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121.
122.
Henning A. Bauch Heidemarie Kassens Olga D. Naidina Martina Kunz-Pirrung Jrn Thiede 《Quaternary Research》2001,55(3):344
A 467-cm-long core from the inner shelf of the eastern Laptev Sea provides a depositional history since 9400 cal yr. B.P. The history involves temporal changes in the fluvial runoff as well as postglacial sea-level rise and southward retreat of the coastline. Although the core contains marine fossils back to 8900 cal yr B.P., abundant plant debris in a sandy facies low in the core shows that a river influenced the study site until 8100 cal yr B.P. As sea level rose and the distance to the coast increased, this riverine influence diminished gradually and the sediment type changed, by 7400 cal yr B.P., from sandy silt to clayey silt. Although total sediment input decreased in a step-like fashion from 7600 to 4000 cal yr B.P., this interval had the highest average sedimentation rates and the greatest fluxes in most sedimentary components. While this maximum probably resulted from middle Holocene climate warming, the low input of sand to the site after 7400 cal yr B.P. probably resulted from further southward retreat of the coastline and river mouth. Since about 4000 cal yr B.P., total sediment flux has remained rather constant in this part of the Laptev Sea shelf due to a gradual stabilization of the depositional regime after completion of the Holocene sea-level rise. 相似文献
123.
Jean-Philippe Boulanger Julie Leloup Olga Penalba Matilde Rusticucci Florence Lafon Walter Vargas 《Climate Dynamics》2005,24(4):393-413
The Paraná-Plata basin is the second largest hydrological basin in South America and is of great importance for the countries of the region (Argentina, Bolivia, Brazil, Paraguay and Uruguay). The present study focuses on the long-term trends in basin-scale precipitation with special emphasis on the role of distribution changes in extreme large-scale precipitation events and on the characteristics and evolution of ENSO teleconnections over the last 50 years. First, we defined a Paraná-Plata basin total precipitation index (PTPI) as the precipitations spatially averaged over the hydrological basin. On interannual time scales, such an index is mainly representative of anomalous monsoon precipitations in the northern part of the basin and large convective precipitation anomalies in the center of the basin (Paraguay-southern Brazil-Uruguay-northern Argentina) typical of the canonical ENSO teleconnection pattern. Our major findings clearly highlight a positive trend in yearly averaged PTPI mainly from the late 1960s to the early 1980s with a strong dependence from month-to-month. The largest precipitation increase is observed from November to May in southern Brazil and Argentina. A close examination of PTPI distributions during the two halves of the period 1950–2001 shows that the changes in the mean state from 1950–1975 to 1976–2001 result from significant changes in each calendar month mean state and in the tails of the PTPI anomaly distributions in May with lesser and weaker large-scale dry events and stronger large-scale wet events. Further studies will be needed to assess whether the observed trend in large-scale extreme precipitation conditions can be related to natural climate variability or anthropogenic activities and whether it is associated to changes in local/regional extreme events. The stronger wet conditions in different months seem to be associated to changes in ENSO characteristics (amplitude, propagation, spatial structure, ...) since the 1982–1983 El Niño. Indeed, spatial ENSO teleconnections (stronger in November and April–May) have greatly evolved from 1950–1975 to 1976–2001. Moreover, we demonstrate that there is a strong modulation and displacement of the teleconnection patterns from one event to another, impeding the definition of robust statistical relationship between ENSO and precipitation in the Paraná-Plata basin (except maybe over a very limited area near the common border between Paraguay, Argentina and Brazil). Finally, the non-antisymmetrical patterns of precipitation between El Niño and La Niña conditions and the non-linear relationship between precipitation and either Niño3.4 or Niño1+2 sea surface temperature indices show that linear statistical forecast systems are actually of very limited use for impact predictions on society on a local or regional scale. 相似文献
124.
125.
From early modern times until the present, Russia (temporarily extended to the USSR) had two capital cities: Moscow and Petersburg. Moscow was the original capital, it was succeeded by Petersburg from the beginning of the 18th century. From the early 20th century onward Moscow again became the capital, but it became a different kind of capital at the end of the 20th century. The paper describes the evolution of the representation of the state function in the appearance of the capital cities by way of the state buildings, the monuments, the street names. In addition it analyses the fate of the former capitals (first Moscow, then Petersburg) in terms of their symbolic functions. Petersburg originated as a capital turned to the outside emphasizing Russia's European vocation, while Moscow was at first the inward looking capital city representing the distinctive spiritual values of Russia. Changes had to do with the changes in the nature of the successive political regimes and with the changing roles of the two cities within those regimes. 相似文献
126.
Geological-structural and hydrogeological features available in the Kamchatka region were used to identify three leading types
of volcanogenic hydrogeological structures: Quaternary volcanogenic basins (VBs), Neogene volcanogenic adbasins (VABs), and
artesian volcanogenic basins (AVBs). The first type subdivides into six subtypes by morphogenetic features. It is these subtypes
that control the conditions under which the VBs are generated. All these are characterized from the standpoint of regional
hydrogeology. 相似文献
127.
128.
Simon Rozalyn A. Ranasinghe Purnika Damindi Barazanji Nawroz Jungeström Malin Bergman Xu Jie Bednarska Olga Serrander Lena Engström Maria Bazylinski Dennis A. Keita Åsa V. Walter Susanna 《中国海洋湖沼学报》2021,39(6):2044-2052
Journal of Oceanology and Limnology - Magnetotactic bacteria (MTB), ubiquitous in soil and fresh and saltwater sources have been identified in the microbiome of humans and many animals. MTB... 相似文献
129.
A. Yu. Lein I. I. Rusanov G. A. Pavlova O. M. Dara Z. I. Verkhovskaya E. E. Zakharova S. K. Yusupov M. V. Ivanov 《Lithology and Mineral Resources》2011,46(2):135-150
Complex investigations of recent and Drevnechernomorian (ancient Black Sea) sediments from the outer shelf, continental slope,
and deep-water basin of the Russian Black Sea sector have been carried out using samples collected during cruise of the R/V
Professor Shtokman organized by the Institute of Oceanology of the Russian Academy of Sciences (March 2009) and expedition of “YUZHMORGEO” (summer
2006). Rates of the main anaerobic processes during diagenesis (sulfate reduction, dark CO2 fixation, methanogenesis, and methane oxidation) were studied for the first time in sediment cores of the studied area. Two
peaks in the rate of microbial processes and two sources of these processes were identified: the upper peak near the water-sediment
contact is related to the solar energy (OM substrate of the water column) and the lower peak at the base of the Drevnechernomorian
sediments with high(>1000 μM) methane concentration related to the energy of anaerobic methane oxidation. The neogenic labile
OM formed during this process is utilized by other groups of microorganisms. According to experimental data, the daily rate
of anaerobic methane oxidation is many times higher than that of methanogenesis, which unambiguously indicates the migration
nature of the main part of methane. 相似文献
130.
For the first time, the structure of the meiobenthos community and marine nematodes in particular was investigated in the
different intertidal zones of Jeju Island (South Sea of Korea). A relationship was found between the density of meiobenthic
communities and the type of the bottom sediment. In addition, in the silty sediments, nematodes were dominant, while in the
sandy sediments harpacticoids and ostracods were dominant groups. Sixty eight species belonging to 60 genera and 19 families
of nematodes were found in the whole area. Four different nematode taxocenosis were distinguished using a cluster analysis.
Dominant feeding groups were omnivores (2B) and epistratum-feeders (2A). The highest number of non-selective deposit-feeders
(1B) was detected in the lagoon with the bottom silty sediments. 相似文献