2005—2018年北京市外来人口迁移特征与影响因素分析     

赵迪  陈鹏  李海成  苗红斌 《地球信息科学学报》2022,24(4):698-710

外来人口是大型或超大型城市人口结构的重要组成部分,研究特定城市外来人口的迁移特征及其影响因素不仅有助于从迁入地视角发现以特定城市为目标的人口迁移规律,对新城镇化背景下的城市化建设与发展也具有重要的现实意义。本文以北京市为例,通过收集2005—2018年的公安机关外来人口登记数据,对外来人口在不同年份的市级迁出地空间分布格局进行了研究,并利用空间回归模型对人口迁移的影响因素进行了分析,得到如下发现：① 北京市外来人口的迁出地在市级尺度下表现出明显的空间聚集效应,且聚集效应逐年增强;外来人口迁出地空间分布基本稳定,热点迁出地分布主要集中在河北-天津和河南省南部-湖北省北部2个主要聚集簇中;② 影响人口向北京迁移的主要变量为各迁出地的人口规模、交通时间、人均收入、高等教育水平、人口密度等,其中人口规模和人均收入对人口迁移的影响较为稳定,而高等教育水平和人口密度的影响分别从2010年和2014年后才开始显现,交通时间对人口迁移的障碍性作用虽然有所下降,但对人口迁移的影响变化不大;③ 空间误差项持续显著,表明迁出地的人口迁出量可能受相邻地市的社会文化等其他变量的影响。  相似文献   

Monitoring regional sea ice of the Bohai Sea by SSM/I scattering index     

Jin Yaqiu 《海洋学报(英文版)》1998,(1):53-61

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Retrievals of rain-rate over oceans from ssm/ i data using som model     

Bian Jianchun  Chen Hongbin  Sun Haibing  Yang Peicai  Lu Daren  Zhou Xiuji 《大气科学进展》1999,16(3):355-360

1.IntroductionOverthepasttwentyyears,anumberoftheoreticalandexperimentalworkhasbeencarriedoutontheretrievalsofrain--ratefromthespace--bornemicrowaveradiometers.Inrecentyears,manyalgorithmshavebeendevelopedtoretrieverain--ratefromtheSSM/Idata(Barrettetal.,1994;Ebertetal.,1996;Ferraroetal.,1995andsoon).However,becauseofthecomplicatednonlinearrelationshipbetweenbrightnesstemperatures(BTs)andrain--ratewhichiscausedbyvariousphysicalprocesses,theretrievalresultsbystatisticallychasedalgorithmsare…  相似文献   

Adsorption of Au(III) and Au(I) complexes on δ-MnO2     

Yong Ran  Jiamo Fu  R. J. Gilkes  R. W. Rate 《中国科学D辑(英文版)》1999,42(2):172-181

The sorption of AuCl₄ ⁻,AuCl₂ ⁻ and Au(S₂O₃)^3- on δ-MnO₂ was investigated at pH2–11.6, 0.01 mol/L and 0.1 mol/L NaNO₃ solutions. At pH 4 in two electrolyte strength solutions, Au sorption densities on δ-MnO₂ are 0.18–0.21 and 0.28μmoL/m² for AuCl₄ ⁻ and Au(S₂O₃)₂ ^3-, respectively, and the Au surface coverage is approximate to or lower than 1%. This adsorption of the two Au complexes decreases as the solution pH increases, which conforms to the sorption regularity of the anion on δ-MnO₂. The Au sorption decreases in the sequence of Au(S₂O₃)₂ ^3- >AuCl₄ ⁻ >AuC1₂ ⁻. The intrinsic equilibrium constants (logK ^int) of the three Au complexes are 1.17–2.7, much higher than those of Cu and Cd. The hydrolysis products of AuCl₄ ^- are preferentially adsorbed by δ-MnO₂ and the inner-sphere Au-surface complexes are formed on the surface. Project supported by the National Studying-abroad Foundation, the National Natural Science Foundation of China (Grant No. 49573200) and the Australian Mining Industry.  相似文献   

Extending the known distribution of the Younger Dryas Vedde Ash into northwestern Russia     

Stefan Wastegrd  Barbara Wohlfarth  Dmitry A. Subetto  Tatyana V. Sapelko 《第四纪科学杂志》2000,15(6):581-586

The known distribution of wind‐blown Vedde Ash (ca. 10.3 ka BP) has been extended to the Karelian Isthmus in northwestern Russia. This has been possible as the result of a density separation technique that separates the rhyolitic Vedde Ash shards from the minerogenic host sediment. The Vedde Ash occurs in the middle of a pollen zone with high percentages of, for example, Artemisia and Chenopodiaceae, suggesting that the Younger Dryas (or GS‐I in the GRIP ice‐core event stratigraphy) was cold and dry throughout its duration. This is in agreement with sites in south Sweden where the Vedde Ash also occurs in the middle of a pollen zone dominated by Artemisia, Chenopodiaceae and Cyperaceae. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

BVRI photometry of possible standard stars in NGC 188     

L. Kaml 《Astronomische Nachrichten》1998,319(3):183-185

CCD photometry of possible standard stars, in Cousins B, V, R and I, in a field in the region of NGC 188 is presented.  相似文献   

http://dx.doi.org/10.1016/j.gsf.2016.04.002   总被引：1，自引：1，他引：0  

Takanori Sasaki  Toshikazu Ebisuzaki 《地学前缘(英文版)》2017,8(2):215-222

Population synthesis studies into planet formation have suggested that distributions consistent with observations can only be reproduced if the actual Type Ⅰ migration timescale is at least an order of magnitude longer than that deduced from linear theories.Although past studies considered the effect of the Type I migration of protoplanetary embryos,in most cases they used a conventional formula based on static torques in isothermal disks,and employed a reduction factor to account for uncertainty in the mechanism details.However,in addition to static torques,a migrating planet experiences dynamic torques that are proportional to the migration rate.These dynamic torques can impact on planet migration and predicted planetary populations.In this study,we derived a new torque formula for Type Ⅰ migration by taking into account dynamic corrections.This formula was used to perform population synthesis simulations with and without the effect of dynamic torques.In many cases,inward migration was slowed significantly by the dynamic effects.For the static torque case,gas giant formation was effectively suppressed by Type I migration;however,when dynamic effects were considered,a substantial fraction of cores survived and grew into gas giants.  相似文献   

新疆县域农林牧渔业空间差异分析——基于ESDA与GIS方法     

景军  张永福  安放舟 《干旱区地理》2015,38(4):821-832

应用ESDA并结合标准差指数(S)、变异系数(V)等方法,从空间相关的视角分析新疆各县市农林牧渔业人均产值的空间差异。结果显示:以农林牧渔业人均产值来计算的新疆县域间的农林牧渔业人均产值呈现北疆高于东疆、南疆的空间差异。2003-2012年间:新疆县域农林牧渔业人均产值的空间自相关测度Moran's I呈曲线性增减态势,表明农林牧渔业人均产值的空间集聚性呈曲线性波动,但农林牧渔业人均产值的年增长率逐年上升。从局部自相关分析来看,区域间呈现两个极端化较为明显,说明新疆农林牧渔业人均产值在空间分布上具有不均衡性。  相似文献   

上海地区不同重现期的风速估算研究     

史军  徐家良  谈建国  刘坚刚 《地理科学》2015,35(9):1191-1197

基于上海气象站历史风速观测资料,采用极值I型和皮尔逊III型分布估算了上海市不同重现期最大风速的时间变化以及各区（县）不同重现期最大和极大风速的空间分布。结果表明,1901~2011年,上海市10、30、50和100 a重现期的最大风速分别为21.0、24.9、26.7和29.2 m/s。1974~2011年期间,上海各区（县）10 m高度10、30、50和100 a重现期的最大风速都是以南部沿海地区南汇或金山最大,分别为19.0、21.4、22.6和24.1 m/s;各重现期极大风速也是以南汇或金山最大,分别为32.3、36.4、38.4和41.0 m/s。中心城区各重现期的最大和极大风速都最小。  相似文献   

iTRAQ-based proteomic profiling of the marine medaka (Oryzias melastigma) gonad exposed to BDE-47     

C.C. Fong  Y.F. Shi  W.K. Yu  F. Wei  J.P. van de Merwe  Alice K.Y. Chan  R. Ye  Doris W.T. Au  Rudolf S.S. Wu  M.S. Yang 《Marine pollution bulletin》2014

A recent study demonstrated that 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) may have an adverse effect on the reproduction in marine medaka (Oryzias melastigma), but the molecular mechanisms remain largely unknown. In this study, we investigated the protein expression profiles of male and female gonads of O. melastigma exposed to dietary BDE-47 at two dosages (0.65 and 1.30 μg/g/day, respectively) for 21 days. Extracted proteins were labeled with iTRAQ and analyzed on a MALDI TOF/TOF analyzer, as results, 133 and 144 unique proteins were identified in testis and ovary, respective, and they exerted dose- and sex-dependent expression patterns. In testis, among the 42 differentially expressed proteins; down-regulation of histone variants and parvalbumins implicated BDE-47 may disrupt the spermatogenesis and induce sterility in fishes. In ovary, 38 proteins were differentially expressed; the elevation of vitellogenins and apolipoprotein A–I expression indicated BDE-47 acts as an estrogen-mimicking compound and led to reproductive impairment in O. melastigma.  相似文献