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51.
Christian Betzler Sebastian Lindhorst John J. G. Reijmer Juan Carlos Braga Thomas Lüdmann Or M. Bialik Jesus Reolid Anna-Lena Geßner Dagmar Hainbucher Dass Bissessur 《Sedimentology》2023,70(1):78-99
Mesophotic reefs, hardgrounds and current-controlled pelagic to hemipelagic carbonates are facies marking carbonate platform drowning successions, irrespective of the factors controlling this evolution. A modern analogue of a carbonate platform in a state of drowning, where these facies occur has not been properly reported on to date. In the present study, the sedimentary environments of the Saya de Malha Bank are characterized using a multi-disciplinary approach including sedimentology, hydroacoustics, seismics and oceanography. The Saya de Malha Bank edifice with a surface of 40 808 km2 is located in the tropical Indian Ocean and lies in a water depth of 8 to 300 m extending from the surrounding more than 2000 m deep ocean floor, with no reef reaching the sea surface. Mesophotic coral and red algal facies co-exist with hemipelagic and bioclastic sands, together with a hardground. Ocean currents and internal waves are identified as major sedimentological controlling factors in the absence of elevated nutrient influx. Many features distributed along the present-day Saya de Malha Bank were described from studies presenting fossil examples of carbonate platform drowning. The results herein can therefore be applied to other drowning examples, in some cases allowing for more accurate interpretation of the stratigraphic record. 相似文献
52.
Joachim Kuhlemann Klaas van der Borg Paul D. Bons Martin Danišík Wolfgang Frisch 《International Journal of Earth Sciences》2008,97(3):549-564
A study of erosion rates by in-situ 10Be concentrations in granites of Miocene high-elevation paleosurfaces in Corsica indicates maximum erosion rates between 8
and 24 mm/kyear. The regional distribution of measured erosion rates indicates that the local climatic conditions, namely
precipitation, the petrographic composition of granites, and the degree of brittle deformation govern erosion rates. Chemical
erosion dominates even at elevations around 2,000 m in presently subalpine climate conditions. Field evidence indicates that
erosion operates by continuous dissolution and/or disintegration to grains (grusification). The erosion rates are relatively
high with respect to the preservation of inferred Early Miocene landscapes. We infer temporal burial in the Middle Miocene
and significantly lower erosion rates in the Neogene until ∼3 Ma to explain the preservation of paleosurfaces, in line with
fission track data. Valley incision rates that are a magnitude higher than erosion rates on summit surfaces result in relief
enhancement and long-term isostatic surface uplift. On the other hand, widening and deepening of valleys by cyclic glaciation
progressively destroys the summit surface relics.
相似文献
Wolfgang FrischEmail: |
53.
Ezzeddin?BakhtavarEmail authorView authors OrcID profile Samuel?Yousefi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(12):3317-3332
This study introduces a method using a multi-goal fuzzy cognitive map (FCM) and multi-criteria decision making based on sensitivity analysis to assess the risks associated with working accidents in underground collieries. Safety, stoppage in operation, and operational and capital costs are considered as the main goals during the FCM process with significant emphasis on safety. Workplace accidents data from Kerman underground collieries are statistically evaluated to find the degrees of occurrence probability, severity, and work-disability duration as the main risk factors. The causes and effects of accidents are analyzed using FCM based on three goals and the effects of risk factors. A sensitivity analysis on the weights of the goals is conducted with the aim of increasing the workplace safety in TOPSIS environment after solving the designed multi-goal FCM. Results indicate that “gas poisoning,” “roof fall,” and “debris and destruction” take the first three ranks and impose high risks to the system. By contrast, “collision, hit, and crash” presents the lowest risk among all accidents. 相似文献
54.
J.?Etxeberria T.?Goicoa M.?D.?UgarteEmail authorView authors OrcID profile 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(10):2951-2969
Joint analyses of two or more related diseases bring advantages over individual studies to look into diseases with low incidence, or to disentangle spatial patterns by age-group and gender. Incidence and/or mortality are not homogeneously distributed according to age-groups and ignoring age may lead to biased estimates. In addition, counts at a very disaggregated level can be very scarce or even zero for rare diseases and powerful models to borrow strength from related processes and geographical areas are strongly recommended. In this paper, gender and age-specific spatial shared component models are proposed for a joint modelling of brain cancer incidence and mortality rates in Navarre and the Basque Country, two regions in the north of Spain with the highest incidence rates among European regions. 相似文献
55.
Thermochronological insights into the structural contact between the Tian Shan and Pamirs,Tajikistan 下载免费PDF全文
Gilby Jepson Stijn Glorie Dmitry Konopelko Jack Gillespie Martin Danišík Noreen J. Evans Yunus Mamadjanov Alan S. Collins 《地学学报》2018,30(2):95-104
Multi‐method thermochronology along the Vakhsh‐Surkhob fault zone reveals the thermotectonic history of the South Tian Shan–Pamirs boundary. Apatite U/Pb analyses yield a consistent age of 251 ± 2 Ma, corresponding to cooling below ~550–350°C, related to the final closure of the Palaeo‐Asian Ocean and contemporaneous magmatism in the South Tian Shan. Zircon (U–Th–Sm)/He ages constrain cooling below ~180°C to the end of the Triassic (~200 Ma), likely related either to deformation induced by the Qiangtang collision or to the closure of the Rushan Ocean. Apatite fission track thermochronology reveals two low‐temperature (<120°C) thermal events at ~25 Ma and ~10 Ma, which may be correlated with tectonic activity at the distant southern Eurasian margin. The late Miocene cooling is confirmed by apatite (U–Th–Sm)/He data and marks the onset of mountain building within the South Tian Shan that is ongoing today. 相似文献
56.
Time domain reflectometry (TDR) is a highly accurate and automatable method for determination of porous media water content and electrical conductivity. Water content is inferred from the dielectric permittivity of the medium, whereas electrical conductivity is inferred from TDR signal attenuation. Empirical and dielectric mixing models are used to relate water content to measured dielectric permittivity. Clay and organic matter bind substantial amounts of water, such that measured bulk dielectric constant is reduced and the relationship with total water content requires individual calibration. A variety of TDR probe configurations provide users with site‐ and media‐specific options. Advances in TDR technology and in other dielectric methods offer the promise not only for less expensive and more accurate tools for electrical determination of water and solute contents, but also a host of other properties such as specific surface area, and retention properties of porous media. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
57.
Magnetic susceptibility measurements were conducted on 24 vibrocores obtained from an area located off the northeastern coast
of Lantau Island in Hong Kong. High intensities of magnetic susceptibility were detected in the uppermost sections of the
majority of the cores. Several magnetic parameters measured for one of the cores suggest that the variations in the magnetic
characteristics over depth are mainly due to varying concentrations of the magnetic minerals. Since a strong correlation has
been found between magnetic susceptibility and the heavy metals Pb, Cu, Zn and Cr, an anthropogenic contamination origin is
thought to be the cause. The present study shows that magnetic susceptibility is a fast, inexpensive and non-destructive method
for the detection and mapping of contaminated sediments.
Received: 12 August 1997 · Accepted: 18 November 1997 相似文献
58.
59.
An Integrated Geostatistical Approach for Contaminated Site and Soil Characterisation 总被引:1,自引:0,他引:1
For several years, abandoned or stopped industrial sites increasingly arouse the interest of politics and investors. Having
a high social and economic estate value, these sites generally reveal contaminated soils that must be remediated first before
receiving any new use. Due to financial, environmental or human health stakes, heuristic methods appear inappropriate because
they do not provide reliable estimations of contaminated soil volumes and ignore spatial uncertainties. Problems at hand may
be very complex, involving multiple correlated contaminants for which spatially varying pollutant grades are to be estimated
and confronted to various regulatory thresholds, depending on redevelopment target areas. In such conditions, geostatistics
provides effective methods to quantify local and global uncertainties about soil contamination and contaminated soil volumes.
By quantifying uncertainties, geostatistical models are useful as support for decision-making about redevelopment scenarios
or remediation techniques. Specific approaches are required, however, to overcome particular modelling issues as related to
the skewness of pollutant grade distributions or change of support. Making use of our practical experience, such an integrated
geostatistical approach is proposed for modelling contaminated sites. It is illustrated by application to a recent actual
case study. 相似文献
60.
Deng-Fei?Duan Shao-Yong?JiangEmail authorView authors OrcID profile 《Contributions to Mineralogy and Petrology》2017,172(5):36
The Tonglvshan deposit is the largest Cu–Fe (Au) skarn deposit in the Edong district, which is located in the westernmost part of the Middle and Lower Yangtze River metallogenic belt, China. In this study, we performed a detailed in situ analysis of major and trace elements in amphiboles from the ore-related Tonglvshan quartz monzodiorite porphyry using electron microprobe (EMPA) analysis and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Two distinct populations of amphiboles, which can be distinguished by their aluminum content, are found in the quartz monzodiorite porphyry. The low-aluminum (Low-Al) amphiboles are subhedral or anhedral and formed at 46.3–73.5 MPa and 713–763 °C. In contrast, the high-aluminum (High-Al) amphiboles are euhedral and formed at 88–165 MPa and 778–854 °C. Some euhedral amphiboles are partially or completely replaced by Low-Al amphibole. The compositions of parental melts in equilibrium with the High-Al amphibole (Melt 1) and Low-Al amphibole (Melt 2) were computed by applying solid/liquid partition coefficients. This modeling shows that magma in equilibrium with High-Al amphibole (Melt 1) underwent 40% fractional crystallization of amphibole, plagioclase and apatite at a depth of ~5 km to evolve to magma in equilibrium with Low-Al amphibole (Melt 2). Copper enrichment occurred in the magma after undergoing fractional crystallization. The magma had a high oxygen fugacity, increasing from NNO + 1 (Melt 1) through NNO + 2 to HM (Melt 2), which could have prevented the loss of Cu (and possibly Au) to sulfide minerals during crystallization. Finally, the evolved magma intruded to shallower depths, where it presumably exsolved aqueous ore-forming fluids. Therefore, the large Cu–Fe–Au reserves of the Tonglvshan deposit can likely be attributed to a combination of controlling factors, including high oxygen fugacity, fractional crystallization, fluid exsolution, and a shallow emplacement depth. 相似文献