全文获取类型
收费全文 | 230篇 |
免费 | 10篇 |
国内免费 | 17篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 20篇 |
地球物理 | 68篇 |
地质学 | 59篇 |
海洋学 | 72篇 |
天文学 | 19篇 |
综合类 | 7篇 |
自然地理 | 8篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 8篇 |
2016年 | 9篇 |
2015年 | 9篇 |
2014年 | 15篇 |
2013年 | 22篇 |
2012年 | 13篇 |
2011年 | 16篇 |
2010年 | 9篇 |
2009年 | 1篇 |
2008年 | 12篇 |
2007年 | 14篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 12篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1938年 | 1篇 |
排序方式: 共有257条查询结果,搜索用时 234 毫秒
251.
ABSTRACTA two-parameter monthly water balance model to simulate runoff can be used for a water resources planning programme and climate impact studies. However, the model estimates two parameters of transformation of time scale (c) and of the field capacity (SC) by a trial-and-error method. This study suggests a modified methodology to estimate the parameters c and SC using the meteorological and geological conditions. The modified model is compared with the Kajiyama formula to simulate the runoff in the Han River and International Hydrological Programme representative basins in South Korea. We show that the estimated c and SC can be used as the initial or optimal values for the monthly runoff simulation study in the model.
EDITOR M.C. Acreman; ASSOCIATE EDITOR S. Kanae 相似文献
252.
A genetic algorithm was used to optimize the parameters of the two-dimensional Storm Surge/Tide Operational Model (STORM)
to improve sea level predictions of storm surges. The model was then tested using data from Typhoon Maemi, which landed on
the Korean Peninsula in 2003. The following model parameters were used: the coefficients for bottom drag, background horizontal
diffusivity, Smagorinsky’s horizontal viscosity, and sea level pressure scaling. The simulation results using the optimized
parameters improved sea level predictions. This study demonstrates that parameter optimizations and their adequate applications
are essential for improving model performance. 相似文献
253.
As one of the largest copper–molybdenum (Cu–Mo) mines in the world, the Erdenet Mine in Mongolia has been active since 1978 and is expected to continue operations for at least another 30 years. In this study, the potential impacts of mining activities on the soil and water environments have been evaluated. Water samples showed high concentrations of sulfate, calcium, magnesium, Mo, and arsenic, and high pH values in the order of high to low as follows: tailing water > Khangal River > groundwater. Statistical analysis and the δ2H and δ18O values of water samples indicate that the tailing water directly affects the stream water and indirectly affects groundwater through recharge processes. Soil and stream sediments are highly contaminated with Cu and Mo, which are major elements of ore minerals. Based on the contamination factor (CF), the pollution load index (PLI), and the degree of contamination (Cd), soil appears to be less contaminated than stream sediments. The soil particle size is similar to that of tailing materials, but stream sediments have much coarser particles, implying that the materials have different origins. Contamination levels in stream sediments display a tendency to decrease with distance from the mine, but no such changes are found in soil. Consequently, soil contamination by metals is attributable to wind-blown dusts from the tailing materials, and stream sediment contamination is caused by discharges from uncontained subgrade ore stock materials. Considering the evident impact on the soil and water environment, and the human health risk from the Erdenet Mine, measures to mitigate its environmental impact should be taken immediately including source control, the establishment of a systematic and continuous monitoring system, and a comprehensive risk assessment. 相似文献
254.
From this research, overconsolidated undrained and drained behaviors of specimens with high sand content were highly dilatant. According to the comparison results of laboratory tests, the deviator stresses of silty sand were greater than sandy silt due to high sand content under increasing OCRs, and both silty sand and sandy silt were presented strain softening tendency after failure under undrained loading. The pore water pressure increased with increasing fines content under increasing OCRs. Silty sand exhibited more dilatancy and increasing shear strength than sandy silt because pore water pressures of silty sand were lower than sandy silt under higher OCRs. In overconsolidated drained tests, silty sand is higher strength than sandy silt because silty sand has a lower volumetric strain and higher deviator stress than sandy silt under increasing OCRs. As the degree of overconsolidation increased, similar behaviors of silty sand and sandy silt observed that volumetric strain decreased to negative values due to dilatancy effect and low-cohesion under current effective confining pressures. 相似文献
255.
Kwon Yong Min Bae Seung Sub Choi Grace Lim Ji Yeon Jung Yoon-Hee Chung Dawoon 《Ocean Science Journal》2021,56(1):1-17
Ocean Science Journal - Studies on marine fungi (termed as ‘marine-derived fungi’ in this paper) have been significantly increasing worldwide because of the critical role displayed by... 相似文献
256.
Chang-Woong Shin Sang-Kyung Byun Cheolsoo Kim Jae Hak Lee Bong-Chae Kim Sang-Chull Hwang Young Ho Seung Hong-Ryeol Shin 《Ocean Science Journal》2013,48(1):35-47
Seasonal variations in the low-salinity intermediate water (ESIW) in the region south of the sub-polar front of the East Sea were investigated by using historical hydrographic data. The salinity of the representative density (sigma-0=27.2) of the ESIW was minimal in summer and maximal in winter in the region south of the sub-polar front. The selected four subregions showed different salinity variations. In the west of Oki Spur and the Yamato Basin, salinity fluctuated similarly, with a minimum during summer. In the Ulleung Basin and northwest of Sado Island, however, variations in salinity showed two minima, one is in winter and the other is in summer. These results imply differences in the flow path of the ESIW into the region south of the sub-polar front over time. 相似文献
257.
Water resources near a gold-mine waste site were studied for the distribution and contents of contaminants, and their behavior
in the surface and groundwater systems. Arsenic, cadmium, and manganese were identified with levels exceeding the drinking
water guidelines of WHO (World Health Organization), and their distribution depended upon the differences in source materials
and in spatial pH variations. Originating from arsenopyrite, concentrations of dissolved arsenic were controlled by sorption
with amorphous iron (Fe(OH)3) and carbonate minerals. Cadmium and manganese were derived from the mineral phase including sphalerite (ZnS), otavite (CdCO3), and rhodochrosite (MnCO3); their concentrations in water resources were limited by the solubility of mineral phases. All of these processes are significantly
pH-dependent, implying that a small decline in pH could result in a drastic increase in contaminant concentrations and become
a pollution threat to the water resources of the Gubong area.
Received: 13 December 1999 · Accepted: 21 March 2000 相似文献