共查询到20条相似文献，搜索用时 15 毫秒
1.
中美两国之间激烈的贸易竞争不仅集中在双边贸易领域,而且延伸为全球市场范围内的博弈。尤其在中国周边地区,厘清两国贸易影响力此消彼长的竞争态势,对维护中国的经济安全与发展具有重要现实意义。基于1996—2017年国家间商品贸易数据,利用时间约束聚类识别中国及周边地区贸易发展的阶段,构建贸易网络对比各阶段中美两国在中国周边地区的贸易发展及影响力变化。研究发现:①1996—2017年间中国及周边地区贸易呈三阶段跳跃式发展,贸易规模不断扩大。②中国在周边地区贸易的总体规模和覆盖程度均超越美国,中国在周边地区贸易收支中普遍存在日益扩大的顺差,而美国在中国周边地区始终保持着稳定大量的贸易逆差。③中国在周边地区的贸易影响力实现了对美国的赶超,中国的出口影响力优势突出,而美国仍旧拥有不俗的进口影响力。④中国与日本的贸易呈阶段式跳跃发展,而美国与日本始终保持着稳定的贸易联系。中国同日本在机电产品上的垂直型产业内贸易发达,但处于产业分工下游的相对不利地位,美国是日本的机电制成品和运输设备等高端产品的最终消费市场。研究结果对于中国维护周边地区经贸合作的稳定与发展和应对美国的冲击有所启示。 相似文献
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This work investigates how potential changes in trade patterns resulting from increased economic integration in the Asia-Pacific region may affect the risk for nonindigenous species spread to the United States. We construct an invasion risk index utilizing the results from a global economic modeling framework in tandem with data for climate similarities between trade partners. The index is based on risk of introduction, determined by changes in trade, and risk of establishment, given by terrestrial and marine climate similarities between countries. The results indicate that Japan may be the riskiest trade partner for the United States in the Asia-Pacific region from a nonindigenous species perspective. This is driven by large expected changes in trade and high environmental similarity between the two countries. This research provides the basis of a risk assessment prediction system to examine the effects of changes in trade on nonindigenous species risk, an important, novel contribution to the trade policy literature. 相似文献
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以1997年中国香港回归为时间节点,从总贸易和高技术产品贸易两个维度,区分短期和长期效应,研究美国加强出口管制对中国香港贸易地理结构的影响。研究发现：出口管制政策在短期抑制了中国香港从美国的进口贸易增长,阻碍了香港对内地的高技术输出贸易;在长期致使中国香港对美国高新技术的依赖程度逐步减弱,对其他未对港设限国家的技术依赖明显增强。中国香港的进出口贸易地理集中度明显增强。美国在中国香港的贸易地理地位呈现大幅下滑。内地在香港的贸易地理地位得到显著提升。 相似文献
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Alan D. MacPherson James E. McConnell Anneliese Vance Vida Vanchan 《The Professional geographer》2006,58(3):266-277
This article examines the extant and potential impact of U.S. antiterrorism policies on Canada‐U.S. cross‐border commerce. Particular attention is focused on the cross‐border trade that takes place between southern Ontario (Canada) and western New York (United States). Evidence from a survey of Canadian and U.S. exporters suggests that U.S. antiterrorism measures have inflated the business costs of exporters on both sides of the border. These measures have also created shipment delays that ultimately imply lost revenues for producers, as well as higher prices for consumers. Security‐related initiatives motivated by a genuine concern for the well‐being of U.S. citizens may nevertheless act as nontariff barriers to bilateral trade. We argue that a potential long‐run consequence of these additional costs is trade diversion. The article concludes with a brief discussion of the implications of the empirical findings for the geography of Canada‐U.S. bilateral trade. 相似文献
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石林地区土壤性质与喀斯特洼地发育 总被引：7，自引：0，他引：7
对石林地区洼地边坡和底部红壤的物理、化学性质差异进行了研究 ,结果表明土壤的化学成分、水分含量和粒度组成都和所处的地貌部位有关。洼地底部的土壤细粘粒含量、水分含量、Al2 O3和Fe2 O3含量低于洼地边坡 ,而粗粉粒含量、SiO2 含量则高于洼地边坡。土壤SiO2 含量随粒径变细而减少 ,Al2 O3和Fe2 O3则随粒径变细而增加 ,土壤中水分含量与细粘粒含量正相关 ,与粗粉粒含量负相关。因此 ,不同地貌部位土壤的粒度组成差异决定了洼地底部和边坡的水分含量及化学组成的差异 相似文献
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Despite its economic and symbolic importance in the arid regions of the Middle East little is still known about the early cultivation of the date palm (Phoenix dactylifera L.). Besides its numerous uses, this fruit tree constitutes the main species and structural element of the date palm gardens that characterize the hot deserts of the Old World. These agrosystems, perfectly adapted to the specific constraints of the environment, concentrate agricultural production in an artificial and intensively cultivated space depending on irrigation. While the first evidence of the cultivation of date palms in southern Mesopotamia dates to the 5th millennium B.C., oasis agriculture seems to have developed mainly during the early Bronze Age (from around 3000 B.C.) when this type of agrosystem can be reconstructed in different parts of the Middle East: Mesopotamia, southeastern Iran and eastern Arabia. The present paper draws together evidence from different kinds of sources (archaeobotany, texts, iconography) bearing on the early history of oasis agriculture. Questions of particular interest are the organization of past date palm gardens and their irrigation. 相似文献
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Bill Pritchard 《Singapore journal of tropical geography》2000,21(3):246-262
Agro-food transnational corporations (TNCs) are pivotal players in the emergent regulatory structures of the East Asian agro-food system, but there has been little explicit concern to account theoretically or empirically for their prevailing socio-spatial practices and strategies. This paper uses the case of Nestlé in South East Asia to make three claims. First, transnational corporate strategy is best understood as comprising an interaction of restructuring processes within the arenas of production, realisation (sales), and reproduction (corporate finance and investment). Second, the analysis of agro-food transnationals in Asia requires elevated attention to the local regulation of food systems. Third, in Nestlé's case at least, the articulation of global strategies with local arenas of production and markets encourages corporate finance to play a key role in the generation of profit. This is evidenced through the extensive use of intra-firm trade and royalty payments (or, related party transactions) by Nestlé in Thailand. 相似文献
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中美两国均为温室气体排放大国,且双边贸易额巨大。由于两国在基础设施、技术、装备水平、能源综合效率和资源禀赋上存在差异,使得通过中美商品贸易,美国将大量的碳排放转移到了中国。本文采用投入产出分析方法,结合经济、能源与贸易3个系统,建立了基于国际商品贸易的碳排放转移模型,并分别测算了1997与2002年中美商品贸易中各相应部门的碳排放转移量。研究表明:(1)1997与2002年,基于中美商品贸易的中国产业部门通过出口转移到美国的载碳量分别达到4010.13×104 与5056.21×104 t C,分别占中国相应产业部门载碳总量的6.61%与8.33%;而美国产业部门出口到中国商品的载碳量仅为290.65×104与335.61×104 t C,相应的仅占美国产业部门载碳总量的 0.53%与 0.66%;(2)1997 与 2002 年,中美商品贸易的碳转移总量分别达 3719.75×104与4719.60×104 t C,其中化学工业、金属冶炼及其压延加工业是主要的碳转移部门。(3)1997与2002年,通过国际商品贸易,美国分别有相当于其相应部门碳排放总量的6.77%与9.32%的碳被泄露到了中国,中国为美国的碳减排做出了很大的潜在贡献,因此,美国等发达国家应该为中国等发展中国家提供切实有效的气候与环境友好型技术援助。 相似文献
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根据分形理论,研究了我国普遍分布的裂隙性粘土粒度成分之分形结构特征,其分维值介于2.600～3.000之间,且灰白色隙壁粘土的分维值≥黄褐色母体土的分维值。在此基础上,讨了分维与土体物质成分、结构特征的关系,以及它所代表的工程地质意义。 相似文献
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从总贸易、出口、进口、外资和人员5个视角构建对美风险系数，测度和比较各省区市对美外贸风险的地理差异。结果表明：上海、浙江和福建与美国的进出口贸易规模最大，对美国市场的依赖程度最高，面临的综合外贸风险最大；河南尤其需要防范对美国的出口风险；海南、新疆、天津和西藏等需要加强从美国进口的风险管理；重庆除了需要防范对美出口风险外，还因为实际利用美资最多且依赖程度最大，亟需加强外资风险管理。宁夏和山西虽然从美国的引资规模不大，但是对美资的依赖程度最高，亟需提升外资多元化水平。从人员跨境流动风险来看，上海、北京和浙江面临的风险最大。中国各省区市在应对美国出口管制时应该加强外贸风险的识别和管理，针对不同的风险采取差别化的防范和化解措施。 相似文献
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对南方丘陵区3种不同母质水稻土时间序列黏粒矿物的X-射线衍射（XRD）进行分析发现：① 紫色砂页岩（PS）母质起源土壤的黏粒矿物以高岭石类似矿物为主;第四纪红黏土（RC）母质起源土壤的黏粒矿物以高岭石类似矿物、伊利石类似矿物与三羟铝石为主;红砂岩（RS）母质起源土壤的黏粒矿物以1.4 nm过渡矿物、高岭石类似矿物与三羟铝石为主。② 这3种母质土壤种稻后黏粒矿物的变化大体可分为2种情况。RC与RS母质的起源土壤种稻后,土壤黏粒矿物的变化相对较小,伊利石类似矿物相对含量有所增加,这可能主要与钾肥的持续施用有关。PS母质的起源土壤种稻后,土壤黏粒矿物变化相对较大,表现为高岭石类似矿物相对含量降低,低结晶度的伊利石或次生绿泥石与三羟铝石相对含量上升。PS母质发育的土壤种稻后脱钾明显且主要集中在原生矿物部分。这种原生矿物的脱钾作用对土壤黏粒含量和黏粒矿物的类型都有较大影响。③ 起源土壤的黏粒矿物通常会被水稻土所继承,并在水稻土发育过程中相对稳定,可以用其来指示起源土壤（或母质）的物源组分。 相似文献
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明中后期澳门的兴起既是历史选择的一次偶然,也是明代特殊海外贸易政策下的必然结果。文章从明代朝贡贸易和市舶司制度的兴衰入手,探讨澳门兴起的动力机制和主要影响因素,特别是在澳门兴起过程中广州所起的作用以及两者的经济互动。同时,基于明代全国视角下的海外贸易与港口分布的总体格局,综合分析澳门、广州以及隆庆以后的月港这3个在明代后期开放的港口,探讨三者在功能、性质、贸易对象等方面的异同点,进一步论证澳门的兴起在很大程度上受益于明代朝贡贸易体制对海外贸易和港口发展的束缚。正是由于广州在明代后期对外通商的垄断性和不完整性,澳门才能以广州外港的性质互补,从而成为当时最大的东西方国际贸易体系之枢纽。 相似文献
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绿色贸易是绿色“一带一路”建设的重要任务。通过选取UN Comtrade 2005—2017年中国与沿线64国APEC环境产品清单中54类环境产品贸易数据,运用产业内贸易指数和边际产业内贸易指数定量研究环境产品贸易竞合关系状况,分析之前格局,基于现有格局,完善未来布局,进而提高域内绿色贸易整体水平。研究发现：“一带一路”绿色贸易总体保持增长趋势,但发展水平、空间分布和进出口之间比较不平衡;进口产品结构相对集中,出口产品结构相对均衡;整体表现为产业间贸易和产业内贸易并存的特征,以合作格局为主,竞争格局为辅;“一带一路”倡议提出以来,绿色贸易增长从主要源于产业间贸易向产业内贸易转变。建议在东南亚地区开展错位合作,主要进行技术研发合作,重点布局新兴绿色产业;在其他地区开展整体合作,主要进行产业规划转移,分层次、分国家、分时段布局传统绿色产业,构建绿色产业生产网络;加快出台“一带一路”环境产品名录,提高绿色产品产业内贸易水平。 相似文献
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Dominic A. Hodgson 《Journal of Paleolimnology》1999,21(3):263-269
Sediments of Lake Fidler, a meromictic lake in south-west Tasmania, contain distinctive laminae. In order to determine their composition and formation, these laminae were studied using a combination of X- ray analysis, scanning electron microscopy, X-ray diffraction and vibrational spectrometry. Results indicated that the laminae were composed of clay originating from the adjacent Gordon River estuary. The clay was also found as part of the general sediment matrix of the core. The evidence indicates that the laminae are formed during incursions of brackish water from the adjacent Gordon River estuary into Lake Fidler which cause the flocculation of clay minerals in the water column. These clay minerals then sink rapidly to the sediments to form laminae. Although the formation of these laminae pre-dates meromixis, their mode of formation corroborates the theory that meromixis is maintained ectogenically by periodic inflows of brackish water replenishing monimolimnetic salts. 相似文献
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Understanding the ways in which children with different life experiences come to terms with day-to-day contexts and constraints has become an important topic of social science research. This study applies the technique of auto-photography to the study of children-environment transactions. How children apprehend their environments is described through a leitmotif analysis and an interpretation of photographs taken by children from middle-class families, homeless children, and children whose mobility is impaired by cerebral palsy. We speculate upon the social and physical contexts of these children based upon the images that they selected to photograph. Although impressionistic, our findings suggest the importance of auto-photography as a method for uncovering children-environment transactions. 相似文献
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沉积物中粘土矿物类型主要有自生粘土矿物和碎屑粘土矿物。其中,自生粘土矿物含量较少,是在沉积环境中形成,可能是沉积再循环或成岩作用的产物,可作为沉积环境某方面的指示标志;而碎屑粘土矿物是母岩风化的产物,受沉积环境影响较小,能够有效示踪物源区化学风化过程,进而反映古气候变化。近年来利用碎屑粘土矿物特征来重建物源区古气候的方法得到了广泛的应用。然而,由于粘土矿物主要存在于<2 μm硅酸盐粘粒中,粘土矿物的提取、鉴定比较困难,且自生粘土矿物易受沉积环境等的影响。因此,在利用粘土矿物重建古气候变化时,需慎重选择粘土矿物的提取方法,并考虑物源和沉积环境变化以及成岩作用等对粘土矿物解释的影响。本文以柴达木盆地东北缘怀头他拉剖面硅酸盐粘土矿物的提取、鉴定及其古环境指示意义为例,介绍粘土矿物的提取及应用,为后期粘土矿物研究提供参考。 相似文献
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关中地区全新世大暖期的土壤与气候变迁 总被引：7，自引：4，他引：3
资料表明,关中地区全新世大暖期土壤中的CaCO3受到了明显淋溶,部分土壤的CaCO3淀积层脱离了粘化层,发育了淋溶性土壤所特有的风化淋滤母质层;该层土壤发生了明显的化学粘化作用,并有Fe2O3和 Al2O3形成以及亚热带土壤所具有的淀积型红色光性粘土胶膜发育;粘土胶膜含量明显大于淋溶褐土而与黄棕壤接近。由此得出,全新世中期成壤作用比现今显著强,土壤应为发育弱的黄棕壤,当时气候比今明显暖湿;在全新世中期,来自东南的夏季降水气团能够较频繁地到达该区,秦岭已失去温带与亚热带气候分界线的作用,其南北两侧均为亚热带气候。 相似文献