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排序方式: 共有131条查询结果,搜索用时 15 毫秒
1.
M.El-Tokhi M.Omran A.E-Muslem 《中国地球化学学报》2005,24(1):9-17
Tholeiitic basalts in various stages of alteration were dredged from Late Cretaceous volcanic rocks (60 -67 Ma) in the Hebrides Terrace seamount area in the Atlantic Ocean. These rocks are extrusive olivine basalts, including high- and low-Al basalts. High-Al basalts are depleted in MgO, CaO, Cr,Sc, V, St, Zr and enriched in TiO2, Na2O, Nb, Rb as compared with low-A1 basalts. Petrography and bulk-rock composition (major, trace and rare-earth elements) data defined clear tholeiitic suites displaying possible liquid lines of descent related to different degrees of crystal fractionation and partial melting.Isotopic dating of dredged samples gave the guyot an age of 60 - 67 Ma, in support of the assumption that it was formed during the Late Cretaceous. 相似文献
2.
Syenogranitic dykes in the north of Egypt’s Eastern Desert are of geological and economic interest because of the presence of magmatic and supergene enrichment of radioactive mineralization. Zircon crystal morphology within the syenogranitic dykes allows precise definition of sub-alkaline series granites and crystallized at mean temperature of about 637 °C. The growth pattern of the zircons suggest magmatic and hydrothermal origins of radioactive mineralization. Hydrothermal processes are responsible for the formation of significant zircon overgrowth; high U-zircon margins might have occurred contemporaneously with the emplacement of syenogranitic dykes which show anomalous uranium (eU) and thorium (eTh) contents of up to 1386 and 7330 ppm, respectively. Zircon chemistry revealed a relative increase of Hf consistent with decreasing Zr content, suggesting the replacement of Zr by Hf during hydrothermal activity. Visible uranium mineralization is present and recognized by the presence of uranophane and autunite. 相似文献
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5.
M. Sayed N. Burham 《International Journal of Environmental Science and Technology》2018,15(1):105-118
A novel polyurethane foam/organobentonite/iron oxide nanocomposite adsorbent was successfully prepared via in situ polymerization of toluene diisocyanate and polyol in presence of 5 wt% organobentonite/iron oxide. The obtained nanocomposite was characterized in detail, and the results revealed that the clay layers are exfoliated and/or intercalated in the polymer matrix forming a nanocomposite structure. The application of the prepared nanocomposite for adsorption of cadmium ions from aqueous solution was tested as a function of various experimental parameters using batch procedures. Adsorptive removal of Cd(II) onto the nanocomposite attained maximum at adsorbent content 1.5 g/L, pH 6, and the equilibrium was established within 60 min. Kinetic studies showed that the experimental data fit very well to pseudo-second-order model, and the adsorption process proceeds through three steps. It was found that external liquid film and intraparticle diffusion steps deeply affect the rate of Cd2+ ions adsorption onto the synthesized nanocomposite. Langmuir isotherm model fitted the adsorption data better than Freundlich with a maximum adsorption capacity (q m) for Cd(II) equal to 78 mg/g under the specified experimental conditions. The synthesized nanocomposite afforded effective extraction for Cd2+ ions from natural water samples and excellent reusability feature. This study declares the potential efficiency of a new clay/polymer nanocomposite as alternative for wastewater remediation. 相似文献
6.
B.A. El Hakim M.M. Dessoky A.A. El Sayed N.Z. Basta B.S. Mohamed E.M. Salem 《Journal of Geodynamics》1991,14(1-4)
Five microearthquake seismographs were used at 11 sites in northern Sinai in the period February 1987 to February 1988 to study the microseismicity of the area around the Maghara coal mine for mine-development studies. A total of 270 events were recorded on 850 records. The magnitude, epicenter and depth of each event were calculated using suitable software for an Egyptian Geological Survey and Mining Authority's (EGSMA) XT computer. The interpretation of the seismic activity in the area is given in view of plate tectonics, the Sinai subplate boundary follows the Gulf of Aqaba and the Dead Sea. The plate and subplate boundaries are presently active, and there seems to be a diffuse zone of deformation between “NW Africa” and “Nubia” affecting the Cairo-Suez district. 相似文献
7.
Shabbir A. S. Sayed 《Ground water》1984,22(2):148-153
In order to understand the flow pattern around a pumping well partially penetrating a vertically extensive aquifer, a specially designed pumping test was carried out in Pakistan. In this paper salient features of the test have been described. The spatial distributions of drawdown have been shown graphically. Some of the preliminary conclusions made from the drawdown pattern include:
- • The distance beyond which the flow is likely to be horizontal increases with decrease in the degree of aquifer penetration.
- • In equidistant observation wells open at different depths, (1) the drawdowns tend to merge at larger times, provided the observation point is located within the screened section of the aquifer; (2) the less the depth of penetration is, the earlier the drawdowns start merging; and (3) the initial rate of drawdown near the aquifer top is slow but catches up with time to exceed those at deeper points.
8.
MERVATSAIDHASSAN SAYEDMAHMOUDSALEM 《中国地球化学学报》2001,20(2):120-129
Clay minerals from different Cretaceous stratigraphic successions of Egypt were investigated using XRD,DTA,dissolution analysis(DCB),IR,Moessbauer and X-ray Electron Spin Resonance(ESR) spectroscopes.The purity of the samples and the degree of their structural order were determined by XRD.The location of Fe in the octahedral sheet is characterized by absorption bands at-875cm^-1 assigned as Al-OH-Fe which persist after chemical dissolution of free iron.The Moessbauer spectra of these clays show two doublets with isomer shift and quadrupole splitting typical of octahedrally coordinated Fe^3 ,in addition to third doublet with hyperfine parameter typical of Fe^2 in the spectra of Abu-Had kaolinite (H) sample.Six-lines magnetic hyperfine components which are consistent with those of hematite are confirmed in the spectra of both Isel and Rish kaolinite samples.Goethite was confirmed by both IR and DTA.Multiple nature of ESR of these clays suggested structural Fe in distorted octahedral symmetry as well as non-structural Fe.Little dispersion and low swelling indices as well as incomplete activation of the investigated montmorillonite samplas by NaCO3 appear to be due to incomplete disaggregation of montmorillonite particles.This can be explained by the ability of Fe-gel to aggregate the montmorillonite into pseudo-particles and retard the rigid-gel structure.However,extraction of this ferric amorphous compound by dithonite treatment recovers the surface properties of the montmorillonite samples.On the other hand,the amount and site occupation of Fe associated with kaolinite samples show an inverse correlation with the parameters used to describe the degree of crystallinity perfection,color,brightness and vitrification range of these kaolinite samples. 相似文献
9.
Omran E. Frihy Dr. 《GeoJournal》1992,27(4):339-344
The Pleistocene/Holocene history of Abu Quir bay and the adjacent shoreline has been studied using textural, petrological and geotechnical information obtained from 33 boreholes. The sedimentary vertical sequence is as follows reading from bottom to top: Late Pleistocene shelf sand and stiff mud, Late Pleistocene/Holocene transgressive sand, Holocene calcareous shelf mud, Holocene nearshore sand, prodelta mud, delta plain lagoonal and marsh mud, delta front mud and sand and coastal sand of beach and dunes. These units are produced as a response to shoreline fluctuation, resulting from a wide variety of deltaic and shelf environments. The study identifies delta lobes of the former Canopic branch which was located in the western part of the bay. 相似文献
10.
Twenty three bathymetric profiles up to a depth of 28 m were surveyed along and across the western inner shelf off the Nile delta. These surveys were conducted during 1919/22, 1976/77 and 1986. Comparison of these profiles establish that there are significant delta-wide changes in the patterns of erosion and accretion that correspond to sediment movement resulting from the prevailing dynamic factors affecting this area. Maximum bottom erosion (negative relief deformation) was detected along Abu Quir bay, on the tip of the Rosetta promontory, along both sides of the Rosetta mouth, and along the Burullus-Baltim coast. In contrast, there has been maximum bottom accretion (positive relief deformation) at Abu Quir cape and at Abu Khashaba. The sources of the accreted sediment probably come from areas of beach erosion as well as from offshore due to the combined effect of the offshore-onshore exchange. 相似文献