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101.
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103.
Jordi Portell Enrique García-Berro Xavier Luri Alberto G. Villafranca 《Experimental Astronomy》2006,21(3):125-149
Gaia is the most ambitious space astrometry mission currently envisaged and it will be a technological challenge in all its
aspects. Here we describe a proposal for the data compression system of Gaia, specifically designed for this mission but based
on concepts that can be applied to other missions and systems as well. Realistic simulations have been performed with our
Telemetry CODEC software, which performs a stream partitioning and pre-compression to the science data. In this way, standard
compressors such as bzip2 or szip boost their performance and decrease their processing requirements when applied to such pre-processed data. These simulations
have shown that a lossless compression factor of 3 can be achieved, whereas standard compression systems were unable to reach
a factor of 2.
相似文献
104.
105.
Enrique A. Torres 《水文科学杂志》2013,58(3):303-315
Abstract This study evaluates the evaporation component of the FAO-56 model under high evaporation demand. To perform this, two data sets were used as field evaluation, and a second model was used for comparison (a model based on the square root of time, SRT). The results show that although FAO-56, the field data and the SRT model present similar cumulative evaporation over the study period (approximately one month), when the data are analysed daily, FAO-56 overestimated evaporation at the beginning of the process and underestimated it at the end. A correction for FAO-56 is proposed to amend the mismatch between FAO-56 and the field-measured data under high evaporation conditions. Consequently, the parameters used by the FAO-56 evaporation component are discussed. Citation Torres, E. A. & Calera, A. (2010) Bare soil evaporation under high evaporation demand: a proposed modification to the FAO-56 model. Hydrol. Sci. J. 55(3), 303–315. 相似文献
106.
Jorge L. Pousa Enrique E. D’Onofrio Mónica M. E. Fiore Eduardo E. Kruse 《Environmental Earth Sciences》2013,68(8):2325-2335
The Argentine shore of the Rio de la Plata estuary and its southwards adjacent maritime front are normally affected by extratropical positive and negative storm surges that affect human activities seriously. Positive surges can raise the water level in the estuary by more than 3 m over the predicted tide; thus, flooding the coastal plain where over 13 million people live and causing extensive property damage. Sometimes, there has been loss of life too. Although less populated than the coastal plain, the maritime front has many important tourist resorts and also undergoes severe beach erosion processes and loss of property owing to positive surges. Negative surges are particularly troublesome in the Rio de la Plata because they critically affect navigation safety and drinking water supply by lowering the predicted water level in an amount that sometimes reached more than 4 m. A remarkable point is that the same storm event can simultaneously give rise to a positive surge on the maritime front and a negative one in the Rio de la Plata. The environmental impacts of positive storm surges are strongly aggravated by human intervention. At the same time, sea level rise due to global climatic change has also its influence. 相似文献
107.
Pere Blay 《Astrophysics and Space Science》2011,335(1):137-140
High Mass X-Ray Binary systems (HMXRB) are composed by a compact object orbiting around a OB massive star. The mass transfer
which takes place from the massive star onto its compact companion is the responsible of the emission of high energy photons
(X-rays) observed in these systems (to which they owe the name of their class). The presence of a compact object must exert
a clear influence in the outer envelopes of the massive star and, thus, must modify the formation and evolution of its stellar
wind. Tidal interactions, mass capture and high energy radiation heating and pressure are among the possible ways in which
the compact companion and the X-ray emission will influence the stellar wind of the massive counterpart. The status of the
observations of such systems from previous UV missions will be reviewed, and perspectives for the incoming WSO-UV space mission
will be reported. 相似文献
108.
LISA Pathfinder is a science and technology demonstrator of the European Space Agency within the framework of its LISA mission,
which aims to be the first space-borne gravitational wave observatory. The payload of LISA Pathfinder is the so-called LISA
Technology Package, which is designed to measure relative accelerations between two test masses in nominal free fall. Its
disturbances are monitored and dealt by the diagnostics subsystem. This subsystem consists of several modules, and one of
these is the magnetic diagnostics system, which includes a set of four tri-axial fluxgate magnetometers, intended to measure
with high precision the magnetic field at the positions of the test masses. However, since the magnetometers are located far
from the positions of the test masses, the magnetic field at their positions must be interpolated. It has been recently shown
that because there are not enough magnetic channels, classical interpolation methods fail to derive reliable measurements
at the positions of the test masses, while neural network interpolation can provide the required measurements at the desired
accuracy. In this paper we expand these studies and we assess the reliability and robustness of the neural network interpolation
scheme for variations of the locations and possible offsets of the magnetometers, as well as for changes in environmental
conditions. We find that neural networks are robust enough to derive accurate measurements of the magnetic field at the positions
of the test masses in most circumstances. 相似文献
109.
Consequences on water retention properties of double-porosity features in a compacted silt 总被引:2,自引:1,他引:1
The paper deals with an experimental investigation aimed at studying microstructural features and their consequences on water
retention properties of statically compacted unsaturated silt. The evolution of the microstructure of the aggregate fabric
induced by compaction is investigated by studying the pore size distribution changes under different initial conditions (void
ratio and water content). The material used is low plasticity silt from Jossigny near Paris, France. A series of mercury intrusion
porosimetry tests (MIP) were performed at different void ratios and water contents to provide microstructural information.
The arrangement of aggregation/particles and pore network was also investigated with environmental scanning electron microscopy
(ESEM). The MIP data were used to determine the water retention curve on drying for the specific pore network configuration
induced on compaction. The MIP data were used to formulate and calibrate a multimodal water retention model for a specific
pore network configuration, which is obtained by linear superposition of subcurves of a modified van Genuchten type. The study
is then complemented with controlled suction oedometer tests on compacted samples to obtain the water retention properties
of the material at two different void ratios. Finally, we compare the water retention properties obtained by the simulated
progression of the different pore network configurations induced on the hydraulic path with the water retention properties
under suction-controlled conditions. Good agreement between the two methods for the drying path is reached. 相似文献
110.
Enrique Serrano Juan José González-Trueba María González-García 《Quaternary Research》2012,78(2):303-314
Geomorphic mapping and stratigraphic analysis of a lake core document the late Quaternary glacial history of the Central and Eastern Massifs of the Picos de Europa, northwestern Spain. The distribution of glacial deposits indicates that at their most advanced positions glaciers occupied 9.1 km2, extended as far as 7 km down-valley and had an estimated equilibrium-line altitude (ELA) ranging between 1666 and 1722 m. Radiocarbon dating of sediment deposited in a lake dammed by moraines of this advance show that the maximum glacial extent was prior to 35,280 ± 440 cal yr BP. This advance was followed by two subsequent but less extensive late Pleistocene advances, recorded by multiple moraines flanking both massifs and sedimentary characteristics in the lake deposits. The last recognized glacial episode is the 19th-century maximum extent of small Little Ice Age glaciers in the highest cirques above 2200 m. 相似文献