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41.
This study presents the identification of wave propagation using the information measured at a fixed point. The mathematical model used to carry out this research is an integral equation. The equation turned out to be a Fredholm integral equation of the first kind. The discretized matrix equation yielded an ill-conditioned system. To secure the stability of the system, Tikhonov regularization was applied to the ill-conditioned system. The analysis of the numerical computation proved that the regularization was able to retain the target spectrum. 相似文献
42.
The authors of the present paper have suggested an iterative scheme to calculate the nonlinear wave profiles [Jang and Kwon, 2005. Application of nonlinear iteration scheme to the nonlinear water wave problem: Stokes wave. Ocean Engineering 32, 1862–1872]. The scheme was shown to be good for estimating nonlinear wave profiles. In the study, the iterative scheme is applied to the wave-diffraction problem by a long breakwater to calculate a diffracted wave by the breakwater. The iterative solution of diffraction was compared with the linear solution of Sommerfeld, 1896. [Mathematische Theoried der Diffraction. Mathematical Annals 47, 317–374]. For a small wave slope, the two solutions were in good agreement. However, the scheme enabled us to observe the nonlinear behaviors of a beating phenomenon and of wave profile such as Stokes’ wave for a relatively large wave slope: as the wave slope becomes larger, we can examine the nonlinear wave characteristics of the actual shapes of waves, i.e., the crests are steeper and the troughs are flatter. 相似文献
43.
Lee Seok Oh Kyung-Hee Jang Sung-Tae You Hak Yoel Park Joonsung Song Kyu-Min 《Ocean Science Journal》2019,54(1):39-50
Ocean Science Journal - A practical method to estimate the M2 tidal current is proposed based on one-day current observations. In this method, the semi-diurnal constituent, composed of several... 相似文献
44.
The warming of the Earth's atmosphere system is likely to change temperature and precipitation, which may affect the climate, hydrology and water resources at the river basins over the world. The importance of temperature change becomes even greater in snow or glacier dominated basins where it controls the snowmelt processes during the late‐winter, spring and summer months. In this study hydrologic responses of streamflow in the Pyanj and Vaksh River basins to climate change are analysed with a watershed hydrology model, based on the downscaled atmospheric data as input, in order to assess the regional climate change impact for the snowfed and glacierfed river basins in the Republic of Tajikistan. As a result of this analysis, it was found that the annual mean river discharge is increasing in the future at snow and glacier dominated areas due to the air temperature increase and the consequent increase in snow/ice melt rates until about 2060. Then the annual mean flow discharge starts to decrease from about 2080 onward because the small glaciers start to disappear in the glacier areas. It was also found that there is a gradual change in the hydrologic flow regime throughout a year, with the high flows occuring earlier in the hydrologic year, due to the warmer climate in the future. Furthermore, significant increases in annual maximum daily flows, including the 100‐year return period flows, at the Pyanj and Vaksh River basins toward the end of the 21st century can be inferred from flood frequency analysis results. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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47.
Kinmen is located in the south‐west of Mainland China and mainly has two islands, Large Kinmen and Leiyu. Residents in Kinmen have drunk groundwater over several decades. This work characterized the quality of groundwater in Kinmen using factor analysis (FA), cluster analysis (CA) and geochemical simulation. The factor scores were plotted spatially to illustrate the groundwater quality and were used to discuss the grouped relationship using CA. Salinization, redox and organic matter factors are identified from 17 hydrochemical measurements in 18 wells. Acidic and oxidizing groundwater with nitrate‐N pollution is distributed mainly in the west of Large Kinmen. Saline groundwater is distributed to the north‐east of Large Kinmen and in the south of Leiyu. Groundwater with organic matter is present throughout Leiyu. Five groups of the groundwater quality divided by CA can be interpreted according to one to three factors. The grouped characteristics of the groundwater quality help the local government and industries to plan the use and protection of groundwater resources. Furthermore, a geochemical simulation was used to demonstrate the formation processes of the acidic and oxidizing groundwater properties in granitic sediments. A large amount of the precipitation of the kaolinite and magnetite releases concentrations of hydrogen ion and raises the redox potential in the aquifers. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
48.
Plagioclase separates from the Layered Series (LS), Upper Border Series (UBS), and Marginal Border Series (MBS) of the Skaergaard
intrusion were analyzed to examine major and trace element variations. In general, plagioclase from the LS, UBS, and MBS show
similar trends in major elements vs. crystallization: SiO2, Na2O, and K2O progressively increase, and CaO and MgO progressively decrease with fractionation. No abrupt changes in the trends of major
components of Skaergaard plagioclase during the differentiation of the intrusion are observed. Trace elements in plagioclase
reflect changes in the Skaergaard magma and changes in plagioclase distribution coefficients with differentiation. Sr, Ga,
and probably Ba are included elements in Skaergaard plagioclase, but were excluded from the other cumulus phases, and as a
result systematically increased in the magma and plagioclase during differentiation. Be, Cs, Hf, Rb, Ta, U, and Zr, and the
transition metals Co, Cr, Cu, Ni, Sc, V, and Zn were excluded elements in Skaergaard plagioclase, and remained low in plagioclase
during differentiation. Changes in the abundances of these elements in plagioclase during differentiation reflect changes
in their abundance in the magma. With the exception of the lower zone, which is enriched in the light rare earth elements,
rare earth elements in LS plagioclase, in general, increase with differentiation of the Skaergaard intrusion, but decrease
dramatically at the UZa/UZb boundary where abundant apatite first appears. Rare earth elements in UBS plagioclase followed
a similar trend to LS plagioclase, except during the initial and final stages of differentiation. UBS plagioclase is much
more enriched in rare earth elements during the final 20% of crystallization, except for Eu, which is similar in plagioclase
from the two series. The observed trends suggest that the floor and roof sequences became isolated from each other and that
the floor sequence may have been more reducing and the roof sequence more oxidizing during the final 20% of crystallization.
As the Skaergaard magma ceased convection, or convected as isolated cells, during the final stages of differentiation, volatile
elements may have accumulated in the UBS magma, resulting in an increase in ƒO2, and a decrease in Eu/Sm in UBS plagioclase. The observed trends of rare earth elements in plagioclase from the LS and UBS
fit well with theoretical calculations that assume closed-system crystallization, and would be difficult to reconcile with
any model requiring significant discharge of magma from the chamber during the final 20% of crystallization. The enrichment
of light rare earth elements in plagioclase, suggests that the lower part of the intrusion re-equilibrated with a late, light
rare earth element-rich fluid or melt. The recharge model proposed by earlier workers to explain anomalous Sr and Nd isotopes
appears unlikely in light of the two to fourfold enrichment of light rare earth elements in these samples.
Received: 1 October 1999 / Accepted: 14 May 2000 相似文献
49.
For materials of very low hydraulic conductivity used in the landfill liner systems, e.g., natural clay liners, soil-cement liners, etc., diffusion characteristics should be evaluated, as the transport mechanism of contaminant through them is diffusion controlled. Studies on the diffusion characteristics of the hardened liner materials, such as the soil cement, are relatively few compared with those of clayey soils. In this paper, diffusive characteristics of hardened liner materials (HLMs) applied to the liner system of Sudokwon Metropolitan Landfill in Korea, were studied. Laboratory pure diffusion column tests in the pure- and the advection-diffusion status were performed for the chemicals, NaCl, KCl, and CaCl2. To evaluate the diffusion coefficient of a HLMs system, a one-dimensional numerical transport program was developed for use in a multi-layered HLMs system. The range of dispersion coefficients of advection diffusion column tests was a little narrower than that of diffusion coefficients of pure diffusion tests, although the two coefficients were quite close. The effective diffusion coefficients of chloride ions of a HLMs were about a half of those in clayey soil due to the high density by compaction and curing. Diffusion coefficients of chloride ions in this study were correlated closely with hydraulic conductivities of the materials tested and were consistent with work in the literature. 相似文献
50.
Abstract Paleostress fields of the Late Paleozoic to Early Mesozoic Pyeongan Supergroup that is distributed along the northeastern part of the Ogcheon Belt in South Korea were investigated using the calcite strain gauge (CSG) technique. Combining the results of this study with those of other studies investigating the relationship between twin strain, twin density and width, which are used as indicators of deformation conditions in the natural low-temperature deformation of limestone, it was estimated that calcite twins in the study area were probably formed at temperatures lower than 170°C. From two samples, two different principal paleostress directions were inferred from calcite twins, while only one direction was inferred from two other samples. This result suggests that deformation occurred during two or more different tectonic events in the Pyeongan Supergroup during the Mesozoic era. The maximum shortening axis was oriented in two directions, northeast–southwest and northwest–southeast, respectively, which coincide well with the paleostress directions inferred from the stress inversion for many fault sets. Combining the results of the paleostress analysis from this and other studies, we hypothesize that the directions of the maximum shortening axis in the Pyeongan Supergroup changed from northeast–southwest during the pre-Daebo orogeny period (Late Triassic period) to northwest–southeast during the syn-Daebo orogeny period (Early Jurassic to Early Cretaceous period) in the Mesozoic era. 相似文献