全文获取类型
收费全文 | 531篇 |
免费 | 71篇 |
国内免费 | 84篇 |
专业分类
测绘学 | 22篇 |
大气科学 | 6篇 |
地球物理 | 126篇 |
地质学 | 184篇 |
海洋学 | 272篇 |
综合类 | 22篇 |
自然地理 | 54篇 |
出版年
2023年 | 3篇 |
2022年 | 12篇 |
2021年 | 13篇 |
2020年 | 13篇 |
2019年 | 17篇 |
2018年 | 23篇 |
2017年 | 25篇 |
2016年 | 23篇 |
2015年 | 11篇 |
2014年 | 21篇 |
2013年 | 44篇 |
2012年 | 22篇 |
2011年 | 18篇 |
2010年 | 18篇 |
2009年 | 33篇 |
2008年 | 33篇 |
2007年 | 35篇 |
2006年 | 36篇 |
2005年 | 26篇 |
2004年 | 35篇 |
2003年 | 25篇 |
2002年 | 39篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 9篇 |
1998年 | 17篇 |
1997年 | 14篇 |
1996年 | 17篇 |
1995年 | 16篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1986年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有686条查询结果,搜索用时 31 毫秒
51.
依据地热资料研究天然气水合物稳定带厚度在东海海域的分布情况。东海在地质构造上位于新生代环太平洋构造带西部边缘岛弧的内侧,又是欧亚板块、太平洋板块和菲律宾海板块的相互作用带。依据国际热流委员会(IHFC)提供的东海地热数据,经过统计确定出该区域的热流分布,热流平均值为121·0mW/m2,最小值为73·0mW/m2,最大值为168·0mW/m2。同时利用天然气水合物温压模型计算了稳定带厚度,数据显示稳定带厚度平均值为92·2m,最小值为1·4m,最大值为190·6m,薄于其他已经发现的海洋天然气水合物稳定带厚度(约400m)。天然气水合物大部分分布在条件适宜的陆坡和岛坡上,冲绳海槽底部水合物稳定带厚度相对较薄。统计分析表明本区热流值与水合物稳定带厚度相关性很差,相关系数仅有0·12。这是由于天然气水合物所在海域水深较浅时,海底温度的变化迫使运算所应用的非线性方程影响因子迅速积累,从而导致相关系数降低。最后结合东海陆坡的地质条件,探讨了在天然气水合物存在的情况下,陆坡失稳的可能性及其造成的环境影响。 相似文献
52.
53.
近岸水平场地液化侧向大变形影响因素分析 总被引:2,自引:0,他引:2
利用改进的软化模量分析方法,对近岸水平场地液化侧向大变形进行数值计算,以研究地震波波形和幅值大小、液化、竖向地震动对侧向大变形的影响。结果表明:不同的地震波作用下,即使峰值加速度相同,液化程度与侧移距离也可能有较大不同,表现了土体变形的强非线性性质,但大地震下液化导致的侧移几乎都在米的量级上;计算区域中无液化区时,岸壁侧向永久位移很小,在几公分左右,随水平峰值加速度及不同地震动输入改变不大;计算区域中有液化区时,岸壁侧向永久位移显著增大,且随输入水平峰值加速度的增大而明显增大,其机理是强地震动使液化范围加大;水平竖向两向地震动输入与单独水平地震动输入相比,前者场地液化范围增大,平均增大42%,侧移量增加,平均增加37%。 相似文献
54.
Current plate motions across the Red Sea 总被引:3,自引:0,他引:3
55.
MAXIMUMINFORMATIONENTROPYTHEORYOFEFFLUENTBANDINOPENCHANNELUNIFORMFLOWKeZhongHUANG1andTaoJIANG2ABSTRACTTheprincipleofmaximum... 相似文献
56.
A number of compressional anticlinal structures are identified in the western and northern part of the Faroe–Rockall Plateau. These structures occur on that part of the Faroe–Rockall Plateau which was above sea level during the latest phase of Paleocene plateau basalt extrusion. Three post-basalt compressional phases have affected the plateau. Most of the compressional structures in the northern part of the plateau are related to NE–SW- to ENE–WSW-oriented stress which we date to Late Paleocene–Early Eocene. The Oligocene phase is interpreted as resulting from N–S-directed compressional stress which also mainly affected the compressional structures on the northern part of the plateau. Compressional stress from the northwest seemed to affect the whole of the Faroe–Rockall Plateau and we suggest it to be of Miocene age. It is proposed that during the Late Paleocene–Early Eocene phase of compression local structure, and anomalously oriented gravitational ridge-push from the now extinct Aegir Axis contributed to a local NE–SW compressional stress system. The two later deformation phases were apparently connected to the regional northwest European stress system with small local modifications. 相似文献
57.
58.
Dagmar Kieke Birgit Klein Lothar Stramma Monika Rhein Klaus Peter Koltermann 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(10):1656-1674
The variability of two modes of Labrador Sea Water (LSW) (upper and deep Labrador Sea Water) and their respective spreading in the interior North Atlantic Ocean are investigated by means of repeated ship surveys carried out along the zonal WOCE line A2/AR19 located at 43–48°N (1993–2007) and along the GOOS line at about 48–51°N (1997–2002). Hydrographic section data are complemented by temperature, salinity, and velocity time series recorded by two moorings. They have been deployed at the western flank of the Mid-Atlantic Ridge (MAR) in the Newfoundland Basin during 1996–2004. The analysis of hydrographic anomalies at various longitudes points to a gradual eastward propagation of LSW-related signals, which happens on time scales of 3–6 years from the formation region towards the MAR. Interactions of the North Atlantic Current (NAC) with the Deep Western Boundary Current (DWBC) close to Flemish Cap point to the NAC being the main distributor of the different types of LSW into the interior of the Newfoundland Basin. Comparisons between the ship data and the mooring records revealed that the mooring sites are located in a region affected by highly variable flow. The mooring time series demonstrate an elevated level of variability with eddy activity and variability associated with the NAC considerably influencing the LSW signals in this region. Hydrographic data taken from Argo profiles from the vicinity of the mooring sites turned out to mimic quite well the temporal evolution captured by the moorings. There is some indication of occasional southward flow in the LSW layer near the MAR. If this can be considered as a hint to an interior LSW-route, it is at least of minor importance in comparison to the DWBC. It acts as an important supplier for the interior North Atlantic, distributing older and recently formed LSW modes southward along the MAR. 相似文献
59.
60.
海洋能源获取、传输与管理是实现海洋透明化的关键技术。以能源获取的方式进行分类调研,分析探讨国内外海洋能源的获取、传输与能源管理方法,以及各个方式的优缺点,并对能源获取、传输与管理进行核心技术分解,对比我国研究现状得出各个技术与国外现有差距,预测我国在该技术领域的未来发展趋势。 相似文献