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61.
E. O. Oladiran 《Pure and Applied Geophysics》1981,119(5):966-977
Investigation was carried out to study the interaction of positive streamers with charged and uncharged drops in a vertical electric field configuration. Results obtained for vertical and horizontal positions of the photographic films show that streamer interactions with neutral and negative drops are similar and further confirmed earlier results byPhelps (1972). It showed that indirect streamer interaction with droplets is effected by branches being sent to the drops from the main channel. The visibility of the branches on the Lichtenberg figures and the degree of interaction of streamers with drops depend on the drop size, its initial charge and shape, and/or the separation of the drops from the main channel. Suppression of streamer propagation among the positively charged drops was observed. 相似文献
62.
In this paper, we first apply the assumption h = εh′ of topographic variation (h is the nondimensional topographic height and is a small parameter) to obtain nonlinear equations describing three-wave quasi-resonant
and non-resonant interactions among Rossby waves for zonal wavenumbers 1—3 over a wavenumber-two bottom topography (WTBT).
Some numerical calculations are made with the fourt-order Rung-Kutta Scheme. It is found that for the case without topographic
forcing, the period of three-wave quasi-resonance (TWQR) is found to be independent of the zonal basic westerly wind, but
dependent on the meridional wavenumber and the initial amplitudes. For the fixed initial data, when the frequency mismatch
is smaller and the meridional wavelength is moderate, its period will belong to the 30–60-day period band. However, when the
wavenumber-two topography is included, the periods of the forced quasi-resonant Rossby waves are also found to be strongly
dependent on the setting of the zonal basic westerly wind. Under the same conditions, only when the zonal basic westerly wind
reaches a moderate extent, intraseasonal oscillations in the 30–60-day period band can be found for zonal wavenumbers 1–3.
On the other hand, if three Rossby waves considered have the same meridional wavenumber, three-wave non-resonant interaction
over a WTBT can occur in this case. When the WTBT vanishes, the amplitudes of these Rossby waves are conserved. But in the
presence of a WTBT, the three Rossby waves oscillate with the identical period. The period, over a moderate range of the zonal
basic westerly wind, is in the intraseasonal, 30–60-Day range. 相似文献
63.
64.
The environments and clustering properties of 2dF Galaxy Redshift Survey selected starburst galaxies
Matt S. Owers Chris Blake Warrick J. Couch Michael B. Pracy Kenji Bekki 《Monthly notices of the Royal Astronomical Society》2007,381(2):494-510
We investigate the environments and clustering properties of starburst galaxies selected from the 2dF Galaxy Redshift Survey (2dFGRS) in order to determine which, if any, environmental factors play a role in triggering a starburst. We quantify the local environments, clustering properties and luminosity functions of our starburst galaxies and compare to random control samples. The starburst galaxies are also classified morphologically in terms of their broad Hubble type and evidence of tidal merger/interaction signatures. We find the starburst galaxies to be much less clustered on large (5–15 Mpc) scales compared to the overall 2dFGRS galaxy population. In terms of their environments, we find just over half of the starburst galaxies to reside in low to intermediate luminosity groups, and a further ∼30 per cent residing in the outskirts and infall regions of rich clusters. Their luminosity functions also differ significantly from that of the overall 2dFGRS galaxy population, with the sense of the difference being critically dependent on the way their star formation rates are measured. In terms of pin-pointing what might trigger the starburst, it would appear that factors relating to their local environment are most germane. Specifically, we find clear evidence that the presence of a near neighbour of comparable luminosity/mass within 20 kpc is likely to be important in triggering a starburst. We also find that a significant fraction (20–30 per cent) of the galaxies in our starburst samples have morphologies indicative of either an ongoing or a recent tidal interaction and/or merger. These findings notwithstanding, there remain a significant portion of starburst galaxies where such local environmental influences are not in any obvious way playing a triggering role, leading us to conclude that starbursts can also be internally driven. 相似文献
65.
Abundance diagnosis of E+A (post-starburst) galaxies 总被引:1,自引:0,他引:1
Tomotsugu Goto 《Monthly notices of the Royal Astronomical Society》2007,377(3):1222-1228
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When two vessels are moored side-by-side with a narrow gap between them, intense free surface motions may be excited in the gap as a result of complex hydrodynamic interactions. These influence the motions of the two vessels, and the forces in any moorings. The present paper uses first and second order wave diffraction analysis to investigate this phenomenon. Key theoretical aspects of the numerical analysis are first summarised, including the vital need to suppress “irregular frequency” effects; and results are given to validate the code used. The case of a tanker alongside a large floating FLNG barge is then considered in detail. 相似文献
69.
Fine‐scale diet of the Australian sea lion (Neophoca cinerea) using DNA‐based analysis of faeces 下载免费PDF全文
Kristian J. Peters Kathy Ophelkeller Nathan J. Bott Bruce E. Deagle Simon N. Jarman Simon D. Goldsworthy 《Marine Ecology》2015,36(3):347-367
We applied DNA‐based faecal analysis to determine the diet of female Australian sea lions (n = 12) from two breeding colonies in South Australia. DNA dietary components of fish and cephalopods were amplified using the polymerase chain reaction and mitochondrial DNA primers targeting the short (~100 base pair) section of the 16S gene region. Prey diversity was determined by sequencing ~50 amplicons generated from clone libraries developed for each individual. Faecal DNA was also combined and cloned from multiple individuals at each colony and fish diversity determined. Diets varied between individuals and sites. Overall, DNA analysis identified a broad diversity of prey comprising 23 fish and five cephalopod taxa, including many species not previously described as prey of the Australian sea lion. Labridae (wrasse), Monacanthidae (leatherjackets) and Mullidae (goat fish) were important fish prey taxa. Commonly identified cephalopods were Octopodidae (octopus), Loliginidae (calamary squid) and Sepiidae (cuttlefish). Comparisons of fish prey diversity determined by pooling faecal DNA from several samples provided a reasonable but incomplete resemblance (55–71%) to the total fish diversity identified across individual diets at each site. Interpretation of diet based on the recovery of prey hard‐parts identified one cephalopod beak (Octopus sp.) and one fish otolith (Parapriacanthus elongatus). The present study highlights the value of DNA‐based analyses and their capabilities to enhance information of trophic interactions. 相似文献
70.
In batch cultures of Lake Taupo water, phosphorus was the nutrient limiting plant growth from January to June, and nitrogen took over this role from July to December. Chlorophyll production by algae was often stimulated by trace element additions, but it was uncertain whether total cytoplasmic production was also involved. 相似文献