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11.
Stimulated Raman scattering is used to prepare ensembles of aligned acetylene molecules in thev
2=1 excited vibrational level. Decay and transfer of the alignment is followed by laser induced fluorescence. Measurements of the initially excited alignment agree well with theoretical calculations. The rate constants for decay decrease as the rotational quantum numberJ of the excited level increases. 相似文献
12.
13.
Julius Pia 《International Journal of Earth Sciences》1924,15(2):123-143
Ohne Zusammenfassung 相似文献
14.
Environmental settings on the Ionian coastal plain and inner shelf seaward of Locri‐Epizephiri in Calabria, Italy, differed markedly before, during, and following settlement by the Greeks. Sediment core analyses and geophysical surveys in this study support recent archaeological findings and the hypothesis that the margin may once have served as a harbor and/or shipyard. The subsurface Holocene stratigraphy records that (1) the shoreline advanced to a maximum landward position before Greek settlement, then regressed offshore to what is now the inner shelf before once again migrating landward. These marked coastal shifts were triggered primarily by land uplift and probable subsidence offshore along this structurally active Calabrian Arc segment. Associated with this are: (2) a sediment fining‐upward sequence in Greek–Roman time that indicates only partial protection of the coastal area, and (3) possible presence of subsurface structures seaward of the city wall in a sector now positioned ∼200 m offshore. © 2010 Wiley Periodicals, Inc. 相似文献
15.
Maria Pia Di Mauro JØrgen Christensen-Dalsgaard Lucio Paternò Francesca D'Antona 《Solar physics》2004,220(2):185-198
HR 5235, better known as η Bootis, is a bright and well-known star for which very accurate observations have recently enabled
Kjeldsen et al. (2003) and Carrier, Bouchy, and Eggenberger (2003) not only to confirm the presence of solar-like oscillations, but also
to identify the excitation in the oscillation spectrum of several p-mode frequencies with harmonic degrees l = 0 – 2. Here we show how such observational success, through the calculation and the investigation of theoretical structure
models and the comparison of the observed oscillation spectra with the predicted p-mode frequencies of oscillations, permits one to draw conclusions about the actual evolutionary state of this star and on
the physical properties of its internal structure. The computation of the structure models is based on the use of updated
global parameters and includes overshooting from the convective core. In particular, we consider the effect on the stellar
structure, and hence on the theoretical frequencies, of employing different equations of state and different formalisms to
describe the convective energy transport. 相似文献
16.
Anaerobic ammonium oxidation by nitrite (anammox): Implications for N2 production in coastal marine sediments 总被引:2,自引:0,他引:2
The respiratory reduction of nitrate (denitrification) is acknowledged as the most important process that converts biologically available nitrogen to gaseous dinitrogen (N2) in marine ecosystems. Recent findings, however, indicate that anaerobic ammonium oxidation by nitrite (anammox) may be an important pathway for N2 formation and N removal in coastal marine sediments and in anoxic water columns of the oceans. In the present study, we explored this novel mechanism during N mineralization by 15N amendments (single and coupled additions of 15NH4+, 14NO3− and 15NO3−) to surface sediments with a wide range of characteristics and overall reactivity. Patterns of 29/30N2 production in the pore water during closed sediment incubations demonstrated anammox at all 7 of the investigated sites. Stoichiometric calculations revealed that 4% to 79% of total N2 production was due to this novel route. The relative importance of anammox for N2 release was inversely correlated with remineralized solute production, benthic O2 consumption, and surface sediment Chl a. The observed correlations indicate competition between reductants for pore water nitrite during early diagenesis and that additional factors (e.g. availability of Mn-oxides), superimposed on overall patterns of diagenetic activity, are important for determining absolute and relative rates of anammox in coastal marine sediments. 相似文献
17.
18.
On June 30, 2001, a debris flow occurred in the Acquabona Creek, a small catchment of the Eastern Dolomites, Italy. This debris
flow originated shortly after an intense rainstorm, characterised by a peak intensity of 8.6 mm per 10 min; it transported
a total volume of 30,000 m3, consisting of poorly sorted gravely sand with boulders up to 3 m in diameter. The sediment erosion yield rate reached as
high as 20 m3/m. In order to verify the accuracy of the field measurements, the total volume of debris deposits have was calculated using
three different topographic measurement techniques: 3D laser scanning, terrestrial stereo-photogrammetry survey and total
topographic station survey. Data collected so far show that no debris flow has occurred at Acquabona with a rainfall intensity
lower than 4.6 mm per 10 min. Channel cross section measurements indicate that debris flow velocity ranges from 2.0 to 7.2 m/s
along the lower flow channel and peak discharge ranges between 22 and 300 m3/s. Field estimates of the rheological properties indicate a yield strength ranging from 2,088 to 5,313 Pa and Bingham viscosity
between 70 and 337 Pa · s. It is not still possible to identify a rainfall intensity and amount threshold for debris flow
triggering, but the data so far collected emphasise that debris flows do not occur with a rainfall intensity lower than 4.6 mm
per 10 min. 相似文献
19.
Pia VOLDET 《Geostandards and Geoanalytical Research》1983,7(2):281-282
The rare-earth elements (REE) content of the FER-1, -2, -3, -4 canadian reference samples has been determined by neutron activation and high-resolution X-ray or γ-ray spectrometry. As these rocks are included in a new project of standardisation, the present results have not been compared with other data. 相似文献
20.
Changes in storm track and cyclone activity in three SRES ensemble experiments with the ECHAM5/MPI-OM1 GCM 总被引:2,自引:1,他引:2
J. G. Pinto U. Ulbrich G. C. Leckebusch T. Spangehl M. Reyers S. Zacharias 《Climate Dynamics》2007,29(2-3):195-210
Synoptic activity over the Northern Hemisphere is evaluated in ensembles of ECHAM5/MPI-OM1 simulations for recent climate
conditions (20C) and for three climate scenarios (following SRES A1B, A2, B1). A close agreement is found between the simulations
for present day climate and the respective results from reanalysis. Significant changes in the winter mid-tropospheric storm
tracks are detected in all three scenario simulations. Ensemble mean climate signals are rather similar, with particularly
large activity increases downstream of the Atlantic storm track over Western Europe. The magnitude of this signal is largely
dependent on the imposed change in forcing. However, differences between individual ensemble members may be large. With respect
to the surface cyclones, the scenario runs produce a reduction in cyclonic track density over the mid-latitudes, even in the
areas with increasing mid-tropospheric activity. The largest decrease in track densities occurs at subtropical latitudes,
e.g., over the Mediterranean Basin. An increase of cyclone intensities is detected for limited areas (e.g., near Great Britain
and Aleutian Isles) for the A1B and A2 experiments. The changes in synoptic activity are associated with alterations of the
Northern Hemisphere circulation and background conditions (blocking frequencies, jet stream). The North Atlantic Oscillation
index also shows increased values with enhanced forcing. With respect to the effects of changing synoptic activity, the regional
change in cyclone intensities is accompanied by alterations of the extreme surface winds, with increasing values over Great
Britain, North and Baltic Seas, as well as the areas with vanishing sea ice, and decreases over much of the subtropics. 相似文献