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41.
20世纪末"生产网络范式"取代了"现代企业范式"成为世界生产组织方式的主流,随之生产网络成为了西方经济地理学的研究热点之一。本文综述了西方学者从不同视角对生产网络的理解,概括了生产网络所具有的几个重要特征,对生产网络在不同尺度的应用进行了评述。总体上看,生产网络对解释各尺度经济现象都具有重要的作用,但相比国际、区域和全球等大尺度生产网络的广泛研究,国家和地方中小尺度的生产网络明显受到忽视。事实上,在大尺度生产网络的研究基础和背景下,国家生产网络在构建国家创新系统上、地方生产网络在分析地方经济上将会发挥更加重要的作用。 相似文献
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S. E. JOHNSON 《Journal of Metamorphic Geology》1993,11(5):621-634
Abstract Seventy-seven spatially orientated, serial thin sections cut from a single rock reveal changes in the geometry of spiral-shaped inclusion trails (SSITs) in garnet porphyroblasts. The observed SSITs are doubly curved, non-cylindrical surfaces, with total inclusion-trail curvature decreasing systematically from the cores to the rims of porphyroblasts. The three-dimensional geometry of the SSITs, reconstructed with the aid of computer graphics, shows that the orientations of spiral axes defined by the SSITs are not related in any expected nor predictable way to the main foliation in the matrix. This suggests continued deformation after or during the latest stages of porphyroblast growth, which has important implications for the use of SSITs as shear-sense indicators. Whether the formation of SSITs involves significant porphyroblast rotation with respect to a geographically fixed reference frame cannot be determined from the available data. 相似文献
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De-bugging the 'millipede' porphyroblast microstructure: a serial thin-section study and 3-D computer animation 总被引:1,自引:0,他引:1
ABSTRACT Seventy-five spatially orientated, serial thin sections cut from a single rock containing ‘millipede’ porphyroblast microstructure from the Robertson River Metamorphics, Australia, reveal the three-dimensional (3-D) geometry of oppositely concave microfolds (OCMs) that define the microstructure. Electronic animations showing progressive serial sections of the 3-D microstructure are made available via the World Wide Web. The OCM amplitudes decrease regularly from a maximum in near-central sections to a minimum in near-marginal sections, whereas the OCM interlimb angles increase regularly from a minimum in near-central sections to a maximum in near-marginal sections. These observations illustrate that the OCMs are noncylindrical surfaces with culminations located in near-central sections. Because the porphyroblast cores appear to have been present before significant development of the syn-OCM foliation, all of the OCMs were formed by heterogeneous extension around these cores. The overall geometry of the OCMs described here reflects the strain state, and cannot be used to constrain deformation paths. 相似文献
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The High Plains are a vast, low relief landscape that contains thousands of upland-embedded depressional playa wetlands. Lunettes are isolated dunes that form from prolonged periods of aeolian deposition along the downwind margin of some larger playas. Playa-lunette systems are important landscape elements that have the potential to preserve high-resolution records of past environments, and several archeological sites have been associated with playa-lunette systems throughout the High Plains. While a comprehensive playa wetland geospatial database has been developed for the High Plains, lunettes have only been mapped for the Southern High Plains of Texas and New Mexico. The purpose of this research was to map and characterize the geomorphology of all lunettes associated with playas in the High Plains and bordering regions of western Kansas. Results indicate 129 lunettes are associated with 104 playas in Kansas. All lunettes are associated with playas larger than 5 ha, and about 10% of these larger playas have a lunette. Lunette height ranges from approximately 1.5–12 m, with a median height of 3 m. Most lunettes (60%) are in Finney, Gray, Lane, and Scott counties, which have broad, flat uplands with few major drainages upwind of playas and lunettes. 相似文献
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