全文获取类型
收费全文 | 7972篇 |
免费 | 1405篇 |
国内免费 | 1294篇 |
专业分类
测绘学 | 469篇 |
大气科学 | 496篇 |
地球物理 | 2472篇 |
地质学 | 4813篇 |
海洋学 | 1000篇 |
天文学 | 37篇 |
综合类 | 486篇 |
自然地理 | 898篇 |
出版年
2024年 | 18篇 |
2023年 | 60篇 |
2022年 | 231篇 |
2021年 | 329篇 |
2020年 | 312篇 |
2019年 | 340篇 |
2018年 | 315篇 |
2017年 | 326篇 |
2016年 | 335篇 |
2015年 | 387篇 |
2014年 | 482篇 |
2013年 | 607篇 |
2012年 | 471篇 |
2011年 | 506篇 |
2010年 | 441篇 |
2009年 | 501篇 |
2008年 | 531篇 |
2007年 | 559篇 |
2006年 | 541篇 |
2005年 | 474篇 |
2004年 | 381篇 |
2003年 | 314篇 |
2002年 | 277篇 |
2001年 | 273篇 |
2000年 | 240篇 |
1999年 | 269篇 |
1998年 | 232篇 |
1997年 | 174篇 |
1996年 | 137篇 |
1995年 | 136篇 |
1994年 | 98篇 |
1993年 | 107篇 |
1992年 | 71篇 |
1991年 | 40篇 |
1990年 | 38篇 |
1989年 | 21篇 |
1988年 | 37篇 |
1987年 | 13篇 |
1986年 | 5篇 |
1985年 | 14篇 |
1984年 | 14篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1979年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1954年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
AnomalouschangeoftheAntarcticseaiceandglobalsealevelchange¥XieSimei;ZouBing;WangYiandBaoChenglan(1.NationalMarineEnvironmentF... 相似文献
72.
The sway, heave and roll added masses of three uniform cylinders with semi-circular, rectangular and triangular cross-sectional shapes in shallow and narrow water are numerically analysed. The method is based on simulation of the potential flow induced by the cylinder's mode of motion. The effects of shallow and narrow water on added mass are analysed and presented. It is concluded that the shallow and narrow water effects on added mass depend on the different cross-section shapes of the cylinders. In particular, the water depth effect on sway added mass is stronger than that on heave added mass while the narrow water effect on sway is weaker than that on heave. The shallow water effect on added mass tends to weaken the narrow water effect. Lastly the effect of shallow and narrow water on added mass on a rectangular cylinder is the strongest while that on a triangular cylinder is the weakest. 相似文献
73.
Bridge scour modeling requires storm surge hydrographs as open ocean boundary conditions for coastal waters surrounding tidal inlets. These open coast storm surge hydrographs are used to accurately determine both horizontal and vertical circulation patterns, and thus scour, within the inlet and bay for an extreme event. At present, very little information is available on the effect that tidal inlets have on these open coast storm surge hydrographs. Furthermore, current modeling practice enforces a single design hydrograph along the open coast boundary for bridge scour models. This study expands on these concepts and provides a more fundamental understanding on both of these modeling areas. 相似文献
74.
应用多年的实测资料 ,分析了曹娥江河口高水位成因 ,结果表明 ,曹娥江河口洪水位具有山溪性和可冲性的特点 ,人类活动对高水位有较大影响。应用统计分析法和成因分析法推求 1 %设计高水位 ,讨论了成因分析法中上、下边界条件的选取 ,其选取原则对其他潮汐河口确定设计高水位具有借鉴意义 相似文献
75.
Jue Lin-Ye Begoña Pérez-Gómez Enrique Álvarez-Fanjul Javier García-Valdecasas 《Marine Geodesy》2020,43(5):509-539
AbstractThe sea level station operating since 1996 at Mazagón (Huelva, Spain) has been progressively upgraded to fit tsunami warning requirements, due to its location in one of the main regions at risk. Its radar water level sensor was complemented in 2017, with the addition of a pressure sensor. The performance of both sea level sensors and their response to sea level oscillations, at different frequencies, is assessed. Particular emphasis is put on the effect of extreme events, such as Storm Emma, when alternative methods to obtain 1-min data are tested, in contrast to the one based on arithmetic means. The overall differences are small, for the whole period of study (centered-root-mean-square-error below 1?cm, for 5-min, and hourly data; similar tidal parameters and sea level oscillations with periods between 30?s and 5?min). However, during Storm Emma, the pressure sensor presents sensibly lower readings than the radar, with the centered-root-mean-square-error rising to 80?mm on the March 2nd 2018. A new method to compute 1-min data, based on medians, reduced this value to 10?mm for the same day. 相似文献
76.
根据海南岛榆林验潮站1954~1992年连续39a潮位观测资料,经过统一基准面校正后,运用多种统计分析方法研究,得出近40a来海南岛南岸的相对海平面变化呈上升趋势,相应的平均上升速率为0.64mm/a,这一数值较近百年来1~2mm/a的全球海平面上升速率明显偏小,反映出同期海南岛南岸的地面是微弱抬升的。 相似文献
77.
This paper is concerned with the models appropriate for the dynamic assessment of jack-ups, concentrating particularly on the long-term response due to random ocean waves and on work-hardening plasticity models used for spud-can response. A methodology for scaling of short-term statistics, calculated using a Constrained NewWave technique, is shown in a numerical experiment for an example jack-up and central North Sea location. The difference in long-term extreme response statistics due to various footing assumptions is emphasised. Results for two environmental load conditions are described (one excluding and one including wind and current effects) and the role of sea-state severity in the variation of short-term extreme response statistics is also highlighted. 相似文献
78.
The radiometers on board the satellites ERS-1, TOPEX/Poseidon, ERS-2, GFO, Jason-1, and Envisat measure brightness temperatures at two or three different frequencies to determine the total columnal water vapor content and wet tropospheric path delay, a major correction to the altimeter range measurements. In order to asses the long-term stability of the path delay, the radiometers are calibrated against vicarious cold and hot references, against each other, and against several atmospheric models. Four of these radiometers exhibit significant drifts in at least one of the channels, resulting in yet unmodeled errors in path delay of up to 1 mm/year, thus limiting the accuracy at which global sea level rise can be inferred from the altimeter range measurements. 相似文献
79.
研究取自于东太平洋CC48柱状样的钙质超微化石和底栖有孔虫的氧同位素成分变化的结果表明,该区下中新统至少可分出九个氧同位素地层(期),反映该区在早中新世期间至少经历了4次气温上升和5次下降的古气候变化。南极大陆冰川应是形成于早中新世而不是前人认为的中中新世。在早中新世,南极冰体体积有较大的变化。受古气候变化的影响,在早中新世期间东太平洋水柱热结构或温度梯度有比较大的变化,海平面出现多次上升与下降。 相似文献
80.