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排序方式: 共有1037条查询结果,搜索用时 15 毫秒
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本文探讨了环境地球化学与人体健康的关系,试图以医学与环境地球化学相结合和元素地球化学分布与生态学特征相结合的方式进一步阐述这一问题,揭示其内在联系和规律。最后从营养角度讨论了强身健体、延年益寿的方法。 相似文献
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Field investigations were conducted to measure subsoil trace element content and factors influencing content in an intensive periurban
market garden in Chenggong County, Yunnan Province, South-West China. The area was divided into three di erent geomorphological
units: specifically, mountain (M), transition (T) and lacustrine (L). Mean trace element content in subsoil were determined for Pb (58.2
mg/kg), Cd (0.89 mg/kg), Cu (129.2 mg/kg), and Zn (97.0 mg/kg). Strong significant relationships between trace element content in
topsoil and subsoil were observed. Both Pb and Zn were accumulated in topsoil (RTS (ratio of mean trace element in topsoil to subsoil)
of Pb and Zn >1.0) and Cd and Cu in subsoil (RTS of Cd and Cu 61.0). Subsoil trace element content was related to relief, stoniness,
soil color, clay content, and cation exchange capacity. Except for 7.5 YR (yellow-red) color, trace element content increased with color
intensity from brown to reddish brown. Significant positive relationships were observed between Fe content and that of Pb and Cu.
Trace element content in mountain unit subsoil was higher than in transition and lacustrine units (M > T > L), except for Cu (T > M >
L). Mean trace element content in calcareous subsoil was higher than in sandstone and shale. Mean trace element content in clay texture
subsoil was higher than in sandy and sandy loam subsoil, and higher Cu and Zn content in subsoil with few mottles. It is possible to
model Pb, Cd, Cu, and Zn distribution in subsoil physico-chemical characteristics to help improve agricultural practice. 相似文献
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Lucie Flache Sezin Czarnecki Rolf-Alexander Dring Uwe Kierdorf Jorge A. Encarnao 《环境科学学报(英文版)》2015,27(5):184-193
Metal-contaminated soils and sediments are widespread in urbanized areas due to atmospheric deposition close to emission sources. These metals are bio-available for organisms, e.g., insects, and accumulate in food chains of insectivorous mammals. Especially bats, which live in urban regions and ingest large amounts of food relative to their body mass, are at risk of being poisoned due to the accumulation of trace metals. To determine species-specific trace metal contents in bats from urban environments, hair samples were analyzed by ICP-OES. Observed trace metal concentrations were related to species-specific foraging habitat, prey spectrum and degree of synanthropy. The species studied were Pipistrellus pipistrellus, Myotis daubentonii and Nyctalus noctula. P. pipistrellus showed the highest concentrations of lead and zinc and slightly higher concentrations of cadmium than the other two species, which was related to its high degree of synanthropy with foraging habitat mostly located in cities. In contrast, N. noctula displayed the highest contents of manganese and copper. The reason might be found in its prey spectrum, as N. noctula feeds mainly on beetles that are caught in cultured areas. Trace metal concentrations determined in hair samples of M. daubentonii ranged between the values of P. pipistrellus and N. noctula, probably reflecting an intermediate level of synanthropy. Positive correlations were observed between the concentrations of cadmium and lead and those of manganese and copper. Hair samples from bats are suitable monitoring tools to study trace metal exposure and can be used to determine differences in trace metal levels between species. 相似文献
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Chengrun Wang Kegui Zhang Mei He Chuanjun Jiang Liumin Tian Yuan Tian Xiaorong Wang 《环境科学学报(英文版)》2012,24(2):214-220
Effects of mineral nutrient imbalance, DNA lesion and DNA-protein crosslink on growth of Vicia faba L. seedlings hydroponically cultivated in concentrations of extraneous lanthanum (La) for 20 days were investigated in the present experiment. The results showed that contents of La, Cu or K elements in roots generally changed synchronously with those in leaves, while Ca, Fe, Zn, Mg, Mn or P in the roots altered inversely to those in the leaves. Thus, the extraneous La led to redistribution and imbalance of mineral nutrient elements in the roots and leaves. DNA lesion and DNA-protein crosslink were investigated by single cell gel electrophoresis (SCGE) and sodium dodecyl sulfate/potassium (SDS/K+) precipitation methods, respectively. The results demonstrated that the increasing La induced DNA break and DNA-protein crosslinks (DPCs) in the seedlings. These results suggested that mineral nutrient imbalance, DNA lesion and DNA-protein crosslink were involved in the growth retardation and growth alteration of the seedlings, which may help to understand the mechanisms of rare earth elements (REEs) on plant growth. 相似文献
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安全氛围要素构成与重要性排序 总被引:1,自引:1,他引:0
关键要素构成及关联排序是安全氛围研究的基础性内容.通过文献回顾和事故案例分析,提取出由安全思想与理念、领导重视、危险源识别与风险分析控制、管理方式、员工参与、安全机构及方法、安全培训、标准化和其他共9维度构成的安全氛围架构,建立了72个指标要素和要素层级模型.运用层次分析法计算出各要素的权重,实现了要素的重要性排序,指标要素总的排序结果基本反映出企业现状.研究表明, 企业领导层应保持重视安全的持续性和一致性,工作中宜改变以管理和处罚等负面刺激为主的传统模式,设法激励员工主动参与.在具体实践中,宜重点加强关于个体行为改善、安全教育培训、管理科学、交流与沟通等方面工作. 相似文献
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