全文获取类型
收费全文 | 158篇 |
免费 | 11篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 25篇 |
地球物理 | 43篇 |
地质学 | 40篇 |
海洋学 | 8篇 |
天文学 | 13篇 |
自然地理 | 41篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 7篇 |
2017年 | 2篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 11篇 |
2012年 | 5篇 |
2011年 | 8篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 7篇 |
2007年 | 11篇 |
2006年 | 8篇 |
2005年 | 10篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1964年 | 1篇 |
1961年 | 2篇 |
1960年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有172条查询结果,搜索用时 15 毫秒
81.
Jeroen E. Sonke William C. Burnett Jurian A. Hoogewerff Sieger R. van der Laan Jaco Vangronsveld D. Reide Corbett 《Journal of Paleolimnology》2003,29(1):95-107
Pb-210 dating of two metal-polluted organic sedimentcores obtained near a former pyrometallurgical zinc smelter in Lommel, Belgiumhave been used to reconstruct atmospheric lead deposition rates during the20th century. Independent knowledge concerning historical pollutionevents and 137Cs fall-out profiles has allowed a criticalevaluation of the CRS, CIC and CF-CS models for the 210Pb ageinterpretation. Resulting ages for the three models suggest that, in this case,the CIC model gives the most accurate interpretation of historical pollutionevents and atmospheric lead fall-out. The 210Pbwater-sediment flux was estimated at 141–1158Bq·m–2·yr–1 for one site and62–106 Bq·m–2·yr–1 at theother site, during the last century. The large difference illustrates thatsediment focusing was important on a small spatial scale (10 m).The direction of focusing correlates with the predominant wind direction.Maximum atmospheric lead deposition rates were found to be 1.63 ± 0.59g·m–2·yr–1 around 1968 AD,which is 2 orders of magnitude larger than the Belgian average in 1980 AD, and5 orders larger than Holocene atmospheric lead deposition. 相似文献
82.
Jens Christian Refsgaard Jeroen P. van der Sluijs James Brown Peter van der Keur 《Advances in water resources》2006
Although uncertainty about structures of environmental models (conceptual uncertainty) is often acknowledged to be the main source of uncertainty in model predictions, it is rarely considered in environmental modelling. Rather, formal uncertainty analyses have traditionally focused on model parameters and input data as the principal source of uncertainty in model predictions. The traditional approach to model uncertainty analysis, which considers only a single conceptual model, may fail to adequately sample the relevant space of plausible conceptual models. As such, it is prone to modelling bias and underestimation of predictive uncertainty. 相似文献
83.
Climate change impacts on pricing long-term flood insurance: A comprehensive study for the Netherlands 总被引:2,自引:0,他引:2
Recently long-term flood insurance contracts with a duration of 5, 10 or 15 years have been proposed as a solution for covering flood risk and mitigating increasing flood losses. Establishing a long-term relation between the policyholder and the insurer can provide better incentives to reduce risk through undertaking damage mitigation measures. However, the uncertainty about the development of future flood risk in the face of climate and socio-economic change may complicate insurers’ rate-setting of long-term contracts. This issue has been examined in this study by estimating the effects of these changes on flood risk and pricing flood insurance premiums of short- and long-term flood insurance contracts in all (53) dike-ring areas in the Netherlands. A broad range of simulations with hydrological and flood damage models are used to estimate the future development of flood risk and premiums. In addition, the long-term development of insurance funds is estimated with a spatial “Climate Risk Insurance Model (CRIM)” for a private insurance arrangement and for a ‘three-layered’ public-private insurance program. The estimation of flood insurance premiums of long-term insurance contracts reveals fundamental problems. One is that there is an incentive for either the consumer or the insurer to prefer short-term rather than long-term contracts in the face of climate-related uncertainty. Therefore, it seems advisable to examine the introduction of one-year flood insurance contracts in the Netherlands, at least until the large uncertainties with climate and socio-economic change on flood risk have been resolved. The estimations performed with the Climate Risk Insurance Model indicate that a private insurance fund could have difficulties with building up enough financial reserves to pay for flood damage, while the layered public-private insurance scheme is more robust. 相似文献
84.
The interaction of the lanthanides (Ln) with humic substances (HS) was investigated with a novel chemical speciation tool, Capillary Electrophoresis-Inductively Coupled Plasma Mass Spectrometry (CE-ICP-MS). By using an EDTA-ligand competition method, a bi-modal species distribution of LnEDTA and LnHS is attained, separated by CE, and detected online by sector field ICP-MS. We quantified the binding of all 14 rare earth elements (REEs), Sc and Y with Suwannee river fulvic acid, Leonardite coal humic acid, and Elliot soil humic acid under environmental conditions (pH 6-9, 0.001-0.1 mol L−1 NaNO3, 1-1000 nmol L−1 Ln, 10-20 mg L−1 HS). Conditional binding constants for REE-HS interaction (Kc) ranged from 8.9 < log Kc < 16.5 under all experimental conditions, and display a lanthanide contraction effect, ΔLKc: a gradual increase in Kc from La to Lu by 2-3 orders of magnitude as a function of decreasing ionic radius. HS polyelectrolyte effects cause Kc to increase with increasing pH and decreasing ionic strength. ΔLKc increases significantly with increasing pH, and likely with decreasing ionic strength. Based on a strong correlation between ΔLKc values and denticity for organic acids, we suggest that HS form a range of tri- to tetra-dentate complexes under environmental conditions. These results confirm HS to be a strong complexing agent for Ln, and show rigorous experimental evidence for potential REE fractionation by HS complexation. 相似文献
85.
R. Unger W.A. van Kampen A.J. Berkhout R.G. Boiten A.M. Ziolkowski A.R. Ritsema D.Ph. Schmidt 《Geophysical Journal International》1987,89(1):41-46
Summary. A new-technology, broad-band seismic land source based on the principle of magnetic levitation is under development. The new source is designed to overcome limitations experienced with controlled-signal seismic sources at the present time, and to create new possibilities. In particular, She new source extends the constant peak force frequency band down to 2 Hz, and is capable of at least several weeks continuous, coherent transmission. It will enable three-dimensional long-range (>200 km) controlled-signal seismology with the potential for active earth tomography down into the mantle and systematic earthquake precursor measurement, and should improve shallow and deep seismic profiling technology. The optimum transmission frequencies depend on Q, transmission range, and noise spectrum. 相似文献
86.
Kathrin Abraham Sophie Opfergelt François Fripiat Anne-Julie Cavagna Jeroen T.M. de Jong Stephen F. Foley Luc André Damien Cardinal 《Geostandards and Geoanalytical Research》2008,32(2):193-202
We report silicon isotopic determinations for USGS rock reference materials BHVO-1 and BHVO-2 using a Nu Plasma multi-collector (MC)-ICP-MS, upgraded with a new adjustable entrance slit, to obtain medium resolution, as well as a stronger primary pump and newly designed sampler and skimmer cones ("B" cones). These settings, combined with the use of collector slits, allowed a resolution to be reached that was sufficient to overcome the 14 N16 O and 14 N2 interferences overlying the 30 Si and the 28 Si peaks, respectively, in an earlier set-up. This enabled accurate measurement of both δ30 Si and δ29 Si. The δ value is expressed in per mil variation relative to the NBS 28 quartz reference material. Based on data acquired from numerous sessions spread over a period of six months, we propose a recommended average δ30 Si of −0.33 ± 0.05‰ and −0.29 ± 0.11‰ (2se) for BHVO-1 and BHVO-2, respectively. Our BHVO grand mean silicon isotope composition (δ30 Si =−0.31 ± 0.06‰) is significantly more negative than the only published value for BHVO-2, but is in very good agreement with the recently established average value of ocean island basalts (OIB), confirming the conclusion that the OIB reservoir has a distinct isotopic composition from the solar reservoir as sampled by chondrites. 相似文献
87.
Development of a sustainable livelihood security model for storm-surge hazard in the coastal areas of Bangladesh 总被引:2,自引:1,他引:1
Mahmuda Mutahara Anisul Haque M. Shah Alam Khan Jeroen F. Warner Philippus Wester 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(5):1301-1315
Coastal communities in Bangladesh are at great risk due to frequent cyclones and cyclone induced storm-surges, which damages inland and marine resource systems. In the present research, seven marginal livelihood groups including Farmers, Fisherman, Fry (shrimp) collectors, Salt farmers, Dry fishers, Forest resource extractors, and Daily wage labourers are identified to be extremely affected by storm- surges in the coastal area of Bangladesh. A livelihood security model was developed to investigate the security status of the coastal livelihood system in a participatory approach. In the model, livelihood security consists of five components: (1) Food, (2) Income, (3) Life & health, (4) House & properties, and (5) Water security. Analytical hierarchy process was followed to assess the livelihood security indicators based on respondents’ security options. The model was verified through direct field observation and expert judgment. The Livelihood Security Model yields a Livelihood Security Index which can be used for assessing and comparing the household security level (in %) of different livelihood groups in the storm-surge prone coastal areas. The model was applied with data from two major coastal areas (Cox’s Bazar and Satkhira) of Bangladesh and is applicable to other coastal areas having similar settings. 相似文献
88.
89.
90.
The Triptych approach is a sectoral approach for differentiation of quantitative greenhouse gas emission reduction objectives. In this study we investigate the ranges in emission reduction targets that result from differences in valueladen assumptions and uncertainties in input data and parameters. In order to assess the effect of highly valueladen assumptions on resulting objectives we used two approaches. First we performed a sensitivity analysis. Then we elaborated the approach from four ideal-typical value-orientations: the administrator, the businessman, the campaigner and the survivor. For each of these value-orientations we specified corresponding sets of assumptions of highly valueladen parameters. Within each set, we also assessed uncertainties for the remaining parameters and input data. We assessed the strength and we quantified their inexactnesses with probability distribution functions. Next, we carried out Monte Carlo simulations in each of the four value-orientations to quantify error propagation from the inexactnesses in input data and parameters. We found targets for the year 2015 for Annex I countries differed up to around 20%-points over the four value-orientations. For developing countries differences in allowances were found up to the order of four. In addition, results are affected to a large extent by uncertainties in the other input data and parameters. Ranges in the outcome resulting from uncertainties are between 10 and 35%-points for Annex I countries, depending on the value-orientation chosen and between 20 and 120%-points for non-Annex I countries. However, the ranking of countries within the calculated differentiation remains roughly the same, an exception being the ranking that resulted from the businessman’s perspective. Other consistent combinations of valueladen assumptions may result in objectives that are outside the range that we based on the four value-orientations. We concluded that care should be taken when assessing valueloading in calculations schemes for emissions objectives based on a limited number of value-orientations only. Our analysis clearly underlines the relevance of making explicit policy variables in schemes for the differentiation of commitments. It is necessary to reach consensus on these variables if such schemes are to support negotiations on greenhouse gas emissions allowances. 相似文献