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241.
In this paper we investigate the behaviour of Newton's kernel in the integration for topographical effects needed for solving the boundary value problem of geodesy. We follow the standard procedure and develop the kernel into a Taylor series in height and look at the convergence of this series when the integral is evaluated numerically on a geographical grid, as is always the case in practice. We show that the Taylor series converges very rapidly for the integration over the distant zone, i.e., the zone well removed from the point of interest. We also show that the series diverges in the vicinity of the point of interest when the grid becomes too dense. Generally, when the grid step is smaller than either the height of the point of interest, or the difference between its height and those of the neighbouring points. Thus we claim that the Taylor series version of Newton's kernel cannot be used for evaluating topographical effects on too dense a topographical mesh. 相似文献
242.
We report the results from a 250 km long transect, from the Danish coast to the North Sea at 55°30′ N, which was sampled every
32 km in order to study the composition and distribution of phytoplankton, and their dependence on the distance from the coast,
depth and other environmental factors. Altogether 144 species of algae were identified by light, epifluorescence and electron
microscopy. Some ecological preferences were found on the basis of measured environmental parameters and compared with the
literature. Possible controlling mechanisms for the distribution patterns of the plankton algae were analyzed by multivariate
statistics. Only distance from the coast was found to be a significant factor for algal distribution along the transect. Three
main areas of the transect were found: the coastal, middle and oceanic areas. Diatoms, mainly the centric ones, were the most
abundant group of algae. The other less abundant groups were Dinophyceae, Dictyochophyceae, Prasinophyceae and Chlorophyceae.
The pattern of distribution of diatoms and dinophytes along the transect was more or less similar, with larger numbers of
cells found close to both the eastern and western parts of the transect, although the species composition was different. Some
species were found to prefer coastal waters, other species were characterized as oceanic, and several species were found at
all stations. Porosira glacialis showed an atypical distribution along the transect, with highest abundances at both coastal and oceanic stations. 相似文献
243.
Impact of Brunswick River Mouth Training Walls on Adjacent Beaches, Brunswick Heads, New South Wales, Australia 总被引:1,自引:0,他引:1
1 .IntroductionTheBrunswickbeach barrierbegantodeveloparound 6 50 0yearsagoattheendofthepostglacialmarinetransgression .Onshoreandalongshoretransportofmarinesandsoccurredfollowingthestabi lizationofsealevelresultinginbeachandduneextensionwhichoccurredonmanyNSWbeachesuntilabout30 0 0to 1 0 0 0yearsBP (Roy ,1 980 ) ,followedbyperiodsofstabilitytorecession .TherecessionalongthenorthernNSWandsouthernQLDcoastisattributedtocontinuingnorthwardlongshoresandtransportestimatedatbetween 2 0 0 0 0 0m… 相似文献
244.
245.
Lo?c Cahierre 《Journal of Geodesy》1951,25(1):42-56
Conclusion Les travaux de nivellement effectués sur la Gironde ont done permis à l’Institut Géographique National de préciser ses idées
sur des méthodes nouvelles. Il a pu constater, en particulier, qu’une méthode qu’il considère comme une méthode expédiée permet
actuellement d’exécuter des nivellements qui valent ceux du réseau de 1er ordre, effectués par une méthode beaucoup plus longue et plus compliquée.
Ces résultats sont dus pour une part à l’habileté technique des opérateurs. Ils sont dus aussi aussi à la qualité du matériel
utilisé. Les perfectionnements apportés dans la construction des instruments. en particulier la précision des réalisations
mécaniques actuelles, permet de s’affranchir d’un traditionnalisme devenu sans objet, et d’abandonner des modes opératoires,
ingénieux certes et mathématiquement séduisants, qu’on avait imaginés pour pallier l’insuffisance des appareils. Confort dans
les observations, économie de peine pour les opérateurs, gain de temps dans les travaux, augmentation de la précision dans
les mesures, ce sont là des avantages sérieux qui concourent tous à l’amélioration de la qualité des résultats.
相似文献
246.
P. Wilh Werner Dr.-Techn. h. c. 《Pure and Applied Geophysics》1953,25(1):37-43
Summary The present paper deals with certain problems of non-artesian aquifers, with special reference to non-steady flow due to replenishment from the ground surface. Solutions are obtained by direct integration ofBoussinesq's differential equation (transformed), taking also the inclination of the groundwater surface and the slope of the bottom of the aquifer into account. — The study has some bearing on hydrological investigations. For example, it may be desired to find the location of a moving groundwater divide between two water courses, or to determine the quantity of groundwater passing between them. Problems of this nature are also often met with in water supply (artificial infiltration, etc.) and other fields of engineering practice. 相似文献
247.
248.
Marianne Pavoni 《Aquatic Sciences - Research Across Boundaries》1967,29(1):161-171
Ohne Zusammenfassung 相似文献
249.
Zusammenfassung Aus der schon früher bewiesenen Eindeutigkeit des Dichtegesetzes der sphäroidischen Gleichgewichtsfiguren ergibt sich die Möglichkeit, aus einer gegebenen Gleichgewichtsfigur durch «Entblätterung» eine unendliche Reihe neuer Gleichgewichtsfiguren derselben Rotationsgeschwindigkeit mit ständig abnehmender Größe und Masse zu bilden. Auf diese Weise kann man jede beliebige innere Niveaufläche der ursprünglichen Figur bloßlegen und aus der von ihr umschlossenen TeilmasseE, der Rotationsgeschwindigkeit , der Äquatorachsea und der Äquatorachsea
h
des homogenen Ausgangsellipsoides der zugehörigen Figurenreihe (,C) die Abplattung berechnen und gewinnt so die Abplattungsfunktion im Innern einer Gleichgewichtsfigur gänzlich unabhängig von derClairautschen Differentialgleichung. Die Methode der Entblätterung ist auch auf höherparametrige Gleichgewichtsfiguren mit unstetigem Dichtegesetz anwendbar; sie liefert für dasWiechertsche Modell die Kernoberfläche in einer Tiefe von 3864.75 km und einen Dichtesprung von 17.84.
Summary In a previous paper I have shown, that the law of density of the spheroidal figures of equilibrium is strictly individual. This makes it possible from a given figure of equilibrium by the so called method of «stripping of leaves» to gain an infinite series of new figures of equilibrium with permanently decreasing size and mass. In this manner any inner level surface of the given figure can be laid bare and its flattening can be calculated from the enclosed part of massE, the rotation velocity , the equator axisa and from the equator axisa h of theMacLaurin ellipsoid in the beginning of the series (,C) belonging to the seeked figure. So the function of flattening in the interior of any equilibrium figure is gained totally independant fromClairaut's differential equation. The method of «stripping of leaves» also can be used for figures of equilibrium with more than one form-parameter and with discontinual density distribution. It yields forWiechert's model the surface of the core in a depth of 3864.75 km and a discontinuity of 17.84 in density.相似文献
250.
Prof. Dr. Dr. h. c. A. Sieberg 《Pure and Applied Geophysics》1941,3(1):125-141
Riassunto L'A. riferisce sulle esperienze sistematiche eseguite su modelli di edifici soggetti a scosse analoghe ai movimenti tellurici, allo scopo di analizzare e spiegare i processi meccanici che intervengono nella distruzione degli edifici per azione sismica, traendone deduzioni pratiche per la tecnica delle costruzioni asismiche.
Zusammenfassung Diese Versuchsreihe vertieft die früheren des Verfassers, die Klarheit über die mechanischen Vorgänge bei der Zerstörung von Bauwerken durch Erdbeben bringen und gleichzeitig helfen sollen, eine Lücke in den Grundlagen erdbebenkundlicher Bautechnik zu schliessen. Aus den Ergebnissen werden eine Reihe von Folgerungen für die Praxis gezogen.相似文献