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101.
102.
Late Holocene radiocarbon and aspartic acid racemization dating of deep-sea octocorals 总被引:1,自引:0,他引:1
Primnoa resedaeformis is a deep-sea gorgonian coral with a two-part skeleton of calcite and gorgonin (a fibrillar protein), potentially containing long-term records of valuable paleo-environmental information. For various reasons, both radiocarbon and U/Th dating of these corals is problematic over the last few centuries. This paper explores aspartic acid racemization dating of the gorgonin fraction in modern and fossil specimens collected from the NW Atlantic Ocean. Radiocarbon dating of the fossil specimen indicates a lifespan of 700 ± 100 years, the longest yet documented for any octocoral. Gorgonin amino acid compositions were identical in the fossil and modern specimens, indicating resistance to organic diagenesis. Similar to bone collagen, the fibrillar protein of gorgonin may impose conformational constraints on the racemization of Asp at low temperatures. The rate of racemization of aspartic acid (d/l-Asp) was similar to previously published results from an 1800 year old anemone (Gerardia). The age equation was: age (years BP 2000 AD) = [(d/l − 0.020 (±.002))/.0011 (±.0001)]2 (r2 = 0.97, p < .001). The error in an age estimate calculated by d/l-Asp was marginally better than that for 14C dating over the most recent 50-200 years, although the dating error may be improved by inclusion of more samples over a broader time range. These results suggest that d/l-Asp dating may be useful in augmenting 14C dating in cases where 14C calibrations yield two or more intercept ages, or in screening samples for further 14C or U/Th dating. 相似文献
103.
Tobias Owen 《Icarus》1976,29(1):159-163
A brief review of the history of Jovian satellite nomenclature is given to indicate the background for the names proposed for the numbered satellites. The new names are consistent with established tradition and should cause minimal confusion with other named objects in the solar system. 相似文献
104.
Climate Change and Global Wine Quality 总被引:10,自引:0,他引:10
Gregory?V.?JonesEmail author Michael?A.?White Owen?R.?Cooper Karl?Storchmann 《Climatic change》2005,73(3):319-343
From 1950 to 1999 the majority of the world's highest quality wine-producing regions experienced growing season warming trends.
Vintage quality ratings during this same time period increased significantly while year-to-year variation declined. While
improved winemaking knowledge and husbandry practices contributed to the better vintages it was shown that climate had, and
will likely always have, a significant role in quality variations. This study revealed that the impacts of climate change
are not likely to be uniform across all varieties and regions. Currently, many European regions appear to be at or near their
optimum growing season temperatures, while the relationships are less defined in the New World viticulture regions. For future
climates, model output for global wine producing regions predicts an average warming of 2 ∘C in the next 50 yr. For regions producing high-quality grapes at the margins of their climatic limits, these results suggest
that future climate change will exceed a climatic threshold such that the ripening of balanced fruit required for existing
varieties and wine styles will become progressively more difficult. In other regions, historical and predicted climate changes
could push some regions into more optimal climatic regimes for the production of current varietals. In addition, the warmer
conditions could lead to more poleward locations potentially becoming more conducive to grape growing and wine production. 相似文献
105.
James M. Bauer Ted L. RoushThomas R. Geballe Karen J. MeechTobias C. Owen William D. Vacca John T. Rayner Kevin T.C. Jim 《Icarus》2002,158(1):178-190
A spectrum from 1.2 to 2.5 μm of Uranus' small satellite Miranda obtained in June 1999 reveals strong water-ice signatures. It confirms the existence of a 2.0-μm water feature previously detected on Miranda and shows a strong second broad 1.5-μm water-ice absorption feature. The spectra also reveal a weak absorption band at 1.65 μm that is indicative of crystalline water ice. Reflectance models which combine the new spectra with new photometry indicate that the spectra are characteristic of a mostly water-ice surface, with a large fraction of carbonaceous or silicate contaminates, and the possible presence of ammonia hydrate, as implied by an apparent weak feature near 2.2 μm. The possible presence of other volatiles is also investigated. 相似文献
106.
Interactive analysis of the spatial distribution of disease using a geographic information systems 总被引:1,自引:0,他引:1
Geographic information systems (GIS) provide a variety of tools for the manipulation and display of public health data. Few,
however, enable users to interactively evaluate hypotheses on spatial trends in disease risk that may be suggested by maps
of measures of disease impact. We addressed this limitation by developing a seamless interface between a commercial GIS and
a suite of spatial analysis algorithms. Users of the system can utilize the GIS's capability to interactively select and manipulate
geographically referenced data and, through a series of pull-down menus, apply a variety of exploratory analysis methods to
this information. In the presented application, we illustrate this capability by including algorithms for the reduction of
random noise in observed incidence rates, for the detection of unusual aggregations of disease events, and for the statistical
evaluation of inferences drawn from spatial trends. We demonstrate this application by examining lung cancer mortality in
the state of Ohio.
Received: 22 September 1999 / Accepted: 8 March 2000 相似文献
107.
Cochran Anita Veverka Joseph Bell James Belton Michael Benkhoff Johannes Benkhoff Andrew Clark Benton Feldman Paul Kissel Jochen Mahaffy Paul Malin Michael Murchie Scott Neimann Hasso Owen Tobias Robinson Mark Schwehm Gerhard Squyres Steve Thomas Peter Whipple Fred Yeomans Donald 《Earth, Moon, and Planets》2000,89(1-4):289-300
In 1997, the COmet Nucleus TOUR (CONTOUR) was selected byNASA for a new start as part of the Discovery line. In this paper, we review the status of the mission, the mission timeline and the instruments to be flown. Detail is given of the science goals and how they are to be accomplished. 相似文献
108.
R. J. Ivison Ian Smail A. J. Barger J.-P. Kneib A. W. Blain F. N. Owen T. H. Kerr L. L. Cowie 《Monthly notices of the Royal Astronomical Society》2000,315(2):209-222
We present extensive observations of a sample of distant, submillimetre (submm) galaxies detected in the field of the massive cluster lens Abell 1835, using the Submm Common-User Bolometer Array (SCUBA). Taken in conjunction with earlier observations of other submm-selected sources, we now have detailed, multiwavelength observations of seven examples of the submm population, having exploited the combination of achromatic amplification by cluster lenses and lavish archival data sets. These sources, all clearly at z ≳1, illustrate the wide range in the radio and optical properties of distant submm-selected galaxies. We include detailed observations of the first candidate 'pure' starburst submm galaxy at high redshift, a z =2.56 interacting galaxy which shows no obvious sign of hosting an AGN. The remaining sources have varying degrees of inferred AGN activity (three out of seven of the most luminous show some evidence of the presence of an AGN), although even when an AGN is obviously present it is still not apparent whether reprocessed radiation from this source dominates the submm emission. In contrast with the variation in the spectral properties, we see relatively homogeneous morphologies for the population, with a large fraction of merging or interacting systems. Our study shows that virtually identical spectral energy distributions are seen for galaxies that exhibit strikingly different optical/UV spectral-line characteristics. We conclude that standard optical/UV spectral classifications are misleading when applied to distant, highly obscured galaxies, and that we must seek other means of determining the various contributions to the overall energy budget of submm galaxies and hence to the far-infrared extragalactic background. 相似文献
109.
110.
In the Ordovician Northern Belt of the Southern Uplands, basal volcanics (Arenig) are followed by cherts (Llanvirn-?Llandeilo), then by graptolite shales (Llandelio-Lower Caradoc), and finally by Caradoc greywackes. Within the greywackes (Kirkcolm Formation) are a number of occurrences of fossiliferous conglomerate and overlying mudstone; these can be traced along-strike for some 30 km. The conglomerates, and especially the mudstones, yield rich mid- Caradoc shelly assemblages; brachiopods (20 spp.)/ trilobites (14 spp.), gastropods, bivalves, bryozoans, and the first known Palaeozoic scleractiniamorph coral. These occurrences are interpreted as mass-flow deposits derived by downslope movement from a now-vanished shelf to the North, and may belong either to a single gigantic debris flow event, or to a series of smaller, but roughly contemporaneous flows. Strong faunal similarities to faunas at Girvan (western Scotland), and Tyrone (Northern Ireland), lying North of the Southern Upland Fault may suggest sinistral strike-slip movement of no more than a few hundred kilometres. 相似文献