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61.
采用中国地面气象观测站网2007~2016年的辐射日值数据集和中国空气质量在线监测平台2014~2016年逐日观测数据,分析了京津冀、长三角和珠三角近10a太阳总辐射年际和季节变化,近3a臭氧日最大8h平均(O3_8h_max)和细颗粒物(PM2.5)的污染过程频次变化,通过不同因子及其不同强度等级的分型统计,探讨PM2.5、O3_8h_max与太阳总辐射的关系.结果表明:京津冀近10a太阳总辐射显著上升,京津冀春季和珠三角夏季太阳总辐射显著上升.三大经济区PM2.5污染过程年频次均呈现逐年递减,且从北到南递减;O3污染过程年频次时间上呈现先减后增,空间上京津冀多于长三角和珠三角.三大经济区O3_8h_max与太阳总辐射相关系数均在0.71以上,有较强的正相关;而PM2.5与太阳总辐射的相关性具有区域差异性.三大经济区不同季节不同太阳总辐射下O3_8h_max与PM2.5的相关关系差异显著,其中京津冀春夏秋三季O3_8h_max与PM2.5在强太阳总辐射下有较好的正相关,冬季则存在一定的负相关;长三角四季两者相关性均较弱;珠三角夏季两者正相关最为显著;不同PM2.5浓度下O3_8h_max与太阳总辐射的线性拟合效果较好,体现出较强的正相关关系,各经济区拟合曲线的倾向率均随PM2.5升高而增大.PM2.5>75μg/m3时拟合优度均达到最大.  相似文献   
62.
The purpose of this study was to examine the direct toxicity of PM2.5 collected from Beijing on human umbilical vein endothelial cells(HUVEC). A Cell Counting Kit 8(CCK8) assay demonstrated that PM2.5 exposure decreased the proliferation of HUVECs in a dosedependent manner. We also found that PM2.5 exposure induced autophagy in HUVECs, as evidenced by:(1) an increased number of double-membrane vesicles;(2) enhanced conversion and punctuation of the microtubule-associated protein light chain 3(LC3); and(3) decreased levels of the selective autophagy substrate p62 in a time-dependent manner.Furthermore, promoting autophagy in PM2.5-exposed HUVECs with rapamycin increased the cell survival rate, whereas inhibiting autophagy via 3-methyladenine significantly decreased cell survival. These results demonstrate that PM2.5 exposure can induce cytotoxicity and autophagy in HUVECs and that autophagy play a protective role against PM2.5-induced cytotoxicity. The findings of the present study imply a direct toxic effect of PM2.5 on HUVECs and provide novel insight into the mechanism of cardiovascular diseases caused by PM2.5 exposure.  相似文献   
63.
目的 分析某型飞机外翼5—8肋油箱区结构不同程度损伤的原因,制定修复方案。方法采用受载分析、有限元仿真计算、静力试验数据分析等强度计算方法分析损伤产生的原因,采用扫描电子显微镜和光学显微镜对磨痕形貌进行观测等失效分析,对损伤结构件开展失效模式分析,根据损伤原因及失效模式制定科学简便的修复方案,同时对损伤长桁采取的修补措施进行强度校核。结果 通过对外翼油箱充压破坏理论分析、有限元仿真计算、静力试验数据反推,并结合飞机实际损伤情况,得出油箱破坏理论分析危险薄弱部位与真实破坏情况一致的结论。有限元仿真计算最危险结构部位与实际结构首先发生破坏部位吻合,可作为深入制定修复方案及推测实际加载压力的依据。通过静力试验数据反推、结构实际损伤及有限元仿真计算结论得出,外翼5—8肋结构出现损伤时油箱施加压力约0.5 MPa,针对损伤制定了更换外翼油箱内部第5—8肋损伤结构和贴补加强损伤长桁的修理方案,经结构强度校核,满足设计要求。结论 分析认为外翼5—8肋油箱区结构损伤原因为油箱压力超过设计值导致结构过载断裂,采用贴补加强修理损伤长桁和更换第5—8肋损伤结构的修复方案能够满足强度设计要求,可指导同类飞机类似结构损伤故障的原因分析和修理,提醒同类飞机维修人员在飞机维护时应关注外翼油箱压力超压问题。  相似文献   
64.
小流域综合治理新设计研究——猪沼果模式   总被引:3,自引:0,他引:3  
近年来,小流域综合治理的主旨思想改变了,其工作重心在于巩固和发展治理开发的成果,提升综合治理的科技含量,增加治理带来的经济效益。于是将小流域的治理与生产联系起来成为了当前科研人员的研究方向。文章对目前部分地区大力推广的"猪-沼-果"模式在小流域治理方面的概念、发展及综合效益等方面做了一些综述。总的来说,猪沼果模式能够增加农村的能源,增加农民收入,并保护绿植,促进小流域治理。  相似文献   
65.
Recently, the New Morris Method has been presented as an effective sensitivity analysis tool for mathematical models. The New Morris Method estimates the sensitivity of an output parameter to a given set of input parameters (first-order effects) and the extent these parameters interact with each other (second-order effects). This method requires the specification of two parameters (runs and resolution) that control the sampling of the output parameter to determine its sensitivity to various inputs. The criteria for these parameters have been set on the analysis of a well-behaved analytical function (see Cropp and Braddock, Reliab. Eng. Syst. Saf. 78:77–83, 2002), which may not be applicable to other physical models that describe complex processes. This paper will investigate the appropriateness of the criteria from (Cropp and Braddock, 2002) and hence the effectiveness of the New Morris Method to determine the sensitivity behaviour of two hydrologic models: the Soil Erosion and Deposition System and Griffith University Representation of Urban Hydrology. In the first case, this paper will separately analyse the sensitivity of an output parameter on a set of input parameters (first- and second-order effects) for each model and discuss the physical meaning of these sensitivities. This will be followed by an investigation into the sampling criteria by exploring the convergence of the sensitivity behaviour for each model as the sampling of the parameter space is increased. By comparing these trends to the convergence behaviour from Cropp and Braddock (2002), we will determine how well the New Morris Method estimates the sensitivity for each model and whether the sampling criteria are appropriate for these models. It will be shown that the New Morris Method can provide additional insight into the functioning of these models, and that, under a different metric, the sensitivity behaviour of these models does converge confirming the sampling criteria set by Cropp and Braddock.  相似文献   
66.
大气环境质量综合评价加权灰色关联模型的建立与应用   总被引:1,自引:2,他引:1  
利用灰色理论建立大气环境质量综合评价加权灰色关联模型 ,运用污染贡献率确定权重系数。与其它评价模型相比 ,加权灰色关联模型还具有排序功能 ,实例表明该模型是简便有效的  相似文献   
67.
安徽省淮河流域水污染分析与环境目标可达性探讨   总被引:3,自引:0,他引:3  
介绍了安徽省淮河流域水污染的历史与现状,分析了淮河流域水污染的特点,对实现《淮河流域水污染防治“十五”计划》的可能性进行了探讨。  相似文献   
68.
本文报道了以7碘8羟基喹啉5磺酸作荧光增强剂的Zn、Al激光时间分辨荧光测定方法。方法检出限分别为25μg/L和10μg/L。用牛肝粉标准品(NBS1577a)进行了验证  相似文献   
69.
The global cycles of man-produced pollutants entering the natural environment are reflected in changes of pollutant cycles, even in background regions.The system of mathematical balance simulation models of inorganic pollutant distribution and circulation (some heavy metals and pesticides included in the priority list for integrated background monitoring) has been developed for the Lake Baikal drainage basin. The system consists of the following units: (1) inventory and classification of regional sources of pollutants entering the atmosphere, natural waters and soils; (2) computation of the global atmospheric transfer and depositions; (3) regional spreading with atmospheric fluxes and deposition onto the underlying surfaces; (4) transport with waterflows feeding Lake Baikal; (5) transport with the lake currents and balance in the lake.The models developed have enabled improvement of existing programmes and systems of observations, in particular to substantiate the large-scale snow sampling and analysis network, and to develop the programme of integrated surveys of the state of Lake Baikal. Since 1981 these actions have been included in the operational network observations within the Lake Baikal Monitoring System.  相似文献   
70.
For detailed reconstructions of atmospheric metal deposition using peat cores from bogs, a comprehensive protocol for working with peat cores is proposed. The first step is to locate and determine suitable sampling sites in accordance with the principal goal of the study, the period of time of interest and the precision required. Using the state of the art procedures and field equipment, peat cores are collected in such a way as to provide high quality records for paleoenvironmental study. Pertinent field observations gathered during the fieldwork are recorded in a field report. Cores are kept frozen at -18 degree C until they can be prepared in the laboratory. Frozen peat cores are precisely cut into 1 cm slices using a stainless steel band saw with stainless steel blades. The outside edges of each slice are removed using a titanium knife to avoid any possible contamination which might have occurred during the sampling and handling stage. Each slice is split, with one-half kept frozen for future studies (archived), and the other half further subdivided for physical, chemical, and mineralogical analyses. Physical parameters such as ash and water contents, the bulk density and the degree of decomposition of the peat are determined using established methods. A subsample is dried overnight at 105 degree C in a drying oven and milled in a centrifugal mill with titanium sieve. Prior to any expensive and time consuming chemical procedures and analyses, the resulting powdered samples, after manual homogenisation, are measured for more than twenty-two major and trace elements using non-destructive X-Ray fluorescence (XRF) methods. This approach provides lots of valuable geochemical data which documents the natural geochemical processes which occur in the peat profiles and their possible effect on the trace metal profiles. The development, evaluation and use of peat cores from bogs as archives of high-resolution records of atmospheric deposition of mineral dust and trace elements have led to the development of many analytical procedures which now permit the measurement of a wide range of elements in peat samples such as lead and lead isotope ratios, mercury, arsenic, antimony, silver, molybdenum, thorium, uranium, rare earth elements. Radiometric methods (the carbon bomb pulse of (14)C, (210)Pb and conventional (14)C dating) are combined to allow reliable age-depth models to be reconstructed for each peat profile.  相似文献   
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