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101.
A composite standard section (CSS) has been established for the Maokouan (≈ Guadalupian) in Guizhou Province, southwestern
China, which includes stratigraphical ranges of 179 fusulinacean species from five sections of the Maokou Formation in this
area. Based on statistical results of the first and last appearances of fusulinacean species in the CSS, three evolutionary
radiations and four pulses of extinction, characterized by high rates of species origination and extinction significantly
different from the rates of background evolution, are recognized in the Maokouan fusulinacean fauna. The evolutionary pattern
of fusulinacean foraminifer suggests that the Maokouan mass extinction probably started at the middle Maokouan and dramatically
intensified in the late Maokouan.
Project supported by the National Natural Science Foundation of China (Grant No. 49572075) and the Ministry of Education of
China (Grant No. 9528417). 相似文献
102.
Henrique G. Momm Ronald L. Bingner Randall Emilaire Jurgen Garbrecht Robert R. Wells Roger A. Kuhnle 《水文科学杂志》2017,62(10):1564-1582
A qualitative trial-and-error approach is commonly used to define watershed subdivisions through varying a single topographic threshold value. A methodology has been developed to quantitatively determine spatially variable threshold values using topography and a user-defined landscape reference layer. Optimization and topographic parameterization algorithms were integrated to create solutions that minimize the number of sub-watersheds and maximize the agreement between the discretized watershed and the reference layer. The system was evaluated using different reference datasets such as soil type, land management, and landscape form. Comparison of simulated results indicated that the scenario using land management as the reference layer yielded results closer to the scenario subdivided using a constant topographic threshold but with approximately 10 times more sub-catchments and therefore indicating customization of the watershed subdivision to the user-defined reference layer. The proposed optimization technology could be used in adequately applying watershed modeling technology in developing conservation practice implementation plans. 相似文献
103.
Journal of Geographical Sciences - Central Asia is emerging as an important pole of global economic and political power, thanks to its unique location at the heart of Eurasia and its abundance in... 相似文献
104.
超越“演化”:老工业区重构研究进展与范式反思 总被引:1,自引:1,他引:0
老工业区重构是经济地理学的重要研究议题。在全球化步伐放缓和全球制造业下行的宏观背景下,老工业区已愈来愈成为各国发展战略制定的核心对象。对近十年有关老工业区重构的中外文献进行细致梳理,指出了当下研究存在范式应用多元化的趋势,但这些范式在概念使用、尺度聚焦、时空侧重和机制解释上存在显著差异,缺乏相互融合和优势互补,面临现实应用瓶颈。特别是,长期用于解释老工业区重构的演化经济地理学,因其忽视多尺度-多主体-多分析单元的能动性作用而难以有效解释重构过程、机制、结果及其背后的地理性。本文将转型研究中的多层次视角同演化范式相结合,提供了一种具备上下因果辩证解释力的多尺度分析框架,能有效解释老工业区重构问题。在此基础上,探讨了未来研究方向。 相似文献
105.
Meng Guang-wen 《中国地理科学(英文版)》2005,15(2):103-112
Free economic zone (FEZ) has a long history and plays a more and more important role in the world economy. Most studies, however,
focused on the theoretical analysis of benefit and cost as well as the economic role of FEZ in the less developed countries
and little attention has been paid to the evolution of FEZ. This paper will improve the above-mentioned studies and put forward
the structural and spatial evolutionary model of FEZ by analyzing the development of objectives, preferential policy, governance
structure, industrial sectors and location of FEZs based on the international economic and political development. FEZs develop
towards: 1) more comprehensive and macro objectives, 2) more industry-oriented and multi-preferential policies, 3) more cross-national
and combination zones with administrative areas, 4) more technology-intensive and multi-industries, 5) more flexible location
and larger spatial dimensions, 6) more rapid evolution and typologies, and 7) more economic integration to the host economy.
Biography: MENG Guang-wen (1960–), male, a native of Tianjin of China, Ph.D., specialized in regional planning and policy,
environmental planning, tourist planning and management. E-mail: gwmeng98@hotmail.com 相似文献
106.
It is well recognized that the time series of hydrologic variables, such as rainfall and streamflow are significantly influenced by various large‐scale atmospheric circulation patterns. The influence of El Niño‐southern oscillation (ENSO) on hydrologic variables, through hydroclimatic teleconnection, is recognized throughout the world. Indian summer monsoon rainfall (ISMR) has been proved to be significantly influenced by ENSO. Recently, it was established that the relationship between ISMR and ENSO is modulated by the influence of atmospheric circulation patterns over the Indian Ocean region. The influences of Indian Ocean dipole (IOD) mode and equatorial Indian Ocean oscillation (EQUINOO) on ISMR have been established in recent research. Thus, for the Indian subcontinent, hydrologic time series are significantly influenced by ENSO along with EQUINOO. Though the influence of these large‐scale atmospheric circulations on large‐scale rainfall patterns was investigated, their influence on basin‐scale stream‐flow is yet to be investigated. In this paper, information of ENSO from the tropical Pacific Ocean and EQUINOO from the tropical Indian Ocean is used in terms of their corresponding indices for stream‐flow forecasting of the Mahanadi River in the state of Orissa, India. To model the complex non‐linear relationship between basin‐scale stream‐flow and such large‐scale atmospheric circulation information, artificial neural network (ANN) methodology has been opted for the present study. Efficient optimization of ANN architecture is obtained by using an evolutionary optimizer based on a genetic algorithm. This study proves that use of such large‐scale atmospheric circulation information potentially improves the performance of monthly basin‐scale stream‐flow prediction which, in turn, helps in better management of water resources. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
107.
By using the technique for evolutionary power spectrum proposed by Nakayama and with reference to the Kameda formula, an evolutionary spectrum prediction model for given earthquake magnitude and distance is established based on the 80 near-source acceleration records at rock surface with large magnitude from the ground motion database of western U.S.. Then a new iteration method is developed for generation of random accelerograms non-stationary both in amplitude and frequency which are compatible with target evolutionary spectrum. The phase spectra of those simulated accelerograms are also non-stationary in time and frequency domains since the interaction between amplitude and phase angle has been considered during the generation. Furthermore, the sign of the phase spectrum increment is identified to accelerate the iteration. With the proposed statistical model for predicting evolutionary power spectra and the new method for generating compatible time history, the artificial random earthquake accelerograms non-stationary both in amplitude and frequency for certain magnitude and distance can be provided. 相似文献
108.
区域气候模式对东亚气候时空演变特征的模拟研究 总被引:4,自引:2,他引:2
利用区域环境集成模式系统对东亚地区进行了1987年1月到1996年12月的长期积分试验,重点采用经验正交函数分析方法分析和比较模式模拟及观测气候主分量时空特征,从而考察区域气候模式对东亚地区的区域气候模拟能力.结果表明:(1) RIEMS能够较好地抓住地面气温年平均状况及其年变化和年际变率的主要特征;(2)尽管模式对降水的模拟能力没有对地面气温模拟的强,但RIEMS模式基本上能够模拟出降水的空间分布以及降水的季节变化特征,同时能够抓住降水的年际变率.
相似文献
109.
110.
系统探究不同地域乡村聚落的演化机制是构建乡村聚落转型实践逻辑和理论体系的基础。居住形态是涵盖居住空间形态、生活形态和文化形态的综合概念,立足居住形态视角有望揭示乡村聚落格局演化机制及其地域差异的深层逻辑。本文遵循“现象描述—机制分析—典型区对比”的思路,以乡村聚落地域分异为切入点,从“人-地”和“人-人”关系视角探究了人类发展进程中乡村聚落格局演化的一般规律,据此构建居住形态的形成及其对乡村聚落格局演化的作用机制,并以散居和聚居形态主导的样区为对照进行实证研究。研究表明,居住形态是衍生于宏观乡村聚落格局演化过程的多尺度、多维性因子,二者均可从“人-地”关系和“人-人”关系双重视角进行阐释;居住文化形态具有较强的传承性,为乡村聚落格局演化提供了路径遵循和内生机制,乡村聚落格局可视为居住文化形态在乡村地域空间解译和扩散的结果;生产力进步与偶发性事件可导致居住形态发生变革,从而诱发乡村聚落格局演化机制的改变。面向乡村振兴战略,需重视居住形态的研究视角,系统探讨不同地域传统乡村聚落的运行机制、城镇化阶段的演化机制以及乡村振兴背景下治理策略的本质差异,为制定差异化的村落振兴方案提供参考。 相似文献