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231.
At various stages of petroleum reservoir development, we encounter a large degree of geological uncertainty under which a rational decision has to be made. In order to identify which parameter or group of parameters significantly affects the output of a decision model, we investigate decision-theoretic sensitivity analysis and its computational issues in this paper. In particular, we employ the so-called expected value of partial perfect information (EVPPI) as a sensitivity index and apply multilevel Monte Carlo (MLMC) methods to efficient estimation of EVPPI. In a recent paper by Giles and Goda, an antithetic MLMC estimator for EVPPI is proposed and its variance analysis is conducted under some assumptions on a decision model. In this paper, for an improvement on the performance of the MLMC estimator, we incorporate randomized quasi-Monte Carlo methods within the inner sampling, which results in an multilevel quasi-Monte Carlo (MLQMC) estimator. We apply both the antithetic MLMC and MLQMC estimators to a simple waterflooding decision problem under uncertainty on absolute permeability and relative permeability curves. Through numerical experiments, we compare the performances of the MLMC and MLQMC estimators and confirm a significant advantage of the MLQMC estimator. 相似文献
232.
Tetsuya?KomabayashiEmail author Kei?Hirose Yasuo?Ohishi 《Physics and Chemistry of Minerals》2012,39(4):329-338
The phase transition boundary between the face-centered cubic (fcc) structure and hexagonal close-packed (hcp) structure in an Fe–Ni alloy was determined at pressures from 25 to 107 GPa by using an internally resistive-heated diamond
anvil cell (DAC), combined with in situ synchrotron X-ray diffraction measurements. The fcc–hcp phase transition boundary in Fe–9.7 wt% Ni is located at slightly lower temperatures than that in pure Fe, confirming the
previous understanding that the addition of Ni expands the stability field of the fcc phase. The dP/dT slope of the boundary was determined to be 0.0426 GPa/K, which is slightly larger than that of pure Fe. The pressure interval
of the two-phase region is about 6 GPa at a constant temperature, implying that the previous estimates by laser-heated DAC
experiments of 10–20 GPa were overestimated. The two-phase region of fcc + hcp would be limited to a pressure of about 120 GPa even in Fe–15 wt%Ni, excluding the possibility of the existence of the fcc phase in the inner core if the simple linear extrapolation of the two-phase region is applied. The pressure and temperature
dependences of the c/a axial ratio of the hcp phase in Fe–9.7 wt% Ni are generally consistent with those in pure Fe, suggesting that Ni has minor effects on the c/a ratio. 相似文献
233.
234.
235.
Kazuo Abe Norihisa Nakagawa Katsuyuki Abo Mutsumi Tsujino 《Journal of Oceanography》2013,69(2):269-275
Temporary enhancement of the nutrient concentrations in the coastal area was observed after heavy rain in the central Seto Inland Sea in July 2012. After passage of a stationary front accompanied by heavy rain, the river outflow was enhanced, and low salinity and high nutrient concentrations were detected near the mouths of rivers. The offshore salinity and nutrients increased and decreased, respectively, which suggested that a snapshot event, such as heavy rain, could influence the short-term variation of the coastal marine environmental conditions, such as the salinity and nutrient distributions. 相似文献
236.
Numerical model and flume experiments of single- and two-layered hillslope flow related to slope failure 总被引:1,自引:0,他引:1
A hillslope flow model is developed considering 3D saturated and unsaturated flow of water during rainfall events. A finite difference-based numerical model of hillslope flow processes is developed. Four different experiments are done to see the effects of a single- and double-layered soil in pore-water pressure dynamics and slope failure. Results from the numerical model are verified with experimental results. The numerical and experimental values of the pore-water pressure and moisture contents are in good agreement. The results show that the hillslope heterogeneity caused by multiple layers of soil has greater influence on hillslope pore-pressure dynamics and slope failure patterns. The depth of slope failure shows high dependency on layering characteristics of the soil slope and pattern of rainfall. The proposed model provides a perspective on failure mechanism of a single- or double-layered slope under rainfall infiltration. 相似文献
237.
High-pressure experiments have been carried out at 11-22 kbar and 900-1200°C using a piston cylinder apparatus to constrain the thermal peak condition of a granulite characterized by the mineral assemblage of orthopyroxene+sillimanite+quartz from McIntyre Island, Enderby Land, East Antarctica. The bulk composition of the starting material is 85 wt.% McIntyre granulite+15 wt.% sillimanite. At 11 kbar, orthopyroxene, sillimanite and quartz are stable below 1000°C. At 1050°C sillimanite does not appear, and sapphirine coexists with orthopyroxene and quartz. These experimental results indicate that the McIntyre granulite has undergone the ultra high-temperature metamorphism at 1000-1050°C represented by the diagnostic mineral assemblage of orthopyroxene, sillimanite and quartz. 相似文献