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11.
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13.
Dr. Roland Salchow 《Ocean Dynamics》1991,44(5-6):363-382
14.
Edward P. J. Van den Heuvel 《Journal of Astrophysics and Astronomy》1984,5(3):209-233
The peculiar combination of a relatively short pulse period and a relatively weak surface dipole magnetic field strength of
binary radio pulsars finds a consistent explanation in terms of (i) decay of the surface dipole component of neutron-star
magnetic fields on a timescale of (2–5) × 106 yr, in combination with (ii) spin-up of the rotation of the neutron star during a subsequent mass-transfer phase.
The four known binary radio pulsars appear to fall into two different categories. Two of them, PSR 0655 + 64 and PSR 1913
+ 16, have short orbital periods (<25 h) and high mass functions, indicating companion masses 0.7M⊙ (∼1 (± 0.3) M⊙ and 1.4 M⊙, respectively). The other two, PSR 0820 + 02 and PSR 1953 + 29, have long orbital periods (117d),
nearly circular orbits, and low, almost identical mass functions of about 3×10-3 M⊙, suggesting companion masses of about 0.3M⊙. It is pointed out that these two classes of systems are expected to be formed by the later evolution of binaries consisting
of a neutron star and a normal companion star, in which the companion was (considerably) more massive than the neutron star,
or less massive than the neutron star, respectively. In the first case the companion of the neutron star in the final system
will be a massive white dwarf, in a circular orbit, or a neutron star in an eccentric orbit. In the second case the final
companion to the neutron star will be a low-mass (∼ 0.3 M⊙) helium white dwarf in a wide and nearly circular orbit.
In systems of the second type the neutron star was most probably formed by the accretion-induced collapse of a white dwarf.
This explains in a natural way why PSR 1953 + 29 has a millisecond rotation period and PSR 0820 + 02 has not.
Among the binary models proposed for the formation of the 1.5-millisecond pulsar, the only ones that appear to be viable are
those in which the companion disappeared by coalescence with the neutron star. In such models the companion may have been
a red dwarf of mass 0.03M⊙, a neutron star, or a massive (>0.7M⊙) white dwarf. Only in the last-mentioned case is a position of the pulsar close to the galactic plane a natural consequence.
In the first-mentioned case the progenitor system most probably was a cataclysmic-variable binary in which the white dwarf
collapsed by accretion. 相似文献
15.
Zusammenfassung Der Eisengehalt von Andalusiten und Disthenen aus Quarzknauern im Gebiet des Ötztaler—Stubaier Altkristallins wurde regional untersucht. Der Gehalt and Gesamteisen in primären Disthen liegt zwischen 0,17 und 0,22 Gew.% Fe2O3, während primäre Andalusite zwischen 0,26 und 1,93 Gew.% Fe2O3 schwanken. Dieser Unterschied in den Andalusiten wird auf ein wechselndes Angebot von Fe2O3 aus dem Nachbargestein der Knauern zurückgeführt.Ein Zusammenhang zwischen dem Eisengehalt der Andalusite und den verschiedenen Umwandlungsstadien Andalusit—Disthen konnte nicht nachgewiesen werden.
On the iron content of alumosilicates in quartz nodules
Summary A determination of the regional distribution of the ironcontent of andalusites and kyanites in quartz-segregations of the Oetztal—Stubai crystalline complex gave values of 0.17–0.22% for the total iron in primary kyanite and 0.26–1.93% in andalusite. This difference is probably due to a variation in the Fe2O3-content in the country rocks of the quartz veins. No relationship between the iron-content in andalusite and the different stages of transformation from andalusite to kyanite could be established.相似文献
16.
For the period September 1978 to December 1982 we have identified 55 solar flare particle events for which our instruments on board the ISEE-3 (ICE) spacecraft detected electrons above 10 MeV. Combining our data with those from the ULEWAT spectrometer (MPI Garching and University of Maryland) electron spectra in the range from 0.1 to 100 MeV were obtained. The observed spectral shapes can be divided into two classes. The spectra of the one class can be fit by a single power law in rigidity over the entire observed range. The spectra of the other class deviate from a power law, instead exhibiting a steepening at low rigidities and a flattening at high rigidities. Events with power-law spectra are associated with impulsive (<1 hr duration) soft X-ray emission, whereas events with hardening spectra are associated with long-duration (<1 hr) soft X-ray emission. The characteristics of long-duration events are consistent with diffusive shock acceleration taking place high in the corona. Electron spectra of short-duration flares are well reproduced by the distribution functions derived from a model assuming simultaneous second-order Fermi acceleration and Coulomb losses operating in closed flare loops. 相似文献
17.
Prof. Dr. A. Watznauer 《International Journal of Earth Sciences》1965,54(2):853-860
Zusammenfassung Es läßt sich zeigen, daß im erzgebirgischen Raum die jungalgonkische Serie des varistischen Sockels von der Petrofazies diskordant geschnitten wird. Im Bereich des erzgebirgischen Kristallins steigt die Amphibolitfazies beulenförmig bis an die Basis des varistischen Sedimenttroges auf. Mit diesem Aufstieg wird eine Granitbildung regionalen und lokalen Charakters als möglich in Verbindung gebracht.
Herrn Prof. Dr. Dr. h. c.Erich Bederke zum 70. Geburtstag gewidmet. 相似文献
It can be demonstrated that the Upper Algonkian rocks of the Hercynian basement are disconformably cut by the petrofacies of the Erzgebirge. In the environment of crystallin rocks amphibolitic facies ascend to the bottom of the hercynian sedimentary trough. With this rise a granitisation of regional and locally restricted character might seem to be possible.
Résumé On peut montrer que dans la région de l'Erzgebirge les couches de l'Algonkien supérieur du socle hercynien sont recoupées en discordance par le petrofacies. Dans le domaine du cristallin de l'Erzgebirge, le facies amphibolite a la forme d'un dûme atteignant la base de la fosse sédimentaire varisque. On croit pouvoir établir une relation entre la formation de granite à l'échelle régionale et locale et cette montée métamorphique.
. .
Herrn Prof. Dr. Dr. h. c.Erich Bederke zum 70. Geburtstag gewidmet. 相似文献
18.
Potential implications of differential preservation of testate amoeba shells for paleoenvironmental reconstruction in peatlands 总被引:1,自引:0,他引:1
Edward A. D. Mitchell Richard J. Payne Mariusz Lamentowicz 《Journal of Paleolimnology》2008,40(2):603-618
Testate amoebae are now commonly used in paleoenvironmental studies but little is known of their taphonomy. There is some
experimental evidence for differential preservation of some testate amoeba shell types over others, but it is unclear what,
if any impact this has on palaeoenvironmental reconstruction. To investigate this issue we looked at palaeoecological evidence
for the preservation of different shell types. We then investigated the possible impact of selective preservation on quantitative
palaeoenvironmental inference. We first used existing palaeoecological data sets to assess the vertical patterns of relative
abundance in four testate amoeba shell types: (1) shells made of secreted biosilica plates (idiosomes, e.g. Euglypha), (2) idiosomes with thick organic coating (Assulina), (3) proteinaceous shells (e.g. Hyalosphenia), (4) shells built from recycled organic or mineral particles (xenosomes) (e.g. Difflugia, Centropyxis). In three diagrams a clear pattern of decay was only observed for the idiosome type. In order to assess the implications
of differential preservation of testate amoeba taxa for paleoenvironmental reconstruction we then carried out simulations
using three existing transfer functions and a wide range of scenarios, downweighting different test categories to represent
the impact of selective test decomposition. Simulation results showed that downweighting generally reduced overall model performance.
However downweighting a shell type only produced a consistent directional bias in inferred water table depth where that shell
type is both dominant and shows a clear preference along the ecological gradient. Applying a scenario derived from previous
experimental work did not lead to significant difference in inferred water table. Our results show that differential shell
preservation has little impact on paleohydrological reconstruction from Sphagnum-dominated peatlands. By contrast, for the minerotrophic peatlands data-set loss of idiosome tests leads to consistent underestimation
of water table depth. However there are few studies from fens and it is possible that idiosome tests are not always dominant,
and/or that differential decomposition is less marked than in Sphagnum peatlands. Further work is clearly needed to assess the potential of testate amoebae for paleoecological studies of minerotrophic
peatlands. 相似文献
19.
Dr. Th. Zingg 《Pure and Applied Geophysics》1954,29(1):218-225
Zusammenfassung Es wird eine Wolkensystematik vorgeschlagen auf Grund der Wolkenform, der struktur — Verband — des Wolkenhimmels und auf Grund der räumlichen Verteilung der Wolken. Jede an einer Einzelwolke selbständig auftretende Form wird als Hauptform bezeichnet und folgende Typen werden genannt: Schicht, Scheier, Faser, Welle, Linse, Balle, Flocke, Haufen (Cumulus) und Dorn. Andere, dem Verfasser bisher unbekannte Formen könnten dazugefügt werden. Zwischen den Hauptformen treten alle möglichen Uebergänge auf, die noch mit der nicht dominierenden Hauptform, Nebenform genannt, charakterisiert werden. Zusätzliche Formen-elemente, die aber nicht selbständig auftreten können, werden Spielformen genannt (Mammatus etc.).Auf die Bedeutung der Verbandsverhältnisse und der räumlichen Anordnung wurde in Beispielen hingewiesen. Die klare Unterscheidung zwischen Form, Verband und Anordnung gestattet, Wolkenbestimmungstabellen zu erstellen.
Summary The author proposes a systematical cloud classification according to their form (shape), their association (structure) and their repartition on the sky. Every form of a single cloud which appears independent of other forms is called main form or main shape. The following forms can be distinguished: layer, wave, lens, veil, thred, bale, flake, cumulus, thorn. Other forms may be added if necessary. All possible combinations of forms are to be found inbetween the main forms, so that there will be a secondary form next to the mainform (e. g. wave-lens). Additional forms which exist only together with main or secondary forms are details (e. g. mammatus). Some examples given in this study show the importance of combination's assembly and their repartitition in space. A clear difference made between the form, association and repartition allows to establish a convenient way of determining the clouds.
Résumé L'auteur propose une classification des nuages d'après leur forme, leur structure (assemblage) et aussi d'après leur répartition dans l'espace. L'allure d'un nuage indépendant donne sa forme principale définie comme suit: couche, voile, veine, vague, lentille, balle, flocon, cumulus et pointe. D'autres formes peuvent être ajoutées. Entre les formes principales se trouvent toutes les combinaisons possibles qui ne sont pas dominantes, elles sont nommées les formes secondaires. Des états supplémentaires qui ne sont pas indépendants, constituent le jeu des formes.相似文献
20.
The profiles of six photospheric absorption spectral lines (Fei 5250 Å, Fei 5324 Å, Fei 5576 Å, Cai 5590 Å, Cai 6103 Å and Fei 6165 Å), measured in the kernel of a 2N solar flare and in a quiet-Sun area, were compared. The observations were carried out with an echelle spectrograph of the Crimean Astrophysical Observatory. It was shown that, compared to the quiet-Sun profiles, the flare profiles are shallower in the line core and are less steep in the wings. Therefore, measurements of the longitudinal magnetic field made with a magnetograph system which uses the Cai 6103 Å spectral line, can be underestimated by 18–25% in areas of bright H ribbons of a moderate solar flare. Modeling of the solar photosphere performed by using a synthesis method showed that, in a solar flare, the enhanced core emission seems to be related to heating of the photosphere by the flare, whereas the decrease of the slope of the wings was presumably caused by the inhomogeneity of the photospheric magnetic field. 相似文献