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71.
72.
Kirti K. Lal 《The Australian geographer》2011,42(1):41-51
For the first time, a sediment core spanning the entire Holocene has been analysed from Fiji. The 6 m core was obtained from the floor of an ancient coastal lagoon (palaeolagoon) adjacent to Bourewa, the site of the earliest known human settlement in this island group. The basal sediments, just above bedrock, date from 11 470 cal bp. A major transition occurs around 8000 cal bp where marine influences on palaeolagoon sedimentation increase sharply. Full shallow-water marine conditions are attained around 4630 cal bp and last until 3480 cal bp after which there is a regressive phase. The results agree with the area-specific predictions of sea level in the ICE-4G model, particularly in the timing of the highstand. In addition, the results support the ideas (a) that early human colonisation of Fiji occurred during the late Holocene regression, (b) that the first inhabitants of Bourewa utilised both nearshore marine (reefal) and brackish lagoon food sources, and (c) that the abrupt human abandonment of the area around 2500 cal bp could have been prompted by a reduction in these resources driven largely by sea-level fall. 相似文献
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74.
Questionnaires sent to 500 geographers randomly selected from U.S. graduate departments solicited opinions on the quality of scholarship of articles in 34 U.S. geography journals. The five highest ranked were Quaternary Research, Annals, AAG, Arctic and Alpine Research, Geographical Review, and American Cartographer. When familiarity and quality together were ranked, the top five were Annals, AAG, Geographical Review, Professional Geographer, Economic Geography and Journal of Geography. Age and specialty of respondent were most significant in explaining ranking variations. 相似文献
75.
中国科协近期组织开展了2016年度中国科协主管期刊审读工作。中国科协主办或参与主办科技期刊1091种。本次审读共抽审206种期刊,其中72种期刊获得2016年度中国科协主管科技期刊审读“优”级期刊称号。中国地质学会所属期刊编辑部坚持办刊宗旨和编辑方针,严格执行编审制度,完善内部管理,出版质量不断提高。《地质学报》、《地质论评》、《矿床地质》、《岩石矿物学杂志》获2016年度中国科协主管科技期刊审读“优”级期刊称号。科技期刊审读主要是检查科技期刊的编校质量,内容主要是期刊是否严格执行国家标准、是否泄密、是否发生重大错漏(地质学期刊中的地图常易发生重大错漏)及是否规范用字等。 相似文献
76.
SCI/SSCI期刊与中文权威核心期刊论文的学术价值评价——基于地理工作者的感知分析 总被引:2,自引:2,他引:2
进入信息全球化时代,SCI/SSCI 论文越来越成为中国各高校及科研院所等单位衡量其基础研究实力的评价标准,甚至出现“唯‘SCI/SSCI’论”的现象,中文权威核心期刊论文的学术价值评定和认可度则相应降低,这在一定程度上对中文权威核心期刊的发展造成了不小的冲击。基于探索性因子分析,构建了中文权威核心期刊论文学术价值认可度的结构方程假设模型,以地理科学工作者为例,通过验证性因子分析,实证研究了地理工作者对中文权威核心期刊论文学术价值认可度的影响因素。结果显示:① 学术成果影响力是影响中文权威核心期刊论文学术价值认可度的关键因素,科研评价和学术地位认定政策及学术影响力评价是影响中文权威核心期刊论文学术价值认可度的重要因素;② 学术成果影响力对认可度影响程度最大,其影响路径系数为0.52,其次为学术影响力评价,路径系数为0.25,科研评价和学术地位认定政策影响程度较小;③ 学术成果影响力和学术影响力评价与认可度表现为正相关关系,而科研评价和学术地位认定政策与认可度之间则表现为负相关关系。最后,提出了增强科研工作者对中文权威核心期刊论文学术价值认可度的相关对策,以期提升作者发表中文权威核心期刊论文的意愿度,来促进中文权威核心期刊的持续发展。 相似文献
77.
利用地震资料进行AVO油气检测,需要提供准确的储层岩石物性参数.通过对准噶尔盆地西部储层岩样实验室测定,得出合不同流体岩石在不同温度、压力下纵横波速度、速度比、泊松比的变化规律及差异.根据其差异性,用Zoeppritz方程做模型正演,以确定目的层有无AVO响应,以便对地震剖面做针对性的特殊处理.实际应用结果表明,用实验室测试的岩石物性参数做模型正演,可提高AVO检测的准确性,为用地震资料结合实验室岩芯测试参数预测地层油、气、水边界提供了有效手段. 相似文献
78.
Abstract The solution of the full nonlinear hydromagnetic dynamo problem is a major numerical undertaking. While efforts continue, supplementary studies into various aspects of the dynamo process can greatly improve our understanding of the mechanisms involved. In the present study, the linear stability of an electrically conducting fluid in a rigid, electrically insulating spherical container in the presence of a toroidal magnetic field Bo(r,θ)lø and toroidal velocity field Uo(r,θ)lø, [where (r,θ,ø) are polar coordinates] is investigated. The system, a model for the Earth's fluid core, is rapidly rotating, the magnetostrophic approximation is used and thermal effects are excluded. Earlier studies have adopted a cylindrical geometry in order to simplify the numerical analysis. Although the cylindrical geometry retains the fundamental physics, a spherical geometry is a more appropriate model for the Earth. Here, we use the results which have been found for cylindrical systems as guidelines for the more realistic spherical case. This is achieved by restricting attention to basic states depending only on the distance from the rotation axis and by concentrating on the field gradient instability. We then find that our calculations for the sphere are in very good qualitative agreement both with a local analysis and with the predictions from the results of the cylindrical geometry. We have thus established the existence of field gradient modes in a realistic (spherical) model and found a sound basis for the study of various other, more complicated, classes of magnetically driven instabilities which will be comprehensively investigated in future work. 相似文献
79.
80.
P. A. Sturrock 《Solar physics》2008,252(2):221-233
There has for some time been evidence of variability in radiochemical solar neutrino measurements, but this evidence has seemed
suspect since the Cerenkov experiments have not shown similar evidence of variability. The present reanalysis of Super-Kamiokande
data shows strong evidence of r-mode oscillations. The frequencies of these oscillations correspond to a region with a sidereal
rotation rate of 13.97 year−1. This estimate is incompatible with the rotation rate in the convection zone but is compatible with current estimates of
the rotation rate in the radiative zone. The excitation of r modes in the radiative zone may be due to a velocity field originating
in or related to the nuclear-burning core. 相似文献