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951.
Core Psd-590 (length 947 cm, water depth 124 m) penetrated the entire sequence of marine (Littorina) mud (730 cm) and stopped
in gray lacustrine (Ancylus) clays with hydrotroilitic films. The Littorina mud is gray-colored, microlaminated in the interval
of 730 to 700 cm, and dark gray with hydrotoilitic films and obscure microlamination higher in the section. According to the
diatom data, typical marine sediments begin at the level of 620 cm, while the lithological-geochemical data indicate this
change at the level of 730 cm. This level is marked by a considerable increase in the concentrations of SiO2amorph, CO2, Corg, and Mn in the sediments. In the interval of 730 to 620 cm, diatoms are represented by both freshwater and brackish-water
species. The Littorina transgression began in the form of individual flows of saline North Sea waters into the Baltic Sea,
which is evident from the microlamination and sharp peaks in the concentrations of the chemical elements. The transgression
exhibits two weakening and one strengthening (core interval of 380 to 220 cm) stages; the latter was marked by the maximal
water salinity. The post-Littorina mud contains molluscan shells and fish bones and is enriched in the fraction of 0.05–0.01
mm. The microlaminated Littorina mud was deposited during periods with stagnant conditions in the bottom water layer, while
the homogenous sediments accumulated during periods of its aeration. 相似文献
952.
This study describes the stratigraphic and palaeoenvironmental significance of the Lower-“middle” Oligocene sediments based on the fauna from the Delikarkas? Formation and the microflora from the ?ncesu Formation of the ?ncesu area (northern part of the western Taurides, Isparta province, Turkey). In the area, the Oligocene sediments show a regressive succession, which begins with the limestones of the Delikarkas? Formation indicating marine conditions followed by conglomerates, sandstones and coaly mudstones of alluvial and fluvial (shallow marine-continental) origin. A well preserved foraminiferal assemblage including Nummulites intermedius, Nummulites vascus and Halkyardia maxima proves an Early Oligocene age for the Delikarkas? Formation. Due to palynological markers such as Boehlensipollis hohli, Slowakipollis hippophaëoides, Dicolpopollis kockelii, Magnolipollis neogenicus ssp. minor, Plicapollis pseudoexcelsus, Caryapollenites simplex and Intratriporopollenites instructus the ?ncesu Formation, which concordantly rests on the Delikarkas? Formation, may be assigned to the Early-“middle” Oligocene. From the palynomorph assemblage, three zones have been recognised according to abundance of species. Zone 1 is characterized by predominance of C. simplex and Momipites punctatus and rarely presence of tricolpate and tricolporate pollen. Zone 2 consists mainly of Inaperturopollenites dubius, Leiotriletes maxoides ssp. maximus, Verrucatosporites favus, Verrucatosporites alienus and infrequently marine dinoflagellate cysts. Zone 3 is characterized by a high percentage of ferns such as Echinatisporis?chattensis and Polypodiaceoisporites saxonicus. The presence of marine dinoflagellate cysts like Apectodinium sp. and Cleistosphaeridium sp., back-mangrove elements such as Acrostichum aureum and lepidocaryoid palms (e.g. Longapertites discordis, Longapertites punctatus and Longapertites psilatus) in the sediments of the ?ncesu Formation imply coastal or near-coastal conditions. Terrestrial palynomorphs in more inland settings were transported by running water towards the sea. Conifers are represented by poorly preserved and rare pollen grains of Pityosporites, Cathayapollis and Piceapollis which may have been transported by wind. In this study, the terrestrial climate of the ?ncesu Formation is also discussed on the basis of the Coexistence Approach method. The climate was warm at the coast (over 20 °C), as evidenced by A. aureum and lepidocaryoid palms, whereas there was a mean annual temperature of 17.2–17.4 °C must be assumed for the upland environment(s). 相似文献
953.
Mantle xenoliths in within-plate Cenozoic alkaline mafic lavas from NE Spain are used to assess the local subcontinental lithospheric
mantle geotherm and the influence of melting and metasomatism on its oxidation state. The xenoliths are mainly anhydrous spinel
lherzolites and harzburgites and gradations between, with minor pyroxenites. Most types show protogranular textures, but transitional
protogranular–porphyroclastic and equigranular lherzolites also exist. Different thermometers used in the estimates provide
higher subsolidus equilibrium temperatures for harzburgites (1,062 ± 29°C) than for lherzolites (972 ± 89°C), although there
is overlap; the lowest temperatures correspond to porphyroclastic lherzolites, whereas pyroxenites give the highest temperatures
(up to 1,257°C). Maximum pressures for subsolidus equilibrium of peridotites are at 2.0–1.8 GPa. Later they followed adiabatic
decompression and harzburgites registered lower pressures (1.02 ± 0.19 GPa) than lherzolites (1.41 ± 0.27 GPa). One pyroxenite
gives values consistent with the spinel lherzolite field (1.08 GPa). The shallowest barometric data are in agreement with
the highest local conductive geotherms, which implies that the lithosphere–asthenosphere boundary is at 70–60 km minimum depth.
Higher equilibrium temperatures for the harzburgites could be explained by the existence of mafic magma bodies or dykes at
the lower crust–mantle boundary. Paleo-fO2 conditions during partial melting as inferred from the covariation between V and MgO concentrations are mainly between QFM−1
and QFM−2 in log units. However, most thermobarometric fO2 estimates are between QFM−1 and QFM+1, suggesting oxidation caused by later metasomatism during uplift and cooling. 相似文献
954.
Peter Bauer-Gottwein Bibi R. N. Gondwe Guillaume Charvet Luis E. Mar��n Mario Rebolledo-Vieyra Gonzalo Merediz-Alonso 《Hydrogeology Journal》2011,19(3):507-524
The Yucatán Peninsula karst aquifer is one of the most extensive and spectacular karst aquifer systems on the planet. This transboundary aquifer system extends over an area of approximately 165,000? km2 in México, Guatemala and Belize. The Triassic to Holocene Yucatán limestone platform is located in the vicinity of the North American/Caribbean plate boundary and has been reshaped by a series of tectonic events over its long geologic history. At the end of the Cretaceous period, the Yucatán Peninsula was hit by a large asteroid, which formed the Chicxulub impact crater. The Yucatán Peninsula karst aquifer hosts large amounts of groundwater resources which maintain highly diverse groundwater-dependent ecosystems. Large parts of the aquifer are affected by seawater intrusion. Anthropogenic pollution of the aquifer has been increasing over the past few decades, owing to relentless economic development and population growth on the Peninsula. This review summarizes the state of knowledge on the Yucatán Peninsula karst aquifer and outlines the main challenges for hydrologic research and practical groundwater-resources management on the Peninsula. 相似文献
955.
M. I. Carretero M. Pozo F. Ruiz J. Rodríguez Vidal L. M. Cáceres M. Abad J. M. Muñoz F. Gómez J. M. Campos M. L. González-Regalado M. Olías 《Environmental Earth Sciences》2011,64(5):1215-1223
The multidisciplinary analysis of core sediments from Doñana National Park, south Spain, permits to delimitate both the paleoenvironmental changes and the geochemical evolution of this area during the Holocene. In a first phase (10–6.5 kyr cal), this area was occupied by freshwater/brackish marshes with periodical alternation of dry periods and humid intervals. In a second phase, these marshes were inundated during the Flandrian transgression (~6.5 kyr cal), with the deposition of bioclastic sands. The third phase (6.5–3.6 kyr cal) is characterized by the transition to an old lagoon, with unpolluted, bottom sediments. The geochemical concentrations of these clayey sediments can be used as a geochemical background for present-day and future environmental evaluations of this area. In the following 600 years approximately, two tsunamis caused the partial infilling of this area with bioclastic, marine sediments. In the interval comprised between these two tsunamis, this lagoon was polluted with heavy metals derived from historical mining activities. This environmental contamination represents one of the oldest evidences of mining pollution in the world (>3 kyr cal BP). 相似文献
956.
Józef Żychowski 《Environmental Earth Sciences》2011,64(2):437-448
The investigations were carried out to identify processes and mineral products in the diversified subsoil sediments of mass
graves from WW1 (four graves) and 2 (five graves) and their surroundings, as well as the relations between the development
of sediments within the mass graves and the scale of migration of the products of corpse decomposition. The author studied
the role of iron compounds and clay minerals in the decomposition of human corpses buried in mass graves, followed by the
migration of selected elements. In particular, he concentrated on the list of elements found in the diversified sediments
of nine mass graves from SE Poland and to their relationship with phosphorus compounds. The methods applied included scanning
electron microscopy (SEM) and optical polarizing microscopy. Samples were collected from various depths in trenches and holes
dug in the vicinity of the graves, the sediments from the burial horizon and, when possible, the sediments underlying the
grave (studied downslope). Detected phosphorus occurs as a weakly crystalline compound in silt-rich sediments with relatively
stable water conditions. In silt-rich sediments with relatively stable moisture content, phosphorus occurs as a weakly crystalline
compound. More stable aggregates of decomposition products have been found on quartz grains covered with clay-ferruginous
rims. Fragments of human soft tissue were found only in those graves from WW2. There is no link between the spectrum of elements
in the sediments of the graves and the period of burials. The decomposition products that form depend primarily on the type
of sediments in which the mass graves were dug and, secondarily, although related, on the moisture content of the sediments.
It has been found that stabilization of decomposition products in situ is related to the presence of iron compounds and clay
minerals, particularly in finer-grained, aleuritic–pelitic sediments. 相似文献
957.
Acid mine drainage at Cerro Rico de Potosí I: unabated high-strength discharges reflect a five century legacy of mining 总被引:1,自引:1,他引:0
Intensive mining and processing of Ag, Sn, Pb and Zn ores have occurred in various locations within and around the city of
Potosí, Bolivia since 1545. Surface and subsurface waters, stream sediments and soils are contaminated with various ecotoxic
metals in the headwaters of the economically vital, yet highly impacted, upper Rio Pilcomayo watershed. Previous studies have
documented downstream trace metal contamination, however, not addressed specific sources. The AMD discharges identified in
this study help link downstream pollution to primary origins. The majority of AMD would be considered high-strength due to
metal concentrations and acidity orders of magnitude greater than typical AMD. Discharges from both operating and abandoned
portals as well as tailings-related deposits displayed a high degree of heterogeneity with total metal concentrations ranging
from 0.11 to 7480, <0.022 to 889, <0.0006 to 65.3, <0.001 to 310, 0.12 to 72,100, 0.3 to 402, <0.012 to 34.8, and 0.24 to
19,600 mg/L of Al, As, Cd, Cu, Fe, Mn, Pb and Zn, respectively. Net acidity and pH ranged from −10 to 246,000 mg/L as CaCO3 equivalent and 0.90–6.94 standard units, respectively. Data were gathered during two sampling events centered around the
most extreme periods of the dry and wet seasons of one water-year. Loadings to local streams were marginally greater for most
metals in the wet season. If observed loadings are historically representative, Cerro Rico AMD has contributed thousands of
tonnes of ecotoxic metals to the upper Rio Pilcomayo over the last five centuries. Metal and hydrogen ion concentrations in
the majority of AMD sampled were several orders of magnitude above discharge limits set by the Bolivian government, yet no
action has historically or contemporarily been taken. 相似文献
958.
Chemistry of the Ferraria thermal water, S. Miguel Island, Azores: mixing and precipitation processes 总被引:1,自引:1,他引:0
Maria do Rosário Carvalho António Mateus Jo?o C. Nunes José M. Carvalho 《Environmental Earth Sciences》2011,64(2):539-547
The Ferraria thermal water emerges at the sea level in the Ferraria lava delta (western edge of S. Miguel Island, Azores)
with temperature of ca. 60°C and pH varying between 5.4 and 6.2. It is of sodium chloride type, resulting from ca. 50% seawater
mixing with an acid brackish, at ≈100°C, denoting the presence of significant CO2(g) and the progress of water–rock interactions in open system conditions. The thermal Na–Cl water is strongly enriched with
Sr and Mn and, comparatively, has low concentrations in Al, Fe and As. These elements are removed from the solution as critical
conditions for the formation of several neo-formed mineral phases are gradually attained. Thermodynamic equilibrium calculations
are consistent with this interpretation, showing that the thermal fluid can precipitate Fe3+-(hydr-)oxides, kaolinite and non-crystalline silica. Wells logging show fracture planes and pores fully/partly filled up
with polyphase botryoidal aggregates mostly composed of goethite + ferrihydrite and displaying variable adsorbed contents
of Si, P and As. These neo-formed phases result from the pristine fluid oxidation due to seawater mixing; its precipitation
is easily affected by pH and redox variations of the brackish, due to volcanic gases pressure alterations, and fluid pressure
or flow-velocity oscillation in the fractured aquifer. 相似文献
959.
960.
János Kovács Szabolcs Á. Fábián Gábor Varga Karoly Németh Corina Risso Francisco Nullo Gabor Kereszturi Titusz Bugya Szabolcs Á. Fábián Noémi L. Görcs István P. Kovács Bertalan Radvánszky Gabriella Barta Rudolf Musil Alice Ghiselli Marzio Merazzi Andrea Strini Roberto Margutti Michele Mercuriali Rauf Gardashov Daria Gushchina Boris Dewitte Martin Michálek Marián Putiš Christoph A. Hauzenberger Jindřich Šancer Martin Štrejbar Aneta Maleňáková George Migiros George D. Bathrellos Hariklia D. Skilodimou Theodoros Karamousalis 《Central European Journal of Geosciences》2011,3(2):229-229