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151.
Pure-iron end-member hibbingite, Fe2(OH)3Cl(s), may be important to geological repositories in salt formations, as it may be a dominant corrosion product of steel waste canisters in an anoxic environment in Na–Cl- and Na–Mg–Cl-dominated brines. In this study, the solubility of Fe2(OH)3Cl(s), the pure-iron end-member of hibbingite (FeII, Mg)2(OH)3Cl(s), and Fe(OH)2(s) in 0.04 m to 6 m NaCl brines has been determined. For the reactionFe2(OH)3Cl(s) + 3H+ ? 3 H2O + 2 Fe2+ + Cl?,the solubility constant of Fe2(OH)3Cl(s) at infinite dilution and 25 °C has been found to be log10 K = 17.12 ± 0.15 (95% confidence interval using F statistics for 36 data points and 3 parameters). For the reactionFe(OH)2(s) + 2H+ ? 2 H2O + Fe2+,the solubility constant of Fe(OH)2 at infinite dilution and 25 °C has been found to be log10 K = 12.95 ± 0.13 (95 % confidence interval using F statistics for 36 data points and 3 parameters). For the combined set of solubility data for Fe2(OH)3Cl(s) and Fe(OH)2(s), the Na+–Fe2+ pair Pitzer interaction parameter θNa+/Fe2+ has been found to be 0.08 ± 0.03 (95% confidence interval using F statistics for 36 data points and 3 parameters). In nearly saturated NaCl brine we observed evidence for the conversion of Fe(OH)2(s) to Fe2(OH)3Cl(s). Additionally, when Fe2(OH)3Cl(s) was added to sodium sulfate brines, the formation of green rust(II) sulfate was observed, along with the generation of hydrogen gas. The results presented here provide insight into understanding and modeling the geochemistry and performance assessment of nuclear waste repositories in salt formations. 相似文献
152.
The direct aqueous carbonation of fibrous tremolite was investigated by TEM, powder XRD, and FT-IR to elucidate the transformation mechanism of tremolite into calcite. The TEM study revealed that tremolite dissolves along the weak cleavage on (1 0 0) and (1 1 0) and the cleavage fragment fibers. The preferential release of Ca, relative to Si or Mg, into the solution resulted in the crystallization of compositionally homogeneous calcite and in the concurrent formation of proto-saponite. X-ray diffraction analysis revealed that the amount of product calcite increased rapidly within 15 min. Subsequently, after a 5 h carbonation period, it increased slowly to about 60%. The product calcite is euhedral. In contrast, the unreacted tremolite grains retain the original crystal structure even after prolonged carbonation. The morphological modification of tremolite from fibrous to round may have important implications for the elimination of its toxicity. 相似文献
153.
本文分析了航摄仪检定的环境条件(压力、温度)对内方位元素、畸变差的影响,并进行了不同环境压力和不同环境温度影响的检定实验。实验结果表明:环境压力和环境温度对航摄仪检定的影响是不容忽略的。本文针对国内目前航摄仪检定现状,提出了改进意见。 相似文献
154.
Bu-Yo Kim Kyu-Tae Lee Il-Sung Zo Sang-Ho Lee Hyun-Seok Jung Se-Hun Rim Jeong-Pil Jang 《Asia-Pacific Journal of Atmospheric Sciences》2018,54(4):639-648
The pyranometer for observing the solar radiation reaching the surface of the earth is manufactured by various companies around the world. The sensitivity of the pyranometer at the observatory is required to be properly controlled based on the reference value of the World Radiometric Center (WRC) and the observatory environment; otherwise, the observational data may be subject to a large error. Since the sensitivity of the pyranometer can be calibrated in an indoor or outdoor calibration, this study used a CSTM-USS-4000C Integrating Sphere by Labsphere Inc. (USA) to calibrate the sensitivity of CMP22 pyranometer by Kipp&Zonen Inc. (Netherlands). Consequently, the factory sensitivity of CMP22 was corrected from 8.68 μV·(Wm?2)?1 to 8.98 μV·(Wm?2)?1, and the result from the outdoor calibration according to the observatory environment was 8.90 μV·(Wm?2)?1. After the indoor calibration of the pyranometer sensitivity, the root mean square error (RMSE) of the observational data at the observatory on a clear day without clouds (July 13, 2017) was 7.11 Wm?2 in comparison to the reference pyranometer. After the outdoor calibration of the pyranometer sensitivity based on these results, the RMSE of the observational data was 1.74 Wm?2 on the same day. Periodic inspections are required because the decrease of sensitivity over time is inevitable in the pyranometer data produced at the observatory. The initial sensitivity after indoor calibration (8.98 μV·(Wm?2)?1) is important, and the sensitivity after outdoor calibration (8.90 μV·(Wm?2)?1) can be compared to the data at the Baseline Surface Radiation Network (BSRN) or can be used for various studies and daily applications. 相似文献
155.
This study investigates the impacts of shallow convection schemes on a simulated seasonal climatology in the Global and Regional Integrated Model system (GRIMs). The eddy-diffusivity scheme of Tiedtke (TDK) is evaluated, focusing on the dependency upon deep convection schemes. Drying and warming near the top of the planetary boundary layer (PBL) and opposing effects above are observed. The height of PBL is reduced due to the increase of thermal stability near the PBL top. The weakened PBL turbulence is partly compensated with the increased downward solar radiation due to the reduction of low clouds. These effects are pronounced over the oceans, which leads to the modulation of tropical precipitation. It is found that the original TDK scheme shows similar behavior regardless of the choice of deep convection schemes. A revised TDK scheme that explicitly couples the PBL and shallow convection processes is proposed and evaluated. The proposed scheme generally improves the simulated climatology over the results with the original TDK scheme, along with further improvement in the case of the revised deep convection scheme. Our results indicate that the role of the shallow convection scheme needs to be carefully examined to improve the performance of atmospheric models, with a focus on modulated PBL and deep convection processes. 相似文献
156.
Yeon-Soo Jang 《Environmental Earth Sciences》2013,69(3):987-997
The behavior of the Gimpo #2 landfill, which is an active landfill and the largest in Korea, is analyzed using field measurement data obtained from various field instruments installed within the landfill. The data included in this analysis are the leachate head within the landfill, waste load data using soil pressure plate and settlement data from settlement plate on the surface of the waste of each stage fill including the settlement of the soft foundation clay soil. Landfill blocks are selected both near the embankment and in the center area of the landfill. The analysis of the field-monitored data showed that the leachate head increase was negligible near the embankment. It was significant in the central block as the waste loads increase and reached 15 m at the fourth stage of waste disposal. The reason that the leachate head is higher in the central block than near the embankment is due to the long drainage path and the loss of gradient of drain pipes. The range of unit weight of the waste converted from the measurement data of earth pressure cell was 0.91–1.24 t/m3 and the average value was 1.05 t/m3. The values reflect well the waste compositions recently buried in GML #2, since from 1998 the waste disposed in GML #2 did not contain food waste. The magnitude of final settlements that occurred in each stage loading of 5 m thickness in the peripheral block was very close to 120 cm. The settlement rate of the waste by dividing the thickness of waste was 24 %. This rate can be divided into 10 % by waste loading and 14 % by waste decomposition. The delay of settlements is recognized in each waste layer for second and third loading in the central block due to the accumulation of leachate within the landfill. 相似文献
157.
There has been substantial development in computer codes for linear hydroelasticity in recent years, driven in part by the motivation to investigate the wave-induced response of very large floating structures (VLFSs). A recent International Ship and Offshore Structures Congress (ISSC) state-of-the-art report on VLFS design and analysis [ISSC, 2006. Report of Specialist Task Committee VI.2, very large floating structures. In: Frieze, P.A., Shenoi, R.A. (eds.), Proceedings of the 16th International Ship and Offshore Structures Congress, Elsevier, Southampton, UK, pp. 397-451] included a brief comparative study of the simulation results from different computer codes for a pontoon (mat-like) VLFS. The codes covered a mix of both fluid models (potential and linear Green-Naghdi) and structural models (3-D grillage, 2-D plate, 3-D shell). A more detailed comparison of the results from a select group of models from that study is provided and discussed herein. The similarities in the results increase the confidence level of the state-of-the-art in predicting the hydroelastic response of such structures, and the differences, including in computational efficiency, lead to an understanding of the significance of specific modeling assumptions and their impact on the predicted response. 相似文献
158.
159.
Azyleah Cañizares Abino Sung Yong Kim Roscinto Ian Canicosa Lumbres Mi Na Jang Ho Joong Youn Ki Hyung Park Young Jin Lee 《山地科学学报》2016,13(5):822-830
This study was carried out to determine the performance of percentile-based Weibull diameter distribution model for Pinus thunbergii stands thriving along the eastern coast of South Korea. The parameter recovery technique was used to estimate the three parameters of the Weibull model. The analysis demonstrated satisfactory results based on the following test statistics for the principal percentile models: fit index (FI) range from 0.501 (minimum diameter) to 0.932 (50th diameter percentiles) and root mean square error (RMSE) range from 0.112 (quadratic mean diameter) to 3.572 (minimum diameter). The developed model was further evaluated by determining the mean bias (ē) in trees per ha (TPH) for each diameter class, and the results showed highest over-prediction in the 20 cm, and under-prediction in the 16 cm and 24 cm diameter classes. The goodness of fit tested by Kolmogorov-Smirnov (KS) test showed no significant differences (p>0.05) between the observed and predicted diameter distributions for almost all plots. Using site index and aboveground biomass (AGB) models developed for P. thunbergii in South Korea, a model to predict the AGB per ha for each diameter class and subsequently the total AGB of the stand was created. An application guide was also created, which will serve as a decision-support tool for forest managers in quantifying the future total AGB in P. thunbergii stands located in the eastern coast of South Korea and, subsequently, the quantification of potential carbon stocks aside from being a vital input in designing efficient management and protection strategies for these stands. 相似文献
160.
Heeok Jung Yong-seok Jang Jung Mo Lee Wooil M. Moon Chang-Eob Baag Ki Young Kim Bong Gon Jo 《Tectonophysics》2007,429(3-4):253-265
We analyzed the short period Rayleigh waves from the first crustal-scale seismic refraction experiment in the Korean peninsula, KCRUST2002, to determine the shear wave velocity and attenuation structure of the uppermost 1 km of the crust in different tectonic zones of the Korean peninsula and to examine if this can be related to the surface geology of the study area. The experiment was conducted with two large explosive sources along a 300-km long profile in 2002. The seismic traces, recorded on 170 vertical-component, 2-Hz portable seismometers, show distinct Rayleigh waves in the period range between 0.2 s and 1.2 s, which are easily recognizable up to 30–60 km from the sources. The seismic profiles, which traverse three tectonic regions (Gyeonggi massif, Okcheon fold belt and Yeongnam massif), were divided into five subsections based on tectonic boundaries as well as lithology. Group and phase velocities for the five subsections obtained by a continuous wavelet transform method and a slant stack method, respectively, were inverted for the shear wave models. We obtained shear wave velocity models up to a depth of 1.0 km. Overall, the shear wave velocity of the Okcheon fold belt is lower than that of the Gyeonggi and Yeongnam massifs by 0.4 km/s in the shallowmost 0.2 km and by 0.2 km/s at depths below 0.2 km. Attenuation coefficients, determined from the decay of the fundamental mode Rayleigh waves, were used to obtain the shear wave attenuation structures for three subsections (one for each of the three different tectonic regions). We obtained an average value of Qβ− 1 in the upper 0.5 km for each subsection. Qβ− 1 for the Okcheon fold belt ( 0.026) is approximately three times larger than Qβ− 1 for the massif areas ( 0.008). The low shear wave velocity in the Okcheon fold belt is consistent with the high attenuation in this region. 相似文献