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81.
Mehdi A. Guemache Djamel Machane Hamoud Beldjoudi Sofiane Gharbi Leila Djadia Sihem Benahmed Hayet Ymmel 《Natural Hazards》2010,54(2):273-288
On March 20, 2006, an earthquake (M
w = 5.3; SED) struck the mountainous region of the Babors chain (Wilaya of Bejaia, northeast Algeria). The seismic epicenter
was located near the Kherrata village. This earthquake was felt on a large area of the northeastern part of Algeria. It reached
an intensity of VII (EMS scale) at the Laalam village, situated at about 20 km northeast of Kherrata. Here, many old and recent
houses were damaged or collapsed totally, four people died and 68 were injured. Field investigations revealed that these casualties
were caused by a landslide triggered by the earthquake. Many fissures were visible on ground throughout the site. They were
generated by both sliding and settling phenomena. The Laalam site is prone to landslide, as revealed by some evidences on
old instabilities. This is due to two main factors: local geomorphology and geology. These factors intervene synchronously
for reducing the slope instability at the Laalam village. The March 20, 2006 Kherrata earthquake was the trigger that released
the Laalam landslide. 相似文献
82.
Asmae Mhamdi Alaoui Mohamed Choura Mohamed Maanan Bendahhou Zourarah Marc Robin Maria Freitas Conceição César Andrade Mehdi Khalid Christian Carruesco 《Environmental Earth Sciences》2010,61(2):275-286
The metal content in surface sediments (0–2 cm, 26 samples), in a sediment core (120, 1 cm slices), taken from Moulay Bousselham
(Morocco) was investigated. Concentrations of Al, Fe, Mn, Pb, Zn, Cu, Ni, Cr, Cd, As, and Hg were evaluated in surface and
cored sediments of Moulay Bousselham lagoon. Significantly high concentrations in μg g−1 dw of Pb (31.7–6.2), Zn (758.9–167), Cu (310.7–22), Ni (96–10.5), Cr (113–18.9), Cd (0.84–0.02), As (1–0.1), and Hg (0.61–0.02)
were found in sediment samples from Moulay Bousselham lagoon. Calculated enrichment factors [EFMe = (Me/Al)sample/(Me/Al)background], using Al as a normalizer, and correlation matrices showed that metal pollution in Merja Zerga of Moulay Bousselham lagoon
was the product of anthropogenic sources, while the metal content in Merja Kehla was of natural origins. The results suggest
that a major change in the sedimentary regime of the lagoon, associated with internal trapping and re-distribution of heavy
metal, has been occurring in the past few decades. The cause would appear to be the construction of a Nador Canal at the lagoon.
Probable effects concentrations (PEC) were often exceeded for heavy metals in the lagoon sediments, especially for Zn, Cu,
Ni, and Cr, and four stations, stations MZ-11, MZ-12, MZ-13, MZ-14, MZ-16, and MZ-17, had multiple metals at presumptively
toxic levels. These comparisons suggest that sediment metal levels in the river are clearly high and probably pose an environmental
risk at some stations. The levels of most of the metals were not greatly enriched, a consideration that is of the utmost importance
when contamination issues are at stake. Metal concentrations found in Moulay Bousselham lagoon were comparable to aquatic
systems classified as contaminated from other regions of the world. 相似文献
83.
Leila Djadia Djamel Machane Jean-Luc Chatelain Abdesslam Abtout Rabah Bensalem Mehdi Amine Guemache Bertrand Guillier Amar Boudella El-Hadi Oubaiche 《Environmental Earth Sciences》2010,59(5):1149-1158
Results from geophysical investigations (electrical resistivity, electromagnetic mapping and seismic refraction) on an excavated
cell of the Ouled Fayet (Algiers, Algeria) pilot landfill indicated the presence of an underground runoff and permeable soil
underneath the cell. These results contradict those obtained by a feasibility study, based, however, only on the analysis
of seventy-six 10-m drilling cores. The 1D boreholes information has been proven to be insufficient and to give biased results.
The presence of water at depth is evidenced by lower resistivity, high conductivity anomalies and increase of P-wave velocity.
Thus, to the contrary of what is claimed in the feasibility study, a threat of leachate pollution is real. This study shows
that landfill construction studies cannot give trustful results without geophysical investigations. More specifically, in
Algeria, it is imperative to elaborate a landfill construction code, which should include mandatory geophysical prospecting
and deeper drilling cores. 相似文献
84.
Much research has been conducted on the use of sketch maps to search in spatial databases, nevertheless, they have faced challenges, such as modeling of the data abstraction level, aggregated features in sketches, modeling of semantic aspects of data, data redundancy, and evaluation of the results. Considering these challenges, in this article a new solution is presented for searching in databases based on data matching. The main difference between this solution and the other approaches lies in the parameters introduced to match data and how to solve the matching problem. Using geometrical, topological, and semantic parameters in the matching, as well as performing the matching process in the two phases of partial and global, has resulted in an of about 78%. The evaluation process is performed based on the matching parameters and the matching procedure; finally, the result is acceptable compared to previous implementations. 相似文献
85.
86.
Organic material in meteorites provides insight into the cosmochemistry of the early solar system. The distribution of polycyclic aromatic hydrocarbons (PAHs) in the Allende and Murchison carbonaceous chondrites was investigated by use of a technique called microprobe laser-desorption laser-ionization mass spectrometry, which permits spatial resolution with approximately a 40-μm spot size. Sharp chemical gradients of PAHs are associated with specific meteorite features. The ratios of various PAH intensities relative to the smallest PAH, naphthalene, are nearly constant across the sample. These findings suggest a common origin for PAHs dating before or during the formation of the parent body, consistent with proposed interstellar formation mechanisms. 相似文献
87.
MehdiYazdi ManizhehShirani 《中国地质大学学报(英文版)》2002,13(2):T002-T006
Abundant ichthyoid remains, conodonts and holothurians sclerites were recovered near the Permian/Triassic boundary from a section south of Isfahan. Recovered ichthyoid remains include shark micro teeth and scales. The ichthyolith material is similar to a Fasanian ichthyolith from the Zakazane area in the Slovak karst of the Western Carpathians, which represents a subspecies of Acodina triassia. Conodont species are mostly neogondolellids. This fauna indicates that the sedimentary environment was marine, while to the north of localities near Isfahan and Zagross, terrestrial deposition was dominant at that time. Aluminasilicate and kaolin are present in a continental unit in Dopolan refractory main (Shahid Nilchian mine) and a section south of Chahriseh Village, north of Isfahan. Pisolitie, ironstone facies and bauxite clay are common near the Permian/Triassic boundary in the Chahriseh region. 相似文献
88.
Strong motion records of Turkey are studied in order to prepare a catalog to be used as a database for further studies (for instance empirical attenuation laws). The network started to be installed in 1973, and the first record was obtained in 1976. The instruments are of SMA-1 analog recorders and SIG SM-2 and GeoSys GSR-16 digital types. Out of a total of 426 records released on the web sites of the General Directorate of the Disaster Affairs and of Kandili Observatory, a set of 210 records was selected with a satisfactory quality, for which it was possible to associate correctly determined source parameters (source magnitudes and epicentral distances). Most of the records are obtained from around North and East Anatolian Fault zones, as well as from western and southwestern parts of Turkey. The main outcome of this paper is a strong motion catalog of Turkey, with the indication of site conditions, of the frequency band of the reliability of the records, peak values of acceleration, velocity and displacements, source parameters (magnitude, epicentral and macroseismic distances), intensity and finally the fault plane solutions whenever possible. The aim is to have, with other regional dataset, a homogenous and good quality dataset. 相似文献
89.
90.
The drift pushover analysis method for tall and regular buildings is extended in this paper to the third dimension. The focus of study is on the structures with important torsional response. For this purpose, 10, 15, 20 and 30-story steel moment frame buildings having unsymmetrical plans with 5–30% eccentricity ratios are studied. For evaluation of accuracy, nonlinear dynamic response of the buildings is determined under a consistent suit of earthquake ground motions. The maxima of the story drifts and shears and cumulative plastic hinge rotations of stories are calculated under the ground motions and their averages along with those of the modal pushover procedure are compared with the results of the presented method. The comparative analysis establishes the good accuracy of the three dimensional drift pushover method. 相似文献