全文获取类型
收费全文 | 103篇 |
免费 | 4篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 3篇 |
地球物理 | 34篇 |
地质学 | 54篇 |
海洋学 | 8篇 |
天文学 | 4篇 |
自然地理 | 3篇 |
出版年
2024年 | 2篇 |
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 4篇 |
2011年 | 5篇 |
2009年 | 10篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 4篇 |
2005年 | 1篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有107条查询结果,搜索用时 156 毫秒
1.
2.
Harald Behrens Susanne Ohlhorst Michel Champenois 《Geochimica et cosmochimica acta》2004,68(22):4687-4703
The solubility of CO2 in dacitic melts equilibrated with H2O-CO2 fluids was experimentally investigated at 1250°C and 100 to 500 MPa. CO2 is dissolved in dacitic glasses as molecular CO2 and carbonate. The quantification of total CO2 in the glasses by mid-infrared (MIR) spectroscopy is difficult because the weak carbonate bands at 1430 and 1530 cm−1 can not be reliably separated from background features in the spectra. Furthermore, the ratio of CO2,mol/carbonate in the quenched glasses strongly decreases with increasing water content. Due to the difficulties in quantifying CO2 species concentrations from the MIR spectra we have measured total CO2 contents of dacitic glasses by secondary ion mass spectrometry (SIMS).At all pressures, the dependence of CO2 solubility in dacitic melts on xfluidCO2,total shows a strong positive deviation from linearity with almost constant CO2 solubility at xCO2fluid > 0.8 (maximum CO2 solubility of 795 ± 41, 1376 ± 73 and 2949 ± 166 ppm at 100, 200 and 500 MPa, respectively), indicating that dissolved water strongly enhances the solubility of CO2. A similar nonlinear variation of CO2 solubility with xCO2fluid has been observed for rhyolitic melts in which carbon dioxide is incorporated exclusively as molecular CO2 (Tamic et al., 2001). We infer that water species in the melt do not only stabilize carbonate groups as has been suggested earlier but also CO2 molecules.A thermodynamic model describing the dependence of the CO2 solubility in hydrous rhyolitic and dacitic melts on T, P, fCO2 and the mol fraction of water in the melt (xwater) has been developed. An exponential variation of the equilibrium constant K1 with xwater is proposed to account for the nonlinear dependence of xCO2,totalmelt on xCO2fluid. The model reproduces the CO2 solubility data for dacitic melts within ±14% relative and the data for rhyolitic melts within 10% relative in the pressure range 100-500 MPa (except for six outliers at low xCO2fluid). Data obtained for rhyolitic melts at 75 MPa and 850°C show a stronger deviation from the model, suggesting a change in the solubility behavior of CO2 at low pressures (a Henrian behavior of the CO2 solubility is observed at low pressure and low H2O concentrations in the melt). We recommend to use our model only in the pressure range 100-500 MPa and in the xCO2fluid range 0.1-0.95. The thermodynamic modeling indicates that the partial molar volume of total CO2 is much lower in rhyolitic melts (31.7 cm3/mol) than in dacitic melts (46.6 cm3/mol). The dissolution enthalpy for CO2 in hydrous rhyolitic melts was found to be negligible. This result suggests that temperature is of minor importance for CO2 solubility in silicic melts. 相似文献
3.
Developing an appropriate data collection scheme to infer stream–subsurface interactions is not trivial due to the spatial and temporal variability of exchange flowpaths. Within the context of a case study, this paper presents the results from a number of common data collection techniques ranging from point to reach scales used in combination to better understand the spatial complexity of subsurface exchanges, infer the hydrologic conditions where individual influences of hyporheic and groundwater exchange components on stream water can be characterized, and determine where gaps in information arise. We start with a tracer‐based, longitudinal channel water balance to quantify hydrologic gains and losses at a sub‐reach scale nested within two consecutive reaches. Next, we look at groundwater and stream water surface levels, shallow streambed vertical head gradients, streambed and aquifer hydraulic conductivities, water chemistry, and vertical flux rates estimated from streambed temperatures to provide more spatially explicit information. As a result, a clearer spatial understanding of gains and losses was provided, but some limitations in interpreting results were identified even when combining information collected over various scales. Due to spatial variability of exchanges and areas of mixing, each technique frequently captured a combination of groundwater and hyporheic exchange components. Ultimately, this study provides information regarding technique selection, emphasizes that care must be taken when interpreting results, and identifies the need to apply or develop more advanced methods for understanding subsurface exchanges. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
4.
5.
Climatic Change - Recent water resources planning studies have proposed climate adaptation strategies in which infrastructure and policy actions are triggered by observed thresholds or... 相似文献
6.
François Holtz Donald B. Dingwell Harald Behrens 《Contributions to Mineralogy and Petrology》1993,113(4):492-501
The effects of F, B2O3 and P2O5 on the H2O solubility in a haplogranite liquid (36 wt. % SiO2, 39 wt. % NaAlSi3O8, 25 wt. % KAlSi3O8) have been determined at 0.5, 1, 2, and 3 kb and 800, 850, and 900°C. The H2O solubility increases with increasing F and B content of the melt. The H2O solubility increase in more important at high pressure (2 and 3 kb) than at low pressure (0.5 kb). At 2 kb and 800°C, the H2O solubility increases from 5.94 to 8.22 wt. % H2O with increasing F content in the melt from 0 to 4.55 wt. %, corresponding to a linear H2O solubility increase of 0.53 mol H2O/mol F. With addition of 4.35 wt. % B2O3, the H2O solubility increases up to 6.86 wt. % H2O at 2 kb and 800°C, corresponding to a linear increase of 1.05 mol H2O/mol B2O3. The results allow to define the individual effects of fluorine and boron on H2O solubility in haplogranitic melts with compositions close to that of H2O-saturated thermal minima (at 0.5–3 kb). Although P has a dramatic effect on the phase relations in the haplogranite system, its effect on the H2O solubility was found to be negligible in natural melt compositions. The concominant increase in H2O solubility and F can not be interpreted on the basis of the available spectroscopic data (existence of hydrated aluminofluoride complexes or not). In contrast, hydrated borates or more probably boroxol complexes have been demonstrated in B-bearing hydrous melts. 相似文献
7.
8.
In the present work the kinetics and the feasibility of batch anaerobic filter operations for the treatment of beet molasses distillery slops have been investigated. Up to 50% of the influent COD up to 25 g/l are removed after 5… 10 h and up to 80% after 24… 40 h treating time. Highest removal rates were obtained for 50% removal and influent COD concentration ≧13 kg. m?3. The highest methane productivity was observed in the same range of COD influent concentration during the first 10 hours (initial velocity) of the treatment. The benefits of the anaerobic treatment of waste water applying systems with biomass retention are discussed. 相似文献
9.
Municipal activated sludge was cultivated in a medium composed of formaldehyde, glucose and mineral salt. By passages with increasing formaldehyde content a bacterial culture was selected which remained active also at initial concentrations of 1 g/1 formaldehyde. With this culture, formaldehyde and glucose were oxidized simultaneously to formate and gluconate, which subsequently served simultaneously as substrate for the growth of bacteria. Glucose alone was also oxidized to gluconate, which then was used as substrate for growth. Formaldehyde alone was only oxidized. If the actual formaldehyde concentration was kept low, however, by fed-batch cultivation, it was assimilated also through formate formation. The biochemical background and the importance of the findings for the purification of formaldehyde-containing wastewaters are discussed. 相似文献
10.
All of the major deep-water sedimentary provinces of the Gulf of Mexico were sampled with 48 piston cores, representative of the late Quaternary. The amount (per cent) and δ5C13 of the organic carbon in the sediment was measured at intervals within each core.Graphs of δC13 versus depth for each core give an indication of the sedimentological history of the Gulf. They show the extent of terrestrial influence on the Gulf during the late Pleistocene.Changes in δC13 of up to 6.0%.(from ~ ?19%.to ?25%. vs NBS-20) were measured across the Pleistocene-Holocene boundary in cores from the abyssal plain. These changes are consistent with a model wherein varying amounts of land-derived organic carbon were transported to the Gulf basin during glacial periods.By comparing graphs for cores from different areas, it was concluded that the major parameter affecting the δC13 values of organic carbon from marine sediments is the relative amount of terrestrial material present in the sediment. The maximum possible effect of the Pleistocene-Holocene temperature change in the Gulf was determined to be ~1.0%, if such an effect occurs at all. 相似文献