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51.
A recent build-up of atmospheric CO2 over Europe. Part 1: observed signals and possible explanations
By MICHEL RAMONET PHILIPPE CIAIS TUULA AALTO CÉLINE AULAGNIER FRÉDÉRIC CHEVALLIER DOMENICO CIPRIANO THOMAS J. CONWAY LASZLO HASZPRA VICTOR KAZAN FRANK MEINHARDT JEAN-DANIEL PARIS MARTINA SCHMIDT PETER SIMMONDS IRÈNE XUEREF-RÉMY JAROSLAW N. NECKI 《Tellus. Series B, Chemical and physical meteorology》2010,62(1):1-13
We analysed interannual and decadal changes in the atmospheric CO2 concentration gradient (ΔCO2 ) between Europe and the Atlantic Ocean over the period 1995–2007. Fourteen measurement stations are used, with Mace-Head being used to define background conditions. The variability of ΔCO2 reflects fossil fuel emissions and natural sinks activity over Europe, as well as atmospheric transport variability. The mean ΔCO2 increased by 1–2 ppm at Eastern European stations (∼30% growth), between 1990–1995 and 2000–2005. This built up of CO2 over the continent is predominantly a winter signal. If the observed increase of ΔCO2 is explained by changes in ecosystem fluxes, a loss of about 0.46 Pg C per year would be required during 2000–2005. Even if severe droughts have impacted Western Europe in 2003 and 2005, a sustained CO2 loss of that magnitude is unlikely to be true. We sought alternative explanations for the observed CO2 build-up into transport changes and into regional redistribution of fossil fuel CO2 emissions. Boundary layer heights becoming shallower can only explain 32% of the variance of the signal. Regional changes of emissions may explain up to 27% of the build-up. More insights are given in the Aulagnier et al. companion paper. 相似文献
52.
53.
Pressure, Temperature, and Structural Evolution of West-Central New Hampshire: Hot Thrusts over Cold Basement 总被引:2,自引:0,他引:2
KOHN MATTHEW J.; ORANGE DANIEL L.; SPEAR FRANK S.; RUMBLE DOUGLAS III; HARRISON T. MARK 《Journal of Petrology》1992,33(3):521-556
Pressure-temperature (P-T) paths have been calculated from pelitesand amphibolites of several major Acadian structures in west-centralNew Hampshire by using both inclusion thermobarometry and differentialthermodynamics (the Gibbs method). P-T paths calculated forrocks exposed in the Orfordville and Bronson Hill anticlinoriaare clockwise and show 12.5 kb of exhumationwith 30100 C of heating. Because this type of path ischaracteristic of the lower plate of overthrust terranes, theserocks are interpreted to be (para)autochthonous. P-T paths forrocks exposed in an intervening synclinorium (the Hardscrabblesynclinorium) show isothermal loading of 13 kb followedby possible isobaric cooling. This behavior is characteristicof rocks occupying a middle-plate structural position withina multiple thrust package, and so these rocks are interpretedto be allochthonous. The interpretation that the Hardscrabblerocks are allochthonous differs from previous models, but betterexplains the petrologic data and is consistent with the stratigraphicand structural data on which other models have been based. Correlation of the P-T paths with deformational events throughkinematic and textural analysis indicates that during nappestage deformation, the synclinorial rocks were transported westward,and that the anticlinorial and synclinorial rocks were buriedto depths of 2530 and 2025 km respectively. Theexhumation with heating recorded by the anticlinorial samplesoccurred during the dome stage of deformation, and differentiallyuplifted the anticlinorial rocks relative to the synclinorialrocks; this differential uplift may have been accommodated throughreactivation of early thrust faults with normal movement sense.P-T paths of the Hardscrabble synclinorium rocks are suggestiveof a relatively elevated initial geothermal gradient for theirpre-nappe source terrane, which is interpreted to have beenbetween the Kearsarge-Central Maine basin and the Bronson Hillparautochthon. 相似文献
54.
FRANK J. WOBBER 《Sedimentology》1967,9(4):265-317
Geologists increasingly concerned with detailed laboratory analyses at times overlook space-age techniques that promise the collection of valuable sedimentological data. Orbital remote sensing, and particularly space photography, can provide synoptic environmental data for geoscientists including those familiar with applying aerial photography to the analysis of sedimentary environments. Color space photographs obtained incident to the Gemini Program provide unique tools for analyzing sedimentary environments and processes and provide data that cannot be duplicated by conventional aerial photographic techniques. The principal advantages of orbital geoscience data collection include frequency of coverage leading to environmental analysis within the full spectrum of seasonal contrasts, and opportunities for environmental syntheses by synoptic observations. Gemini space photography is an available source of semi-quantitative data concerning changing environmental phenomena and mechanisms of sediment distribution. It also enables the survey and inventory of global sedimentary landforms. With the application of advanced sensors, increased system resolution, and repetitious photographic coverage, speedier and more reliable quantitative sedimentological analyses can be performed. 相似文献
55.
Classification and regression techniques are among the most used tools by chemometricians.Withclassification,the two classic methods are discriminant analysis and SIMCA.In this paper we discuss theconnection between these two methods and introduce two new ones of the same family:DASCO(discriminantanalysis with shrunken covariances)and RDA(regularized discriminant analysis).We demonstrate on bothsimulated and real data sets that their performance is superior to the old favorites.This is especially truein small-sample/high-dimension settings typical in chemistry. 相似文献
56.
A new, detailed tectonic model is presented for the Acadianorogenic belt of central New England (Vermont and New Hampshire)that accounts for a wide range of petrological and structuralobservations. Three belts are considered: the Eastern Vermont,Merrimack, and intervening Bronson Hill belts. Specific observationsin eastern Vermont that are accounted for in the model includethe following. PT paths are clockwise with maximum pressuresnear the Athens, Chester, and Strafford domes of 811kbar, but with maximum pressures decreasing to 35 kbarat the boundary with the Bronson Hill belt. Differential exhumationof the Vermont domes relative to the rocks in easternmost Vermontis required by the recorded differences in maximum pressure(56 kbar; 1520 km) and the present-day geographicalseparation (710 km). Specific observations in New Hampshirethat are explained include the following. PT paths inthe Merrimack belt are counter-clockwise with maximum pressuresof 45 kbar and are related to high regional heat flowand heat transfer by early Acadian plutons. PT pathsin the Bronson Hill belt are intimately associated with structuralposition. An early contact metamorphism is evidenced in theSkitchewaug and Fall Mountain nappes near contacts with theearly Acadian Bethlehem gneiss ( 相似文献
57.
KEITH E. BARBER FRANK M. CHAMBERS DARREL MADDY 《Boreas: An International Journal of Quaternary Research》2004,33(2):132-144
Plant macrofossil remains have been analysed from two raised peat bogs in northern Germany and Denmark. The quantified vegetation reconstructions of each profile were subjected to multivariate analyses to extract records of changing bog surface wetness (BSW), which are interpreted in these rain-fed bogs as being proxy climate signals. Age/depth models were constructed using radiocarbon dates and a number of drier and wetter phases were defined. The records both register cooler/wetter conditions around 2700, 1800 and 1400 cal. yr BP, and at the beginning of the Little Ice Age around AD 1250–1350. These rising bog water tables must have been reflected in poorer conditions for agriculture, and in particular near Dosenmoor where the profile records a catastrophic change to such conditions culminating at 2750–2600 cal. yr BP. 相似文献
58.
FRANK WAGNER DANIELE BORTOLI SÉRGIO PEREIRA MARIA JOÃO COSTA ANA MARIA SILVA BERNADETT WEINZIERL MICHAEL ESSELBORN REAS PETZOLD KATHI RASP BERND HEINOLD INA TEGEN 《Tellus. Series B, Chemical and physical meteorology》2009,61(1):297-306
Aerosol properties of mineral particles in the far field of an African desert dust outbreak were investigated that brought Saharan dust over the Mediterranean in different layers to Portugal. The measurements were performed inside the project Desert Aerosols over Portugal (DARPO) which was linked to the Saharan Mineral Dust Experiment (SAMUM). The maximum particle mass concentration was about 150 μg m−3 and the corresponding scattering coefficient was 130 M m−1 which results in a mass scattering efficiency of 0.87 m2 g−1 . The aerosol optical depth reached values up to 0.53 and the lidar ratio was between 45 and 50 in the whole dust loaded column. A comparison between particle size distributions and refractive indices derived from different instruments and models showed a general good agreement but some minor differences could also be observed. Measurements as well as calculations with a particle transport model suggest that there is a relatively higher concentration of very large particles in the upper region of the dust layer than on the surface which is likely connected with meteorological conditions at the observational site (Évora, Portugal). 相似文献
59.
CEES VAN der LAND FURU MIENIS HENK DE HAAS NORBERT FRANK RUDY SWENNEN TJEERD C. E. VAN WEERING 《Sedimentology》2010,57(3):912-931
Cold water coral covered carbonate mounds at the south‐west margin of the Rockall Trough form ridges several kilometres long and up to 380 m high. Piston cores obtained at three mound crests reveal the complex internal structure of the mound build up, with alternating unlithified coral‐dominated intervals and lithified intervals. The most recent lithified interval is covered by corals embedded in a fine‐grained matrix, comprising ca 11 000 years of continuous mound evolution. Before this time 230Th/U dating shows the presence of several hiatuses in mound build‐up. Aragonitic coral material is absent or only present as mouldic porosity in the lithified intervals and coccoliths display widespread overgrowth. Downcore X‐ray fluorescence scanning, computer tomography scan images and petrographic observations indicate different degrees of diagenetic alteration. The upper boundary of the most recent lithified interval shows some erosional features, but petrographic observations indicate that initial lithification of the sediments is not related to this erosive event or to long‐term non‐sedimentation, but to earlier sub‐surface diagenesis. Organic matter oxidation and the subsequent lowering of the saturation state of the carbonate system drives dissolution of the unstable aragonitic coral skeletons. Depending on the openness of the system, this can lead to precipitation of a more stable low‐magnesium carbonate. A model is presented describing the sedimentary and diagenetic processes leading to the formation of lithified intervals. 相似文献
60.
KIRSTIN WERNER PAVEL E. TARASOV REI A. ANDREEV STEFANIE MÜLLER FRANK KIENAST MICHAEL ZECH WOLFGANG ZECH BERNHARD DIEKMANN 《Boreas: An International Journal of Quaternary Research》2010,39(1):56-68
Werner, K., Tarasov, P. E., Andreev, A. A., Müller, S., Kienast, F., Zech, M., Zech, W. & Diekmann, B. 2009: A 12.5‐kyr history of vegetation dynamics and mire development with evidence of Younger Dryas larch presence in the Verkhoyansk Mountains, East Siberia, Russia. Boreas, 10.1111/j.1502‐3885.2009.00116.x. ISSN 0300‐9483. A 415 cm thick permafrost peat section from the Verkhoyansk Mountains was radiocarbon‐dated and studied using palaeobotanical and sedimentological approaches. Accumulation of organic‐rich sediment commenced in a former oxbow lake, detached from a Dyanushka River meander during the Younger Dryas stadial, at ~12.5 kyr BP. Pollen data indicate that larch trees, shrub alder and dwarf birch were abundant in the vegetation at that time. Local presence of larch during the Younger Dryas is documented by well‐preserved and radiocarbon‐dated needles and cones. The early Holocene pollen assemblages reveal high percentages of Artemisia pollen, suggesting the presence of steppe‐like communities around the site, possibly in response to a relatively warm and dry climate ~11.4–11.2 kyr BP. Both pollen and plant macrofossil data demonstrate that larch woods were common in the river valley. Remains of charcoal and pollen of Epilobium indicate fire events and mark a hiatus ~11.0–8.7 kyr BP. Changes in peat properties, C31/C27 alkane ratios and radiocarbon dates suggest that two other hiatuses occurred ~8.2–6.9 and ~6.7–0.6 kyr BP. Prior to 0.6 kyr BP, a major fire destroyed the mire surface. The upper 60 cm of the studied section is composed of aeolian sands modified in the uppermost part by the modern soil formation. For the first time, local growth of larch during the Younger Dryas has been verified in the western foreland of the Verkhoyansk Mountains (~170 km south of the Arctic Circle), thus increasing our understanding of the quick reforestation of northern Eurasia by the early Holocene. 相似文献