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61.
Summary. The decay of the post-depositional remanent magnetization (post-DRM) during desiccation in magnetic field free space is measured as a function of the loss of water. The decay is ascribed to the drying effect and the time decay of viscous remanent magnetization (VRM). The VRM forms only 10 per cent of the total of loss of remanent magnetization. The decay due to the drying effects depends both on the loss of water and on either the evaporation rate or the period of storage. The percentage of loss of magnetization is independent of its intensity.
A critical drying stage appears (about 60 per cent in water content on a dry basis) which is characterized as a vanishing point of mobile particles or particle units. The mobile particles or units play an important role both in acquisition and demagnetization through physical rotational motion within wet sediments before the critical drying stage. More than 80 per cent of the total loss of the post-DRM is destroyed before the desiccation proceeds to the critical drying stage. The decay of post-DRh4 is concluded to be mainly due to the physically random rotation of the magnetic particles trapped in shallow energy wells which are overcome by the torques caused by the application of the alternating magnetic field less than 200 Oe. 相似文献
A critical drying stage appears (about 60 per cent in water content on a dry basis) which is characterized as a vanishing point of mobile particles or particle units. The mobile particles or units play an important role both in acquisition and demagnetization through physical rotational motion within wet sediments before the critical drying stage. More than 80 per cent of the total loss of the post-DRM is destroyed before the desiccation proceeds to the critical drying stage. The decay of post-DRh4 is concluded to be mainly due to the physically random rotation of the magnetic particles trapped in shallow energy wells which are overcome by the torques caused by the application of the alternating magnetic field less than 200 Oe. 相似文献
62.
In order to understand the distribution of sulfur in igneous rooks, we determined the solubility of sulfur in volcanic rock melts (tholeiite basalt, hawaiite and rhyodacite from Hawaii) at various gas compositions and at 1250° and 1300°C and 1 atm total pressure. The solubility of sulfur in the melt passes through a minimum with change in oxygen partial pressure, if other factors are held constant. For the basaltic liquid at 1200°C, most sulfur in the melt is as dissolved sulfide (S?2) at oxygen partial pressures below 10?8 atm and as dissolved sulfate at oxygen partial pressures above 10?8 atm. Based on the present solubility data, 5 per cent is inferred for volcanic gas at 1 atm total pressure in equilibrium with subaerially extruded Hawaiian tholeiite basalt (Pele's hair with 180 ppm S) at 1200°C and 10?8 atm PO2. 相似文献
63.
As a result of the sea bottom survey of continental shelf northwest off Kyushu including Tsushima, Iki and Goto Islands which has been carried out by the Hydrographic Department of Japan, the following features of the area are revealed. Topographically, three groups of shelf channels, trending NE-SW, N-S and NW-SE respectively, are discovered and several small banks are found. Sand wave-like shapes are also seen in a seafloor about 200 m deep in the vicinity of Tsushima Straits. Geologically, remarkable tectonic lines characterized by faults and folding axes are confirmed and named Tsushima, Iki, Hirato and Goto Tectonic Lines. Several tectonic provinces can be defined by these tectonic lines. Each province consists of small geological blocks formed by indivisual tectonic movement such as tilting, uplifting and sinking. Such differential tectonic movement is often seen on the continental shelves around active island arc. In this area, these tectonics might be caused by activity of the Ryukyu Arc. This area may thus be a metastable portion existing between the northwestern Kyushu and the Asiatic continental block. The present submarine topography is probably closely related to these tectonics in addition to the eustatic sea-level changes in Quaternary age. 相似文献
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66.
Tomoo Katsura 《Physics and Chemistry of Minerals》1993,20(3):201-208
The thermal diffusivity of silica glass was measured at pressures up to 9 GPa and temperatures up to 1200 K. The measurements involve adopting the Ångström method to a cylindrical geometry in a uniaxial split-sphere apparatus. This method can be used to determine thermal diffusivity in samples with dominant conductive heat transfer. The thermal diffusivity of silica glass has a negative first pressure derivative but a positive second pressure derivative. Although the elastic moduli have minima near 3 GPa, the thermal diffusivity does not has minimum up to 9 GPa, which cannot be explained by the model of Kittel (1949). The negative pressure derivative of thermal diffusivity is a feature probably unique in silica glass, and its magnitude should decrease with the addition of Na2O. 相似文献
67.
Masakazu Chijimatsu Lenart Börgesson Tomoo Fujita Petri Jussila Son Nguyen Jonny Rutqvist Lanru Jing 《Environmental Geology》2009,57(6):1255-1261
In the international DECOVALEX-THMC project, five research teams study the influence of thermal-hydro-mechanical (THM) coupling
on the safety of a hypothetical geological repository for spent fuel. In order to improve the analyses, the teams calibrated
their bentonite models with results from laboratory experiments, including swelling pressure tests, water uptake tests, thermally
gradient tests, and the CEA mock-up THM experiment. This paper describes the mathematical models used by the teams, and compares
the results of their calibrations with the experimental data. 相似文献
68.
T. Katsura T. Yoshino G. Manthilake T. Matsuzaki 《Russian Geology and Geophysics》2009,50(12):1139-1145
The electrical conductivity of the major upper mantle minerals, namely, olivine, wadsleyite and ringwoodite, is reviewed in this paper. There are mainly three electrical conduction mechanisms for three upper mantle minerals: hopping, ionic and proton conductions. The charge carriers for these conduction mechanisms are an electron hole in Fe ion, a vacancy in Mg site, and a proton, respectively. Hopping conduction is the most essential conduction mechanism for the major upper mantle minerals. Because ionic conduction has high activation energy, it becomes a dominant conduction mechanism only at high temperatures. Proton conduction contributes at relatively low temperatures. If the mantle minerals contain large amount of water (more than 0.1 wt.%), proton conduction can be a dominant conduction mechanism, even at high temperatures. 相似文献
69.
The comparability of chemical analyses of Hawaiian volcanic rocks by different laboratories is investigated. The comparability is reasonably good for most purposes, but small differences in compositions of rocks determined by different laboratories should not be used as a basis of classification or to support petrogenic deductions. 相似文献
70.