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511.
Paula Meth 《Area》2001,33(3):228-241
Historical accounts of relocation settlements in South Africa have emphasized processes of dispossession in the creation of these settlements. This paper considers other related histories of movement into relocation settlements as evidence of seldom considered contradictory and ambiguous experiences around movement and attachment to place — hence encouraging a rethink of the laden term 'the dumping grounds'. 相似文献
512.
A. Castro C. Fernández J. D. De la Rosa I. Moreno-Ventas H. El-Hmidi M. El-Biad J. F. Bergamín N. Sánchez 《International Journal of Earth Sciences》1996,85(1):180-185
New data on the petrology and structure of the Aracena metamorphic belt shows that this is a subduction-related, low-pressure/high-temperature complex developed by plate convergence at the north margin of Gondwana during the Paleozoic. The low-pressure, inverted metamorphic gradient in MORB-derived amphibolites resulted from heating from the continental hanging wall during subduction. This implies that the previous heating of the continental rocks was related to subduction of an oceanic ridge and the creation of a slab window beneath the continental margin. This slab window brought the asthenosphere in contact with the continental margin inducing a shallow thermal anomaly and partial melting of the lithospheric mantle resulting in boninite magmatism. 相似文献
513.
Validation of present-day regional climate simulations over Europe: LAM simulations with observed boundary conditions 总被引:5,自引:2,他引:5
J. H. Christensen B. Machenhauer R. G. Jones C. Schär P. M. Ruti M. Castro G. Visconti 《Climate Dynamics》1997,13(7-8):489-506
Nested limited-area modelling is one method of down-scaling general circulation model (GCM) climate change simulations. To
give credibility to this method the nested limited-area model (LAM) must be shown to simulate local present-day climate conditions
fairly accurately. Here seven different European limited-area models driven by observed boundary conditions (operational weather
forecast analyses) are validated against observations, and inter-compared for summer and winter months. Relatively large biases
are found. In summer large positive surface air temperature biases are found over southeast Europe. The main reason is deficiencies
in the surface hydrological schemes causing an unrealistic drying of the soil. In at least one of the models, most likely
several of them, an additional factor is an overestimation of incoming solar radiation. Apart from excessive precipitation
in mountainous areas in some models they generally show a negative bias due to the drying and decreased advection from the
Atlantic. In winter most models have a positive precipitation bias which seems to be caused by an enhancement of advection
from the Atlantic and enhanced cyclone activity. Surface air temperature biases are negative probably due to an underestimation
of the incoming longwave radiation.
Received: 11 December 1996 / Accepted: 17 March 1997 相似文献
514.
Pirjo Lindstrm-Sepp Sirpa Huuskonen Maija Pesonen Paula Muona Osmo Hnninen 《Marine environmental research》1992,34(1-4)
The polysubstrate monooxygenase system has been shown to be highly responsive to chemical pollution. The present study summarizes the enzyme based biomonitoring of the waste waters released by a pulp mill producing unbleached pulp and paperboard. Cytochrome P4501A enzyme activities of feral and caged fish, as well as cultures of fish hepatocytes, were tested. The 7-ethoxyresorufin-O-deethylase (EROD) activity was clearly induced in fish hepatocytes exposed to biotreated unbleached pulp mill effluent fractions in vitro. The effluent increased EROD activities also in feral perch, compared with controls. Caging experiments showed similar effects to those seen in feral fish: however, the maximal induction coefficients observed were higher. Unbleached effluents contain compounds that are able to affect the P4501A activities in fish. 相似文献
515.
Mrcia Cristina Costa de Azevedo Francisco Gerson Araújo Antnio Gomes da Cruz-Filho Andr Luiz Machado Pessanha Mrcio de Araújo Silva Ana Paula Penha Guedes 《Estuarine, Coastal and Shelf Science》2007,75(4):468-480
This study analyzed the factors structuring demersal fish community in a tropical bay in southeastern Brazil. The results were used to quantify the partitioning of ecological variation among the environmental, spatial and temporal components molding the fish community. Three bay zones (inner, middle and outer) were defined according to depth and salinity gradient. Monthly samplings were conducted by bottom trawl tows during daylight hours, between October 1998 and September 1999. In each zone, three replicate samples were taken. Ninety-three fish species from 73 genera and 37 families were recorded in the 108 samples. Two demersal fish assemblages were evidenced, one in the inner and the other in the outer zone. These assemblages were characterized by changes in species composition and relative abundance. Depth, followed by transparency and salinity, influenced spatial pattern of fish assemblages. The largest part of the explained variation occurred as a result of the spatial structure of environmental variables, which means that both species and environmental variables presented similar spatial structure. The spatial effect, not the seasonal, explained the highest part of species variations. The amount of unexplained variation was relatively high (76%), even assuming that part of it is due to nondeterministic fluctuation, which could be due to local effects of unmeasured (biotic and abiotic) controlling variables. Knowing the relative importance of these factors can be of decisive importance when applying casual hypotheses in the framework of some precise ecological theory and should facilitate management, planning, and usage of bay resources. 相似文献
516.
Larval fish distribution in shallow coastal waters off North Western Iberia (NE Atlantic) 总被引:2,自引:1,他引:2
Ulisses Miranda Azeiteiro Leonor Bacelar-Nicolau Paula Resende Fernando Gonalves Mrio Jorge Pereira 《Estuarine, Coastal and Shelf Science》2006,69(3-4):554
Monthly sampling for ichthyoplankton was conducted at three stations very near to the coast (near to shore shallow stations before the surf zone in direction to the shoreline) of Atlantic northwestern Portugal within contrasting localities: rocky shore, in front of a sandy beach receiving an estuary and a fishing port with heavy anthropogenic impact. Sampling was conducted from August 2002 to October 2003, always at full moon, at low tide and high tide in daylight hours, at the water column using a 48 cm diameter plankton net with 335 μm mesh. Analysis of the physico-chemical parameters pointed out the spatial (horizontal) homogeneity of the sampling area. Fish larvae from 41 taxa belonging to 17 families were identified; Blenniidae, Labridae, Ammodytidae, Clupeidae, Gobiidae, Soleidae and Gobiesocidae were the most representative during the study period. Parablennius gattorugine, Ammodytes tobianus, Symphodus melops, Sardina pilchardus, Lipophrys pholis and Coryphoblennius galerita were the most representative species (percentage contribution to total abundance). Peak abundance of fish eggs occurred during May, June and August 2003 and fish larvae occurred during May and July 2003 and August 2002 and 2003; there was a pronounced winter/early spring (March 2003) peak in larval abundance dominated by the small sandeel A. tobianus. This study identifies the occurrence of a conspicuous assemblage of larval fishes at very nearshore shallow environments of a variety of species with different adult habitats: the fish larvae assemblage was dominated by intertidal species. The present study has shown that temporal and spatial variations in the larval fish assemblage are related to environmental conditions and biological dynamics: the results suggest that abiotic conditions mediate biotic parameters, and that both abiotic and biotic characteristics regulated the larval fishes at very nearshore shallow environments. 相似文献
517.
CCD images of NGC 7129 were carried out in July 1988. These observations have better spatial resolution than former ones. Several Herbig-Haro objects and reflection nebulae have been observed. Some of these objects are new detections; in addition, we find new structures in previously known NGC 7129 nebulosities.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain. 相似文献
518.
Two six-year simulations, a land degradation scenario and a control, were performed by applying a regional climate model nested in ECMWF analyzed data to the Iberian Peninsula. The simulated time period (1993-98) includes extremely anomalous dry and rainy years. The land degradation scenario assumed a decrease in vegetation cover and an alteration of the soil properties resulting from future increases of greenhouse gases and human activity. Simulation results show that the impact of land degradation on the climate of the Iberian Peninsula depends on local factors (the intensity of degradation and geographical location) but some noticeable non-local effects are also present. Local factors result in an increase of the surface temperature which is almost linearly related to the degradation intensity. A stronger decrease in precipitation is observed in the less degraded regions, indicating that non-local effects are more relevant to changes in precipitation. The highest sensitivity to land degradation is observed in the summer season, consisting of an increase in 2 m temperature and a reduction in precipitation. In winter, the rainiest season on the Iberian Peninsula, the impact of land degradation on precipitation is almost negligible. 相似文献
519.
Jiménez J. C. Raga G. B. Baumgardner D. Castro T. Rosas I. Báez A. Morton O. 《Natural Hazards》2004,31(1):21-37
A 17-day field campaign was carried out in April–May 1999 to determine thecontribution that gaseous volcanic emissions make to the compositionof solid particles,particularly to the presence and quantity of sulfates. Theexperimental site was located inTonantzintla (in the State of Puebla), only 30 km E from the volcanoPopocatépetl, whichhas been in an active phase since the end of 1993. An analysis ofthe carbon monoxide(CO) and sulfur dioxide (SO2) in the ambient air identifiedvolcanic influence in 6 out ofthe 17 days sampled. Particles collected in an 8-stage cascadeimpactor were analyzed for inorganic ions (by liquid chromatography).A non-parametric test indicates asignificant difference on the total particle mass and thesulfate fraction between days withand without volcanic influence. This difference was predominantlyobserved in the stages that collect the smaller particles. Windsat 500 mb (roughly corresponding to thesummit of the volcano) indicate a westerly transport from thevolcano to the experimentalsite, even though surface winds do not show a clear signal ofsuch a transport. Back trajectories from the experimental site werecalculated and clearly indicated that air parcels on the daysindependently identified as with volcanic influence had indeed passed over the volcano. 相似文献
520.