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141.
A serious problem in Spain is presented, where the water and soil were contaminated by lindane produced by the chemical industry,
at a time when environmental legislation was limited, and the hydrogeological characterization of the low permeability materials
was insufficient. The waste-disposal sites where the lindane accumulated lacked suitable sealing and also had notable filtration.
The non-existence of a safe waste-disposal site, and the economic and social problems of transporting lindane residues forced
the alternative proposal of confining these residues in situ (Government of Aragón, 1995, 1996). Once the surface sealing was carried out, the problem centred on the site's underground
confinement. The purpose of this publication is to present the particular hydrogeological behaviour of materials, which were
initially considered impermeable because of the presence of very consolidated sandstone beddings and the vertical disposition
of the strata, and so allowed the lindane to escape through the groundwater. In addition, this publication describes the procedures
carried out in order to achieve effective underground confinement at the waste-disposal site.
Received: 12 October 1999 · Accepted: 31 January 2000 相似文献
142.
Lidia Romero-Viana Brendan J. Keely Antonio Camacho Eduardo Vicente M. Rosa Miracle 《Journal of Paleolimnology》2010,43(4):771-786
We analysed photosynthetic pigments in annually laminated sediment of meromictic Lake La Cruz, Spain, to cope with the timing
and characterisation of primary productivity changes over the last four centuries. The photosynthetic pigments identified
included chlorophyll a and b (and its derivatives) and specific carotenoids of different algal groups, such as zeaxanthin, lutein, alloxanthin, diadinoxanthin
and diatoxanthin among others. Marker pigments of phototrophic sulfur bacteria were also observed, including bacteriochlorophyll
a derivatives, homologue series of bacteriophaeophytins d and bacterial carotenoids okenone and chlorobactene. We investigated the diagenetic processes of pigment alteration in anoxic
sediments and the possible implications for paleoproductivity reconstruction and interpretation. The lack of systematic down-core
changes in diagenetic indicators suggests that variability of sedimentary pigment concentrations is the result of changes
in lake productivity. The lower concentration of algal photosynthetic pigments in the bottom of sediment sequence corresponds
to the onset of meromictic conditions. Before that, sediment was not continuously anoxic and the preservation of pigments
was reduced. Regarding photosynthetic bacteria, green sulfur bacteria derivatives indicate that population growth was limited
until the settled organic matter was sufficient to provide enough sulphide. Moreover, the presence of bacterioviridine, an
oxidised derivative of bacteriochlorophyll a, suggest the competitive relation among photosynthetic bacteria. The high relative abundance of zeaxanthin indicates the
dominance of picocyanobacteria in the primary productivity over the last centuries. Fluctuations of the pigment signal observed
in the sediment sequence during the meromictic period were well correlated with fluctuations of solar activity. 相似文献
143.
Jean Carlos Montero-Serrano Manuel Martínez Armelle Riboulleau Nicolas Tribovillard Gonzalo Márquez José Vicente Gutiérrez-Martín 《Marine and Petroleum Geology》2010
The early Miocene Pedregoso Formation is one of the numerous formations rich in organic matter within the stratigraphic record of the Urumaco Trough, in the central area of the Falcón Basin. Due to its lithological characteristics and stratigraphic position, this formation is of great interest regarding the basin's petroliferous systems. The evaluation of various inorganic and organic geochemical parameters indicates that the organic matter is primarily of marine origin, deposited in a marine carbonate environment typical of reefal systems, under oxic-to-dysoxic conditions. The low variability in the TOC concentrations and in the distributions of the biomarkers extracted from the samples suggests that the paleoenvironmental conditions and the organic-matter supply remained approximately constant throughout the sedimentation of this unit. The Pedregoso type-II organic matter (marine origin) and initial organic richness value (∼1.8%) suggest that this unit has probably generated hydrocarbons within the Urumaco Trough. However, present-day thermal maturity parameters reveal that the Pedregoso organic matter is overmature (dry gas window), indicating that this unit is only capable to generate gas. In addition, the geothermal gradient, maturity parameters, and the maximum paleotemperature estimated in this study suggest that the Pedregoso Formation reached a maximum burial depth the ∼6.5 km, consistent with the value obtained from data of stratigraphic thickness in the Urumaco Trough. This implies that the thermal anomaly that affected the basin during the Late Eocene–Early Miocene did not reach the central part of the basin, and therefore, the organic matter maturation in this unit is due to the sedimentary burial. 相似文献
144.
O.R. Chaparro Y.A. Montiel C.J. Segura V.M. Cubillos R.J. Thompson J.M. Navarro 《Estuarine, Coastal and Shelf Science》2008,76(4):861-868
The suspension-feeding gastropod Crepipatella dilatata occurs in estuaries in southern Chile that experience considerable fluctuations in salinity, driven by tidal and atmospheric forces. In the Quempillén estuary salinities as low as 9 psu may occur after severe rainstorms, and persist for several hours. In this study salinity was the major factor influencing the clearance rate of C. dilatata. At salinities below 20 psu, filtration ceased, whereas at high salinities (>22 psu) mean clearance rate was 0.24 l h−1 standard animal−1 (S.D. 0.18) for actively filtering individuals. This was confirmed by laboratory experiments under controlled conditions. Endoscopic observations were consistent with measurements of clearance rate, and showed that at salinity 25–30 psu the rate of transport along the gill filaments of particulate material embedded in mucus was 759 μm s−1 (S.D. 480), but particle transport ceased at and below salinity 20 psu. Complete or partial isolation of the mantle cavity from the environment may be a mechanism to protect soft tissues and/or incubated egg capsules from osmotic stress. 相似文献
145.
Presence of groundwater flow in the ‘Somontano de Huesca’ Area, derived from low‐permeability detrital Tertiary rocks, is considered. A groundwater flow model is constructed for these Tertiary rocks. This model explains both water flow through them and the chemical characteristics of the water. Groundwater flow has clear surface manifestations: it causes wetlands (which are called ‘paules’ in the area) with sodic waters, it produces saline, sodic or alkaline soils, and it produces modifies the chemical composition of rivers in Somontano. Irrigation has increased the volume of filtered water, especially in the interfluve areas, causing the extension of the wetlands in the valley thalwegs, and also the greater movement of salts has increased the problems of saline and/or sodic soils in the area. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
146.
This work presents a new design of disc infiltrometer, which, associated with a microflowmeter (MF) and a solenoid valve set, makes it possible to automate the infiltration rate (Q) measurements at different soil pressure heads (ψ). The MF consists of a 13·8‐cm long and 1·5 mm i.d. pipe, with a pressure transducer connecting the two ends of the MF, inserted in a water‐flow pipe that connects the Mariotte tube and the water‐supply reservoir of the disc infiltrometer. Water flow is calculated from the head losses in the MF. Changes in ψ in the bubble tower, automatically affected when the infiltration rate reaches steady state, are controlled by a datalogger connected to four solenoid valves. The new design was tested in laboratory and field conditions, and the results showed that the MF allows the soil water infiltration rates to be correctly estimated for different soil characteristics. The solenoid valve set plus datalogger system satisfactorily monitored the changes in ψ and allowed the measurement time to be optimized. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
147.
Cari Zazo Norbert Mercier Pablo G. Silva Cristino J. Dabrio Jos Luis Goy Elvira Roquero Vicente Soler Francisco Borja Javier Lario Dolores Polo Luis de Luque 《Geomorphology》2005,68(3-4):269-290
The coastal evolution of the El Abalario area (Huelva, southern Spain) during the Late Pleistocene and Holocene is reinterpreted after a refinement of the available geochronology by means of optically stimulated luminescence (OSL) dating. New data come from the analysis of soft sediment deformation, palaeosols, geomorphological mapping, and published seismic surveys on the onshore and offshore Gulf of Cadiz.The present structure of El Abalario dome resulted from the complex interaction of littoral-catchment processes and sea-level changes upon an emergent coastal plain, conditioned by the upwarping of the underlying Pliocene–Pleistocene prograding deltaic sequence. Upwarping is probably related to escape of over-pressurized fluids, accompanied by dewatering, prior to (?) and during OIS (Oxygen Isotopic Stage) 5. Continued upwarping produced the large NW–SE gravitational fault of Torre del Loro (TLF) in the southwestern flank of the dome, roughly parallel to the present coastline during OIS 5–OIS 4. The resulting escarpment favoured the accumulation of aeolian sand dunes (units U1, U2, and U3) from OIS 5 to early OIS 1. Unit U1 (OIS 5) ends upwards in a supersurface with a thick weathering profile that suggests moist and temperate climatic conditions. Unit U2 accumulated mainly during OIS 4 and OIS 3 with prevailing W/E winds. The supersurface between U2 and U3 records a part of OIS 2, with relative low sea level. Sedimentation of unit U3 took place during the Last Deglaciation (radiocarbon and OSL ages) with prevailing W/SW winds, under a temperate moist climate, that became more arid towards the top (Holocene). A major supersurface with an iron crust-like layer (SsFe) developed during the Holocene Climatic Optimum (OIS 1) under wetter and more temperate conditions than before, fossilizing the TLF. The supersurface is covered by younger aeolian dunes (U4, U5, U6, and U7) transported by W–SW winds since the Late Neolithic–Chalcolithic cultural period (5.0 ky cal BP). 相似文献
148.
149.
By observations at Calar Alto (Spain), La Silla (Chile) and Cananea (Mexico), we measured redshifts of 108 candidate members
in 19 Shakhbazian compact galaxy groups ShCG 44, 105, 149, 168, 270, 276, 278, 279, 298, 303, 304, 310, 317, 331, 339, 340,
345, 358, and 359. Redshifts of another ten members were taken from the NED. We found that nine out of 118 candidate member
galaxies are stars, and twelve galaxies are not members of the corresponding groups and are projected over them. The group
ShCG 168 is the core of a cluster. The groups ShCG 276, ShCG 298, and ShCG 303 are either strongly contaminated by field galaxies
with redshift differing not very much from that of the corresponding group, or are the results of a chance projection of field
galaxies. 相似文献
150.
Prof. Jean -Claude Vicente 《International Journal of Earth Sciences》1975,64(1):343-394
Hercynian absolute ages obtained from many plutonites and metamorphites of the Sierras Pampeanas compel to consider this polymetamorphic domain rather as an intermediate hinterland and axis of divergent symmetry between the two elementary geosyncline ranges (Cuyanides and Bolivianides) of the south america hercynian orogen. Attempt of Cuyanides paleogeographic organization indice to define during the geosyncline period (Cambrian to Devonian): the Pampean zone which consist of:
- an internal sub-zone (eastern) or pampean s. st. with hinterland significance
- a more external sub-zone (western) or transpampean or Umango sub-zone with intermediate features between eugeanticlinal ridge and eugeosynclinal furrow;
- the Calingasta zone as a typical eugeosynclinal furrow with pelagic-terrigenous ordovician sedimentation and ophiolitic magmatism followed by early silurian than devonian Flyschs;
- the Zonda zone as an external ridge with neritic cambro-ordovician facies and devonian flyschs.