全文获取类型
收费全文 | 222篇 |
免费 | 15篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 9篇 |
大气科学 | 35篇 |
地球物理 | 49篇 |
地质学 | 86篇 |
海洋学 | 25篇 |
天文学 | 20篇 |
综合类 | 1篇 |
自然地理 | 14篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 6篇 |
2015年 | 11篇 |
2014年 | 11篇 |
2013年 | 14篇 |
2012年 | 5篇 |
2011年 | 16篇 |
2010年 | 18篇 |
2009年 | 13篇 |
2008年 | 18篇 |
2007年 | 9篇 |
2006年 | 11篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1997年 | 6篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1966年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有239条查询结果,搜索用时 31 毫秒
1.
2.
Gas hydrate disturbance fabrics of southern Hydrate Ridge sediments (ODP Leg 204): Relationship with texture and physical properties 总被引:1,自引:0,他引:1
Elena Piñero Eulàlia Gràcia Francisca Martínez-Ruiz Juan Cruz Larrasoaña Alexis Vizcaino Gemma Ercilla 《Geo-Marine Letters》2007,27(2-4):279-288
Soupy and mousse-like fabrics are disturbance sedimentary features that result from the dissociation of gas hydrate, a process
that releases water. During the core retrieval process, soupy and mousse-like fabrics are produced in the gas hydrate-bearing
sediments due to changes in pressure and temperature conditions. Therefore, the identification of soupy and mousse-like fabrics
can be used as a proxy for the presence of gas hydrate in addition to other evidence, such as pore water freshening or anomalously
cool temperature. We present here grain-size results, mineralogical composition and magnetic susceptibility data of soupy
and mousse-like samples from the southern Hydrate Ridge (Cascadia accretionary complex) acquired during Leg 204 of the Ocean
Drilling Program. In order to study the relationship between sedimentary texture and the presence of gas hydrates, we have
compared these results with the main textural and compositional data available from the same area. Most of the disturbed analyzed
samples from the summit and the western flank of southern Hydrate Ridge show a mean grain size coarser than the average mean
grain size of the hemipelagic samples from the same area. The depositional features of the sediments are not recognised due
to disturbance. However, their granulometric statistical parameters and distribution curves, and magnetic susceptibility logs
indicate that they correspond to a turbidite facies. These results suggest that gas hydrates in the southern Hydrate Ridge
could form preferentially in coarser grain-size layers that could act as conduits feeding gas from below the BSR. Two samples
from the uppermost metres near the seafloor at the summit of the southern Hydrate Ridge show a finer mean grain-size value
than the average of hemipelagic samples. They were located where the highest amount of gas hydrates was detected, suggesting
that in this area the availability of methane gas was high enough to generate gas hydrates, even within low-permeability layers.
The mineralogical composition of the soupy and mousse-like sediments does not show any specific characteristic with respect
to the other samples from the southern Hydrate Ridge. 相似文献
3.
Ocean tide loading (OTL) displacements from global and local grids: comparisons to GPS estimates over the shelf of Brittany, France 总被引:1,自引:0,他引:1
Stavros A. Melachroinos R. Biancale M. Llubes F. Perosanz F. Lyard M. Vergnolle M. -N. Bouin F. Masson J. Nicolas L. Morel S. Durand 《Journal of Geodesy》2008,82(6):357-371
In this paper we examine OTL displacements detected by GPS stations of a dedicated campaign and validate ocean tide models.
Our area of study is the continental shelf of Brittany and Cotentin in France. Brittany is one of the few places in the world
where tides provoke loading displacements of ∼10–12 cm vertically and a few cm horizontally. Ocean tide models suffer from
important discrepancies in this region. Seven global and regional ocean tide models were tested: FES2004 corrected for K2,
TPXO.7.0, TPXO.6.2, GOT00.2, CSR4.0, NAO.99b and the most recent regional grids of the North East Atlantic (NEA2004). These
gridded amplitudes and phases of ocean tides were convolved in order to get the predicted OTL displacements using two different
algorithms. Data over a period of 3.5 months of 8 GPS campaign stations located on the north coast of Brittany are used, in
order to evaluate the geographical distribution of the OTL effect. We have modified and implemented new algorithms in our
GPS software, GINS 7.1. GPS OTL constituents are estimated based on 1-day batch solutions. We compare the observed GPS OTL
constituents of M2, S2, N2 and K1 waves with the selected ocean tide models on global and regional grids. Large phase-lag and amplitude discrepancies over
20° and 1.5 cm in the vertical direction in the semi-diurnal band of M2 between predictions and GPS/models are detected in the Bay of Mont St-Michel. From a least squares spectral analysis of the
GPS time-series, significant harmonic peaks in the integer multiples of the orbital periods of the GPS satellites are observed,
indicating the existence of multipath effects in the GPS OTL constituents. The GPS OTL observations agree best with FES2004,
NEA2004, GOT00.2 and CSR4.0 tide models. 相似文献
4.
Agricultural Census data is summarised over spatially coarse reporting units for reasons of farm confidentiality. This is problematic for research at a local level. This article describes an approach combining dasymetric and volume preserving techniques to create a national land use dataset at 1 km2 resolution. The results for an English county are compared with contemporaneous aggregated habitat data. The results show that the accurate estimates of local agricultural land use (Arable and Grass) patterns can be estimated when individual 1 km squares are combined into blocks of > 9 squares, thereby providing local estimates of agricultural land use. This in turn allows more detailed modelling of land uses related to specific livestock and cropping activities. The dataset created by this work has been subject to extensive external validation through its incorporation into a number of other national models: nitrate leaching (e.g. MAGPIE, NEAP‐N), waste, and pathogen modelling related to agricultural activity. 相似文献
5.
6.
Low melting temperature for calcite at 1000 bars on the join CaCO3‐H2O – some geological implications 下载免费PDF全文
Melting experiments of calcite were performed on the join CaCO3‐H2O at a pressure of 1000 bars. The system evolves to the ternary CaO‐H2O‐CO2 system during melting experiments. Our experiments show that partial melting of calcite begins at a low temperature, below 650 °C. Such a low partial melting temperature for carbonates revives the debate about the presence of carbonate melts in the upper crust. More specifically, the conditions for carbonate partial melting are present in carbonate host rocks undergoing contact metamorphism at high temperatures in the presence of water‐rich fluid. The presence of carbonate melts influences physical parameters such as viscosity and permeability in contact aureoles, and, furthermore, decarbonation reactions release massive amounts of CO2. 相似文献
7.
Joel Sanchez-Bermudez Florentin Millour Fabien Baron Roy van Boekel Laurent Bourgès Gilles Duvert Paulo J. V. Garcia Nuno Gomes Karl-Heinz Hofmann Thomas Henning Jacob W. Isbell Bruno Lopez Alexis Matter J-Uwe Pott Dieter Schertl Eric Thiébaut Gerd Weigelt John Young 《Experimental Astronomy》2018,46(3):457-473
During the last two decades, the first generation of beam combiners at the Very Large Telescope Interferometer has proved the importance of optical interferometry for high-angular resolution astrophysical studies in the near- and mid-infrared. With the advent of 4-beam combiners at the VLTI, the u ? v coverage per pointing increases significantly, providing an opportunity to use reconstructed images as powerful scientific tools. Therefore, interferometric imaging is already a key feature of the new generation of VLTI instruments, as well as for other interferometric facilities like CHARA and JWST. It is thus imperative to account for the current image reconstruction capabilities and their expected evolutions in the coming years. Here, we present a general overview of the current situation of optical interferometric image reconstruction with a focus on new wavelength-dependent information, highlighting its main advantages and limitations. As an Appendix we include several cookbooks describing the usage and installation of several state-of-the art image reconstruction packages. To illustrate the current capabilities of the software available to the community, we recovered chromatic images, from simulated MATISSE data, using the MCMC software SQUEEZE. With these images, we aim at showing the importance of selecting good regularization functions and their impact on the reconstruction. 相似文献
8.
Diana Tingley Jóhann Ásmundsson Edward Borodzicz Alexis Conides Ben Drakeford Ingi Rúnar Eðvarðsson Dennis Holm Kostas Kapiris Sakari Kuikka Bogi Mortensen 《Marine Policy》2010
This paper presents the findings of risk identification and risk perception research conducted in relation to the fisheries systems of four distinct and diverse European countries: Faroes, Iceland, Greece and the UK. Risk research traditionally attempts to quantify the potential threat or consequences from a range of risk events or hazards. This research, however, adopted a social sciences perspective and so assumed that a risk event or hazard can mean different things to different people and that these perceptions are also context and culturally dependent. Risk perceptions were examined and risk registers developed in each country for a range of stakeholder groups. A ‘mental modelling’ approach was adopted in a series of qualitative interviews. Findings were examined in terms of a wide range of psychological, social and cultural risk theories. Differences in risk perceptions were noted between stakeholder groups and countries and contextual influences were examined such as the widely differing fisheries management systems used in each country. This research provides one of the first attempts to systematically evaluate risks and perceptions across a range of fisheries-systems. The findings support social science theories which argue that risk is a subjective, as opposed to objective, concept and that this subjectivity will therefore affect our attempts to assess and manage those hazards we think we can potentially influence or control. 相似文献
9.
A. Weill C. Mazaudier F. Baudin C. Klapisz F. Leca M. Masmoudi D. Vidal Madjar R. Bernard O. Taconet B. S. Gera A. Sauvaget A. Druilhet P. Durand J. Y. Caneil P. Mery G. Dubosclard A. C. M. Beljaars W. A. A. Monna J. G. Van Der Vliet M. Crochet D. Thomson T. Carlson 《Boundary-Layer Meteorology》1988,42(3):251-264
10.
Jean-Pierre Pagès Jean-Pierre Frangi Pierre Durand Claude Estournel Aimé Druilhet 《Boundary-Layer Meteorology》1988,43(1-2):183-203
This paper presents data concerning the energy budget in the surface layer in the Sahel region (a semi-desert area). The results
are drawn from a measurement campaign made in the Niamey region in the Niger, in April–May 1984 (the Yantala Campaign). The
sensible heat flux is computed with the profile method, the ground heat flux is deduced from measurement of the temperature
field, and the radiative net flux is measured directly with a balancemeter. The latent heat flux, which is deduced from the
energy budget balance is very weak and within the accuracy limit of the method. The diurnal variation of the net flux is symmetrical,
with a maximum at noon. On the other hand, the sensible heat flux variation is asymmetrical, with an afternoon decrease much
slower than the morning increase. After 3.30 pm, it becomes higher than the net flux. This is compensated for by the sign
change of the ground heat flux, whose maximum is found in the morning at 11 am.
The second part of this paper shows the importance of one term in the surface-layer energy budget: the long-wave radiative
divergence between the ground and the top of the surface layer in high superadiabatic conditions. We show, with a radiative
model on the one hand and direct measurement of the radiative divergence on the other hand, that this term reaches several
tens of W m-2 in the superadiabatic conditions found in the Sahel region.
相似文献