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101.
102.
Josep Maria Trigo-Rodriguez Jeremie Vaubaillon José Luís Ortiz Alberto Castro-Tirado Jordi Llorca Esko Lyytinen Martin Jelínek Antonio de Ugarte Postigo Pablo Santos Sanz Francisco J. Aceituno Castro Albert Sánchez Caso Antonio Bernal González Juan Pastor Erades Francisco Ocaña 《Earth, Moon, and Planets》2005,97(3-4):269-278
Jupiter and Saturn produce important gravitational impulses on meteoroids released by comet 109P/Swift-Tuttle. The meteoroids from this comet once released follow retrograde orbits that during their periodic approaches to these planets (within 1.6 and 0.9 A.U., respectively) are impulsed gaining orbital energy. This perturbation effect is translated into a net inward shift in the node of the perturbed meteoroids. Such geometry with Jupiter occurred in 2004 over a meteoroid trail ejected by this comet during the 1862 A.D. return of the comet to perihelion. In order to study the predicted outburst produced by one-revolution meteoroids, the Spanish Photographic Meteor Network (SPMN) performed an extensive campaign. As a part of this observational effort here are presented 10 accurate meteoroid orbits. We discuss their origin by comparing them with the theoretical orbital elements of the dust trails intercepting the Earth during the 2004 Perseid return. 相似文献
103.
The interferometer visibility of Jupiter, observed at a wavelength of 3.4 mm, is used to determine the global limb darkening of the planet's brightness. From a single-parameter fit to the visibility curve, we find an ammonia-to-molecular hydrogen mixing ratio of 6.4[+5.1, ?1.9] × 10?5, which corresponds to 35[+28, ?10]% of the solar nitrogen abundance if all of the nitrogen is in the form of ammonia. The fitting procedure uses a simple model atmosphere for the Jovian atmosphere which is based on other observations of the planet. The dependence of the result on the various model parameters is studied. 相似文献
104.
Competing rationalities in water conflict: Mining and the indigenous community in Chiu Chiu,El Loa Province,northern Chile 总被引:1,自引:0,他引:1
Francisco Molina Camacho 《Singapore journal of tropical geography》2012,33(1):93-107
Conflict over water is a significant phenomenon in many parts of the world where globally linked neoliberal economic activities encroach on the lands of indigenous peoples. This case study from Chile examines how water scarcity affecting indigenous agricultural communities in the Chilean Altiplano has been exacerbated by legally sanctioned mining‐related practices. Notably, the legal framing of the 1981 Water Code promotes private ownership of water rights and enhanced mining activity usually at the expense of the ancestral territorial rights of indigenous communities. In the case of the Atacameño community of Chiu Chiu, a serious decrease in subsistence and agriculture production has been suffered as a consequence of reduced flow in the Loa River, resulting from the water intensive needs and extraction practices of the nearby Chuquicamata mine owned by Codelco, the National Copper Corporation of Chile. Via an analysis of the political ecology of competing rationalities this paper explores how an economic rationality based on utilitarian and reductionist thinking manifested by Codelco has taken precedence locally over a socionatural rationality grounded in holistic thinking and sustainability concerns as articulated by the Chiu Chiu community. 相似文献
105.
Francisco Estrada Benjamín Martínez-López Cecilia Conde Carlos Gay-García 《Climatic change》2012,110(3-4):1029-1046
This paper presents a review of the methodology applied for generating the regional climate change scenarios utilized in important National Documents of Mexico, such as the Fourth National Communication to the United Nations Framework Convention on Climate Change, the Fourth National Report to the Convention on Biological Diversity and The Economics of Climate Change in Mexico. It is shown that these regional climate change scenarios, which are one of the main inputs to support the assessments presented in these documents, are an example of the erroneous use of statistical downscaling techniques. The arguments presented here imply that the work based on such scenarios should be revised and therefore, these documents are inadequate for supporting national decision- making. 相似文献
106.
Decadal prediction skill in a multi-model ensemble 总被引:4,自引:3,他引:1
Geert Jan van Oldenborgh Francisco J. Doblas-Reyes Bert Wouters Wilco Hazeleger 《Climate Dynamics》2012,38(7-8):1263-1280
Decadal climate predictions may have skill due to predictable components in boundary conditions (mainly greenhouse gas concentrations but also tropospheric and stratospheric aerosol distributions) and initial conditions (mainly the ocean state). We investigate the skill of temperature and precipitation hindcasts from a multi-model ensemble of four climate forecast systems based on coupled ocean-atmosphere models. Regional variations in skill with and without trend are compared with similarly analysed uninitialised experiments to separate the trend due to monotonically increasing forcings from fluctuations around the trend due to the ocean initial state and aerosol forcings. In temperature most of the skill in both multi-model ensembles comes from the externally forced trends. The rise of the global mean temperature is represented well in the initialised hindcasts, but variations around the trend show little skill beyond the first year due to the absence of volcanic aerosols in the hindcasts and the unpredictability of ENSO. The models have non-trivial skill in hindcasts of North Atlantic sea surface temperature beyond the trend. This skill is highest in the northern North Atlantic in initialised experiments and in the subtropical North Atlantic in uninitialised simulations. A similar result is found in the Pacific Ocean, although the signal is less clear. The uninitialised simulations have good skill beyond the trend in the western North Pacific. The initialised experiments show some skill in the decadal ENSO region in the eastern Pacific, in agreement with previous studies. However, the results in this study are not statistically significant (p?≈?0.1) by themselves. The initialised models also show some skill in forecasting 4-year mean Sahel rainfall at lead times of 1 and 5?years, in agreement with the observed teleconnection from the Atlantic Ocean. Again, the skill is not statistically significant (p?≈?0.2). Furthermore, uninitialised simulations that include volcanic aerosols have similar skill. It is therefore still an open question whether initialisation improves predictions of Sahel rainfall. We conclude that the main source of skill in forecasting temperature is the trend forced by rising greenhouse gas concentrations. The ocean initial state contributes to skill in some regions, but variations in boundary forcings such as aerosols are as important in decadal forecasting. 相似文献
107.
The Global Paleomonsoon as seen through speleothem records from Asia and the Americas 总被引:3,自引:0,他引:3
Hai Cheng Ashish Sinha Xianfeng Wang Francisco W. Cruz R. Lawrence Edwards 《Climate Dynamics》2012,39(5):1045-1062
The regional monsoons of the world have long been viewed as seasonal atmospheric circulation reversal—analogous to a thermally-driven land-sea breeze on a continental scale. This conventional view of monsoons is now being integrated at a global scale and accordingly, a new paradigm has emerged which considers regional monsoons to be manifestations of global-scale seasonal changes in response to overturning of atmospheric circulation in the tropics and subtropics, and henceforth, interactive components of a singular Global Monsoon (GM) system. The paleoclimate community, however, tends to view ‘paleomonsoon’ (PM), largely in terms of regional circulation phenomena. In the past decade, many high-quality speleothem oxygen isotope (δ18O) records have been established from the Asian Monsoon and the South American Monsoon regions that primarily reflect changes in the integrated intensities of monsoons on orbital-to-decadal timescales. With the emergence of these high-resolution and absolute-dated records from both sides of the Equator, it is now possible to test a concept of the ‘Global-Paleo-Monsoon’ (GPM) on a wide-range of timescales. Here we present a comprehensive synthesis of globally-distributed speleothem δ18O records and highlight three aspects of the GPM that are comparable to the modern GM: (1) the GPM intensity swings on different timescales; (2) their global extent; and (3) an anti-phased inter-hemispheric relationship between the Asian and South American monsoon systems on a wide range of timescales. 相似文献
108.
Francisco Salamanca Andrea Krpo Alberto Martilli Alain Clappier 《Theoretical and Applied Climatology》2010,99(3-4):331-344
The generation of heat in buildings, and the way this heat is exchanged with the exterior, plays an important role in urban climate. To analyze the impact on urban climate of a change in the urban structure, it is necessary to build and use a model capable of accounting for all the urban heat fluxes. In this contribution, a new building energy model (BEM) is developed and implemented in an urban canopy parameterization (UCP) for mesoscale models. The new model accounts for: the diffusion of heat through walls, roofs, and floors; natural ventilation; the radiation exchanged between indoor surfaces; the generation of heat due to occupants and equipments; and the consumption of energy due to air conditioning systems. The behavior of BEM is compared to other models used in the thermal analysis of buildings (CBS-MASS, BLAST, and TARP) and with another box-building model. Eventually, a sensitivity analysis of different parameters, as well as a study of the impact of BEM on the UCP is carried out. The validations indicate that BEM provides good estimates of the physical behavior of buildings and it is a step towards a modeling tool that can be an important support to urban planners. 相似文献
109.
In this paper, the unfeasibility of producing “objective” probabilistic climate change scenarios is discussed. Realizing that the knowledge of “true” probabilities of the different scenarios and temperature changes is unachievable, the objective must be to find the probabilities that are the most consistent with what our state of knowledge and expert judgment are. Therefore, subjective information plays, and should play, a crucial role. A new methodology, based on the Principle of Maximum Entropy, is proposed for constructing probabilistic climate change scenarios when only partial information is available. The objective is to produce relevant information for decision-making according to different agents’ judgment and subjective beliefs. These estimates have desirable properties such as: they are the least biased estimate possible on the available information; maximize the uncertainty (entropy) subject to the partial information that is given; The maximum entropy distribution assigns a positive probability to every event that is not excluded by the given information; no possibility is ignored. The probabilities obtained in this manner are the best predictions possible with the state of knowledge and subjective information that is available. This methodology allows distinguishing between reckless and cautious positions regarding the climate change threat. 相似文献
110.