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991.
Y.-F. Yuan Jeremy S. Heyl † 《Monthly notices of the Royal Astronomical Society》2005,360(4):1493-1505
We study the evolution of a rigidly rotating protoneutron star (PNS) with hyperons and nucleons or solely nucleons in its core due to the escape of trapped neutrinos. As the neutrinos escape, the core nucleonic neutron star (NS) expands and the stellar rotation slows. After the neutrinos escape, the range of the spin periods is narrower than the initial one, but the distribution is still nearly uniform. A PNS with hyperons, at the late stage of its evolution, keeps shrinking and spinning up until all the trapped neutrinos escape. Consequently, the distribution of the stellar initial spin periods is skewed towards shorter periods. If the hyperonic star is metastable, its rotational frequency accelerates distinguishedly before it collapses to a black hole. 相似文献
992.
The South Karakorum margin, east of the Himalayan syntaxis, consist of an E–W elongated zone of young (10–3 Ma) high‐grade metamorphic rocks (M2) and related migmatitic domes. This late tectono‐metamorphic event post‐dates the Palaeogene (55–37 Ma) phase of thickening of the belt featured by NW–SE structures and associated M1 amphibolite facies metamorphism (0.7 GPa, 700 °C). This M2 metamorphism is characterised by low‐pressure, high‐temperature conditions coeval with migmatite formation in response to a thermal increase of c. 150 °C compared to M1, culminating at a temperature of c. 770 °C and a pressure of 0.5–0.6 GPa. Rapid exhumation of migmatitic domes, at a rate of 5 mm yr?1, was accommodated by vertical extrusion, in the core of E–W crustal‐scale folds. These crustal‐scale folds formed in response to N–S syn‐collisional shortening and were enhanced by thermal weakening of the migmatised continental crust. M2 metamorphism is spatially and temporarily associated with granitoids showing a mantle affinity, firmly suggesting that this could be the advective heat source for the granite and syenite generation and the subsequent migmatisation of the mid‐crustal level. Such relationships between a mantle‐related magmatism and a high‐temperature metamorphism in a convergent shortening context are suggestive of the breakoff of the subducted Indian slab since 20 Ma. 相似文献
993.
Erkan Gökaşan Cem Gazioğlu Bedri Alpar Zeki Yücel Şükrü Ersoy Oğuz Gündoğdu Cenk Yaltırak Buser Tok 《Geo-Marine Letters》2001,21(4):183-199
Active faults aligning in NW–SE direction and forming flower structures of strike-slip faults were observed in shallow seismic data from the shelf offshore of Avc?lar in the northern Marmara Sea. By following the parallel drainage pattern and scarps, these faults were traced as NW–SE-directed lineaments in the morphology of the northern onshore sector of the Marmara Sea (eastern Thrace Peninsula). Right-lateral displacements in two watersheds of drainage and on the coast of the Marmara Sea and Black Sea are associated with these lineaments. This right-lateral displacement along the course of these faults suggests a new, active strike-slip fault zone located at the NW extension of the northern boundary fault of the Ç?narc?k Basin in the Marmara Sea. This new fault zone is interpreted as the NW extension of the northern branch of the North Anatolian Fault Zone (NAFZ), extending from the Ç?narc?k Basin of the Marmara Sea to the Black Sea coast of the Thrace Peninsula, and passing through B üy ük çekmece and K ü ç ük çekmece lagoons. These data suggest that the rupture of the 17 August 1999 earthquake in the NAFZ may have extended through Avc?lar. Indeed, Avc?lar and ?zmit, both located on the Marmara Sea coast along the rupture route, were strongly struck by the earthquake whereas the settlements between Avc?lar and ?zmit were much less affected. Therefore, this interpretation can explain the extraordinary damage in Avc?lar, based on the newly discovered rupture of the NAFZ in the Marmara Sea. However, this suggestion needs to be confirmed by further seismological studies. 相似文献
994.
995.
Large-scale, decelerating, relativistic X-ray jets from microquasar XTE J1550−564 has been recently discovered with Chandra by Corbel et al. (2002). We find that the dynamical evolution of the approaching jet at the late time is consistent with
the well-known Sedov evolutionary phase R∝ t
2/5. A trans-relativistic external shock dynamic model by analogy with the evolution of gamma-ray burst remnants, is shown to
be able to fit the proper-motion data of the approaching jet reasonably well. The inferred interstellar medium density around
the source is well below the canonical value n
ISM∼1 cm−3. The rapidly fading X-ray emission can be interpreted as synchrotron radiation from the non-thermal electrons in the adiabatically
expanding ejecta. These electrons were accelerated by the reverse shock (moving back into the ejecta) which becomes important
when the inertia of the swept external matter leads to an appreciable slowing down of the original ejecta. 相似文献
996.
997.
L. A. BARRIE Y. YI W. R. LEAITCH U. LOHMANN P. KASIBHATLA G.J. ROELOFS J. WILSON F. McGOVERN C. BENKOVITZ M. A. MÉLIÈRES K. LAW J. PROSPERO M. KRITZ D. BERGMANN C. BRIDGEMAN M. CHIN J. CHRISTENSEN R. EASTER J. FEICHTER C. LAND A. JEUKEN E. KJELLSTRÖM D. KOCH P. RASCH 《Tellus. Series B, Chemical and physical meteorology》2001,53(5):615-645
998.
We present results from a global simulation of the interaction of the solar wind with Earth's magnetosphere, ionosphere, and
thermosphere for the Bastille Day geomagnetic storm and compare the results with data. We find that during this event the
magnetosphere becomes extremely compressed and eroded, causing 3 geosynchronous GOES satellites to enter the magnetosheath
for an extended time period. At its extreme, the magnetopause moves at local noon as close as 4.9 R
E to Earth which is interpreted as the consequence of the combined action of enhanced dynamic pressure and strong dayside reconnection
due to the strong southward interplanetary magnetic field component B
z, which at one time reaches a value of −60 nT. The lobes bulge sunward and shield the dayside reconnection region, thereby
limiting the reconnection rate and thus the cross polar cap potential. Modeled ground magnetic perturbations are compared
with data from 37 sub-auroral, auroral, and polar cap magnetometer stations. While the model can not yet predict the perturbations
and fluctuations at individual ground stations, its predictions of the fluctuation spectrum in the 0–3 mHz range for the sub-auroral
and high-latitude regions are remarkably good. However, at auroral latitudes (63° to 70° magnetic latitude) the predicted
fluctuations are slightly too high.
Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1014228230714 相似文献
999.
The nonlinear motion (collapse/explosion) of a homogeneous, rapidly rotating, gaseous ellipsoid has been studied with the effects of an external gravitational field incorporated. The non-axisymmetric motion has been followed using an efficient numerical code based on certain properties of the potential functions. The gravitational radiation associated with the phenomenon was calculated, and the wave forms studied to extract information on the dynamics of the source. Possible implications of our results for various astrophysical processes are discussed. 相似文献
1000.
The linear and nonlinear properties of the modified electron thermal waves are studied. The waves are of acoustic nature and can exist without significant damping in a two-electron temperature plasma. Nonlinearly, they can form propagating localized regions with depletion of hot electrons. Practical applications of our results to space plasmas are discussed. 相似文献