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101.
1978—1994年分省农业旱灾灾情的经验正交函数EOF分析 总被引:10,自引:0,他引:10
本文利用1978~1994年各省、市、自治区的农业旱灾受灾面积及播种面积的资料,以旱灾受灾率(即旱灾受灾面积与播种面积之比)作为刻划旱灾灾情的指标。对标准化的旱灾受灾率进行经验正交函数分析,发现前五个典型场方差贡献达70.7%,可以概括我国旱灾灾情的空间分布主要类型。其中,前三个典型场的正负区域分界线的大体位置分别为长城一线、秦淮线和江南丘陵北缘 相似文献
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对铅芯橡胶双向隔震铁路桥梁在列车荷载作用下的力学性能进行了研究,针对双向隔震铁路桥梁中存在的问题,提出了设置限位器的解决方案,并对设置限位器的双向隔震铁路桥梁进行了车桥耦合动力响应分析.研究结果表明,采用常规隔震设计方法的铅芯橡胶支座在横桥向的初始刚度和屈服强度均不能满足规范要求,设置限位器后,双向隔震铁路桥梁的力学性... 相似文献
105.
开展了包裹碎石群桩复合地基振动台模型试验,分析了包裹碎石桩轴向动应力及桩土之间水平剪切应力的响应特性。结果表明:地震波作用下,包裹碎石桩轴向动应力沿桩身向下迅速衰减。在地震作用过程中,包裹碎石桩上部承受的水平应力较大。某一地震作用下,取包裹碎石桩桩顶水平应力时程曲线的最大值,发现该值随输入地震加速度波峰值(0.1g~0.4g)的增大先增大,之后随输入加速度波峰值(0.6g、0.9g)的增大而减小,这表明桩顶的剪切强度降低了。 相似文献
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Qiang WANG Lijuan ZHAO Xuekun FANG Jianhua XU Yifan LI Yehong SHI Jianxin HU 《Frontiers of Environmental Science & Engineering》2013,7(1):10-18
Chlordane (1,2,4,5,6,7,8,8-octachloro-3a,4,7, 7a-tetra-hydro-4,7-methanoindane) is one of organochlorine pesticides (OCPs) which has been listed as one of the persistent organic pollutants (POPs) to be reduced and finally eliminated in the Stockholm Convention on Persistent Organic Pollutants, because of its great persistence, toxicity, bio-accumulation and long-range transport potential. It is critical to create a national chlordane usage inventories for China to compile chlordane emission inventories, which is helpful for carrying out risk assessments and other researches related to chlordane in China. The annual data of chlordane usage was calculated and modified in accordance with the reported annual production of chlordane which was caculated on the basis of the termite distribution, the data of chlordane usage rate and the annual new construction area (NCA).With the help of Geographic Information System, the usage data of this NCA were allocated to a grid system then, with a 1/4° longitude by 1/6° latitude resolution and a size for each grid cell of approximately 25 km by 25 km. Between 1988 and 2008, the total usage of chlordane in China was 2745 t, accounting for approximately 80% of the production in the same period. Zhejiang Province was the largest consumer of chlordane in China, whose usage adds up to 980 t, greatly exceeding other provinces/regions, followed by Jiangsu Province (534 t) and Sichuan Province (428 t). The region with the least usage of chlordane was Beijing. Provinces of Guizhou, Henan and Hebei did not use any chlordane, even though termites had occurred in these provinces. Gridded usage inventories showed that the intensive use of chlordane was concentrated in the southeast part of China, Yangtze River Delta and Pearl River Delta in particular. The satisfaction of the inventories was supported by the consistence between the estimated data of annual usage and the reported annual production of chlordane, and by the consistence between distribution pattern of chlordane’s usage and ambient air concentration. 相似文献
108.
Xuemei Hu Shijie You Fang Li Yanbiao Liu 《Frontiers of Environmental Science & Engineering》2022,16(4):48
109.
邻苯二甲酸酯(Phthalate esters, PAEs)是环境介质中的一类典型的有机污染物。已有研究表明,PAEs具有明显的内分泌干扰毒性,并会对动物和人体的生殖发育与神经系统造成损伤。体外细胞评价模型因具有高通量、测试周期短、成本低和毒性效应易于探明等技术优点,被广泛应用到PAEs毒理学效应的研究中。本文从内分泌干扰毒性、胚胎发育毒性、神经毒性、免疫毒性、遗传毒性以及致癌作用等方面,对PAEs的一些体外细胞毒性评价模型进行了分类和总结,并对其相应的研究进展进行了综述。本文旨在为体外细胞毒性评价模型的有效利用提供借鉴,并对PAEs毒性作用机制的深入研究提供思路和依据。 相似文献
110.
This study presents the chemical composition of dry deposition by using dry deposition plate and water surfaces sampler during daytime and nighttime sampling periods at a near highway traffic sampling site. In addition, the characterization for mass and water soluble species of total suspended particulate (TSP), PM2.5 and PM10 were also studied at this sampling site during August 22 to October 31 of 2006 around central Taiwan. The samples collected were analyzed by using Ion Chromatography (DIONEX 100) for the ionic species analysis. Results of the particulate dry deposition fluxes are higher in the water surfaces sampler than that of the dry deposition plate. In other words, the results also indicated that water surface can absorb more ambient dry deposition inorganic pollutants than that of dry deposition plate in this study. The results obtained in this study indicated that the ionic species of Cl(-), NO3(-) and SO4(2-) occupied about average 60-70% downward flux out of total ionic species for either dry deposition plate or water surfaces sampler during August to October of 2006 at this near highway traffic sampling site. 相似文献