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311.
C. Reylé R.-D. Scholz M. Schultheis A. C. Robin M. Irwin 《Monthly notices of the Royal Astronomical Society》2006,373(2):705-714
We present spectra of 59 nearby star candidates, M dwarfs and white dwarfs, previously identified using high proper motion catalogues and the DENIS database. We review the existing spectral classification schemes and spectroscopic parallax calibrations in the near-infrared J band and derive spectral types and distances of the nearby candidates. Forty-two stars have spectroscopic distances smaller than 25 pc, three of them being white dwarfs. Two targets lie within 10 pc, one M8 star at 10.0 pc (APMPM J0103−3738), and one M4 star at 8.3 pc (L 225−57). One star, LHS 73, is found to be among the few subdwarfs lying within 20 pc. Furthermore, together with LHS 72, it probably belongs to the closest pair of subdwarfs we know. 相似文献
312.
313.
In the present paper various observational data are used to compare seven most common models proposed to describe the behaviour
of the interstellar extinction in different parts of the sky. The data for field stars, open and globular clusters are used
to select the most adequate model at different distances and for different directions in the Galaxy. The results of this study
allow to select the best models for particular distances and directions. They also make it possible to propose a synthesized
model describing the interstellar extinction.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
314.
Farvacque Manon Corona Christophe Lopez-Saez Jrme Mainieri Robin Stoffel Markus Bourrier Franck Eckert Nicolas Toe David 《Landslides》2022,19(1):7-18
Landslides - The spatial and temporal quantification of rockfall frequency remains a major challenge in mountain environments, especially also in terms of rockfall management. Approaches that have... 相似文献
315.
Pizzella Laure Alais Robin Lopez Simon Freulon Xavier Rivoirard Jacques 《Mathematical Geosciences》2022,54(1):95-130
Mathematical Geosciences - When too few field measurements are available for the geological modeling of complex folded structures, the results of implicit methods typically exhibit an... 相似文献
316.
Return migration of 1.5 generation Korean New Zealanders: Short‐term and long‐term motives 下载免费PDF全文
Through in‐depth interviews and participant observation with 40 1.5 generation Korean New Zealander returnees, we explore life trajectories and identify both short‐ and long‐term reasons for return. Short‐term reasons for return include moving home when entering adulthood in order to begin a career, gaining new experiences and finding a future spouse. Longer term influences include the difficulties of living as minority‐status immigrants in the host society, transnational connections and a longing for a sense of ‘home’. Our consideration of longer term migration strategies sheds light upon the often forgotten difficulties and complexities that can underlie an individual's return. 相似文献
317.
318.
Ghylaine Quitt Eric Robin Sylvain Levasseur Franoise Capmas Robert Rocchia Jean‐Louis Birck Claude Jean AllGre 《Meteoritics & planetary science》2007,42(9):1567-1580
Abstract— It is now established that a large extraterrestrial object hit the Earth at the end of the Cretaceous period, about 65 Ma ago. We have investigated Re‐Os, Hf‐W, and Mn‐Cr isotope systems in sediments from the Cretaceous and the Paleogene in order to characterize the type of impactor. Within the Cretaceous‐Tertiary (K‐T) boundary layer, extraterrestrial material is mixed with terrestrial material, causing a dilution of the extraterrestrial isotope signature that is difficult to quantify. A phase essentially composed of Ni‐rich spinel, formed in the atmosphere mainly from melted projectile material, is likely to contain the extraterrestrial isotopic signature of the impactor. We show that the analysis of spinel is indeed the best approach to determine the initial isotope composition of the impactor, and that W and Cr isotopes confirm that the projectile was a carbonaceous chondrite. 相似文献
319.
320.
Pablo Samaniego Jean-Luc Le Pennec Claude Robin Silvana Hidalgo 《Journal of Volcanology and Geothermal Research》2011,199(1-2):69-84
Understanding the processes at the origin of explosive events is crucial for volcanic hazard mitigation, especially during long-lasting eruptions at andesitic volcanoes. This work exposes the case of Tungurahua volcano, whose unrest occurred in 1999. Since this date, the eruptive activity was characterized by low-to moderate explosiveness, including phases with stronger canon-like explosions and regional ash fallout. However, in 2006, a sudden increase of the explosiveness led to pyroclastic flow-forming eruptions on July 14th (VEI 2) and August 16–17th (VEI 3). All magmas emitted from 1999 to 2005, as well as the samples from the 2006 eruptions, have homogeneous bulk-rock andesitic compositions (58–59 wt.% SiO2), and contain the same mineral assemblage consisting of pl + cpx + opx + mag ± ol. However, during the August 16–17th event, the erupted tephra comprise two types of magmas: a dominant, brown andesitic scoria; and scarce, light-grey pumice representing a subordinate, silica-rich juvenile component. For the andesitic magma, thermobarometric data point to magmatic temperatures ranging from 950 to 1015 °C and pressures in the range of 200 to 250 MPa, which corresponds to 7.5–9.5 km below the summit. Disequilibrium textures in plagioclase and pyroxene phenocrysts, particularly thin overgrowth rims, indicate the recharge of this magma body by mafic magma. Between 1999 and 2005, repeated injections from depth fed the intermittent eruptive activity observed while silica-rich melts were produced by in-situ crystallization in the peripheral parts of the reservoir. In April 2006, the recharge of a primitive magma produced strong convection and homogenisation in the reservoir, as well as pressure increase and higher magma ascent rate after seven years of only moderately explosive activity. This work emphasizes the importance of petrological studies in constraining the pre-eruptive magmatic conditions and processes, as a tool for understanding the fundamental causes of the changes in the eruptive dynamism, particularly the occurrence of paroxysmal phases in andesitic systems with open-vent behaviour. 相似文献