首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5篇
  免费   0篇
地质学   3篇
天文学   2篇
  2024年   1篇
  2005年   1篇
  2000年   1篇
  1997年   1篇
  1995年   1篇
排序方式: 共有5条查询结果,搜索用时 15 毫秒
1
1.
The crustal dichotomy of Mars describes the topographic division between the young plains in the northern hemisphere and the old terrain in the southern hemisphere. The highland-lowland boundary separates the younger plains from the older, high-standing terrain and consists of three geologically-distinct regions: the Tharsis Province, the chaotic terrain, and the fretted terrain (which includes gradational boundary types)-all are characterised by tensional tectonics. This paper presents new geological evidence that shows the topographic division at the fretted terrain formed in the late Noachian-early Hesperian time period: the same time period in which the Tharsis Province and chaotic terrain formed, and fracturing of a southern-hemisphere-type surface beneath the northern plains occurred. These are inherent features of the crustal dichotomy, indicating it must have also formed during the late Noachian-early Hesperian time period. An analogy is made between the northern lowlands and sedimentary basins on Earth: both are basin like and are surrounded by provinces that have been subjected to pronounced tensional tectonics. This paper uses the White and McKenzie model (1989a) to propose that a lithospheric-stretching event on Mars, in the late Noachian-early Hesperian time period, produced the crustal dichotomy; the Tharsis Province formed by uplift (over a sub-surface hotspot) and gave rise to lithospheric stretching, and the northern lowlands formed by subsidence (over normal asthenospheric temperatures). Detachment faults, operating from the Tharsis Province and around northern lowlands, allowed structural equilibrium and large lithospheric extensions to be attained during this period: they also defined the geometry of the lowlands. The proposal is supported with calculations used to estimate the amount of subsidence that can be achieved in this way.  相似文献   
2.
C. Gdaniec 《GeoJournal》2000,50(4):379-387
In a former industrial part of Barcelona, as in the de-industrialising neighbourhoods of many big cities, the ‘new’ economy and the ‘cultural’ economy have started to replace the ‘old’ economy, bringing new life into a declining district but also causing conflicts of land use, housing or the preservation of architectural heritage. The latter is an important part of regeneration and marketing policies of city governments, whereby the ‘new’ economy not only emerges from the old but the physical space of the old industrial quarter becomes the tool and setting in which the city can re-present itself and its success story of transformation and regeneration. Through the increasing use of information and communication technologies, which are at the same time driving this transformation - an industry as such as well as business-aid in various sectors, cultural industries in particular - the city has acquired a second, virtual presence. The city exists and ‘lives’ on numerous websites. Those by city government and city organisations often have the express purpose of marketing and presenting the city, while those by (cultural) businesses and other organisations in the district add to the mosaic of the virtual city. As a result, the old industrial space continues to live and be productive, its economic value having changed largely into a cultural value. This coexistence of the real and the virtual, old and new, also meets with a conflict at certain junctures. There is the positive representation of plans and events on the city's websites on the one hand, and the undercurrent of protest and disenchantment among the local population who find themselves marginalised from the profits and success of development, on the other. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
3.
Cordula Gdaniec 《GeoJournal》1997,42(4):377-384
Reconstruction of the historic centre of Moscow and the construction of apartment blocks on the citys outskirts are the citys two main programmes within what must be regarded as its urban policy. With these priorities, the strategy of relying on a mixture of city and private investments, the city governments policies contribute to an increasing exclusiveness of the city centre. This process, which includes a process of gentrification, reflects the impact of the transition to a free-market economy. City planning and reconstruction projects are subject to the new, still chaotic, market opportunities and constraints while the soviet planning principles and organizations have not yet been replaced by efficient new ones. There is a lack of control and regulation, as well as a concentration of power in the mayoral cabinet on the one hand, but on the other hand, the finance strategies make large-scale regeneration possible. With entering the global economy, post-soviet Moscow is acquiring more traits of western, capitalist cities. These include marketing the centres historic character, subsidising private investment, and a new residential segregation based on capital.  相似文献   
4.
The paper presents examples illustrating the current blind predictive capabilities of the diffuse double layer model (DDLM) as the model requiring the smallest set of parameters and thus being most suitable for substituting even more empiric sorption approaches such as distribution coefficients KD. The general strategy for the selection of numerical data are discussed. Based on the information about the minerals compiled in the sorption database RES3T (Rossendorf Expert System for Surface and Sorption Thermodynamics), first a set of relevant surface species is generated. Then relevant surface complexation parameters are taken from RES3T: the binding site density for the minerals, the surface protolysis constants, and the stability constants for all relevant surface complexes. To be able to compare and average thermodynamic constants originating from different sources, a normalization concept is applied.Our demonstration is based on a blind prediction exercise, i.e., the goal was not to provide optimal fits. The system considered is Cu(II) sorption onto goethite. The predictions are compared with raw data from three independent experimental investigations. The calculations were performed with the FITEQL 3.2 code. In most cases the model predictions represented the experimental sorption values for the sorbed amount of Cu(II), expressed as conventional distribution coefficients, within one order of magnitude or better.We conclude that the application of DDLM can indeed be used for estimating distribution coefficients for contaminants in well defined mineral systems. A stepwise strategy of species selection, data collection, normalization, and averaging is outlined. The SCM database so far assembled within the RES3T project is able to provide the parameter sets.  相似文献   
5.
In this work, we study how to improve well-known techniques for detecting progenitors/descendants of galaxies, such as the NDpredict program, when applied to galaxies in clusters. The improvement of this particular method is based on the use of the red sequence of galaxies in those environments. Objects close to the red sequence in the color and magnitude diagram are more likely to belong to the cluster. This defines a probability scale which is then combined with the one generated by NDpredict. This procedure is optimized for the study of galaxies in clusters over different epochs. Our main result is that, for a sample composed of 120 $$ 120 $$ clusters, with masses greater than 10 13.25 M $$ {10}^{13.25}{M}_{\odot } $$ , selected from the IllustrisTNG simulations (namely, the TNG100 runs). In 99 % $$ 99\% $$ of the cases (i.e., 119 $$ 119 $$ systems), we obtain better performance with the red sequence method in comparison to the original NDpredict, and the average gain obtained is 28 % $$ 28\% $$ in the identification of descendants for this sample of cluster galaxies.  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号