全文获取类型
收费全文 | 122篇 |
免费 | 9篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 15篇 |
地球物理 | 32篇 |
地质学 | 54篇 |
海洋学 | 11篇 |
天文学 | 5篇 |
自然地理 | 13篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 8篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 13篇 |
2012年 | 8篇 |
2011年 | 7篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 7篇 |
2007年 | 11篇 |
2006年 | 1篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1991年 | 3篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1982年 | 2篇 |
1978年 | 1篇 |
1921年 | 2篇 |
1920年 | 1篇 |
排序方式: 共有134条查询结果,搜索用时 156 毫秒
61.
Jane Hunter Charles Brooking Lucy Reading Sue Vink 《International Journal of Digital Earth》2016,9(2):197-214
The 3D Water Chemistry Atlas is an intuitive, open source, Web-based system that enables the three-dimensional (3D) sub-surface visualization of ground water monitoring data, overlaid on the local geological model (formation and aquifer strata). This paper firstly describes the results of evaluating existing virtual globe technologies, which led to the decision to use the Cesium open source WebGL Virtual Globe and Map Engine as the underlying platform. Next it describes the backend database and search, filtering, browse and analysis tools that were developed to enable users to interactively explore the groundwater monitoring data and interpret it spatially and temporally relative to the local geological formations and aquifers via the Cesium interface. The result is an integrated 3D visualization system that enables environmental managers and regulators to assess groundwater conditions, identify inconsistencies in the data, manage impacts and risks and make more informed decisions about coal seam gas extraction, waste water extraction, and water reuse. 相似文献
62.
The first use of Fulton's K for assessing and comparing the conditions of inter‐tidal fish populations
下载免费PDF全文
![点击此处可从《Marine Ecology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Fulton's K condition factor was applied, for the first time, to inter‐tidal specimens of the shanny (Lipophrys pholis) and long‐spined scorpion fish (Taurulus bubalis) from two English rocky shore and two Welsh rocky shore sites during summer 2010 and winter 2011. As both species contribute to the diet of commercial species such as cod (Gadus morhua) and near‐threatened species such as the European otter (Lutra lutra), their condition may affect that of these predators. Fulton's K found that inter‐tidal Welsh fish maintained a ‘good’ condition between seasons, whereas the inter‐tidal English fish were in a poorer condition during winter. Although condition also changed amongst the sites on each coast, further studies are needed into fish morphologies, environmental parameters, prey availabilities and abundances, and fish specimen sex and maturities. 相似文献
63.
The climatic potential of maize under dryland farming in Lesotho, southern Africa, was investigated using five suitability indices comprising probability of accumulating heat units of greater than 1,500 growing degree days, probability of a frost-free growing season, probability of seasonal rainfall of more than 500 mm, probability of drought during the flowering to grain-filling stages and the slope of an area. A geographic information system layer was prepared for each of these parameters and the layers overlaid using different weights for each of the climatic suitability indices to obtain an agroclimatic maize suitability map for Lesotho. This analysis yielded different suitability classes. This variability points to prevalence of climatic constraints that need to be acknowledged when attempting to identify management strategies that can optimize the rain-fed maize production in climatically variable environments. 相似文献
64.
65.
Internal parts of the Alps have undergone widespread extensional deformation in the course of their Neogene exhumation history. Palaeostress inversion methods are used to map the prevailing stress fields and their evolution through time. Here we present new data from 100 sites with a total of about 2000 faults/striae couples, covering a large portion of the inner north‐western Alps. Palaeostress tensors are mostly extensional, although one‐third of them are transcurrent. The dominant direction of minimum horizontal stress axes (σ3) is in an orogen‐parallel (N30° to N70°) orientation around the bend of the north‐west alpine arc. A comparison between this older (Neogene, post‐metamorphic) stress field with the current stress and strain field determined from seismotectonics and geodesy indicates a change in deformation mode from early orogen‐parallel extrusion to a late and ongoing orogen‐perpendicular spreading. 相似文献
66.
67.
Sandrine Roy Riccardo Vassallo Joseph Martinod Matías C. Ghiglione Christian Sue Pascal Allemand 《地学学报》2020,32(1):1-10
Across the extreme south of Patagonia, the Magallanes‐Fagnano Fault (MFF) accommodates the left‐lateral relative motion between South America and Scotia plates. In this paper, we present an updated view of the geometry of the eastern portion of the MFF outcropping in Tierra del Fuego. We subdivide the MFF in eight segments on the basis of their deformation styles, using field mapping and interpretation of high‐resolution imagery. We quantify coseismic ruptures of the strongest recorded 1949, Mw7.5 earthquake, and determine its eastern termination. We recognize several co‐seismic offsets in man‐made features showing a sinistral shift up to 6.5 m, greater than previously estimated. Using 10Be cosmogenic nuclides depth profiles, we date a cumulated offset in post‐glacial morphologies and estimate the long‐term slip rate of the eastern MFF. We quantify a 6.4 ± 0.9 mm/a left‐lateral fault slip rate, which overlaps geodetic velocity and suggests stable fault behaviour since Pleistocene. 相似文献
68.
Jan Alexander Jenni Barclay Janez Sušnik Sue C. Loughlin Richard A. Herd Amii Darnell Sian Crosweller 《Journal of Volcanology and Geothermal Research》2010
On 20th May 2006 the Soufrière Hills Volcano on the Caribbean island of Montserrat experienced a large dome collapse and intense rainfall generated flash floods. The floods had very high loads of volcanic debris derived both from this and previous eruptions and can thus be classified as lahars. The floods reached unusually high water levels and caused substantial geomorphic change in the Belham Valley. Detailed rainfall and geomorphological data, coupled with the precise timing of events and yewitness accounts have facilitated an assessment of the relative importance of rainfall volume and intensity, older volcanic debris, pre- and syn-flood tephra fall and the extent of pre-flood vegetation damage for the behavior of this and subsequent sediment-laden floods in this setting. The change in runoff behavior was controlled by preexisting vegetation damage and synchronous tephra fall and this was critically important in controlling the impact of these flash floods. Although rainfall intensity and volume have some control on flood occurrence they are not the critical control on flash flood impact on the geomorphology in the Belham Valley. A significant conclusion of this study is that the extreme nature of the flash floods was not caused by extreme rainfall (as is commonly believed to be the primary cause of flash floods) but rather it was the result of changed runoff behaviour caused by the widespread syn-flood tephra deposition and importantly the widespread vegetation damage by volcanic-associated acid rain in the preceding weeks. 相似文献
69.
Kerrie?J.?Schmehl Sue?Ellen?HauptEmail author Michael?J.?Pavolonis 《Pure and Applied Geophysics》2012,169(3):519-537
Variational data assimilation methods optimize the match between an observed and a predicted field. These methods normally
require information on error variances of both the analysis and the observations, which are sometimes difficult to obtain
for transport and dispersion problems. Here, the variational problem is set up as a minimization problem that directly minimizes
the root mean squared error of the difference between the observations and the prediction. In the context of atmospheric transport
and dispersion, the solution of this optimization problem requires a robust technique. A genetic algorithm (GA) is used here
for that solution, forming the GA-Variational (GA-Var) technique. The philosophy and formulation of the technique is described
here. An advantage of the technique includes that it does not require observation or analysis error covariances nor information
about any variables that are not directly assimilated. It can be employed in the context of either a forward assimilation
problem or used to retrieve unknown source or meteorological information by solving the inverse problem. The details of the
method are reviewed. As an example application, GA-Var is demonstrated for predicting the plume from a volcanic eruption.
First the technique is employed to retrieve the unknown emission rate and the steering winds of the volcanic plume. Then that
information is assimilated into a forward prediction of its transport and dispersion. Concentration data are derived from
satellite data to determine the observed ash concentrations. A case study is made of the March 2009 eruption of Mount Redoubt
in Alaska. The GA-Var technique is able to determine a wind speed and direction that matches the observations well and a reasonable
emission rate. 相似文献
70.
Assessment of agricultural drought using a simple water balance model in the Free State Province of South Africa 总被引:1,自引:1,他引:0
Water Requirement Satisfaction Index (WRSI) at three different probability levels (20%, 50%, and 80%) was used to quantify drought affecting rain-fed maize production in the Free State Province of South Africa based on climate data from 227 weather stations. Results showed high spatial variability in the suitability of different areas: the southern and southwestern localities are unsuitable due to high drought incidences; the northern, central, and western regions are marginally suitable; the eastern, northerneastern areas and a few patches in the northwest are highly suitable with relatively low drought severity. Proper choice of maize varieties to suit conditions at different localities is crucial. The Mann–Kendall test and coefficient of variation were further used to determine trends and temporal variability, respectively, in the WRSI, seasonal rainfall, and seasonal maize water requirements. Results of this analysis revealed no significant positive trends in the WRSI, no significant negative trends in seasonal rainfall, and no significant positive trends in maize water requirements, contradicting previous findings of increased drought severity. Seasonal rainfall and the WRSI showed high interseasonal variability, while seasonal maize water requirements showed low variability. In view of these observations, it is apparent that realignment of management practices is an overdue prerequisite for sustainable maize production. 相似文献