全文获取类型
收费全文 | 93篇 |
免费 | 20篇 |
国内免费 | 23篇 |
专业分类
测绘学 | 1篇 |
地球物理 | 22篇 |
地质学 | 78篇 |
海洋学 | 27篇 |
综合类 | 4篇 |
自然地理 | 4篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 10篇 |
2011年 | 10篇 |
2010年 | 1篇 |
2009年 | 12篇 |
2008年 | 10篇 |
2007年 | 5篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有136条查询结果,搜索用时 0 毫秒
81.
在现有的矩形方箱和透空结构的基础上,提出一种由立管和水平板组合而成的消浪结构。利用波浪水槽物理模型试验,测试该结构在单向规则波作用下的消浪性能。分别探讨了其单排布置和双排布置时的透射系数随结构宽度、相对吃水深
度、相对间距等因素的变化规律。结果表明:单排布置时,透射系数随结构宽度的增大而减小,总体上随吃水深度的增大而减小;双排布置时,透射系数相对总宽度相同的单体结构减少 10 %,透射系数随吃水深度的增大而减小,前后间距对透射系数的影响不明显。对试验结果数据进行曲线拟合,得到了透射系数关于各影响因素的函数表达式。 相似文献
82.
The natural flux of groundwater into coastal water bodies has recently been shown to contribute significant quantities of nutrients and trace metals to the coastal ocean. Groundwater discharge and hyporheic exchange to estuaries and rivers, however, is frequently overlooked though it often carries a distinctly different chemical signature than surface waters. Most studies that attempt to quantify this input to rivers use multiple geochemical tracers. However, these studies are often limited in their spatial and temporal extents because of the labor-intensive nature of integrating multiple measurement techniques. We describe here a method of using a single tracer, 222Rn, to rapidly characterize groundwater discharge into tidally-influenced rivers and streams. In less than one week of fieldwork, we determined that of six streams that empty into the Indian River Lagoon (IRL), Florida, three (Eau Gallie River, Turkey Creek, and Main Canal) did not receive substantial groundwater inputs, one canal (C-25 Canal) was dominated by groundwater exchange, and the remaining two (Sebastian River system and Crane Creek) fell somewhere in between. For more detailed discharge assessments, we focused on the Sebastian River system, a stratified tidal river estuary, during a relatively dry period (June) and a wet period (July) in 2008. Using time-series 222Rn and current velocity measurements we found that groundwater discharge into all three branches of the Sebastian River increased by 1–2 orders of magnitude during the wetter period. The estimated groundwater flow rates were higher than those reported into the adjacent IRL, suggesting that discharge into these rivers can be more important than direct discharge into the IRL. The techniques employed here should work equally well in other river/stream systems that experience significant groundwater discharge. Such assessments would allow area managers to quickly assess the distribution and magnitude of groundwater discharge nature into rivers over large spatial ranges. 相似文献
83.
84.
85.
86.
张赤军 《大地测量与地球动力学》1997,(3)
利用重力测量资料,分析了喜马拉雅地区的均衡异常和板块水平挤压的重力效应,结果表明:沿喜马拉雅山脊存在一条正的均衡异常带;板块水平挤压的均衡效应不明显。基于热异常地幔的观点,讨论了异常的场源,并估算了喜马拉雅的相对上升高度和速率,指出:场源深度在莫氏面以下;推测该场源为一高温异常地幔体,其形状似一水平圆柱;相对上升高度为2.5km,上升速率为5.2mm/a。 相似文献
87.
88.
以北京昌平未来科技城试验基地的降雨强度为降雨条件,通过室内降雨试验平台,研究了4种典型不透水下垫面(沥青、砼面、SBS改性沥青和砼方砖)和4种典型透水下垫面(草坪砖A、草坪砖B、风积砂砖A和风积砂砖B)分别在8种恒定雨强条件下形成薄层产流后的糙率系数、沿程阻力系数和径流系数的变化过程。结果显示:平面尺寸、表面光滑度、材质对不透水下垫面的糙率和沿程阻力系数影响较为明显;而结构、材质对透水下垫面的糙率和沿程阻力系数影响较为明显;两类下垫面的糙率值和沿程阻力系数均随雨强增加呈现减小的变化趋势,但变化的幅度较小,之后逐渐趋于稳定;两类下垫面的径流系数在不同雨强下保持相对稳定。 相似文献
89.
通过对复杂地层的结构和各种防渗材料进行深入研究,选择合适的施工机具,改进工艺。在试验分析的基础上,根据不同的地层确定科学的施工控制参数,进一步对两层强透水带采取简单易行的深层充填堵漏工程措施,达到理想防渗效果。经对嘉陵江和白龙江流域砂卵(砾)石地层多个工程实例统计分析,其防渗系数 >1×10-4 cm/s,而复杂强透水地层经试验分析计算和抽水验证, <5×10-5 cm/s。介绍了采用单排孔替代2双排或三排高喷孔在复杂地层中的施工过程控制措施和充填式堵漏工程处理措施,应用实例可供类似工程借鉴。 相似文献
90.
The numerical study of wave-induced pore water pressure response in highly permeable seabed 总被引:1,自引:1,他引:1
The coupling numerical model of wave interaction with porous medium is used to study waveinduced pore water pressure in high permeability seabed.In the model,the wave field solver is based on the two dimensional Reynolds-averaged Navier-Stokes(RANS) equations with a k-ε closure,and Forchheimer equations are adopted for flow within the porous media.By introducing a Velocity-Pressure Correction equation for the wave flow and porous flow,a highly efficient coupling between the two flows is implemented.The numerical tests are conducted to study the effects of seabed thickness,porosity,particle size and intrinsic permeability coefficient on regular wave and solitary wave-induced pore water pressure response.The results indicate that,as compared with regular wave-induced,solitary wave-induced pore water pressure has larger values and stronger action on seabed with different parameters.The results also clearly show the flow characteristics of pore water flow within seabed and water wave flow on seabed.The maximum pore water flow velocities within seabed under solitary wave action are higher than those under regular wave action. 相似文献