全文获取类型
收费全文 | 65篇 |
免费 | 6篇 |
国内免费 | 5篇 |
专业分类
大气科学 | 6篇 |
地球物理 | 27篇 |
地质学 | 27篇 |
海洋学 | 8篇 |
天文学 | 2篇 |
综合类 | 2篇 |
自然地理 | 4篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 3篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 6篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 5篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 4篇 |
1999年 | 2篇 |
1996年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有76条查询结果,搜索用时 15 毫秒
41.
Akpabio G. Thompson George N. Jimmy Udofia K. Michael 《Central European Journal of Geosciences》2012,4(3):388-394
In this study, specific development of empirical models for estimation of laboratory thermal conductivities from wire line log thermal conductivity within the ambience of locally oriented wells located in the Niger Delta have been established. The laboratory thermal conductivity is characterised with high fidelity compared to wire line log thermal conductivity whose values vary as the dependence of lithology of the subsurface geomaterials, well effects, as well as the effects of the limited bed thickness of the adjacent lithological units of the Niger Delta where the study was stationed. The generalised equation k leff = 0.709 k weff + 0.188 is an empirically estimated model based on site variables (porosity, permeability and temperature) and constants (cementation factor, formation factor and tortuosity) of the locally oriented wells in the Niger Delta. It can be used to set bounds on the unstable wire line log thermal conductivity values within the 1-2.5 km depths where the oil-rich geomaterials in the Niger Delta are usually found. Equations have been established which show inter-convertibility between laboratory and wire line log thermal conductivity. These equations are considered useful in converting the available wire line log thermal conductivity data of nearby wells in the area to the usually desired and stable laboratory thermal conductivity. Various diagrams in 2-D and 3-D have been established to show the distribution of the parameters considered, and this could help the operating companies in the zone to predict the density of oil. 相似文献
42.
Xingxing Kuang Xin Luo Jiu Jimmy Jiao Sihai Liang Xiaolang Zhang Hailong Li Junguo Liu 《水文研究》2019,33(13):1835-1850
Characterization of stable isotope compositions (δ2H and δ18O) of surface water and groundwater in a catchment is critical for refining moisture sources and establishing modern isotope–elevation relationships for paleoelevation reconstructions. There is no consensus on the moisture sources of precipitation in the Yellow River source region during summer season. This study presents δ2H and δ18O data from 111 water samples collected from tributaries, mainstream, lakes, and groundwater across the Yellow River source region during summertime. Measured δ18O values of the tributaries range from ?13.5‰ to ?5.8‰ with an average of ?11.0‰. Measured δ18O values of the groundwater samples range from ?12.7‰ to ?10.5‰ with an average of ?11.9‰. The δ18O data of tributary waters display a northward increase of 1.66‰ per degree latitude. The δ18O data and d‐excess values imply that moisture sources of the Yellow River source region during summertime are mainly from the mixing of the Indian Summer Monsoon and the Westerlies, local water recycling, and subcloud evaporation. Analysis of tributary δ18O data from the Yellow River source region and streamwater and precipitation δ18O data from its surrounding areas leads to a best‐fit second‐order polynomial relationship between δ18O and elevation over a 4,600 m elevation range. A δ18O elevation gradient of ?1.6‰/km is also established using these data, and the gradient is in consistence with the δ18O elevation gradient of north and eastern plateau. Such relationships can be used for paleoelevation reconstructions in the Yellow River source region. 相似文献
43.
Air and water flows induced by pumping tests in unconfined aquifers with low‐permeability zones
下载免费PDF全文
![点击此处可从《水文研究》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Air flows from the atmosphere into an unconfined aquifer when the water table falls during pumping tests. Pumping test results in unconfined aquifers may be significantly affected by low‐permeability zones (LPZs) near the initial water table position, because they restrict the downward movement of air. A transient, three‐dimensional air–water two‐phase flow model is employed to investigate numerically the effects of local heterogeneity on pumping test results in unconfined aquifers. Two cases of local heterogeneities are considered herein: a LPZ around the pumping well and on one side of the pumping well. Results show that the drawdown with the LPZ is significantly greater than that of the homogeneous aquifer. The differences in drawdown are the most significant at intermediate times and gradually diminish at later times. The LPZ significantly reduces air flow from the atmosphere to the aquifer. The pore air velocity in the LPZ is very low. The air pressure at the observation point under the LPZ when air begins to enter is significantly lower than the air pressure of the homogeneous aquifer at the same point. After that, the air pressure increases quickly and then increases slowly. The time for the air pressure to reach the atmospheric pressure is significantly longer. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
44.
45.
Springs and seeps occur in the spaces around Po Hing Fong Street in the Mid‐Levels area, Hong Kong. Most of the springs occur through the drainage weepholes on retaining walls at the street. This paper first examines the geology and history of the springs. The paper then reports the findings from a 1‐year comprehensive spring monitoring programme. The temporal variations of flow rate, physiochemical parameters and hydrochemistry of the springs are discussed. The average temperatures of the springs were close to the mean air temperature, although there was a systematic lag time of 40 to 50 days between the peak air temperature and highest water temperatures. Spring waters from two rows of weepholes in the retaining wall showed significantly different physical and hydrochemical responses to the changes in rainfall and temperature, though their vertical distance is only about 1 m. The results suggest that water from the upper row of weepholes may represent a recharge source that is shallow or close to the spring outlets, whereas that from the lower row of weepholes may represent a recharge source that is much deeper or further up the hill. Although the spring flows increased rapidly after rainstorms, analysis of the total dissolved solids showed a delayed response to rainstorm events. The concentration of individual ions in the spring water varied in a unique way in response to rainstorm events. It is clear that the presence of underground man‐made drainage systems and the leakage from water mains in the study area may add complexity to the solute responses and transport mechanisms. Further studies are required to constrain the impacts of these man‐made structures on the hydrogeology of the springs. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
46.
47.
48.
Jianmei Cheng Jennifer C. McIntosh Xinong Xie Jiu Jimmy Jiao 《Journal of Geochemical Exploration》2006,88(1-3):86
The Sanzhao depression and Qijia-gulong depression are two of the most important hydrocarbon-bearing sub-depressions in the Songliao basin, dominated by Cretaceous fluvial and lacustrine strata with volcanic and volcaniclastic rocks. In this paper, the pressure distributions and hydrochemistry variations in those two depressions are investigated. It is found that the Qijia-gulong depression is dominated by overpressure, but the Sanzhao depression is dominated by underpressure, especially in the Quantou formation. The salinity of formation water ranges from 1.0 g/L to 20 g/L, with a mean of 4 g/L in most formations. Water composition is dominated by NaHCO3 water type but varies greatly in salinity and ionic ratios in the different depressions. The results of mass balance calculation reveal that, fluid chemistry in the Qijia-gulong depression is dominated by dissolution of silicate minerals and halite, whereas in the Sanzhao depression it is dominated by silicate mineral dissolution, evaporite dissolution (halite and gypsum), carbonate mineral dissolution/precipitation, and cation exchange. 相似文献
49.
Transfer zones and fault reactivation in inverted rift basins: Insights from physical modelling 总被引:2,自引:0,他引:2
Elena A. Konstantinovskaya Lyal B. Harris Jimmy Poulin Gennady M. Ivanov 《Tectonophysics》2007,441(1-4):1-26
Carbonate mylonites with varying proportions of second-phase minerals were collected at positions of increasing metamorphic grade along the basal thrust of the Morcles nappe (Helvetic nappes, Switzerland). Variations of temperature, stress, and strain rate, changes in chemistry of solid and fluid phases, and differing degrees of strain localization and annealing were tracked by measuring the shapes, mean sizes, and size distributions of both matrix and second-phase grains, as well as crystal preferred orientation (CPO) of the matrix. Field structures suggest that strain rate was constant along the fault. The mean and distribution of the calcite grain sizes were affected most profoundly by temperature: Increased temperature, presumably accompanied by decreased stress, correlated with larger mean sizes and wider size distributions. At a given location, the matrix grains in mylonites with more second-phase particles are, on average, smaller, have narrower size distributions, and have more elongate shapes. For example, mylonites with 50 vol.% of second phases have matrix grain sizes half that of pure mylonites. Changes in calcite chemistry and the presence of synkinematic fluids seemed to influence microfabric only weakly. Temporal variations in conditions, such as exhumation-induced cooling, apparently provoke changes in temperature, stress, and strain rate along the nappe. These changes result in further strain localization during retrograde conditions and cause the grain size to be reduced by an additional 50%. The matrix CPO strengthens with increasing temperature or strain, but weakens and rotates with increasing second-phase content. These fabric changes suggest differing rates of grain growth, grain size reduction, and development of CPO owing to variations in the deformation conditions and, perhaps, mechanisms. To interpret natural mylonite structures or to extrapolate mechanical data to natural situations requires careful characterization of the microfabric, and, in particular, second-phase minerals. 相似文献
50.
The long-term trends in the occurrence frequency of pre-summer daytime and nocturnal extreme hourly rainfall(EXHR) during 1988-2018 in Hong Kong and their spatial distributions are examined and analyzed. Despite a significant increasing trend observed in the occurrence frequency of pre-summer EXHRs during the investigated period,the increase in daytime and nocturnal EXHRs show distinct spatial patterns. Nocturnal EXHRs show uniform increasing trends over the entire Hong Kong. However, the increa... 相似文献