东亚地缘政治格局演变对东北亚资源合作的影响研究（英文）     

于会录  董锁成  李泽红  李飞  程昊  李富佳 《资源与生态学报(英文版)》2015,6(2):93-100

以美国实施亚太再平衡战略和中国推进丝绸之路经济带建设为背景,本研究总结了地缘政治、地缘经济、地缘战略的基本概念和相互之间的关系,并回顾了基本的地缘政治理论及其研究进展。继而在概括东亚地缘政治环境变化特点的基础上,论文总结了中蒙之间、中俄之间地缘政治关系发展趋势,认为美国亚太再平衡战略打破了亚太地缘力量平衡格局,中国利益受到来自日本、越南、菲律宾等国的强力挑战。随后,论文以东北亚能源市场为例探讨了地缘环境变化对区域资源市场的影响。其中,对中国而言,建设丝绸之路经济带是应对地缘环境危机的策略;与此同时,俄罗斯在受到西方制裁后将眼光投向亚洲,加之中俄之间具有很强的经济互补性,双方的资源合作水平有望进一步提高;蒙古国经济上对中国依赖很大,美国重返亚洲之后,蒙古国调整了自己的地缘战略,企图借美国力量制衡中俄在蒙古国的影响力,虽然中蒙之间的地缘政治关系总体上是向好发展,但美国的介入增加了中蒙资源合作的不确定性;因日韩为美国盟友,中俄与美国的地缘利益冲突将减少其在东北亚资源市场上的份额;对朝鲜来说,因其经济总量很小,对区域资源市场影响不大。  相似文献   

Lithium isotopic composition of Central American Volcanic Arc lavas: implications for modification of subarc mantle by slab-derived fluids   总被引：7，自引：0，他引：7  

L. H. Chan  W. P. Leeman  C. -F. You 《Chemical Geology》1999,160(4):964-280

Li contents and isotopic compositions were determined for a suite of well-characterized basaltic lavas from the Central American Volcanic Arc (CAVA). Variable Li/Y (0.2–0.5), Li/Sc (0.1–0.4), and δ⁶Li values (+2.6 to −7.7‰) attest to significant compositional heterogeneity in the subarc mantle. Within specific arc segments, these parameters correlate strongly with each other and with a number of other constituents (e.g., K, Rb, Ba, B/La, ¹⁰Be/⁹Be, ⁸⁷Sr/⁸⁶Sr, U/Ce, and ²³⁰Th/²³²Th, among others); these correlations are particularly strong for Nicaragua samples. Coupling of this particular set of constituents is best explained in terms of addition of ‘subduction components' to the subarc mantle. Moreover, their selective enrichment with respect to relatively fluid-immobile incompatible elements signifies the dominance of fluid vs. silicate melt transport of slab components to the subarc mantle. Several interesting nuances are revealed by the Li data. First, although Li and B are strongly correlated in both Costa Rica and Nicaragua, there are systematic along-strike variations in Li/B that are consistent with these elements having different ‘fluid release patterns' from subducted slab segments. For example, Li/B is highest in Costa Rica where auxiliary evidence indicates higher subduction zone temperatures; apparently B is preferentially depleted and Li retained in the slab under warmer conditions. The same relations are reflected in Li/¹⁰Be and other subduction tracer systematics, all of which point to larger subduction contributions below Nicaragua. Yet, even Nicaragua lavas vary widely in levels of subduction enrichment. High-Ti basalts from Nejapa are the least enriched and have the highest δ⁶Li (1.4 to 2.6‰); these values are greater than in fresh MORB (ca. −4‰) and are not easily explained by additions of subducted Li because most oceanic crustal rocks and marine sediments have lower δ⁶Li than MORB (with typical values between −8 and −20‰). Thus, it appears the Nejapa data may be representative of isotopically light mantle domains. Relatively light δ⁶Li values in an undepleted spinel lherzolite (+11.3‰) from Zabargad Is. (Red Sea) and in primitive backarc basalts (−1.6 to −0.5‰) from Lau Basin support this conclusion. Considering representative fluid and mantle endmember compositions, the CAVA data are consistent with limited (up to a few percent) additions of slab-derived fluids to a heterogeneous mantle containing variably depleted and enriched domains to form the respective magma sources. In our view, the subarc mantle is heterogeneous on a small scale, but some arc sectors clearly received greater slab inputs than others.  相似文献   

Automated egg counting and sizing from scanned images: Rapid sample processing and large data volumes for fecundity estimates   总被引：1，自引：0，他引：1  

K.D. Friedland  D. Ama-Abasi  M. Manning  L. Clarke  G. Kligys  R.C. Chambers 《Journal of Sea Research》2005,54(4):307-316

The production of eggs in a fish population is a fundamental parameter in fisheries management and ecology. Management decisions are based largely on the abundance and composition of the spawning stock; hence it is essential to estimate the contribution of viable eggs by females of various ages, which may depend on the size and maturation schedules in females of younger ages, and the size and reproductive senescence of older ones. The level of recruitment may also be influenced by the size and quality of eggs. Egg quality can be characterised in a number of ways; however, the most useful methods are those that are efficient and widely available. Estimating potential fecundity and egg size in fish and invertebrate populations has been hindered by the processing time, toxicity, and resources required by traditional methods. We have developed an imaging-based technique that counts and measures oocytes from a gravimetric gonadal sub-sample in relatively little time and at low cost. Sub-samples were preserved in a non-toxic formulation of Gilson's solution, which offers an alternative to other preservatives commonly used in fecundity studies. The technique uses high-resolution optical scans of plated oocytes, imaging software, and user-defined object classifications to separate oocyte from ancillary material likely to be present in a processed sample. Estimates of misclassification are as low as 1% (false-negatives) in automated counts.  相似文献   

Maturation of Newfoundland American plaice (Hippoglossoides platessoides): long-term trends in maturation reaction norms despite low fishing mortality?     

Barot  S.; Heino  M.; Morgan  M.J.; Dieckmann  U. 《ICES Journal of Marine Science》2005,62(1):56-64

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Spatial assimilation and its discontents: Asian ethnic neighborhood change in California     

Emily Walton 《Urban geography》2017,38(7):993-1018

This study investigates the geographic and compositional dynamics of ethnic neighborhoods over time among the fastest growing racial group in California, Asian Americans. I conduct spatial analysis of Census data from 2000 and 2010 to represent changes in ethnic neighborhood boundaries and their associated structural and demographic characteristics. First, I document changing ethnic neighborhood patterns among four Asian national origin groups—Chinese, Filipino, Korean, and Vietnamese Americans. Second, I synthesize this information, assessing the theoretical implications of these changes by describing indications of spatial assimilation, ethnic stratification, and resurgent ethnicity among ethnic neighborhoods and the potential repercussions for the successful incorporation of both immigrant and native-born Asian Americans. Overall, this paper demonstrates that Asian ethnic neighborhood dynamics are far from monolithic and that different spatial incorporation processes manifest both within and between groups.  相似文献   

美国东海岸海滩养护工程对中国砂质海滩旅游资源开发与保护的启示   总被引：5，自引：2，他引：5  

张振克 《海洋地质前沿》2002,18(3):23-27

借鉴美国长期以来东部海岸的海滩养护工程投入大量资金物力所取得的显著成效，提出了中国砂质海滩资源开发面临的问题，如海岸侵蚀造成砂质海滩资源丧失、砂质海滩旅游资源面临严重的污染、砂质海滩旅游资源的利用程度差异悬殊、砂质海滩旅游资源的人为破坏严重等，预见到中国实施海滩养护工程将是大势所趋，该工程将会被纳入国家或地方海岸综合规划管理与相关法律中。  相似文献   

Perceptions and attitudes of stakeholders towards the wildlife refuge of Ilha dos Lobos,a marine protected area in Brazil     

《Marine Policy》2014

At the north coast of Rio Grande do Sul state, southern Brazilian coast, the Wildlife Refuge of Ilha dos Lobos (29°20′S; 49°43′W), is a full protection area and a seasonal resting refuge for South American sea lions (Otaria flavescens). The regular presence of sea lions on the island is not only a touristic attraction in the region, but also a problem to the fishery community. This community faces economic impacts in its activities due to fish depredation caused by sea lions. Because of this issue, the perceptions and attitudes of different stakeholders from the region are important to be considered by managers, so that a realistic and decentralized action plan can be designed. The goal of this study was to analyze how different local stakeholders perceived the Wildlife Refuge of Ilha dos Lobos. Additionally, how these stakeholders differed from each other in terms of attitudes, knowledge and perceptions. In October 2011, January and March 2012, face-to-face interview surveys were conducted with fishermen and tourists, and drop-off questionnaires surveys with business, and tourism professional and teachers, in a total of 150 questionnaires, 30 for each group. The results indicated existence of differences across the five stakeholder groups. It was also suggested that non-direct stakeholders had a more favorable view of the Wildlife Refuge of Ilha dos Lobos and the sea lion, whereas direct stakeholder (the fishermen) saw it as an obstacle to their fisheries activities.  相似文献   

古老碳酸盐岩层系油气储层地质特征     

刘伟  孟庆阳  张光亚  张磊 《海相油气地质》2010,15(1):15-20

对研究程度较高的北美奥陶系碳酸盐岩油气田特征参数作了统计和分析,对比中国下古生界碳酸盐岩油气田,分析了古老碳酸盐岩油气储层的特点及主要控制因素。北美大陆奥陶纪沉积环境以环潮坪—浅水陆棚为主,储集岩可简单地划分为四种岩相类型,包括泥晶灰岩、粒泥灰岩、泥粒灰岩以及颗粒灰岩。晶间孔、角砾岩相关孔隙及溶蚀孔隙是最主要的孔隙类型,其中尤以晶间孔最为普遍。中国下古生界碳酸盐岩油气储层的演化更为复杂,原生孔隙损失殆尽。北美和中国的研究都表明,岩溶储层和白云岩储层是主要的有效储层。当埋深超过3000m时,白云岩是主要的储层岩石类型。在埋深增大的情况下白云岩保持更好的储集性能,这是一个基本的趋势。中国下古生界碳酸盐岩埋深较大,所以白云岩储层是一个特别值得关注的领域。  相似文献   

以“通灵宝玉”看《红楼梦》玉文化     

李国忠 《地质科学译丛》2011,(2):56-62

＂通灵宝玉＂是《红楼梦》中所构拟的一枚具有神力的玉石。《红楼梦》通过对＂通灵宝玉＂的情节设计,对我国传统玉文化进行了全方位的反思,既没有全面肯定,也没有全盘否定。《红楼梦》对玉石成因和功能的理解带有浓重的神话和宗教色彩,对玉石的自然美给予了浓墨重彩的歌颂,对社会不同阶层的人对玉石的态度进行了准确的描绘,对玉石市场上赝品流行的现象进行了揭露,并对平民百姓制作玉石赝品给予了一定程度的同情。＂通灵宝玉＂不仅是一块美玉,也是一个象征符号,具有封建世袭继承制的象征意味,它可以决定一个人的政治权力、经济地位、生活方式和婚姻选择,曹雪芹对此做了巧妙而深刻的批判。《红楼梦》中的玉文化是曹雪芹对他所处时代的玉文化的立体写照。  相似文献   

Inferences about winter temperatures and summer rains from the late Quaternary record of C4 perennial grasses and C3 desert shrubs in the northern Chihuahuan Desert     

Camille A. Holmgren  Jodi Norris  Julio L. Betancourt 《第四纪科学杂志》2007,22(2):141-161

Late Quaternary histories of two North American desert biomes—C₄ grasslands and C₃ shrublands—are poorly known despite their sensitivity and potential value in reconstructing summer rains and winter temperatures. Plant macrofossil assemblages from packrat midden series in the northern Chihuahuan Desert show that C₄ grasses and annuals typical of desert grassland persisted near their present northern limits throughout the last glacial–interglacial cycle. By contrast, key C₃ desert shrubs appeared somewhat abruptly after 5000 cal. yr BP. Bioclimatic envelopes for select C₄ and C₃ species are mapped to interpret the glacial–interglacial persistence of desert grassland and the mid‐to‐late Holocene expansion of desert shrublands. The envelopes suggest relatively warm Pleistocene temperatures with moist summers allowed for persistence of C₄ grasses, whereas winters were probably too cold (or too wet) for C₃ desert shrubs. Contrary to climate model results, core processes associated with the North American Monsoon and moisture transport to the northern Chihuahuan Desert remained intact throughout the last glacial–interglacial cycle. Mid‐latitude effects, however, truncated midsummer (July–August) moisture transport north of 35° N. The sudden expansion of desert shrublands after 5000 cal. yr BP may be a threshold response to warmer winters associated with increasing boreal winter insolation, and enhanced El Niño–Southern Oscillation variability. Published in 2006 by John Wiley & Sons, Ltd.  相似文献