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581.
Previous phase equilibrium and oxygen isotopic researches on the high-pressure, low-temperature metamorphic rocks of the Franciscan and Sanbagawa blueschist type terranes have demonstrated the near ubiquity of a fluid at high (≈ total) pressure and its oxygen-rich nature during metamorphism. The coexistence of quartz with a CaCO3 polymorph instead of wollastonite, and of sphene rather than rutile + quartz + calcium carbonate in these rocks places narrow, rather low limits on the partial pressures of CO2, as computed in this note; equilibrium calculations indicate that the mole fraction of carbon dioxide in the fluid must have been less than about 0.04 in the Sanbagawa terrane and less than 0.01 in the Franciscan terrane. The rocks are not sulfated or strongly oxidized, hence the only other likely component which could comprise the balance of this phase is H2O. Evidently metamorphism in the Sanbagawa belt and particularly in the Franciscan terrane must have taken place in the presence of a highly aqueous fluid. 相似文献
582.
125 whole rock samples from the productive Marysville, Montana, granodiorite and the surrounding metamorphic rocks were analyzed by neutron activation analysis for gold and silver, and by atomic absorption for copper, lead and zinc. In the vicinity of known gold veins, anomalous values for gold and silver were found in both types of bedrock. Anomalies for the base metals were much less pronounced. The results indicate that systematic analysis of igneous bodies could be useful in exploration for hydrothermal ore deposits.
Zusammenfassung 125 Gesteinsproben des sogenannten produktiven Granodiorits in Marysville (Montana) wurden durch Neutronenaktivierungsanalyse auf Gold und Silber und mittels Atomabsorptionsanalyse auf Kupfer, Blei und Zink analysiert. In der Nähe bekannter Goldadern wurden in beiden Gesteinsarten ungewöhnlich hohe Gold- und Silber-Werte gefunden. Anomale Werte für Kupfer, Blei und Zink waren seltener. Die Ergebnisse zeigen, daß eine systematische Untersuchung magmatischer Gesteinskomplexe bei der Suche nach hydrothermalen Erzlagerstätten von Nutzen sein kann.相似文献
583.
Prof. Dr. Th. Ernst 《International Journal of Earth Sciences》1962,51(2):364-374
Zusammenfassung Die früheren Angaben über die Pyroxenführung, besonders über den Gehalt an rhombischem Pyroxen, wurden in den Basalten der südwestlichen Ausläufer des Vogelsberges überprüft. Es kann in Abhängigkeit vom SiO2-Gehalt dieser Gesteine eine Beziehung über die Zusammensetzung der Basalte und die Art der auftretenden Pyroxene aufgestellt werden. Vereinfacht ergibt sich, daß die Olivinbasalte keinen rhombischen Pyroxen in der Grundmasse führen - abgesehen von den Olivinknollen - und die Gesteine mit Bronzitführung dem gabbrodioritischen bzw. dioritischen Magmentyp angehören. Daneben kommt Pigeonit in weiter Verbreitung vor. Diese Befunde unterstützen die Auffassung, daß die Olivinknollen der Basalte Reste von assimilierten Peridotiten sind. die dem basaltischen primären Magma zugefügt werden. Dadurch wird ein Hinweis auf den Ort der Bildung der basaltischen Magmen gegeben. 相似文献
584.
Natural submarine basalt glasses define liquidus trends which may be summarized as curvilinear regression lines in the normative plagioclase-pyroxene-olivine ternary. Individual basalt suites separated in time or space may differ in major element composition; these differences translate into systematic differences in normative plagioclase, leading to efficient discrimination of individual trends in this ternary. Comparison of two contrasted sets of trends to available experimental and petrographic data confirms the similarity of the natural basalt trends to those predicted by 1-atm experiments, in general agreement with earlier studies based on whole-rock data. These contasted liquidus trends are believed to reflect major element heterogeneity and varying degrees of melting of the mantle source. This major element heterogeneity is not simply correlated with heterogeneity in incompatible trace elements, and like incompatible trace element heterogeneity, there is growing evidence that it may vary abruptly in space and time. The existence of these compositionally contrasted basalt suites must be considered in petrogenetic modelling; specifically, they will introduce scatter in most generalized variation diagrams, and will increase the likelihood of “misfits” in fractionation calculations utilizing parent and residual compositions drawn from different suites. 相似文献
585.
A procedure for generating joint statistically homogeneous random fields is examined. The method is based on the spectral
representation theorem. It handles large fields easily and is both rapid and flexible. Algorithm development and examples
are presented. The procedure is adapted further to include the possibility of generating fields that are jointly conditioned
on data from two related fields. 相似文献
586.
Summary Remote sensing and ground measurements were used to evaluate the homogeneity of the Scots pine plantation of Hartheim and the interactions between the forest and its surroundings during HartX.Remote sensing data contribute to characterization of the Scots pine plantation of Hartheim in terms of surface properties and thermal and biological characteristics of the forest. The surroundings of the main experiment site in the forest has homogenous normalized difference vegetation index, microwave specle and brightness temperatures to all directions for at least 500 m. Local sensible heat flux estimates using satellite measured brightness temperatures andin situ measured wind and air temperatures showed good agreement.On some days during HartX the test area was influenced by advection of dry air from the northern Upper Rhine Valley. Agricultural surroundings close to the forest are influenced by breezes flowing out of the forest during radiative nights with weak large-scale motion.With 7 Figures 相似文献
587.
588.
Estimating the crust permeability from fluid-injection-induced seismic emission at the KTB site 总被引:8,自引:0,他引:8
During the hydraulic-fracturing experiment in the German Continental Deep Drilling Borehole (KTB) in December 1994, microseismic activity was induced. Here we develop a technique for estimating permeability using the spatio-temporal distribution of the fluid-injection-induced seismic emission. The values we have obtained for the KTB experiment (0.25times10-16 to 1.0times10-16 1.0times10-16 m2 ) are in a very good agreement with the previous hydraulic-type permeability estimates from KTB deep-observatory studies. In addition, our estimates of the hydraulic diffusivity support the previously calculated value for the upper crust, which is of the order of 1 m2 s-1 . However, this estimate now relates to the depth range 7.5-9 km. 相似文献
589.
The Henry's law constants, K
H, of dilute aqueous formic and acetic acids were determined experimentally as a function of concentration and temperature using a new counterflow packed-column technique. K
H was found to be (8.9±1.3)×103 and (4.1±0.4)×103 M atm-1 at 25°C for HCOOH and CH3COOH, respectively. The reaction enthalpies, H, were found to be –51±2 kJ mol-1 and –52±1 kJ mol-1 for formic and acetic acid, respectively. These are in good agreement with calculated thermochemical values.Whereas the K
H values are in reasonably good agreement with certain other experimentally determined values, K
H (HCOOH) is two to three times higher than calculated thermochemical values while K
H (CH3COOH) is lower than the two calculated values.The best experimental values appear to be (11±2)×103 M atm-1 and (7±3)×103 M atm-1 for HCOOH and CH3COOH, respectively. 相似文献
590.
Jean-Yves Collot Jean Delteil Keith B. Lewis Bryan Davy Geoffroy Lamarche Jean-Christophe Audru Phil Barnes Franck Chanier Eric Chaumillon Serge Lallemand Bernard Mercier de Lepinay Alan Orpin Bernard Pelletier Marc Sosson Bertrand Toussaint Chris Uruski 《Marine Geophysical Researches》1996,18(2-4):357-381
The southern Kermadec-Hikurangi convergent margin, east of New Zealand, accommodates the oblique subduction of the oceanic Hikurangi Plateau at rates of 4–5 cm/yr. Swath bathymetry and sidescan data, together with seismic reflection and geopotential data obtained during the GEODYNZ-SUD cruise, showed major changes in tectonic style along the margin. The changes reflect the size and abundance of seamounts on the subducting plateau, the presence and thickness of trench-fill turbidites, and the change to increasing obliquity and intracontinental transpression towards the south. In this paper, we provide evidence that faulting with a significant strike-slip component is widespread along the entire 1000 km margin. Subduction of the northeastern scrap of the Hikurangi Plateau is marked by an offset in the Kermadec Trench and adjacent margin, and by a major NW-trending tear fault in the scarp. To the south, the southern Kermadec Trench is devoid of turbidite fill and the adjacent margin is characterized by an up to 1200 m high scarp that locally separates apparent clockwise rotated blocks on the upper slope from strike-slip faults and mass wasting on the lower slope. The northern Hikurangi Trough has at least 1 km of trench-fill but its adjacent margin is characterized by tectonic erosion. The toe of the margin is indented by 10–25 km for more than 200 km, and this is inferred to be the result of repeated impacts of the large seamounts that are abundant on the northern Hikurangi Plateau. The two most recent impacts have left major indentations in the margin. The central Hikurangi margin is characterized by development of a wide accretionary wedge on the lower slope, and by transpression of presubduction passive margin sediments on the upper slope. Shortening across the wedge together with a component of strike-slip motion on the upper slope supports an interpretation of some strain partitioning. The southern Hikurangi margin is a narrow, mainly compressive belt along a very oblique, apparently locked subduction zone. 相似文献