全文获取类型
收费全文 | 140篇 |
免费 | 2篇 |
国内免费 | 10篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 3篇 |
地球物理 | 27篇 |
地质学 | 45篇 |
海洋学 | 4篇 |
天文学 | 3篇 |
综合类 | 1篇 |
自然地理 | 67篇 |
出版年
2022年 | 1篇 |
2019年 | 2篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 7篇 |
2012年 | 4篇 |
2011年 | 2篇 |
2010年 | 5篇 |
2009年 | 3篇 |
2008年 | 4篇 |
2007年 | 10篇 |
2006年 | 6篇 |
2005年 | 8篇 |
2004年 | 1篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 11篇 |
1996年 | 13篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1986年 | 3篇 |
排序方式: 共有152条查询结果,搜索用时 62 毫秒
91.
Alberto Malinverno 《Pure and Applied Geophysics》1989,131(1-2):139-155
Stochastic models can generate profiles that resemble topography by taking uncorrelated, zero-average noise as input, introducing some correlation in the time series of noise, and integrating the resulting correlated noise. The output profile will depict a nonstationary, randomly rough surface. Two models have been chosen for comparison: a fractal model, in which the noise is correlated even at large distances, and an autoregressive model of order 1, in which the correlation of the noise decays rapidly. Both models have as an end-member a random walk, which is the integration of uncorrelated noise. The models have been fitted to profiles of submarine topography, and the sample autocorrelation, power spectrum and variogram have been compared to the theoretical predictions. The results suggest that a linear system approach is a viable method to model and classify sea-floor topography. The comparison does not show substantial disagreement of the data with either the autoregressive or the fractal model, although a fractal model seems to give a better fit. However, the amplitudes predicted by a nonstationary fractal model for long wavelengths (of the order of 1000 km) are unreasonably large. When viewed through a large window, ocean floor topography is likely to have an expected value determined by isostasy, and to be stationary. Nonstationary models are best applied to wavelengths of the order of 100 km or less. 相似文献
92.
93.
矿产勘查中化探异常下限的多重分形计算方法 总被引:5,自引:0,他引:5
孙忠军 《物探化探计算技术》2007,29(1):54-57
化探异常下限计算方法在矿产勘查和资源预测中非常重要。传统的计算方法存在依据不充分的问题。这里在研究地球化学场数据分布的基础上,提出了多重含量~频数分形计算方法。研究表明,多重分形异常下限计算方法较之传统的方法具有理论基础扎实、适用性较广的特点。 相似文献
94.
This article shows some important scaling aspects that exist in hydrological process grid modelling with GIS, with respect to selecting the optimal grid width. Hydrologically relevant space parameter fields should often be regarded as self-similar fractals for which certain invariance characteristics are applied. These characteristics are especially important if there is an extensive change in the model grid width. The self-similarity generates simple scaling laws, which can be used for rescaling procedures. © 1997 John Wiley & Sons, Ltd. 相似文献
95.
96.
《The Professional geographer》2013,65(1):88-89
Scale and resolution have long been key issues in geography. The rapid development of analytical cartography, GIS, and remote sensing (the mapping sciences) in the last decade has forced the issues of scale and resolution to be treated formally and better defined. This paper addresses the problem of scale and resolution in geographical studies, with special reference to the mapping sciences. The fractal concept is introduced, and its use in identifying the scale and resolution problem is discussed. The implications of the scale and resolution problem on studies of global change and modeling are also explored. 相似文献
97.
98.
99.
高应力下颗粒材料一维力学特性研究(Ⅱ):蠕变性质 总被引:1,自引:0,他引:1
现场和试验观测表明,高应力下砂土的蠕变过程伴随着颗粒破碎现象。通过开展砂土的一维蠕变试验发现,试样的颗粒破碎量随时间增加而增加,且蠕变速率与颗粒破碎速率成正比。在此基础上,分析了蠕变过程中能量转化关系,利用表面物理学和分形几何学理论,得到了一维蠕变条件下颗粒破碎速率与宏观蠕变速率之间的关系表达式。研究结果表明,高应力一维蠕变条件下颗粒材料的宏观蠕变速率与颗粒破碎速率成正比。最后,对该研究采用的等效化方法进行了讨论。 相似文献
100.
以沈阳经济区城市体系为研究对象,利用聚集维数、关联维数及计盒维数的基本模型对该城市体系的空间结构进行了分析,认为沈阳经济区城市体系结构具有分形特征,测算结果表明:沈阳经济区城市体系的空间分布呈现围绕中心城市-沈阳的向心式聚集,城市之间交通网络通达性好,空间形态较辽宁省城市体系紧凑。沈阳经济区城市体系的划分相对合理,但仍需优化。建议充分发挥沈阳作为中心城市的强辐射与带动作用,并通过打造沈抚、沈本、沈铁、沈辽鞍营和沈阜5条城际连接带,推动城镇化、加速区域一体化进程;通过产业整合和产业集群化促进资源优化配置,提高城市之间的相互作用,促进沈阳经济区形成联系紧密的"区域经济共同体"。 相似文献