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排序方式: 共有271条查询结果,搜索用时 31 毫秒
71.
K. Onder Cetin T. Leslie Youd Raymond B. Seed Jonathan D. Bray Rodolfo Sancio W. Lettis M. Tolga Yilmaz H. Turan Durgunoglu 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):1083-1092
This paper presents a study of liquefaction-induced ground deformations at the Hotel Sapanca site during the 1999 Kocaeli (Izmit)—Turkey earthquake. The paper discusses: (1) observed ground deformations and displacements after the earthquake, (2) the results of field investigations by means of borings and in situ index tests including standard penetration tests (SPT), static cone penetration tests (CPT) and piezocone (CPTU) tests, (3) analyses of observed ground settlements and lateral deformations by a suite of methods, and (4) comparisons of observed and calculated ground movements. 相似文献
72.
Huiwei Chen Mee Kam Ng Murat Es Joanna Lee Winnie W. S. Mak Yuying Tong 《Urban geography》2018,39(7):969-987
This paper draws on theoretical discussions of world cities to analyze socio-spatial polarization and (re-)distribution of deprived groups in Hong Kong in the 2000s. Intensifying global economic restructuring processes have induced socio-economic polarization, thereby producing deprived groups although the spatial outcomes may depend on the city-specific context. When local policies do not counteract the polarization trend, a spatial manifestation of widening socio-economic gaps can be expected. Intensified pro-growth policies adopted since Hong Kong’s return to Chinese rule in 1997 and during its economic recession in the early 2000s have worsened the impact of globalization-induced socio-economic and spatial restructuring. Census data from 2001 and 2011 show increasingly differentiated socio-economic profiles at the district level. The analysis offered in this study also points to a decreased socially mixed society in 2011 when the deprived groups lived in districts with less presence of the advantaged population. 相似文献
73.
Cokriging for enhanced spatial interpolation of rainfall in two Australian catchments 总被引:1,自引:0,他引:1
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Rainfall data in continuous space provide an essential input for most hydrological and water resources planning studies. Spatial distribution of rainfall is usually estimated using ground‐based point rainfall data from sparsely positioned rain‐gauge stations in a rain‐gauge network. Kriging has become a widely used interpolation method to estimate the spatial distribution of climate variables including rainfall. The objective of this study is to evaluate three geostatistical (ordinary kriging [OK], ordinary cokriging [OCK], kriging with an external drift [KED]), and two deterministic (inverse distance weighting, radial basis function) interpolation methods for enhanced spatial interpolation of monthly rainfall in the Middle Yarra River catchment and the Ovens River catchment in Victoria, Australia. Historical rainfall records from existing rain‐gauge stations of the catchments during 1980–2012 period are used for the analysis. A digital elevation model of each catchment is used as the supplementary information in addition to rainfall for the OCK and kriging with an external drift methods. The prediction performance of the adopted interpolation methods is assessed through cross‐validation. Results indicate that the geostatistical methods outperform the deterministic methods for spatial interpolation of rainfall. Results also indicate that among the geostatistical methods, the OCK method is found to be the best interpolator for estimating spatial rainfall distribution in both the catchments with the lowest prediction error between the observed and estimated monthly rainfall. Thus, this study demonstrates that the use of elevation as an auxiliary variable in addition to rainfall data in the geostatistical framework can significantly enhance the estimation of rainfall over a catchment. 相似文献
74.
Geotechnical evaluation of Miocene gypsum from Sivas (Turkey) 总被引:2,自引:0,他引:2
Gypsum is widely distributed in Sivas (Turkey), occurring chiefly in the formations of Miocene age. The gypsum is generally of the alabastrine type with a little of the porphiroblast type and contains traces of clay minerals, anhydrite and calcite. It is a moderately strong rock in terms of its unconfined compressive strength which is related to the crystal size. Strength increases as the crystal size decreases. The strength of gypsum was reduced by approximately 55%, when the samples were kept in the water for 20 days. Most samples exhibit plastic–elastic–plastic deformation. The gypsum has a high modulus ratio, and is a moderately deformable rock. High lateral deformations and low vertical deformations are observed under the vertical stress conditions in accordance with the relationship between modulus ratio and strain. 相似文献
75.
Caitlin Balthrop Moffitt Faisal Hossain Robert F. Adler Koray K. Yilmaz Harold F. Pierce 《International Journal of Applied Earth Observation and Geoinformation》2011
Although the TRMM-based Flood Detection System (FDS) has been in operation in near real-time since 2006, the flood ‘detection’ capability has been validated mostly against qualitative reports in news papers and other types of media. In this study, a more quantitative validation of the FDS over Bangladesh against in situ measurements is presented. Using measured stream flow and rainfall data, the study analyzed the flood detection capability from space for three very distinct river systems in Bangladesh: (1) Ganges– a snowmelt-fed river regulated by upstream India, (2) Brahmaputra – a snow-fed river that is braided, and (3) Meghna – a rain-fed and relatively flashier river. The quantitative assessment showed that the effectiveness of the TRMM-based FDS can vary as a function of season and drainage basin characteristics. Overall, the study showed that the TRMM-based FDS has great potential for flood prone countries like Bangladesh that are faced with tremendous hurdles in transboundary flood management. The system had a high probability of detection overall, but produced increased false alarms during the monsoon period and in regulated basins (Ganges), undermining the credibility of the FDS flood warnings for these situations. For this reason, FDS users are cautioned to verify FDS estimates during the monsoon period and for regulated rivers before implementing flood management practices. Planned improvements by FDS developers involving physically-based hydrologic modeling should transform the system into a more accurate tool for near real-time decision making on flood management for ungauged river basins of the world. 相似文献
76.
Ali Kiliçoğlu Ahmet Direnç Hasan Yildiz Murat Bölme Bahadir Aktuğ Mehmet Simav Onur Lenk 《Studia Geophysica et Geodaetica》2011,55(4):557-578
Turkish regional geoid models have been developed by employing a reference earth gravitational model, surface gravity observations
and digital terrain models. The gravimetric geoid models provide a ready transformation from ellipsoidal heights to the orthometric
heights through the use of GPS/leveling geoid heights determined through the national geodetic networks. The recent gravimetric
models for Turkish territory were computed depending on OSU91 (TG-91) and EGM96 (TG-03) earth gravitational models. The release
of the Earth Gravitational Model 2008 (EGM08), the collection of new surface gravity observations, the advanced satellite
altimetry-derived gravity over the sea, and the availability of the high resolution digital terrain model have encouraged
us to compute a new geoid model for Turkey. We used the Remove-Restore procedure based on EGM08 and applied Residual Terrain
Model (RTM) reduction of the surface gravity data. Fast Fourier Transformation (FFT) was then used to obtain the residual
quasigeoid from the reduced gravity. We restored the individual contributions of EGM08 and RTM to the whole quasi-geoid height
(TQG-09). Since the Helmert orthometric height system is adopted in Turkey, the quasi-geoid model (TQG-09) was then converted
to the geoid model (TG-09) by making use of Bouguer gravity anomalies and digital terrain model. After all we combined a gravimetric
geoid model with GPS/leveling geoid heights in order to obtain a hybrid geoid model (THG-09) (or a transformation surface)
to be used in GPS applications. The RMS of the post-fit residuals after the combination was found to be ± 0.95 cm, which represents
the internal precision of the final combination. And finally, we tested the hybrid geoid model with GPS/leveling data, which
were not used in the combination, to assess the external accuracy. Results show that the external accuracy of the THG-09 model
is ± 8.4 cm, a precision previously not achieved in Turkey until this study. 相似文献
77.
The teleseismic P receiver functions are customarily inverted to attain the seismic velocities beneath a seismic station. Surface wave dispersion
data are often added to reduce the effect of the non-uniqueness. The combination of P receiver function and surface wave works well in resolving the structures in the crust and uppermost mantle, but is less
effective in characterizing greater (lithosphere and asthenosphere) depths due to the interference from crustal multiples.
A solution to this problem is jointly to model teleseismic S receiver functions with surface wave and P receiver functions. This study adopts a fast, one-dimensional (1-D) inversion scheme. To avoid the effect of multidimensional
structures away from the seismic station, we eliminate multiples that reverberate between the surface and interfaces below
a restriction depth (RD), as well as S-to-P conversions below an inversion depth (ID). P-to-S conversions off the interfaces above the half-space and S-to-P conversions above the ID and multiples above the RD are properly modelled. This approach favours ray paths travelling close
to stations and is, therefore, more suitable for 1-D inversions. We perform numerical experiments with and without noise and
highlight the advantages of a joint receiver function and surface wave analysis. 相似文献
78.
The Miocene Kahramanmara? Peripheral Foreland Basin (KPFB) resemble to classic foreland basin model, with small differences. In the classic model, both the accretionary wedge and foredeep extend lengthways parallel to the plate margin. In addition, accretionary wedge includes wedge top basin or piggy back basin that extends parallel to foredeep. However, the accretionary wedge of the KPFB contains small half-graben type basins that obliquely intersect the plate margin between the Arabian Plate and the Anatolide–Taurides Platform (due to the irregular shape of the plate boundary). Tectonic lineaments controlled the shape and orientation of these basins and larger main depocentre of the KFPB, which were predominantly filled with deep-sea sediments. This paper focuses on the provenance of features of the KFPB, predominantly was fed from the northern basin margin, while also aiming to resolve the complex basin evolution that occurred during the Miocene.Clasts of Palaeozoic and Mesozoic limestone and ophiolites are common components of the confined deep-water clastic systems, which evolved as elongated trenches in the north-western sector of the KPFB during the Early-Middle Miocene. During the Middle Miocene, continuous thrusting of the northern basin margin to south caused depocentre migration to south-east, through the basin interior. At that time, the north-east and central depocentres of the KPFB were filled primarily by clasts of ophiolite and metamorphic units. The tectonic control on basin fill architecture can be observed anywhere in the KFPB. The principal tectonic features controlled the geometry and orientation of the canyon, the channel geometry of the deep-water slope on the northern basin margin, the frequency and distribution of slump-slide-debris flows and the overall pattern of sedimentation cycles in the stratigraphy of the slope and the central basin floor. Some basin sectors have continuously reactivated and as a result, different sediment entry points with substantial local accumulation of sediment and deformation have evolved on the slope and basin floor. Three scales of provenance were used to investigate the source rock: (a) field-based observation and analysis of conglomerate clasts, (b) modal analysis of sandstone facies and (c) geochemical analysis, all of which were in agreement. 相似文献
79.
A GIS model for preliminary hazard assessment of swelling clays,a case study in Harran plain (SE Turkey) 总被引:2,自引:1,他引:1
Swelling behavior of clayey soils regarded as a hidden disaster, causes a great deal of damage in light hydraulic structures
such as drinking water network, irrigation pipes or open canal linings through which water can easily leak and penetrate into
soil during loading and unloading stages. Early identification during site investigation and laboratory testing is extremely
important to ensure that the appropriate design strategy is adopted. The clay soils having swelling potential are generally
found in arid and semi-arid regions, such as in the Şanlıurfa-Harran plain located in the southeast of Turkey. The problems
associated with swelling clays occurred for the lightweight hydraulic structures constructed in Turkey have been met during
the construction of irrigation structures in the scope of Southeast Anatolian Project as the Turkey’s greatest water resources
project. Therefore, the identification of such soils and the assessment of their swelling potential parameters are necessary
for hazard mitigation planning and land-use management. In this scope, extensive geotechnical study is executed for an investigation
area. The samples were obtained from the Harran plain where many irrigation canal structures are constructed, and geotechnical
study was performed on these samples. Atterberg limit tests often provide the basic field information to substantiate the
soil’s swelling nature. The plasticity index (PI) and liquid limit (LL) values are also used extensively for classifying swelling
soil and should always be determined during preliminary investigations. Because of this, LL and PI are assessed by using geographical
information system (GIS)-based computer software, and LL and PI contour maps are created. Swelling percentages of the soil
samples were carried out on both undisturbed and compacted soil samples by using direct methods. As a result of this extensive
study, the values of swelling percentages determined for each location are used to obtain the swelling potential hazard map
of the area by means of a GIS program. The results of GIS analyses for this area indicate that the analyses based on a lot
of data introduce meaningful results for this study. It is expected that these maps will be a useful tool for planners and
engineers in their efforts to achieve better land-use planning and to decide necessary remedial measures. 相似文献
80.
Trend and homogeneity analysis in temperature and rainfall series in western Black Sea region,Turkey
Theoretical and Applied Climatology - This paper includes a study which applied homogeneity and trend tests on time series of monthly mean temperature and monthly total rainfall recorded in the... 相似文献