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91.
92.
Effects of waterborne nitrite onphase I–II biotransformation in channel catfish(Ictalurus punctatus)
The effects of waterborne nitrite (3 mg/l NO2) on channel catfish were studied to evaluate changes in hematological parameters and phase I–II biotransformation in liver slices. Nitrite-exposed fish had significantly higher methemoglobin, blood and liver nitrite, and significantly lower pO2 than control fish. Total phase I-mediated metabolism of 7-ethoxycoumarin (EC) was not altered in nitrite-exposed fish compared with control fish (291±43 and 312±20 pmol/mg/h, respectively). However, phase II glucuronosyltransferase-mediated metabolism of 7-hydroxycoumarin (HC), both as a phase I metabolite of EC and as a parent substrate, was elevated in nitrite-exposed fish (204±17 and 1007±103 pmol/mg/h, respectively) as compared to control fish (149±14 and 735±87 pmol/mg/h) (P<0.05). Sulfotransferase-mediated metabolism of HC (as a metabolite of EC and as a parent substrate) was not notably altered in nitrite-exposed fish (95±16 and 617±33 pmol/mg protein/h, respectively) as compared with control fish (118±24 and 575±55 pmol/mg/h, respectively). These studies indicate that in vivo nitrite exposure and associated changes in hematological parameters do not appear to affect hepatic phase I EC biotransformation in channel catfish. However, subtle but significant changes in phase II glucuronidation, but not sulfation activity, were observed. The mechanism of these alterations is unclear. However, the data suggest that environmentally realistic concentrations of nitrite may affect the dynamics of conjugative metabolism in exposed fish. 相似文献
93.
Nicolas Delépine Vincent Clochard Karine Labat Patrice Ricarte 《Geophysical Prospecting》2011,59(1):132-144
In the Norwegian North Sea, the Sleipner field produces gas with a high CO2 content. For environmental reasons, since 1996, more than 11 Mt of this carbon dioxide (CO2) have been injected in the Utsira Sand saline aquifer located above the hydrocarbon reservoir. A series of seven 3D seismic surveys were recorded to monitor the CO2 plume evolution. With this case study, time‐lapse seismics have been shown to be successful in mapping the spread of CO2 over the past decade and to ensure the integrity of the overburden. Stratigraphic inversion of seismic data is currently used in the petroleum industry for quantitative reservoir characterization and enhanced oil recovery. Now it may also be used to evaluate the expansion of a CO2 plume in an underground reservoir. The aim of this study is to estimate the P‐wave impedances via a Bayesian model‐based stratigraphic inversion. We have focused our study on the 1994 vintage before CO2 injection and the 2006 vintage carried out after a CO2 injection of 8.4 Mt. In spite of some difficulties due to the lack of time‐lapse well log data on the interest area, the full application of our inversion workflow allowed us to obtain, for the first time to our knowledge, 3D impedance cubes including the Utsira Sand. These results can be used to better characterize the spreading of CO2 in a reservoir. With the post‐stack inversion workflow applied to CO2 storage, we point out the importance of the a priori model and the issue to obtain coherent results between sequential inversions of different seismic vintages. The stacking velocity workflow that yields the migration model and the a priori model, specific to each vintage, can induce a slight inconsistency in the results. 相似文献
94.
Simona Petrosino Paola Cusano Mario La Rocca Danilo Galluzzo Justo Orozco-Rojas Mauricio Bretón Jesus Ibáñez Edoardo Del Pezzo 《Bulletin of Volcanology》2011,73(7):887-898
This paper presents an analysis of seismicity associated with the volcanic activity of Volcàn de Colima (México) and recorded
in the period November 2005–April 2006 during a field survey by the Istituto Nazionale di Geofisica e Vulcanologia (INGV)–Osservatorio
Vesuviano, the Observatorio Vulcanologico de Colima of Colima University and the Instituto Andaluz de Geofisica, University
of Granada. Three different types of volcanic earthquakes have been identified on the basis of their spectral properties:
Type A (0.3–1 Hz), Type B (1–5 Hz) and Type C (3–4 Hz). Results of polarization analysis applied to Type A events show a predominance
of radial motion, indicating that the wavefield comprises compressional waves (P) and shear waves polarized in the vertical
plane (SV), while the signal always begins with a negative polarity. Type A, B and C earthquakes have been located using both
a flat layered model and a 3D model including topography. Hypocentre distributions indicate that the source of Type A signals
is very shallow and confined to a small volume lying about 1 km below the crater. In contrast, the source of Type B and C
events is significantly deeper, with most hypocentres located in a volume of about 1 km3 centred at 2.5–3 km depth. A cluster analysis based on the cross-correlation among the waveforms of different events recorded
at the same station was applied to Type A earthquakes. Only two clusters, which include only a small percentage of events
were found, indicating that earthquake families were uncommon during the period of our survey. 相似文献
95.
T. Rossetto N. Peiris J. E. Alarcon E. So S. Sargeant M. Free V. Sword-Daniels D. Del Re C. Libberton E. Verrucci P. Sammonds J. Faure Walker 《Bulletin of Earthquake Engineering》2011,9(1):11-37
On April 6, 2009 an earthquake of magnitude 6.2 (Mw) struck the Abbruzzo region of Italy causing widespread damage to buildings in the city of L??Aquila and surrounding areas. This paper summarizes field observations made by the Earthquake Engineering Field Investigation Team (EEFIT) after the event. The paper presents an overview of seismological and geotechnical aspects of the earthquake as well as a summary of the observed damage to buildings and infrastructure. A brief overview of the earthquake casualties is also reported. 相似文献
96.
Daniele Spiga Gianpiero Tagliaferri Paolo Soffitta Oberto Citterio Stefano Basso Ronaldo Bellazzini Alessandro Brez Wolfgang Burkert Vadim Burwitz Enrico Costa Luca de Ruvo Ettore Del Monte Sergio Fabiani Gisela Hartner Benedikt Menz Massimo Minuti Fabio Muleri Giovanni Pareschi Michele Pinchera Alda Rubini Carmelo Sgrò Gloria Spandre 《Experimental Astronomy》2014,37(1):37-53
The Joint European X-ray Telescope (JET-X) was the core instrument of the Russian Spectrum-X- γ space observatory. It consisted of two identical soft X-ray (0.3–10 keV) telescopes with focusing optical modules having a measured angular resolution of nearly 15 arcsec. Soon after the payload completion, the mission was cancelled and the two optical flight modules (FM) were brought to the Brera Astronomical Observatory where they had been manufactured. After 16 years of storage, we have utilized the JET-X FM2 to test at the PANTER X-ray facility a prototype of a novel X-ray polarimetric telescope, using a Gas Pixel Detector (GPD) with polarimetric capabilities in the focal plane of the FM2. The GPD was developed by a collaboration between INFN-Pisa and INAF-IAPS. In the first phase of the test campaign, we have re-tested the FM2 at PANTER to have an up-to-date characterization in terms of angular resolution and effective area, while in the second part of the test the GPD has been placed in the focal plane of the FM2. In this paper we report the results of the tests of the sole FM2, using an unpolarized X-ray source, comparing the results with the calibration done in 1996. 相似文献
97.
The oblique and diachronous collision of the Apennine-Maghrebian Chain with the Apulian (in the north-east) and Pelagian (in
the south) continental forelands, has determined the characteristic arcuate structure of this orogen. The effects of Plio-Pleistocene
deformation of the Calabrian Arc have been analysed on the basis of available reflection seismic profiles and using local
time-structural maps reconstructed along the main structures. During this period, internal sectors of the Tertiary chain migrated
forward on the oceanic Ionian foreland, and were cut by important strike-slip systems. These last have an orientation approximately
coincident with that of the migration of the front, allowing differential movement of the different sectors of the arc, towards
the weakly buoyant Ionian oceanic domain. The dataset suggests a clear connection between the development of the strike-slip
systems cutting the chain and the direction of tectonic transport, towards the East during Late Messinian/Early Pliocene time,
to the ESE during Late Pliocene/Early Pleistocene time, finally to the SSE during the Middle/Late Pleistocene to Present,
showing a clockwise rotation in well defined stages during the kinematic evolution of the chain. The origin of the Strait
of Messina during the different phases is also interpreted in the context of the analysed regional tectonic setting. 相似文献
98.
Mauro Celussi Alessandro Paoli Fabrizio Bernardi Aubry Mauro Bastianini Paola Del Negro 《Estuarine, Coastal and Shelf Science》2008
Diel sampling was performed during an early spring survey in the Northern Adriatic Sea at a coastal station off the Po River delta. Samples were taken every 6 h at spring tide maxima and minima in the sub-superficial layer, at the maximum fluorescence depth (∼3 m). Variations in microbial community structure and its processes were assessed by considering heterotrophic bacteria, picocyanobacteria, viruses, exoenzymatic activities, microphytoplankton, nanoplankton and bacterial/cyanobacterial Denaturing Gradient Gel Electrophoresis (DGGE) profiles. A considerable diatom bloom, mostly supported by Skeletonema marinoi was detected. All microbial parameters except viruses, showed a sinusoidal trend with a 12 h period; only picocyanobacteria expressed relative maxima during high tide, showing a phase in opposition to the other parameters. No substantial changes in DGGE band patterns were detected. Even though the results showed bacterial activities to be influenced by the phytoplankton bloom, all microbial parameters' diel trends (except viruses) preferentially followed the tidal fluctuation rather than the light:dark cycle. 相似文献
99.
We describe the application of a multi-scale Laplacian-of-Gaussian (LoG) operator and of an iterative version of Medial Axis
Transform (i-MAT) as tools for the segmentation of both photospheric and chromospheric solar features. We introduce the multi-scale LoG
operator in order to extract compact structures in photospheric intensity or Doppler images. The second method, based on a
i-MAT algorithm applied to gray level images, is introduced to recognize reticulated structures like chromospheric network
or intergranular lanes. The developed numerical procedures allow a non-subjective segmentation of solar images in order to
investigate morphological and topological properties of identified features. We discuss the output of the segmentation procedures
when applied to real images. 相似文献
100.
A. Del Popolo M. Gambera N. Ercan 《Monthly notices of the Royal Astronomical Society》2001,325(4):1402-1410
Planets orbiting a planetesimal circumstellar disc can migrate inward from their initial positions because of dynamical friction between planets and planetesimals. The migration rate depends on the disc mass and on its time evolution. Planets that are embedded in long-lived planetesimal discs, having total mass of 10−4 – 0.01 M⊙ , can migrate inward a large distance and can survive only if the inner disc is truncated or as a result of tidal interaction with the star. In this case the semimajor axis, a , of the planetary orbit is less than 0.1 au. Orbits with larger a are obtained for smaller values of the disc mass or for a rapid evolution (depletion) of the disc. This model may explain not only several of the orbital features of the giant planets that have been discovered in recent years orbiting nearby stars, but also the metallicity enhancement found in several stars associated with short-period planets. 相似文献