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81.
82.
Past studies of seismic hazard in the U.K. that have used modern probabilistic methods of hazard assessment have been site-specific studies, mostly in connection with nuclear installations. There has been a need for general-purpose maps of seismic hazard to show relative variation of exposure within the U.K. and to give some guidance on absolute values. Such maps have now been produced, incorporating, for the first time, the wealth of new information on historical earthquakes in Britain that has been gathered over the last 15 years. The hazard calculations were undertaken using a new computer code based on the USGS program SEISRISK III, but incorporating a logic tree approach to model variation in the input parameters (e.g. focal depth) or uncertainty in the formulation of the model (e.g. attenuation parameters). An innovative approach was taken to the formulation of seismic source zones, in which two overlapping models were employed. The first of these uses relatively broad source zones based loosely on an interpretation of seismicity and tectonics, while the second uses numerous small zones that reflect the locations of past significant earthquakes. This double approach (using the logic tree methodology) has the merit of both considering the general trend of earthquake activity as well as focusing in on known danger spots. The results show that the areas of highest hazard are western Scotland, north-western England and Wales, where the intensity with 90% probability of non-exceedance in 50 years is 6 EMS. 相似文献
83.
The Africanized honeybee (AHB; Apis mellifera scutellata) is an invasive species which poses a threat to the United States' agricultural industry because of potential decline in pollination services. Previous research has confirmed that the AHB may still expand its range farther north and that limiting environmental factors for AHB distribution vary across the country. This study examines similarities and differences in AHB distribution and the relative importance of environmental factors between two regions of the southwestern United States: southern Utah and southern California. The Maximum Entropy (MaxEnt) modeling approach was used to create two species distribution models of the AHB. First a model was created based on AHB presence data in Utah. This model was used to estimate the Utah distribution and also to project the California distribution based on Utah environmental preferences. The second model was created to predict distribution in California and to project distribution in Utah based on AHB environmental preferences in California. The level of influence of each variable was measured through percent contribution and permutation importance. Model performance was assessed through the area under the receiver operating characteristic curve (AUC). Models estimated AHB presence with high accuracy (AUC > 0.95) in original environments, but were less accurate (AUC < 0.8) in novel environments. Minimum temperature was the primary controlling factor of AHB distribution in each model, and other variables followed similar ranking of importance between the two models. Species response curves varied substantially between the two models. Models did not transfer well from one region to the other because of local differences in response curves and the relative importance of environmental variables, suggesting that AHB in these regions may not have realized their potential geographic range. 相似文献
84.
Marsh vertical accretion via vegetative growth 总被引:1,自引:0,他引:1
John A. Nyman Russel J. Walters Ronald D. Delaune William H. Patrick Jr. 《Estuarine, Coastal and Shelf Science》2006,69(3-4):370
Coastal marshes accrete vertically in response to sea-level rise and subsidence. Inadequate accretion and subsequent conversion of coastal marshes to open water generally is attributed to inadequate mineral sedimentation because mineral sedimentation is widely assumed to control accretion. Using 137Cs dating to determine vertical accretion, mineral sedimentation, and organic matter accumulation, we found that accretion varied with organic accumulation rather than mineral sedimentation across a wide range of conditions in coastal Louisiana, including stable marshes where soil was 80% mineral matter. These results agreed with previous research, but no mechanism had been proposed to explain accretion via vegetative growth. In an exploratory greenhouse experiment, we found that flooding stimulated root growth above the marsh surface. These results indicated the need for additional work to determine if flooding controls accretion in some marshes by stimulating root growth on the marsh surface, rather than by mineral accumulation on the marsh surface. Restoration or management that focus on mineral sedimentation may be ineffective where a relationship between accretion and mineral sedimentation is assumed rather than tested. 相似文献
85.
The relationship between exports and economic growth is a paradigmatic element of modern economic growth policy, despite the absence of strong evidence of a connection. Until recently, data on export production prevented an extensive empirical analysis of metropolitan-scale trade. This article examines the export growth dynamics across large metropolitan statistical areas (MSAs) within the southern United States, a region that has been impacted by economic globalization. These analyses found that some Southern metropolitan areas differ from regional and national averages in selected measures of export performance. Additionally, the export performance of Southern cities was not correlated with all indicators of economic development. This article concludes that export dynamics should be viewed increasingly from an urban frame, with particular emphasis on the production of globally consumed knowledge products and advanced manufacturing. Moreover, export policy should be directed toward the individual strengths of urban regions. 相似文献
86.
ABSTRACT Changes in growing season length (GSL) are of concern for agricultural, phenological, economic, epidemiological, and bioclimatological reasons. This research identifies spatial and temporal changes over the last several decades in GSL, along with the day-of-year of the last spring freeze and first autumn freeze, for the northeastern United States – a region particularly susceptible to such changes due to the large population and intense economic activities. Results suggest that growing season has significantly increased in length since 1980 as compared to prior to 1980, and both spatial and temporal variation in GSL has decreased for the region over time. Changes to GSL for this region are driven more by a shift in the first autumn freeze date than the last spring freeze date. The areas of greatest increase in GSL in the pre- vs. post-1980 period tend to be in the high elevations, near large water bodies, and near the largest cities. Results will assist environmental planners as they prepare mitigation and adaptation strategies amid a changing environment. 相似文献
87.
This study demonstrates the use of spatially downscaled, monthly general circulation model (GCM) rainfall and temperature data to drive the established HyMOD hydrological model to evaluate the prospective effects of climate change on the fluvial run‐off of the River Derwent basin in the UK. The evaluation results of this monthly hydrological model using readily available, monthly GCM data are consistent with studies on nearby catchments employing high‐temporal resolution data, indicating that useful hydro‐climatic planning studies may be possible using standard datasets and modest computational resources. HyMOD was calibrated against 5 km2 gridded UK Climate Projections dataset data and then driven using monthly spatially interpolated (~5 km2) outputs from Hadley Centre Coupled Model, version 3 and the Canadian Centre for Climate Modelling and Analysis for Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios (IPCC‐SRES) A2a and B2a covering the 2020s, 2050s and 2080s. Results for both GCMs project a decrease in annual run‐off in both GCM models and scenarios with higher values in the summer/autumn months, whereas an increase in the later winter months. Both Hadley Centre Coupled Model, version 3 and the Canadian Centre for Climate Modelling and Analysis show higher ranges of uncertainty during the winter season with higher values of run‐off associated with December in all three simulation periods and two scenarios. A seasonal comparison of run‐off simulations shows that both GCMs give similar results in summer and autumn, whereas disparities due to GCM uncertainties are more conspicuous in winter and spring. In this study, both the GCMs under A2a scenario have demonstrated the high possibility of time shift in monthly average peak run‐offs in the Derwent River by 2080s in comparison with the early 21st century. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
88.
Intellectual property rights and low carbon technology transfer: Conflicting discourses of diffusion and development 总被引:1,自引:0,他引:1
David G. Ockwell Ruediger Haum Alexandra Mallett Jim Watson 《Global Environmental Change》2010,20(4):729-738
Intellectual property rights (IPRs) and the transfer of low carbon technologies to developing countries have been the focus of sustained disagreement between many developed and developing country Parties to the United Nations Framework Convention on Climate Change (UNFCCC). We argue that this disagreement stems from two conflicting political discourses of economic development and low carbon technology diffusion which tend to underpin developing and developed countries’ respective motivations for becoming party to the Convention. We illustrate the policy implications of these discourses by examining empirical evidence on IPRs and low carbon technology transfer and highlight how the two discourses are based on an incomplete understanding of the role of technological capacity in either economic development or technology diffusion. This has important implication for the success of post-2012 international climate agreements. 相似文献
89.
新疆及其邻区的地震窗前兆与短期地震预报 总被引:2,自引:0,他引:2
根据新疆及毗邻的独联体部分国家区域台网微震观测记录,通过普查与统计检验,筛选出22个具有较高短期预报效能的地震窗。较系统地研究了地震窗小震月频度的前兆特征及其用于短期地震预报的判据指标,着重介绍了近两年新疆与独联体科技合作的最新成果,同时给出若干成功预报震例,并对所得结果的可能物理机制等问题进行了讨论。 相似文献
90.
Martin J. Haig 《地球表面变化过程与地形》1979,4(2):183-189
Ground retreat was monitored on two vegetated and two unvegetated profiles over a five-year period. The average annual retreat of the two unvegetated profiles was 5.84 mm and 3.62 mm; that of the two vegetated profiles 2.34 mm and 2.07 mm. Slope evolution was controlled by the mid-slope-ward migration of two zones of accelerated erosion and the resulting replacement of a central rectilinear slope segment by the upper and lower slope elements. 相似文献