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排序方式: 共有645条查询结果,搜索用时 31 毫秒
1.
Multivariate analysis of heavy metal contents of sediments from Gumusler creek, Nigde, Turkey 总被引:2,自引:0,他引:2
In this study, heavy metal contents of samples from Gumusler creek in Turkey were studied and the metal contamination characteristics
were investigated. In this respect, considering the pollutant sites in the area, systematic sediment samples were collected
in a zone starting from the manifestation part of the water to the entrance of the Karasu creek in Gumusler town. Samples
were taken from lower section of the river bed at 30 stations along Gumusler creek, 13 km in length and their heavy metal
contents were analyzed with XRF Spectrometer. Correlation coefficients, element coefitic coefficient correlation, dendogram
hierarchical cluster, model summary and Annova analysis statistical methods were applied to data. Strong positive correlations
were determined for some elements which are believed to have possibly the same origin. In addition, mineralizations in the
area are thought to cause variation in metal contents. Results of chemical analysis show that soil limit values and clark
values were exceeded. The heavy metal accumulation in the creek is believed to be derived from non-operated Sb-Hg-W and Fe
quarries. 相似文献
2.
There could be some discontinuities in a soil media such as layers, earth structures, cracks, and fissures so that estimation
of stresses and deformations in these types of soil masses are somewhat different from continuous masses. The discontinuities
in a soil mass could be considered as a special link between two blocks. Transmitted swelling pressures affected by the soil
properties of the backfill especially at the interface between the backfill and retaining wall. In order to estimate the transmitted
swelling pressure distribution behind a retaining wall, using with interface element, a new finite element model and a code
(SWELPRES) have been developed. To evaluate the effect of backfill characteristics and interface element from the transmitted
lateral swelling pressures, four cases of thickness of backfills with or without interface elements are investigated. 相似文献
3.
Erdal Dolu Erkan Gökaşan Engin Meriç Mustafa Ergin Tolga Görüm Hüseyin Tur Berkan Ecevitoğlu Niyazi Avşar Muhittin Görmüş Fatmagül Batuk Buğser Tok Oktay Çetin 《Geo-Marine Letters》2007,27(6):355-381
The Quaternary evolution of the Gulf of İzmit, situated on the tectonically active North Anatolian Fault Zone (NAFZ), was
investigated using seismic reflection, paleontologic, and sediment textural data. On the basis of seismic stratigraphic and
sedimentologic-paleontologic interpretations, four depositional units were distinguished within the Plio-Quaternary sequence
of the Gulf of İzmit. According to these data, Plio-Quaternary deposits supplied from the northern terrestrial area started
to accumulate during a progradational phase, in a south-facing half-graben. A coarse-grained sedimentary unit prograding into
the gulf from the south since 200 ka b.p. indicates a dramatic variation in the evolution of the gulf, with the initiation of a new strike-slip fault of the NAFZ
and a corresponding uplift of the Armutlu Peninsula in the south of the gulf. During the evolution of this fault from a wide
shear zone consisting of right-stepped strike-slip faults and pull-apart basins to a localized principal fault zone, sediments
were deposited under the influence of northerly prograding terrestrial and shallow-marine conditions due to relative sea-level
fluctuations in the Marmara Sea. During this period, the Gulf of İzmit was invaded mainly by Mediterranean and partly by Black
Sea waters. In the latest glacial period, shallow areas in the gulf became subaerially exposed, whereas the central and western
sub-basins of the gulf turned into lakes. The present evolution of the Gulf of İzmit is controlled by the after effects of
the new rupture of the NAFZ and the estuarine nature of the gulf environment. 相似文献
4.
Capturing strain localization in reinforced soils 总被引:2,自引:1,他引:1
Lade’s single hardening soil model with Cosserat rotation embodied in the finite element method is employed to investigate
the behavior of geosynthetic reinforced soils with special attention to the development of shear banding. The ability of the
finite element model to detect shear banding in a reinforced soil is examined against three high quality small-scale laboratory
plane strain tests on Toyoura sand with and without reinforcement. These three tests were chosen because of the clear failure
surfaces that developed in the soil during loading. The FEM analyses were able to reasonably simulate the plane strain laboratory
tests including both unreinforced and reinforced cases. The FEM analyses gave reasonably good agreement with the experimental
results in terms of global stress–strain relationships and shear band occurrences. Furthermore, and based on FE analyses of
a hypothetical geosynthetic reinforced soil (GRS) retaining wall, it is shown that the geosynthetic reinforcements are very
effective in hindering the formation of shear bands in GRS retaining walls when small spacing between the reinforcement layers
was used. When used properly, the geosynthetic reinforcements made the soil behave as a truly reinforced mass of considerable
stiffness and strength. 相似文献
5.
The study area is situated within the complex structure and karst system of the western Taurids. Basinwide interpretation of the structural features, each of which has great importance, will enlighten many complicated hydrogeologic problems encountered in the area. Thus, considering the previous views on the structural geology of the area, an interpretation of the structural and tectonic features of the study area by means of satellite images was undertaken, and based on the data gained, new approaches were suggested to solve the hydrogeological problems. In particular, determination of the recharge-discharge mechanisms of the Olukköprü and Dumanli karst springs, which are the most important karst groundwater discharge points in the region, has been attempted. Within the framework of this study, a tectonic-lineament map of a large area covering Eirdir, Beyehir, and Sula lakes at the north and the basins to the south of these lakes was prepared. 相似文献
6.
Sven O. Franz Lorenz Schwark Cathrin Brüchmann Burkhard Scharf Ralf Klingel Jon D. Van Alstine Namık Çagatay Umut B. Ülgen 《Journal of Paleolimnology》2006,35(4):715-736
A limnogeological reconnaissance study was carried out on Lake Iznik, located in the southeast of the Marmara region of Turkey,
involving a seismic survey and collection of short sediment cores. This lake is located on the middle branch of the North
Anatolian Fault Zone (NAFZ), a transform plate boundary between the Eurasian and Anatolian Plates. It is, therefore, tectonically
active and offers an opportunity to investigate the interplay of sedimentary and seismo-tectonic processes, as well as climate
change and human impact in the region. Short cores of the three sub-basins, maximum length of 35.5 cm, recovered non-laminated,
blackish clays and silts with varying amounts of biogenic and minerogenic (allochthonous, autochthonous) material, which documented
almost the last 80 years of deposition and environmental history. High sedimentation rates in the deeper core sections are
accompanied by changes in land use (conversion of woodland to farmland) in the northern areas of Lake Iznik, which caused
the deposition of more weathered material (high K/Na ratios) and higher contents of Mn in the lake. A tendency towards eutrophic
conditions within the last 20 years is indicated by high nutrient content (N, TOC, P), decreasing C/N-ratios, and characteristic
diatom and cladoceran associations. Also increased pollution is revealed by higher Pb, Cu, and Zn contents and increased supply
of human and animal faeces (high coprostanol content) during the last two decades. But simultaneous lower sedimentation rates
towards the core tops complicate the reconstruction of recent and past eutrophication and pollution states of Lake Iznik.
This requires an extension of the pilot study and deeper sediment cores, to recover non-anthropogenic influenced sediment
levels. 相似文献
7.
8.
There are several different approaches currently taken by the 15 EU countries in compiling their IPCC inventories for the FCCC. Six countries (France, Ireland, Italy, Luxembourg, Portugal, Spain) use the CORINAIR system and then aggregate and reformat the data into the required IPCC format. Of the remaining countries, two strictly follow the IPCC methodology (Finland and Greece), five (Denmark, Germany, Netherlands, Sweden, United Kingdom) estimate emissions using a combination of national and IPCC methodologies, while the final two (Austria and Belgium) use a combination of national and CORINAIR methodologies (transformed to IPCC). Comparison of the national inventories in both the IPCC and CORINAIR formats shos some revealing discrepancies between the two systems at both sector and gas level that by chance cancel out when aggregated at the EU level. 相似文献
9.
10.