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排序方式: 共有128条查询结果,搜索用时 15 毫秒
41.
Susanne Bleisch Matt Duckham Antony Galton Patrick Laube Jarod Lyon 《International journal of geographical information science》2014,28(2):363-382
In many applications, the environmental context for and drivers of movement patterns are just as important as the patterns themselves. This article adapts standard data mining techniques, combined with a foundational ontology of causation, with the objective of helping domain experts identify candidate causal relationships between movement patterns and their environmental context. In addition to data about movement and its dynamic environmental context, our approach requires as input definitions of the states and events of interest. The technique outputs causal and causal-like relationships of potential interest, along with associated measures of support and confidence. As a validation of our approach, the analysis is applied to real data about fish movement in the Murray River in Australia. The results demonstrate that the technique is capable of identifying statistically significant patterns of movement indicative of causal and causal-like relationships. 相似文献
42.
Seasonal forecasts have potential value as tools for the management of risks due to inter-annual climate variability and iterative adaptation to climate change. Despite their potential, forecasts are not widely used, in part due to poor performance and lack of relevance to specific users’ decision problems, and in part due to a variety of economic and behavioural factors. In this paper a theoretical model of perceived forecast value is proposed and applied to a stylized portfolio-type decision problem with wide applicability to actual forecast users, with a view to obtaining a more complete picture of the determinants of perceived value. The effects of user wealth, risk aversion, and perceived forecast trustworthiness, and presentational parameters, such as the position of forecast parameter categories, and the size of probability categories, on perceived value is investigated. Analysis of the model provides several strong qualitative predictions of how perceived forecast value depends on these factors. These predictions may be used to generate empirical hypotheses which offer the chance of evaluating the model's assumptions, and suggest several means of improving understanding of perceived value based on qualitative features of the results. 相似文献
43.
Do probabilistic expert elicitations capture scientists’ uncertainty about climate change? 总被引:1,自引:0,他引:1
Antony Millner Raphael Calel David A. Stainforth George MacKerron 《Climatic change》2013,116(2):427-436
Expert elicitation studies have become important barometers of scientific knowledge about future climate change (Morgan and Keith, Environ Sci Technol 29(10), 1995; Reilly et al., Science 293(5529):430–433, 2001; Morgan et al., Climate Change 75(1–2):195–214, 2006; Zickfeld et al., Climatic Change 82(3–4):235–265, 2007, Proc Natl Acad Sci 2010; Kriegler et al., Proc Natl Acad Sci 106(13):5041–5046, 2009). Elicitations incorporate experts’ understanding of known flaws in climate models, thus potentially providing a more comprehensive picture of uncertainty than model-driven methods. The goal of standard elicitation procedures is to determine experts’ subjective probabilities for the values of key climate variables. These methods assume that experts’ knowledge can be captured by subjective probabilities—however, foundational work in decision theory has demonstrated this need not be the case when their information is ambiguous (Ellsberg, Q J Econ 75(4):643–669, 1961). We show that existing elicitation studies may qualitatively understate the extent of experts’ uncertainty about climate change. We designed a choice experiment that allows us to empirically determine whether experts’ knowledge about climate sensitivity (the equilibrium surface warming that results from a doubling of atmospheric CO2 concentration) can be captured by subjective probabilities. Our results show that, even for this much studied and well understood quantity, a non-negligible proportion of climate scientists violate the choice axioms that must be satisfied for subjective probabilities to adequately describe their beliefs. Moreover, the cause of their violation of the axioms is the ambiguity in their knowledge. We expect these results to hold to a greater extent for less understood climate variables, calling into question the veracity of previous elicitations for these quantities. Our experimental design provides an instrument for detecting ambiguity, a valuable new source of information when linking climate science and climate policy which can help policy makers select decision tools appropriate to our true state of knowledge. 相似文献
44.
Simon J. Nicol Valerie Allain Graham M. Pilling Jeff Polovina Marta Coll Johann Bell Paul Dalzell Peter Sharples Robert Olson Shane Griffiths Jeffrey M. Dambacher Jock Young Antony Lewis John Hampton Jesus Jurado Molina Simon Hoyle Karine Briand Nic Bax Patrick Lehodey Peter Williams 《Climatic change》2013,119(1):131-145
Climate change presents an emerging challenge to the sustainable management of tuna fisheries, and robust information is essential to ensure future sustainability. Climate and harvest affect tuna stocks, populations of non-target, dependent species and the ecosystem. To provide relevant advice we need an improved understanding of oceanic ecosystems and better data to parameterise the models that forecast the impacts of climate change. Currently ocean-wide data collection in the Pacific Ocean is primarily restricted to oceanographic data. However, the fisheries observer programs that operate in the region offer an opportunity to collect the additional information on the mid and upper trophic levels of the ecosystem that is necessary to complement this physical data, including time-series of distribution, abundance, size, composition and biological information on target and non-target species and mid trophic level organisms. These observer programs are in their infancy, with limited temporal and spatial distribution but recent international and national policy decisions have been made to expand their coverage. We identify a number of actions to initiate this monitoring including: consolidating collaborations to ensure the use of best quality data; developing consistency between sub-regional observer programmes to ensure that they meet the objectives of ecosystem monitoring; interrogating of existing time series to determine the most appropriate spatial template for monitoring; and exploring existing ecosystem models to identify suitable indicators of ecosystem status and change. The information obtained should improve capacity to develop fisheries management policies that are resilient and can be adapted to climate change. 相似文献
45.
46.
Journal of Seismology - We describe the flexible multimethod seismic site characterization technique for obtaining shear-wave velocity (VS) profiles and derivative information, such as the... 相似文献
47.
Antony R. Berger 《Geoarchaeology》2012,27(2):175-187
48.
The propagation and fission process of internal solitary waves (ISWs) with amplitudes of about 170 m are simulated in the northeast of the South China Sea (NSCS) by using the generalized Korteweg-de Vries (KdV) equation under continuous stratification. More attention is paid to the effects of the ebb and flood background currents on the fission process of ISWs. This kind of background current is provided by the composed results simulated in terms of monthly mean baroclinic circulation and barotropic tidal current. It is found that the obtained relation of the number of fission solitons to the water depth and stratification is roughly in accordance with the fission law derived by Djordjevic and Redekopp in 1978; however, there exists obvious difference between the effects of the ebb and flood background currents on the wave-lengths of fission solitons (defined as the distance between two neighboring peaks of ISWs). The difference in nonlinearity coefficient α between the ebb and flood background currents is a main cause for the different wave-lengths of fission solitons. 相似文献
49.
50.
All varieties of base metal sulphide deposits may be classified using base metal ratios viz. Copper Ratio (CR=100Cu/{Cu+Zn}), Zinc Ratio (ZR=100Zn/{Zn+Pb}) and Lead Ratio (PR=100Pb/{Pb+Cu}). Based on this ore group classification an attempt has been made to identify ore groups present in the late Archaean volcanic associated Ingaldhal Sulphide Deposit (ISD) of Karnataka Craton. Using base metal ratios (CR, ZR and PR) five distinct fields are suggested: Cu, Cu-Zn, Cu-Zn-Pb, Zn-Cu and Zn-Cu-Pb/Zn-Pb-Cu with their associated geological and geochemical characteristics. A transitional change in the ore groups is observed from the North Block (Cu rich groups; CR>50) to South Block (Zn and Pb dominated groups; CR<50) and the Main Block is represented by all the five ore groups.This classification may be useful as a pointer in the exploration of polymetallic base metal deposits. Copper rich groups (Cu, Cu-Zn and Cu-Zn-Pb) exhibit high concentration of Bi and Co, and low CaO and Cd whereas the Zn rich groups (Zn-Cu and Zn-Cu-Pb/Zn-Pb-Cu) show high CaO and Cd, and low Bi and Co. The CR of most of the ore groups exhibit a sympathetic relation with Co and Ag. A preliminary attempt has been made for better understanding of ore group genesis of ISD by integrating ore group characteristics with deduced geothermometry. 相似文献