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排序方式: 共有217条查询结果,搜索用时 15 毫秒
111.
Microzonation of Potenza (Southern Italy) in terms of spectral intensity ratio using joint analysis of earthquakes and ambient noise 总被引:1,自引:1,他引:0
Angelo Strollo Stefano Parolai Dino Bindi Leonardo Chiauzzi Rossella Pagliuca Marco Mucciarelli Jochen Zschau 《Bulletin of Earthquake Engineering》2012,10(2):493-516
A temporary seismic network composed of 11 stations was installed in the city of Potenza (Southern Italy) to record local
and regional seismicity within the context of a national project funded by the Italian Department of Civil Protection (DPC).
Some stations were moved after a certain time in order to increase the number of measurement points, leading to a total of
14 sites within the city by the end of the experiment. Recordings from 26 local earthquakes (Ml 2.2−3.8 ) were analyzed to compute the site responses at the 14 sites by applying both reference and non-reference site techniques.
Furthermore, the Spectral Intensity (SI) for each local earthquake, as well as their ratios with respect to the values obtained
at a reference site, were also calculated. In addition, a field survey of 233 single station noise measurements within the
city was carried out to increase the information available at localities different from the 14 monitoring sites. By using
the results of the correlation analysis between the horizontal-to-vertical spectral ratios computed from noise recordings
(NHV) at the 14 selected sites and those derived by the single station noise measurements within the town as a proxy, the
spectral intensity correction factors for site amplification obtained from earthquake analysis were extended to the entire
city area. This procedure allowed us to provide a microzonation map of the urban area that can be directly used when calculating
risk scenarios for civil defence purposes. The amplification factors estimated following this approach show values increasing
along the main valley toward east where the detrital and alluvial complexes reach their maximum thickness. 相似文献
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116.
Igor Petenko Giangiuseppe Mastrantonio Angelo Viola Stefania Argentini Ilaria Pietroni 《Boundary-Layer Meteorology》2012,143(1):125-141
Some characteristics of wavelike motions in the atmospheric boundary layer observed by sodar are considered. In an experiment
carried out in February 1993 in Milan, Italy, Doppler sodar measurements were accompanied by in situ measurements of temperature
and wind velocity vertical profiles using a tethered balloon up to 600 m. The oscillations of elevated wavy layers containing
intense thermal turbulence, usually associated with temperature-inversion zones, were studied by using correlation and spectral
analysis methods. The statistics of the occurrence of wavelike and temperature-inversion events are presented. The height
distributions of Brunt–Vaisala frequency and wind shear and their correlation within elevated inversion layers were determined,
with a strong correlation observed between the drift rate of the wavy layers and the vertical velocity measured by Doppler
sodar inside these layers. Spectral analysis showed similarities regarding their frequency characteristics. The phase speed
and propagation direction of waves were estimated from the time delay of the signals at three antennae to provide estimates
of wavelength. Moreover, wavelengths were estimated from the intrinsic frequency obtained from sodar measurements of the Doppler
vertical velocity and oscillations of wavy turbulent layers. The two wavelength estimates are in good agreement. 相似文献
117.
Yvonne Thompson Brian C. Sandefur A. D. Karathanasis Elisa D’Angelo 《Aquatic Geochemistry》2009,15(3):349-370
Redox potentials (Eh) were monitored bimonthly and porewater chemistry was analyzed seasonally at three slightly-acidic, high-elevation
Kentucky wetlands that differed in hydrology, parent materials, and vegetation. At all sites, Eh values were below 300 mV,
which indicated that reducing conditions persisted within the upper 90 cm and fluctuated mainly within the range of iron and
sulfate reduction. Significant relationships of Eh values with depth were observed only at the Martins Fork wetland, where
precipitation was the primary water source. The strongest and most stable reducing conditions, observed at the Kentenia site,
reflected consistently high water levels, which were sustained by ground water. The third wetland (Four Level) was distinguished
by irregular Eh fluctuations coinciding with strong seasonal ground-water upwelling. Although Fe3+ and SO4
2− were the primary terminal electron acceptors in all wetlands, porewater chemistry also varied significantly by season and
soil depth in response to piezometric water level fluctuations. Additional factors that influenced porewater chemistry included:
(1) the presence of limestone parent materials that affected porewater pH, Ca2+, and Mg2+; and (2) the prevalence of sphagnum moss or graminoid species that influenced dissolved organic carbon, CO2, and CH4. Results from this study indicated the diverse range and importance of multiple factors in controlling biogeochemical processes
and properties in small, high-elevation Appalachian wetlands. 相似文献
118.
Cuoco Emilio Minissale Angelo Di Leo Antonella “Magda” Tamburrino Stella Iorio Marina Tedesco Dario 《International Journal of Earth Sciences》2017,106(7):2429-2444
International Journal of Earth Sciences - The geochemistry of natural thermal fluids discharging in the Mondragone Plain has been investigated. Thermal spring emergences are located along the... 相似文献
119.
Sodar performance and preliminary results after one year of measurements at Adelie land coast, east Antarctica 总被引:1,自引:0,他引:1
S. Argentini G. Mastrantonio A. Viola P. Pettre G. Dargaud 《Boundary-Layer Meteorology》1996,81(1):75-103
Dumont d'Urville, on the Antarctic coast, is an area well known for the presence of strong katabatic winds blowing from the Antarctic plateau toward the sea almost all year. Since January 1993, a three-axis Doppler sodar has been operating in this area to investigate the variability of the boundary layer structure and dynamics. In this paper, the capabilities, behavior and advantages of using this ground-based remote-sensing system in Antarctica are evaluated after one year of measurements. This instrument may play an important role in boundary layer studies in remote regions where other profiling techniques (e.g., kitoons, slow ascent balloons) are difficult and expensive. All year long, except in summer when the signal-to-noise ratio was dramatically reduced by the noise of a large group of Adelie penguins, reliable measurements were available up to 900 m. The reliability of the vertical wind velocity has been checked and the influence of the local topography on the flow pattern has been evaluated. Some preliminary results regarding the statistical analysis of the horizontal and vertical velocities and an overview of the main physical processes are also shown. The statistical analysis of the wind speed shows that the wind blows from the 30 ° angular sectors centered at 90 °, 150 °, 180 °, and 0 °. The winds from 90 ° and 150 ° constitute the main local circulation and have, most of the time, the characteristics of a katabatic flow, whereas the winds blowing from 180 °, arising from the surface temperature difference between the sea and the land, are land breezes. Strong winds coming from the ocean (0 °), attributable to the inland penetration of depressions, have been observed in May, October, and November. Finally, some examples of the observed thermal structures, as depicted in the facsimile recording, are shown. 相似文献
120.
H. J. Beine S. Argentini A. Maurizi G. Mastrantonio A. Viola 《Meteorology and Atmospheric Physics》2001,78(1-2):107-113
Summary
Using a triaxial Doppler sodar the planetary boundary-layer structure and the wind flow dynamics at the Arctic site Ny-?lesund
have been studied. The relationship between winds measured at Ny-?lesund and at the nearby atmospheric research station on
Zeppelin mountain was investigated for the first time. While Ny-?lesund receives predominantly katabatic flow (from 120°)
from the Kongsvegen glacier, the field is rotated within the lowest 500 m and arrives at Zeppelin from southerly directions.
Received January 12, 2000/Revised November 21, 2000 相似文献