全文获取类型
收费全文 | 407篇 |
免费 | 21篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 9篇 |
大气科学 | 21篇 |
地球物理 | 123篇 |
地质学 | 117篇 |
海洋学 | 34篇 |
天文学 | 58篇 |
综合类 | 1篇 |
自然地理 | 66篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 13篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 21篇 |
2017年 | 14篇 |
2016年 | 15篇 |
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 24篇 |
2012年 | 15篇 |
2011年 | 24篇 |
2010年 | 22篇 |
2009年 | 35篇 |
2008年 | 23篇 |
2007年 | 22篇 |
2006年 | 20篇 |
2005年 | 10篇 |
2004年 | 13篇 |
2003年 | 14篇 |
2002年 | 7篇 |
2001年 | 15篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1970年 | 1篇 |
1969年 | 3篇 |
1968年 | 2篇 |
1933年 | 1篇 |
1928年 | 1篇 |
排序方式: 共有429条查询结果,搜索用时 46 毫秒
151.
152.
A. A. Velichko O. K. Borisova A. N. Drenova E. M. Zelikson V. A. Klimanov Yu. M. Kononov 《地理信息系统科学与遥感》2013,50(1):11-27
The authors describe the evolution of a new field in cartography—the substantive basis of which is the preparation of a series of spatial reconstructions (climate, landscape components) of the past on the basis of principles of comprehensive mapping of contemporary geosystems. The paper investigates how such an approach may be used to assess the present status of landscapes from the perspective of their general evolution and assist in the formulation of long-range predictions. Translated by Edward Torrey, Alexandria, VA from: Izvestiya Akademii Nauk, seriya geograficheskaya, 1998, No. 5, pp. 30-43. 相似文献
153.
Dr Helen Mounsey 《International journal of geographical information science》2013,27(3):259-261
Spatial data uncertainty models (SDUM) are necessary tools that quantify the reliability of results from geographical information system (GIS) applications. One technique used by SDUM is Monte Carlo simulation, a technique that quantifies spatial data and application uncertainty by determining the possible range of application results. A complete Monte Carlo SDUM for generalized continuous surfaces typically has three components: an error magnitude model, a spatial statistical model defining error shapes, and a heuristic that creates multiple realizations of error fields added to the generalized elevation map. This paper introduces a spatial statistical model that represents multiple statistics simultaneously and weighted against each other. This paper's case study builds a SDUM for a digital elevation model (DEM). The case study accounts for relevant shape patterns in elevation errors by reintroducing specific topological shapes, such as ridges and valleys, in appropriate localized positions. The spatial statistical model also minimizes topological artefacts, such as cells without outward drainage and inappropriate gradient distributions, which are frequent problems with random field-based SDUM. Multiple weighted spatial statistics enable two conflicting SDUM philosophies to co-exist. The two philosophies are ‘errors are only measured from higher quality data’ and ‘SDUM need to model reality’. This article uses an automatic parameter fitting random field model to initialize Monte Carlo input realizations followed by an inter-map cell-swapping heuristic to adjust the realizations to fit multiple spatial statistics. The inter-map cell-swapping heuristic allows spatial data uncertainty modelers to choose the appropriate probability model and weighted multiple spatial statistics which best represent errors caused by map generalization. This article also presents a lag-based measure to better represent gradient within a SDUM. This article covers the inter-map cell-swapping heuristic as well as both probability and spatial statistical models in detail. 相似文献
154.
Illarionov V. K. Boyko A. N. Borisova A. Yu. Ilyinsky D. A. 《Izvestiya Atmospheric and Oceanic Physics》2021,57(10):1322-1348
Izvestiya, Atmospheric and Oceanic Physics - The morphostructural characteristics of the main taxa of southern Indian Ocean, such as the Del Cano-Crozet, Conrad, and Kerguelen plateaus, are given... 相似文献
155.
Helen E. Fox Carrie S. Soltanoff Michael B. Mascia Kelly M. Haisfield Alfonso V. Lombana Christopher R. Pyke Louisa Wood 《Marine Policy》2012
The relative paucity and heterogeneous distribution of marine protected areas (MPAs) indicates the need for better understanding of factors that foster MPA establishment at local, sub-national, and national levels. The relationship between national-level MPA establishment and geographic, ecological, social, and political factors that may drive patterns and trends in MPA establishment were assessed. A country's coastline length is the strongest predictor of both the number and spatial extent of MPAs. Controlling for coastline, the Human Development Index (HDI) and spatial overlap with designated conservation priority areas are positively correlated with MPA establishment. Surprisingly, some factors influencing MPA establishment in case studies, such as percentage of fishers within a population, were not correlated with MPA establishment on a national scale. These national dynamics explain a relatively small proportion of variation, however, indicating that other biological or social factors, as well as sub-national processes, also influence MPA establishment. Positive and negative outliers illuminate the importance of policy engagement at both national and local levels. Ensuring a supportive enabling environment at the national or even multi-national level can enhance success at the local level. 相似文献
156.
Vegetation and hydraulic-morphological interactions at the individual plant, patch and channel scale
Interactions between vegetation, flow and sediment are a key ingredient for the development of vegetated islands in highly
dynamic, fluvial alpine ecosystems such as the Tagliamento River, north-east Italy. There has been substantial research on
factors influencing the establishment of vegetation and feedback mechanisms between vegetation, hydraulic, and geomorphological
processes in such environments. This has yielded the development of conceptual models identifying different trajectories of
vegetation and landform development from bare gravel to established floodplain forest. Nevertheless, some of the finer-scale
processes underpinning such interactions are not well understood and parameterisation concepts that augment our knowledge
from process understanding to quantified data and prediction models are not available until now. This paper identifies mechanisms
and parameters of vegetation-flow interaction at the individual scale that are reflected at a patch or even at the channel
scale. These mechanisms are reviewed from a multi-disciplinary perspective and concepts and analogies are proposed that provide
ideas to progress research towards the development of predictive vegetation-flow models. Such models must incorporate both
hydraulic and ecological components and this is demonstrated for a simplified force-bending model of Salicaceae seedlings.
The development of such models demands advances in the individual disciplines of hydraulics, morphology, plant ecology and
biomechanics, which offers many possibilities for multidisciplinary research between these disciplines. 相似文献
157.
A comparison of seismic risk maps for Italy 总被引:5,自引:3,他引:2
Helen Crowley Miriam Colombi Barbara Borzi Marta Faravelli Mauro Onida Manuel Lopez Diego Polli Fabrizio Meroni Rui Pinho 《Bulletin of Earthquake Engineering》2009,7(1):149-180
National seismic risk maps are an important risk mitigation tool as they can be used for the prioritization of regions within
a country where retrofitting of the building stock or other risk mitigation measures should take place. The production of
a seismic risk map involves the convolution of seismic hazard data, vulnerability predictions for the building stock and exposure
data. The seismic risk maps produced in Italy over the past 10 years are compared in this paper with recent proposals for
seismic risk maps based on state-of-the-art seismic hazard data and mechanics-based vulnerability assessment procedures. The
aim of the paper is to open the discussion for the way in which future seismic risk maps could be produced, making use of
the most up-to-date information in the fields of seismic hazard evaluation and vulnerability assessment. 相似文献
158.
Lynda C. Howard Paul J. Wood Malcolm T. Greenwood Helen M. Rendell 《Journal of Paleolimnology》2009,42(4):453-466
Sub-fossil insect remains have the potential to characterise changing environmental conditions in both lentic and lotic water
systems, however, relatively few studies have been undertaken in riverine environments. This paper uses sub-fossil caddisfly
larvae (Trichoptera) and aquatic beetles (Coleoptera) to reconstruct river flow conditions for a large paleochannel (from
multiple monoliths) using the Lotic invertebrate Index for Flow Evaluation (LIFE). Examination of the larval Trichoptera and
Coleoptera remains indicated a marked change in the community and flow environment, as suggested by paleoLIFE scores within
the profile of three of the monoliths examined. At the base of the channel the community was characterised by taxa indicative
of high energy lotic habitats with predominantly mineral substrates (e.g. Trichoptera: Hydropsyche
contubernalis and Brachycentrus
subnubilis, Coleoptera: Elmis
aenea and Esolus
parallelepipedus). Within three of the monoliths there was a change in community composition to one indicative of a low energy backwater/lentic
environment with abundant submerged and emergent vegetation (e.g. Trichoptera: Phryganea
bipunctata and Limnephilus
flavicornis, Coleoptera: Colymbetes
fuscus and Hydrobius
fuscipes). Detrended Correspondence Analysis (DCA) and loss of mass on ignition (LOI) indicated the presence of a strong environmental
gradient within the data, associated with river flow. The utilisation of two aquatic insect orders provides clear evidence
of temporal changes within the instream community and when combined with knowledge of ecological and habitat associations,
allows differences between the two groups to be interpreted more clearly. 相似文献
159.
Development and assessment of damage‐to‐loss models for moment‐frame reinforced concrete buildings
下载免费PDF全文
![点击此处可从《地震工程与结构动力学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Luís Martins Vítor Silva Mário Marques Helen Crowley Raimundo Delgado 《地震工程与结构动力学》2016,45(5):797-817
The assessment of earthquake loss often requires the definition of a relation between a measure of damage and a quantity of loss, usually achieved through the employment of a damage‐to‐loss model. These models are frequently characterized by a large variability, which inevitably increases the uncertainty in the vulnerability assessment and earthquake loss estimation. This study provides an insight on the development of damage‐to‐loss functions for moment‐frame reinforced concrete buildings through an analytical methodology. Tri‐dimensional finite element models of existing reinforced concrete buildings were subjected to a number of ground motion records compatible with the seismicity in the region of interest, through nonlinear dynamic analysis. These results were used to assess, for a number of damage states, the probability distribution of loss ratio, taking into consideration member damage and different repair techniques, as well as to derive sets of fragility functions. Then, a vulnerability model (in terms of the ratio of cost of repair to cost of replacement, conditional on the level of ground shaking intensity) was derived and compared with the vulnerability functions obtained through the combination of various damage‐to‐loss models with the set of fragility functions developed herein. In order to provide realistic estimates of economic losses due to seismic action, a comprehensive study on repair costs using current Portuguese market values was also carried out. The results of this study highlight important issues in the derivation of vulnerability functions, which are a fundamental component for an adequate seismic risk assessment. © 2015 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd. 相似文献
160.
Helen M. Roe G. Russell Coope Robert J.N. Devoy Colin J.O. Harrison Kirsty E.H. Penkman Richard C. Preece Danielle C. Schreve 《Quaternary Science Reviews》2009,28(23-24):2342-2373
Multidisciplinary investigations of the vegetational, faunal and sea-level history inferred from the infills of buried channels on the coast of eastern Essex have a direct bearing on the differentiation of MIS 11 and MIS 9 in continental records. New data are presented from Cudmore Grove, an important site on Mersea Island that can be linked to the terrace sequence of the River Thames. The vegetational history has been reconstructed from a pollen sequence covering much of the interglacial represented. The temperate nature of the climate is apparent from a range of fossil groups, including plant remains, vertebrates (especially the rich herpetofauna), molluscs and beetles, which all have strong thermophilous components. The beetle data have been used to derive a Mutual Climatic Range reconstruction, suggesting that mean July temperatures were about 2 °C warmer than modern values for southeast England, whereas mean January temperatures may have been slightly colder. The sea-level history has been reconstructed from the molluscs, ostracods and especially the diatoms, which indicate that the marine transgression occurred considerably earlier in the interglacial cycle than at the neighbouring Hoxnian site at Clacton. There are a number of palynological similarities between the sequence at Cudmore Grove and Clacton, especially the presence of Abies and the occurrence of Azolla filiculoides megaspores. Moreover, both sites have yielded Palaeolithic archaeology, indeed the latter is the type site of the Clactonian (flake-and-core) industry. However, the sites can be differentiated on the basis of mammalian biostratigraphy, new aminostratigraphic data, as well as the differences in the sea-level history. The combined evidence suggests that the infill of the channel at Cudmore Grove accumulated during MIS 9, whereas the deposits at Clacton formed during MIS 11. The infill of a much later channel, yielding non-marine molluscs and vertebrates including Hippopotamus, appears to have formed during the Ipswichian (MIS 5e). This evidence is compared with other important sites of late Middle Pleistocene age in Britain and elsewhere on the continent and the importance of a multidisciplinary approach is stressed. 相似文献