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81.
《The Professional geographer》2013,65(3):328-336
Apartheid in South Africa operates at several levels, notably in the policies of state partition and urban residential segregation. The Black population of South African cities resides in racially exclusive townships where the various linguistic groupings are further separated as part of the apartheid policy of state partition. The extent to which linguistic segregation has been enforced in the complex Witwatersrand townships is measured in this paper. The policy has been less effective than other forms of urban segregation, suggesting constraints by the inherited township structures and management problems. 相似文献
82.
广东省就业空间的性别化及权力特征 总被引:7,自引:0,他引:7
采用2000年第五次人口普查的数据,以市辖区(县、市)为基本地理单元,对广东省的21个地级市133个样本进行性别与就业空间的实证研究。通过分别对男性和女性6类就业区的比较分析发现,①广东省不同性别的就业整体同构与一定程度的性别隔离并存。整体同构来自互补性的就业角色,两性关系是平等的;性别隔离来自于隔离性的就业角色,两性之间存在着控制与被控制的权力关系。女性就业在与男性总体平等的同时,也存在被边缘化的现象。②在经济全球化和世界制造业转移的大背景下,不同性别的就业空间形成了中心-边缘结构。高度集聚的就业活动分布在环珠江口的珠江三角洲的经济中心区,与珠三角以外的其他就业区在空间上形成了核心-边缘结构。③不同性别的就业空间具有权力特征,具有生产性。中心-边缘结构构建了一种以广州和深圳为极点的就业空间秩序,这种结构制约着区域就业空间新秩序的出现,也体现为区域就业秩序下一种社会经济关系的生成。④在地域文化的深刻影响下,除粤东部分传统地区之外,广东不同性别的就业差异并未构成整体的就业空间性别化。 相似文献
83.
Simone Scarpa 《Urban geography》2016,37(7):963-984
In recent years, residential segregation has become a major issue in the Swedish policy debate. The prevailing view is that residential segregation is a crucial contributing factor to the development of income inequality, since individual income prospects are thought to be influenced by the population characteristics of their neighbourhoods. This study takes the opposite approach and analyses the extent to which, in the period 1991–2010, rising income inequality contributed to the development of residential segregation by income in Swedish metropolitan areas. The period was characterized by unprecedented growth in income inequality, which was associated with a decline in the redistributive power of the welfare state. Residential segregation by income mirrored locally the general trend in income inequality. Another factor was the change in income dispersion in neighbourhoods, relative to the metropolitan areas as a whole, which indicates a tendency towards increased population homogeneity in neighbourhoods with respect to income. 相似文献
84.
Groundwater and sediment samples (∼ 1 m depth) at sites representative of different groundwater pathways were collected to determine the aqueous speciation of sulfur and the fractionation of sulfur isotopes in aqueous and solid phases. In addition, selected sediment samples at 5 depths (from oxic to anoxic layers) were collected to investigate the processes controlling sulfur biogeochemistry in sedimentary layers. Pyrite was the dominant sulfur-bearing phase in the capillary fringe and groundwater zones where anoxic conditions are found. Low concentrations of pyrite (< 5.9 g kg− 1) coupled with high concentrations of dissolved sulfide (4.81 to 134.7 mg L− 1) and low concentrations of dissolved Fe (generally < 1 mg L− 1) and reducible solid-phase Fe indicate that availability of reactive Fe limits pyrite formation. The relative uniformity of down-core isotopic trends for sulfur-bearing mineral phases in the sedimentary layers suggests that sulfate reduction does not result in significant sulfate depletion in the sediment. Sulfate availability in the deeper sediments may be enhanced by convective vertical mixing between upper and lower sedimentary layers due to evaporative concentration. The large isotope fractionation between dissolved sulfate and sedimentary sulfides at Owens Lake provides evidence for initial fractionation from bacterial sulfate reduction and additional fractionation generated by sulfide oxidation followed by disproportionation of intermediate oxidation state sulfur compounds. The high salinity in the Owens Lake brines may be a factor controlling sulfate reduction and disproportionation in hypersaline conditions and results in relatively constant values for isotope fractionation between dissolved sulfate and total reduced sulfur. 相似文献
85.
Sand-rich Holocene to modern clastic deposits in the eastern English Channel and the southern North Sea coasts of France and Belgium occur extensively as nearshore-sand bank, estuarine-tidal flat, aeolian dune and beach sub-environments. Sand samples (n = 665) collected from these deposits suggest the presence of three different populations: a largely dominant (83%) medium to fine quartz sand population (“b”), and finer- (14%) and coarser-grained (4%) populations (respectively “c” and “a”). The distribution of these populations among the four sub-environments reflects tide- and storm-dominated sorting and transport processes and a variable degree of mixing. These populations are derived from a mixture of very fine- to very coarse-grained fluvial, outwash and paraglacial sediments deposited on the beds of the eastern English Channel and southern North Sea during the late Pleistocene lowstand. The nearshore-sand bank environment, which also corresponds to the main offshore source area of the coastal deposits, exhibits population heterogeneity reflecting the variability of hydrodynamic conditions and sediment sorting in this zone. The nearshore topography of tidal ridges, banks and troughs in these tidal seas leads to variable bed and tide- and storm-induced shear stress conditions. These conditions only allow for the mobilisation and onshore transport of some of the finer fractions (populations “b” and “c”), leaving an offshore mixture of these finer populations with coarser, less mobilisable sediments (population “a”). Once in the coastal zone, these two finer populations undergo further hydrodynamic sorting and segregation. Variably sorted very fine sands to silts (population “c”) are trapped in the low-energy estuarine-tidal flat sub-environment, while the highly homogeneous population “b” is further sorted in aeolian dune and beach sub-environments. This sorting occurs via a coastal sand transport pathway linking the Somme estuary mouth to the southern North Sea bight where tidal range and wave energy decrease relative to the English Channel. Since this sand transport pathway enables longshore transport of hydrodynamically sorted medium to fine sand derived directly from the immediate nearshore zone, it has further contributed to a net flux of this sand population from the eastern English Channel sea bed to the southern North Sea. 相似文献
86.
87.
摸清浙江漓渚铁矿的硫化矿物的分布规律,尤其是矿物特征,针对该选矿仅有磁选无脱硫装置这一现状,在原矿采出过程中,实行合理配矿,使终产品铁精矿选的有害元素硫的含量得以控制。 相似文献
88.
硫化物矿物氧化反应动力学实验研究 总被引:3,自引:0,他引:3
硫化物矿床和含硫化物矿床(如中高硫煤)在开发过程中由于氧化作用向环境释放大量的酸、硫酸盐、重金属及其它有害物质,造成一定范围内的次生地球化学异常和环境污染;而中国大陆硫化物的排放量2010年将达到39.1×10 6 t。因此,人们对硫化物矿物在表生环境下的氧化行为日益重视。硫化物矿物的氧化速率受矿物本身物理化学特性(组成、结构、表面性质)和介质条件(溶解氧DO、Fe 3+浓度、pH、Eh、温度及微生物)等多种因素的控制。在全面分析近年来国内外文献的基础上,系统介绍了硫化物矿物氧化动力学实验研究方法、实验参数的选择、反应机理、反应产物及反应速率等的研究现状。指出今后应加强对初始阶段的氧化反应速率、反应中间产物、多因素的综合作用、分子水平上的反应机理解释等方面的研究。 相似文献
89.
Abstract Middle Miocene to Quaternary primitive basalts and high magnesian andesite (HMA) in North Hokkaido resulted from three periods of intense volcanism; early-stage (12–10 Ma), middle-stage (9–7 Ma) and late-stage (3–0 Ma). Based on the chemical compositions of olivines and chromian spinels and bulk chemistry of the primitive rocks, we examined depths of segregation of the calculated primary magmas and the degrees of partial melting of the source mantle. In the context of asthenospheric mantle upwelling, petrological data from the present study can be accounted for by the secular change in the depth of magma segregation from the upwelled asthenospheric mantle, which is composed of fertile peridotite. Thus, the early-stage primary magmas were generated by higher degrees of partial melting of the shallower part of hot asthenospheric mantle, whereas the middle- and late-stage primary magmas resulted from lower degrees of partial melting of a deeper part of the asthenospheric mantle. The early-stage HMA magma was generated by partial melting of the remnant subcontinental lithospheric mantle composed of refractory peridotite. This melting might have resulted from an increased geothermal gradient caused by upwelling of hot asthenosphere. 相似文献
90.
北京社会极化与空间分异研究 总被引:95,自引:6,他引:95
本文论述了北京近年来经济体制改革和社会主义市场经济制度运行对城市社会结构的影响,尤其集中在:1.城市社会极化及其动力机制;2.新城市贫困现象及其原因;3城市社会空间分异及其人变化趋势等。 相似文献