实验数据.图3,参5.  相似文献   
655.
Abstract:  Over the last decade, criticisms of null-hypothesis significance testing have grown dramatically, and several alternative practices, such as confidence intervals, information theoretic, and Bayesian methods, have been advocated. Have these calls for change had an impact on the statistical reporting practices in conservation biology? In 2000 and 2001, 92% of sampled articles in Conservation Biology and Biological Conservation reported results of null-hypothesis tests. In 2005 this figure dropped to 78%. There were corresponding increases in the use of confidence intervals, information theoretic, and Bayesian techniques. Of those articles reporting null-hypothesis testing—which still easily constitute the majority—very few report statistical power (8%) and many misinterpret statistical nonsignificance as evidence for no effect (63%). Overall, results of our survey show some improvements in statistical practice, but further efforts are clearly required to move the discipline toward improved practices.  相似文献   
656.
657.
Extra genetic material that is euchromatic is generally regarded to be associated with phenotypic abnormalities. However, recent studies suggest that this is not always the case. Chromosome analysis was performed on amniotic fluid cells from a 37-year-old phenotypi-cally normal patient referred for advanced maternal age. All the cells analysed showed a karyotype of 46, XY, 1p-K The 1p+ chromosome had extra genetic material of uncertain origin in chromosome band region 1p21 →31. Chromosome analysis on the father revealed a normal 46, XY male karyotype. The mother's karyotype showed the same 1p+ chromosome. C and Q banding, as well as silver staining studies, in both the mother and the fetus support the interpretation that the extra chromosomal material was euchromatic in nature. This 1p + chromosome may be characterized as a euchromatic heteromorphism. Euchromatic hetero-morphisms not associated with phenotypic abnormalities have been reported for chromosomes 9 and 16. To the best of our knowledge, this is the first report involving this type of cytogenetic anomaly on chromosome number 1 in a phenotypically normal mother and infant.  相似文献   
658.
加强环境监测第三方检测机构质量管理方法研究   总被引:3,自引:0,他引:3  
第三方检测机构的监测质量直接关系到监测数据的有效性,在使用正常的质控手段外,还可以采用要求强制参与能力验证,对现场监测开展飞行检查,跟踪样品分析的质控过程,对实验室进行现场符合性检查,对质量体系运行考核,跟踪质量管理计划的落实情况等质管手段加强对第三方检测机构的质量控制与管理,规范检测市场,树立质量第一的价值观,使一批技术和管理先进、检测能力雄厚的第三方检测机构成为政府公共检测事业的补充和帮手。  相似文献   
659.
我国海洋环境条件与欧洲海洋环境条件存在明显差异,这对我国海上风电设备提出特殊要求。通过分析影响我国海上风电设备的环境条件,并研究各种环境因素对设备的具体影响,提出各关键设备需要通过的环境试验认证。最后,针对各种环境因素影响,提出需要采取的防护措施,为制定针对我国海上特殊环境条件的风力发电设备环境技术标准提供依据。  相似文献   
660.
以江苏省社会环境检测机构监管工作为基础,介绍了社会环境检测机构业务登记及监管系统的设计思路,并对系统应用后所登记的环境检测机构、人员、业务等情况进行分析,总结监管过程中发现的问题,对系统的二次开发和功能扩展提出了设想及建议,目的在于使该系统功能更加完善和适用,进一步提升社会环境检测机构监管能力水平.  相似文献   
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