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解放后的上海人口迁移 被引量:1
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作者 张开敏 沈安安 张鹤年 《人口与经济》 CSSCI 北大核心 1990年第6期29-32,22,共5页
当代世界人口迁移趋势中最主要的特征是人口由农村永久性地向城市迁移,即城市化。这种迁移对城市和农村两方面的发展都有很大的影响。在当前改革开放的形势下,这种城乡之间的迁移对上海城市发展的规模和趋向,关系尤为重大。因此,本课题... 当代世界人口迁移趋势中最主要的特征是人口由农村永久性地向城市迁移,即城市化。这种迁移对城市和农村两方面的发展都有很大的影响。在当前改革开放的形势下,这种城乡之间的迁移对上海城市发展的规模和趋向,关系尤为重大。因此,本课题着重分析和研究上海市区三十多年来常住人口永久性迁移的变动趋势及其各种构成、迁移的特征和规律,并在此基础上作出预测,探讨在新形势下人口迁移与上海城市建设之关系,为今后妥善管理和合理调节上海人口迁移提供一些参考。 展开更多
关键词 人口迁移 上海市区 迁移人口 解放后 迁移活动 上海城市 常住人口 人口增长 华东地区 总迁移率
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Study on Deliver Analysis Method of Heavy Metal Elements during Cigarette Smoking
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作者 李登科 范国樑 +4 位作者 范学忠 张春涛 李莉霞 马立超 邢立霞 《Agricultural Science & Technology》 CAS 2016年第11期2642-2646,2660,共6页
[Objective] The deliver amount and deliver rate of heavy metal elements during smoking were studied, which could provide a reference for reducing the damage of cigarette products. [Method] Two pretreatment methodsof m... [Objective] The deliver amount and deliver rate of heavy metal elements during smoking were studied, which could provide a reference for reducing the damage of cigarette products. [Method] Two pretreatment methodsof microwave di- gestion and acid extraction were used to process the ash content, the total particu- late matter of mainstream smoke (TPM) and cigarette filter. Detection results of heavy metal elements were compared by the two methods. [Result] The microwave digestion method was better than acid solution extraction method on analysis of TPM, but presented disadvantages on analysis of ash and filter. Meanwhile, the migration amount and rate were studied and resultsshowed that most heavy metal elements were escaped along with sidestream smoke between 66.89% and 95.48%, and almost all Hg escaped through sidestream smoke. Other heavy metal elements, except Hg, were separately found in ash, TPM and filter. Cr, Ni, As and Se were mostly residual in ash, followed by TPM, and filter had the least, while Cd and Pb were just in the reverse order. Normally, 5% or less heavy metal elements were transferred to TPM, only a small part of which could reach 5%-10%. [Conclusion] Most of the heavy metal elements are taken by sidestream smoke, ash and filter, while the migration amounts to mainstream smoke are extremely low. 展开更多
关键词 CIGARETTE Heavy metal Migration rate Total particulate matter (TPM) ASH
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我国人口迁移的流向
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作者 李梦花 《人口研究》 CSSCI 北大核心 1994年第3期48-51,共4页
关键词 省际迁移 人口迁移变动 迁移 全及 城市人口 迁入量 迁移 黑龙江省 人口城市化 总迁移率
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流迁人口研究 被引量:14
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作者 李若建 《人口研究》 CSSCI 北大核心 1994年第4期23-28,共6页
关键词 人口流迁 迁入人口 人口普查资料 人口迁移 1990年 人口流动 总迁移率 中部地带 迁出 三年困难时期
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