全文获取类型
收费全文 | 247篇 |
免费 | 23篇 |
国内免费 | 2篇 |
专业分类
大气科学 | 9篇 |
地球物理 | 80篇 |
地质学 | 114篇 |
海洋学 | 14篇 |
天文学 | 46篇 |
自然地理 | 9篇 |
出版年
2023年 | 1篇 |
2021年 | 3篇 |
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 12篇 |
2017年 | 6篇 |
2016年 | 17篇 |
2015年 | 14篇 |
2014年 | 8篇 |
2013年 | 14篇 |
2012年 | 10篇 |
2011年 | 19篇 |
2010年 | 11篇 |
2009年 | 27篇 |
2008年 | 28篇 |
2007年 | 11篇 |
2006年 | 17篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1982年 | 4篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有272条查询结果,搜索用时 328 毫秒
61.
Rajat M. Thomas Saleem Zaroubi Benedetta Ciardi reas H. Pawlik Panagiotis Labropoulos Vibor Jeli Gianni Bernardi Michiel A. Brentjens A. G. de Bruyn Geraint J. A. Harker Leon V. E. Koopmans Garrelt Mellema V. N. Pandey Joop Schaye Sarod Yatawatta 《Monthly notices of the Royal Astronomical Society》2009,393(1):32-48
62.
Geraint Harker Saleem Zaroubi Gianni Bernardi Michiel A. Brentjens A. G. de Bruyn Benedetta Ciardi Vibor Jeli Leon V. E. Koopmans Panagiotis Labropoulos Garrelt Mellema ré Offringa V. N. Pandey Joop Schaye Rajat M. Thomas Sarod Yatawatta 《Monthly notices of the Royal Astronomical Society》2009,397(2):1138-1152
63.
Angela Ullrich Ronald Miletich Tonci Balic-Zunic Lars Olsen Fabrizio Nestola Manfred Wildner Haruo Ohashi 《Physics and Chemistry of Minerals》2010,37(1):25-43
A compressional study of (Na,Ca)(Ti3+,Mg)Si2O6-clinopyroxenes was carried out at high pressures between 10−4 and 10.2 GPa using in situ single-crystal X-ray diffraction, Raman spectroscopy and optical absorption spectroscopy. Compressional
discontinuities accompanied by structural changes, in particular, the appearance of two distinct Ti3+–Ti3+ distances within the octahedral chains at 4.37 GPa, provide evidence for the occurrence of a phase transition in NaTi3+Si2O6. Equation-of-state parameters are K
0 = 115.9(7) GPa with K′ = −0.9(3) and K
0 = 102.7(8) GPa with K′ = 4.08(5) for the low- and high-pressure range, respectively. The transition involves a C2/c–P
[`1] \overline{1} symmetry change, which can be confirmed by the occurrence of new modes in Raman spectra. Since no significant discontinuity
in the evolution of the unit-cell volume with pressure has been observed, the transition appears to be second-order in character.
The influence of the coupled substitution Na+Ti3+↔Ca2+Mg2+ on the static compression behavior and the structural stability has been investigated using a sample of the intermediate
composition (Na0.54Ca0.46)(Mg0.46Ti0.54)Si2O6. No evidence for a deviation from continuous compression behavior has been found, neither in lattice parameter nor in structural
data and the fit of a third-order Birch–Murnaghan equation-of-state to the pressure–volume data yields a bulk modulus of K
0 = 109.1(5) GPa and K′ = 5.02(13). Raman and polarized absorption spectra have been compared to NaTiSi2O6 and reveal major similarities. The main driving force for the phase transition in NaTi3+Si2O6 is the localization of the Ti3+
d-electron and the accompanying distortion, which is suppressed in the (Na,Ca)(Ti3+,Mg)Si2O6-clinopyroxene. 相似文献
64.
Eva Pacioni Marco Petitta Ezio Burri Maria Fanelli Piero Mazzeo Fabrizio Ruggieri 《Environmental Earth Sciences》2010,61(1):201-216
This paper analyses flow and transport of pesticides from the unsaturated zone to groundwater so as to predict concentration
of those contaminants in the Fucino Plain’s groundwater, by site investigations and numerical simulations. Pesticides were
detected in surface water (peaks of 13 μg L−1) and groundwater (peaks of 0.37 μg L−1). Modelling tools made it possible to identify that pattern of precipitation, organic matter content, and root thickness
are the key factors involved in vertical seepage of pesticides. Numerical simulations indicated that a significant fraction
of contaminants is leached from the most surficial soil layers through runoff, while only a secondary fraction is mobilised
towards groundwater. Likelihood of contaminating deep groundwater is fairly low, whereas surface waters show higher susceptibility.
Results of the proposed conceptual hydrogeological model show that pesticides are more likely to be entrained by mixing of
stream water with shallow groundwater in periods of high water exploitation from shallow wells. 相似文献
65.
Experimental evidence indicates that the diurnal behaviour of the fluxes of heat into the ground and into the atmosphere versus the net flux of radiation can be modelled by closed curves, the hourly values folowing one another in either a clockwise or counter clockfashion. A general formulation to express the different heat fluxes as a function of net radiation is proposed. This relationship between the different heat fluxes and can be expressed as a sum of three terms: the first indicates a direct proportionality to , the second gives the deviation from linearity and depends on /t, and the third gives the value of the flux when = 0. The formulae are then expressed as a function of time and the ratios between the heat fluxes and are evaluated. A comparison with the approximations generally used shows that the latter may be considered as particular cases of the more general equations proposed here. 相似文献
66.
David Besson Olivier Parize Jean-Loup Rubino Jean-Pierre Aguilar Marie-Pierre Aubry Bernard Beaudoin William A. Berggren Georges Clauzon Philippe Crumeyrolle Yann Dexcoté Nicolas Fiet Silvia Iaccarino Gonzalo Jiménez-Moreno Cécile Laporte-Galaa Jacques Michaux Katharina von Salis Jean-Pierre Suc Jean-Yves Reynaud Roland Wernli 《Comptes Rendus Geoscience》2005,337(12):1045-1054
An integrated study combining facies analysis, multiple group biostratigraphy, identification of depositional sequences and mapping has been conducted on the Miocene Molasse Basin of the external Alps (southeastern France). The filling of the basin is described as resulting from a succession of fluvial incisions subsequently filled during marine transgressions. The major incision is dated as Latest Burdigalian and the major transgression as Langhian. This revised interpretation of the Miocene physiographic evolution of the Molasse Basin implies a re-examination of previous stratigraphic correlations within the basin. To cite this article: D. Besson et al., C. R. Geoscience 337 (2005). 相似文献
67.
68.
Edouard Bard Gilles Delaygue Frauke Rostek Fabrizio AntonioliSergio Silenzi Daniel P. Schrag 《Earth and Planetary Science Letters》2002,202(2):481-494
A new oxygen isotope record is reported from a stalagmite collected in the Argentarola Cave located on the Tyrrhenian coast of Italy. As shown from observations and numerical modeling of δ18O in modern precipitation, the recorded δ18O variability for this zone is dominated by the amount of precipitation (so-called ‘amount effect’). The δ18O profile measured in the stalagmite is characterized by a prominent negative excursion (ca. 2-3‰) between 180 and 170 kyr BP. This paleoclimatic feature is interpreted as being due to a relatively wet period which occurred during the penultimate glacial period, more precisely, during Marine Isotope Stage 6.5. This pluvial phase is shown to correspond chronologically to the deposition of the sapropel event 6 (S6). Although this particular sapropel event occurred during a cold phase, the δ18O excursion is similar to those corresponding to other sapropels (S4, S3 and S2). The evidence for humid conditions during S6 in the western Mediterranean basin agrees with previous studies based on deep-sea sediment cores. Taken collectively, the data suggest that during sapropel events dilution of ocean surface waters was not restricted to the output of the river Nile but was rather widespread over the entire Mediterranean Sea due to increased rainfall. 相似文献
69.
70.
Stéphane Gaffet Giovanna Cultrera Michel Dietrich Françoise Courboulex Fabrizio Marra Michel Bouchon Arrigo Caserta Cécile Cornou Anne Deschamps Jean-Paul Glot Robert Guiguet 《Journal of Seismology》2000,4(4):525-541
Strong site effects were observed during the two M
W 5.7 and M
W 6.0 main shocks of the Colfiorito seismic crisis which occured on September 26, 1997 in Umbria-Marche (Central Italy).The most obvious indications of these effects are the dramatic differences in damage shown by buildings of similar construction in neighboring villages.Such observations were specifically made in the Verchiano valley in the fault area, 15 km south of Colfiorito where the Verchiano village and the Colle and Camino hamlets were heavily damaged (MCS intensity IX-X) since the first main shock of 1997/09/26,while in contrast, the Curasci village located 2 km eastwards remains almost intact.In order to study the anomalous ground motion amplifications in this area, an array of 11, 3-components seismo- and accelero-meters was set up during the 1997/10/20-24 period, extending from the western side of the valley, up to the top of Mount San Salvatore, going accross the Colle and Curasci hamlets.During the experiment, 67 aftershocks enlightened the valley from the Colfiorito (10 km north) and the Sellano (6 km south) active swarms.Seismic refraction experiments were conducted at the same time in the 500 m wide, 1500 m long Verchiano valley in order to determine the thickness and main characteristics of the alluvial infilling.The main results are: (i) compared to the valley side ground motion, and for all the events, recordings in the central part of the valley (piana di Verchiano) show relative amplification of 10 with a clear lengthening of the seismogram duration by a factor of 2 – (ii) broad band relative amplification of 6–8 is also clearly identified at the top of the Mount San Salvatore overhanging the valley – (iii) any of the site effect measurements done explains by itself the strongly contrasted damage observed at Colle and Curasci: i.e. the modification of the near-field radiation pattern by interaction with the free heterogeneous surface may have induced local shadow zones that saved Curasci. 相似文献