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91.
92.
Louise K. Harra Nancy U. Crooker Cristina H. Mandrini Lidia van Driel-Gesztelyi Sergio Dasso Jingxiu Wang Heather Elliott Gemma Attrill Bernard V. Jackson Mario M. Bisi 《Solar physics》2007,244(1-2):95-114
We describe the interplanetary coronal mass ejections (ICMEs) that occurred as a result of a series of solar flares and eruptions
from 4 to 8 November 2004. Two ICMEs/magnetic clouds occurring from these events had opposite magnetic orientations. This
was despite the fact that the major flares related to these events occurred within the same active region that maintained
the same magnetic configuration. The solar events include a wide array of activities: flares, trans-equatorial coronal loop
disappearance and reformation, trans-equatorial filament eruption, and coronal hole interaction. The first major ICME/magnetic
cloud was predominantly related to the active region 10696 eruption. The second major ICME/magnetic cloud was found to be
consistent with the magnetic orientation of an erupting trans-equatorial filament or else a rotation of 160° of a flux rope
in the active region. We discuss these possibilities and emphasize the importance of understanding the magnetic evolution
of the solar source region before we can begin to predict geoeffective events with any accuracy. 相似文献
93.
Melanie Louise Inez Witt Stephen Skrabal Robert Kieber Joan Willey 《Journal of Atmospheric Chemistry》2007,58(2):89-109
Significant quenching of fluorescence by Cu in rainwater samples from southeastern North Carolina demonstrates that chromophoric
dissolved organic matter (CDOM) is an effective ligand for Cu in rainwater. A strong inverse correlation between the decrease
in fluorescence upon Cu addition and CDOM abundance suggests the presence of excess binding sites for Cu in high CDOM samples.
Electroanalytical studies indicate that CDOM extracted from C18 cartridges formed Cu complexes with concentrations and conditional stability constants similar to ligands found in ambient
rainwater. When authentic rainwater samples were photolyzed with simulated sunlight both photoproduction and photodestruction
of ligands were observed, suggesting the photochemical response of Cu-complexing ligands in rainwater is the result of two
competing reactions. The rate of CDOM photobleaching was directly related to changes in strong ligands (KCuL ∼ 1015) whereas weaker ligands (KCuL < 1013) were not correlated, suggesting the photolabile CDOM resides in the strong ligand class. A photolysis study comparing filtered
and unfiltered rainwater samples indicated that Cu-complexing ligands adsorbed onto or otherwise associated with particles
are photodegraded much more rapidly than dissolved ligands. Photolysis with UV radiation appears to be most effective at engendering
changes in Cu ligands, however a significant photochemical response was also observed when samples were exposed to photosynthetically
active radiation with wavelengths greater than 400 nm. Results from this study demonstrate that complexation of Cu by CDOM
has important ramifications for controlling both the speciation of the metal and the reactivity of CDOM in rainwater. 相似文献
94.
95.
R. Louise 《Journal of Astrophysics and Astronomy》1982,3(2):145-150
By using the Boller and Chivens spectrograph with a moderate dispersion (59 å mm-1) in the red spectral region, we obtained 65 spectra covering the whole surface of the planetary nebula NGC 2440. Intensities of Hα, [N II] λλ 6548–6584 and [S II] λλ 6717–6731 lines are derived using the IDS system available at the ESO in La Silva (Chile). The nebula is known to be a nitrogen-rich nebula (Peimbert 1978) surrounded by secondary structures (Minkowski 1964). The unusual high value of the [N II]/Hα in the central core (~ 30) is certainly due to the nitrogen overabundance occurring in that part of the nebula. Its variations from scale ionization structure (Capriotti, Cromwell and Williams 1971). The observations show clearly an outward increase of both [NII]/Hα andI(6717)/I(6713) ratios. 相似文献
96.
Williams JN Hollander AD O'Geen AT Thrupp LA Hanifin R Steenwerth K McGourty G Jackson LE 《Carbon balance and management》2011,6(1):11
Background
Quantification of ecosystem services, such as carbon (C) storage, can demonstrate the benefits of managing for both production and habitat conservation in agricultural landscapes. In this study, we evaluated C stocks and woody plant diversity across vineyard blocks and adjoining woodland ecosystems (wildlands) for an organic vineyard in northern California. Carbon was measured in soil from 44 one m deep pits, and in aboveground woody biomass from 93 vegetation plots. These data were combined with physical landscape variables to model C stocks using a geographic information system and multivariate linear regression.Results
Field data showed wildlands to be heterogeneous in both C stocks and woody tree diversity, reflecting the mosaic of several different vegetation types, and storing on average 36.8 Mg C/ha in aboveground woody biomass and 89.3 Mg C/ha in soil. Not surprisingly, vineyard blocks showed less variation in above- and belowground C, with an average of 3.0 and 84.1 Mg C/ha, respectively.Conclusions
This research demonstrates that vineyards managed with practices that conserve some fraction of adjoining wildlands yield benefits for increasing overall C stocks and species and habitat diversity in integrated agricultural landscapes. For such complex landscapes, high resolution spatial modeling is challenging and requires accurate characterization of the landscape by vegetation type, physical structure, sufficient sampling, and allometric equations that relate tree species to each landscape. Geographic information systems and remote sensing techniques are useful for integrating the above variables into an analysis platform to estimate C stocks in these working landscapes, thereby helping land managers qualify for greenhouse gas mitigation credits. Carbon policy in California, however, shows a lack of focus on C stocks compared to emissions, and on agriculture compared to other sectors. Correcting these policy shortcomings could create incentives for ecosystem service provision, including C storage, as well as encourage better farm stewardship and habitat conservation.97.
Stige LC Ottersen G Hjermann DØ Dalpadado P Jensen LK Stenseth NC 《Marine pollution bulletin》2011,62(2):395-398
Two factors determine whether pollution is likely to affect a population indirectly through loss of prey: firstly, the sensitivity of the prey to the pollutants, and secondly, the sensitivity of the predator population to loss of prey at the given life stage. We here apply a statistical recruitment model for Northeast Arctic cod to evaluate the sensitivity of cod cohorts to loss of zooplankton prey, for example following an oil spill. The calculations show that cod cohorts are highly sensitive to possible zooplankton biomass reductions in the distribution area of the cod larvae, and point to a need for more knowledge about oil-effects on zooplankton. Our study illustrates how knowledge about population dynamics may guide which indirect effects to consider in environmental impact studies. 相似文献
98.
Terrestrial laser scanning soil surfaces: a field methodology to examine soil surface roughness and overland flow hydraulics 总被引:1,自引:0,他引:1
Conventional roughness–resistance relationships developed for pipe and open‐channel flows cannot accurately describe shallow overland flows over natural rough surfaces. This paper develops a new field methodology combining terrestrial laser scanning (TLS) and overland flow simulation to provide a high‐resolution dataset of surface roughness and overland flow hydraulics as simulated on natural bare soil surfaces. This method permits a close examination of the factors controlling flow velocity and a re‐evaluation of the relationship between surface roughness and flow resistance. The aggregate effect of flow dynamics, infiltration and depression storage on retarding the passage of water over a surface is important where runoff‐generating areas are distant from well‐defined channels. Experiments to separate these effects show that this ‘effective resistance’ is dominated by surface roughness. Eight measurements of surface roughness are found to be related to flow resistance: standard deviation of elevations, inundation ratio, pit density (measured both perpendicular and parallel to the flow direction), slope, median depth, skewness of the depth distribution and frontal area. Hillslope position is found to affect the significant roughness measures. In contrast, infiltration rate has little effect on the velocity of water fronts advancing over the soil surfaces examined here and the effect of depression storage is limited. Overland flow resistance is depth dependent where complex microtopographic structures are progressively inundated. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
99.
Roberto Bertoni Wade H. Jeffrey Mireille Pujo-Pay Louise Oriol Pascal Conan Fabien Joux 《Aquatic Sciences - Research Across Boundaries》2011,73(3):377-387
The scaling of the solar ultraviolet radiation (UVR, 280–400 nm) effect on phyto- and bacterio-plankton at the ecosystem level
is difficult since its estimate is often based on short-time incubation experiments performed at fixed depths, neglecting
the previous days’ radiation history and the variable radiation caused by vertical mixing. To examine this issue, we measured
primary (PP) and bacterial (BP) production in samples from coastal water in the Northwest Mediterranean Sea incubated at fixed
depths or moving vertically within the water column (0–8 m) with a periodicity of 22 min, exposed to full sun, PAR or maintained
in dark. Three experiments were carried out on consecutive days to measure day-to-day variations in planktonic response. In
surface waters, PP was inhibited by ~32 to 42% by UVR, and BP was inhibited by ~50 to 70% by solar radiation (UVR + PAR).
We observed a general decrease in the integrated inhibition of PP due to UVR for both fixed and moving incubations over the
3 days from ~27% of inhibition to non-significant inhibition. In contrast, large discrepancies were observed in the integrated
inhibition of BP due to solar radiation (UVR + PAR) between fixed and moving incubations. Whereas both type of incubations
gave similar estimation of solar radiation inhibition on day 1 (~25%), inhibition became much higher for fixed incubation
compared to moving incubation on days 2 and 3. Differences in responses between days suggest that light history, spectral
quality, photoadaptation or acclimation may be important factors in daily observed responses. Our results also underline,
for the first time, the importance of the vertical mixing in the BP inhibition by solar radiation. 相似文献
100.
Catherine N. Jex Andy Baker Jonathan M. Eden Warren J. Eastwood Ian J. Fairchild Melanie J. Leng Louise Thomas Hilary J. Sloane 《Quaternary Research》2011,75(3):399-405
A verified instrumental calibration of annually resolved δ18O for a stalagmite from Gümü?hane in northeast Turkey is presented and cross-validated using a ‘leave-one-out’ technique. The amount of late autumn to winter precipitation is negatively correlated with stalagmite δ18O between AD 1938 and 2004. The observed relationship is extrapolated back to ~ AD 1500 leading to the first long winter precipitation reconstruction for this region. Modern day October to January precipitation is linked to pressure fields in Western Russia. Anomalously lower reconstructed rainfall is recorded in AD 1540–1560 at which time higher pressure over the Caspian Sea region is inferred. 相似文献