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991.
为研究大气细颗粒物污染对哮喘门诊就诊的短期影响及各人群的易感性差异,收集杭州市某医院2013年1月1日至2015年12月31日哮喘门诊(含急诊)资料,以及同期空气污染数据和气象数据,考虑到污染物浓度与呼吸系统疾病就诊人次及气象因素之间的非线性关系,采用时间序列广义相加模型及分层分析的方法研究空气污染对哮喘影响的滞后效应及人群按性别、年龄分层的易感性差异,对平均温度、平均相对湿度及长期趋势等采用自然立方样条函数进行平滑拟合,同时用哑元变量控制星期几效应和节假日效应的影响.在P=0.01水平下PM_(2.5)、NO_2、SO_2之间均呈显著的正相关性,而气温与3种污染物之间呈显著的负相关性.PM_(2.5)日均浓度每升高10μg·m~(-3),对哮喘就诊人次影响的相对危险度(relative risk,RR)在滞后5d达到最大值,为1.005 6(95%CI:1.002 1~1.009 1),且具有统计学意义(P0.05).在男性人群和18~64岁人群中,细颗粒物浓度对于哮喘就诊人次的影响在滞后3~5 d的RR值均具有统计学意义,在女性人群和≥65岁人群中,在滞后5 d时RR值均具有统计学意义.在多污染物模型中,引入NO_2的影响后PM_(2.5)对哮喘就诊人次的影响在滞后5 d时的RR有所提升.杭州市PM_(2.5)浓度的升高可能会造成3~5 d内哮喘门诊就诊人次的增加,且对男性人群和老年人群影响更为明显. 相似文献
992.
空气质量指数(AQI)的社会经济影响因素分析——基于指数衰减效应视角 总被引:6,自引:3,他引:3
中国面临着严重的环境恶化问题,其中空气污染问题尤为突出.基于中国2014年全国城市空气质量数据,利用自然正交函数分析城市空气质量指数的时空演变特征,并采用基于衰减效应的矩阵指数空间设定模型探讨了空气污染的影响因素.研究结果表明:(1)AQI以京津冀为高值中心向周边地区呈衰减变化,污染核心区由京津冀逐渐向豫北地区和鲁西北地区扩散,年内AQI在1—9月呈现下降趋势,然后逐渐上升;(2)150个城市的空气质量指数呈现出明显的空间集聚;(3)矩阵指数空间设定模型优于空间滞后模型,并且城市间空气污染呈现出显著的空间衰减效应;(4)人均地区生产总值的提高、SO_2排放量和PM_(2.5)浓度增加是导致空气污染加剧的重要原因,而外商直接投资和环保意识的提高有助于改善中国的空气质量. 相似文献
993.
乳腺癌是女性中常见的癌症,EDCs(environmental endocrine disrupting chemicals,环境内分泌干扰物)具有雌激素活性,能促进乳腺细胞的增殖,明确EDCs在乳腺癌细胞增殖中的作用和机制,有助于乳腺癌的预防.在归纳整理国内外相关研究基础上,总结了EDCs通过激活雌激素受体信号通路、抑制细胞凋亡和改变细胞周期等方面促进乳腺细胞的增殖,并对其分子机制进行了全面综述.EDCs促进乳腺细胞增殖的分子机制有:①EDCs通过与雌激素核受体(nERs)结合形成二聚体,改变受体构象,并结合到靶基因雌激素响应元件(ERE)上,进而调控增殖相关靶基因转录和蛋白表达;②EDCs也可通过与雌激素膜受体(mERs)结合,激活快速非基因组信号通路,改变靶蛋白活性或靶基因表达;③EDCs也可通过上调凋亡抑制蛋白Bcl-2和Bcl-xL的表达,抑制细胞凋亡;④EDCs还可通过上调细胞周期蛋白(cyclin)表达、提高周期依赖性蛋白激酶(CDKs)活性,加快细胞周期;⑤EDCs通过基因组、非基因组信号途径的交互,上调cyclin D和c-Myc表达,再通过CDK磷酸化细胞周期调节因子Rb蛋白,释放转录因子E2Fs,加速细胞从G1期向S期的转变,促进细胞增殖.建议今后从与内源激素交互、影响雌激素E2合成以及低剂量联合作用3个方面来探讨EDCs对乳腺细胞的增殖机制,以期为乳腺致癌物的筛查、乳腺癌预防和治疗以及乳腺细胞增殖机制的深入研究提供参考. 相似文献
994.
995.
正Bisphenol A(BPA,2,2-bis(4-hydroxyphenyl)propane;CAS#80-05-7)is a highly produced industrial chemical,with an estimated four billion kilograms produced worldwide each year(reviewed in Vandenberg et al.,2010).BPA serves as a monomer in the manufacture of polycarbonate,a hard,clear plastic.Polycarbonate plastics are used in many consumer products,such as reusable water bottles.BPA is also widely used to make epoxy resins,which are used as coating on the inside of some 相似文献
996.
997.
William O. Rasmussen 《Environmental management》1994,18(1):129-137
The percentage of the cross-sectional area of two objects (e.g., vehicles, hikers, or animals) that can be seen from each
of their locations in a forested area is generally not the same. There is a directionality to the visibility between them.
This is due to the relative positions and sizes of the vegetation and other view-blocking features between the objects. An
analytical technique has been developed to help understand bidirectional visibility. Its use entails the construction of a
visibility diagram containing the basic visibility information between observers in a given setting.
An example is presented showing the use of the visibility diagram to determine visibility between two moving observers in
a forested environment. The diagram is also used to determine the differences in the percentage each observer has of the other's
visible cross-sectional area (bidirectional visibility). A discussion of the application of the technique in the planning
or development of new facilities, as well as in forest and wildlife management, is provided. 相似文献
998.
Administrative machinery has been set up to regulate and control most of the emissions that are known to have severe local
consequences, such as the discharge of raw sewage into rivers and lakes and the smokestack emission of air pollutants. Now,
the nature of environmental degradation is usually different. We are faced with pollutants and effects with more subtle cause-effect
relationships, often characterized by larger geographic areas of interest and longer term potential damage; the potential
risk is now more chronic than acute. Acid rain and climate change are good examples, in that they are associated with a variety
of pollutants from a number of sources and damage to ecosystems occurs over many years. It is argued that monitoring programs
should evolve to reflect the changing nature of the environmental problems they are addressing. It is now necessary to consider
interactions among many pollutants, mixing among the various media, and potentially affecting many components of the ecosystem
in both indirect and direct ways. Here, integrated monitoring and analysis is presented as a unifying strategy to bring together
different measurement methodologies in different disciplines, addressing environmental questions of complexity beyond the
scope of many existing activites that have a classical narrower focus. The underlying concept is of nested networks, each
tier being composed of sites selected for specific purposes but arranged to maximize the number of common sites where more
multidisciplinary questions can be addressed. 相似文献
999.
G. Mathias Kondolf 《Environmental management》1994,18(4):501-509
The North Fork of Cottonwood Creek, in the White Mountains, Inyo National Forest, California, is a critically important refuge
for the Paiute cutthroat trout (Oncorhynchus clarki seleniris), a federally listed threatened species. Habitat for these fish appears to be limited by excessive levels of fine sediment
in the channel, and livestock grazing of riparian meadows has been implicated in delivery of sediment to the channel. However,
the relationships between land use and sediment yield have not been conclusively determined, in large part because there are
no historically ungrazed sites to serve as long-term controls. Accordingly, land-use decisions must be made under scientific
uncertainty. To reduce erosion and sedimentation in the stream, the Forest Service spent approximately US$260,000 from 1981
to 1991 to repair watershed damage from livestock grazing, prevent livestock from traversing steep banks, and limit livestock
access to the channel. Throughout this period, livestock grazing has continued on these lands, yielding less than $12,000
in grazing fees. In revising its Allotment Management Plan for the basin, the Forest Service rejected the “no-grazing” alternative
because it was inconsistent with its Land and Resource Management Plan, which specifies there is to be no net reduction of
grazing.
Joint appointment with the University of California White Mountain Research Station, East Line Street, Bishop, California
93518, USA. 相似文献
1000.
Helmut Karl 《Environmental management》1994,18(4):617-621
environmental auditing must be rejected if the aim is to make companies introduce a specific management concept. Rather, it
is preferable to leave the search for effective environmental protection strategies to the competitive system, especially
since the criteria for environment-oriented management in the European Community audit proposal are without substance. Environmental
auditing can, however, assume a complementary function in the framework of an overall environmental policy if it is designed
as an information tool with which companies provide information on the development of environmental problems deriving from
their manufacturing processes and products. However, the model required to establish a framework of quantity and evaluation
criteria is not available. Further, auditing does not cover products. Similarly, there are no proposals defining the evaluation
procedure for ecological resource scarcity. Thus, the attempt of the Commission of the European Communities to create the
elementary prerequisites for consistent and verifiable environmental auditing in the corporate sector has failed. 相似文献