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1.
Regional variations in the incidence of premature deaths between 1971 and 1981 arc examined by mapping standardised mortality ratios for deaths under the age of 65. Premature mortality is also examined with regards to the number of years of normal life lost by those who die prematurely, using a specially defined unfulfilled life index. Unfulfilled life and premature deaths arc found to have a higher incidence in the major urban areas and a lower incidence in western counties, although there are some interesting differences in their spatial distributions. Differences with regard to sex. age at death and cause of death are also examined. 相似文献
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Austin白垩层业已钻了4500多口侧向井,本文着眼于Austin这些侧向井估算的最终采收率。通过估算每口井的采收率、钻井密度以及直井生产的影响,计算出桶/英亩的采收率。然后分析了衰竭驱动及加密潜力的资料。应用人工神经网络,对所选地区作进一步研究。网络已经建立,并已用来研究诸如侧向长度,首次开采日期、Austin白垩层构造等参数对采收率值的影响。用所选地区所作的详细分析对研究方法区域和研究结果作 相似文献
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为了降低国家生产的数字地图和纸质地图的价格,在国际上进行地理数据结构的标准化工作很有必要。为此,在1983年成立了数字地理信息工作组,以制定必要的国际地理信息交换标准。目前,该工作组的成员有:比利时,加拿大、丹麦、法国、德国、意大利、荷兰、英国和美国。 相似文献
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近一个世纪以来,萨德伯里地区的自然生态系统受到了不同类型的采矿活动,包括三个Ni-Cu冶炼厂生产活动的影响。在1972年,Coniston冶炼厂关闭前,由于大量SO2的排放,使靠近该厂的土壤严重酸化,并含有高浓度的Ni和Cu。1992年在该地区重复采样并与1972年采样的数据对比发现,冶炼厂周围7km范围内的土壤中Ni,Cu和氢离子的浓度已显著降低。这些土壤中有机物质的低百分数比过去20年也进一步 相似文献
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近地面成像光谱技术在水稻氮诊断方面的应用 总被引:1,自引:0,他引:1
杨锦 《测绘与空间地理信息》2021,44(3):160-163
传统的测量水稻氮含量的形态诊断法和化学分析法,不仅耗费了大量的人力、物力、财力,而且测量的结果也不够精确,并且得不到及时应用,很大程度上影响了水稻的生产和产量.而基于成像光谱技术对水稻进行的氮诊断,可以做到对水稻的无损坏和精确测量,降低了成本,节省了时间,氮的使用效率明显提高,同时产量也大幅度增加,做到了经济利益和生态效益的最大化.本研究是以4种氮素水平的水稻高光谱数据为数据源,经过利用平面场模型进行反射率转换和平滑等一系列的预处理,选出各类别的样本数据,提取出了水稻叶片反射光谱的敏感波段与植被指数等特征,发现最佳识别特征,从而根据识别特征建立决策识别模型,并且不断反复验证和修正模型,总体精度能够达到87.7%. 相似文献
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Krahn MM Hanson MB Baird RW Boyer RH Burrows DG Emmons CK Ford JK Jones LL Noren DP Ross PS Schorr GS Collier TK 《Marine pollution bulletin》2007,54(12):1903-1911
“Southern Resident” killer whales include three “pods” (J, K and L) that reside primarily in Puget Sound/Georgia Basin during the spring, summer and fall. This population was listed as “endangered” in the US and Canada following a 20% decline between 1996 and 2001. The current study, using blubber/epidermis biopsy samples, contributes contemporary information about potential factors (i.e., levels of pollutants or changes in diet) that could adversely affect Southern Residents. Carbon and nitrogen stable isotopes indicated J- and L-pod consumed prey from similar trophic levels in 2004/2006 and also showed no evidence for a large shift in the trophic level of prey consumed by L-pod between 1996 and 2004/2006. ∑PCBs decreased for Southern Residents biopsied in 2004/2006 compared to 1993–1995. Surprisingly, however, a three-year-old male whale (J39) had the highest concentrations of ∑PBDEs, ∑HCHs and HCB. POP ratio differences between J- and L-pod suggested that they occupy different ranges in winter. 相似文献
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Benthic community responses to thin-layer disposal of dredged material were assessed at three sites in Mississippi Sound, USA. Community composition differed between disposal and reference sites (ANOSIM) for each disposal event. Oweniid sand worms, Amphinomid fire worms, and brittle stars (Ophiuriodea) contributed the most to community distinctions between disposal and reference sites (SIMPER), with higher abundances at the disposal sites. Total infaunal abundance was similar to pre-disposal and reference conditions within 3-10 months of thin-layer disposal. Distinctions in community composition between disposal and reference sites (nMDS) persisted throughout the 16-month study period, but were less pronounced at the site where sediment composition was unchanged by disposal. Size distributions of some taxa (e.g., gastropod and hemichordate) suggest adults recolonized the newly deposited sediments either through vertical migration or lateral immigration from adjacent areas. Thin-layer disposal offers a viable alternative to conventional open-water disposal practices and warrants further exploration for other areas with deeper bathymetries and different hydrodynamic regimes. 相似文献
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