全文获取类型
收费全文 | 2846篇 |
免费 | 327篇 |
国内免费 | 694篇 |
专业分类
测绘学 | 138篇 |
大气科学 | 350篇 |
地球物理 | 458篇 |
地质学 | 756篇 |
海洋学 | 1733篇 |
天文学 | 16篇 |
综合类 | 175篇 |
自然地理 | 241篇 |
出版年
2024年 | 15篇 |
2023年 | 59篇 |
2022年 | 122篇 |
2021年 | 111篇 |
2020年 | 112篇 |
2019年 | 136篇 |
2018年 | 115篇 |
2017年 | 127篇 |
2016年 | 113篇 |
2015年 | 144篇 |
2014年 | 179篇 |
2013年 | 203篇 |
2012年 | 149篇 |
2011年 | 180篇 |
2010年 | 124篇 |
2009年 | 201篇 |
2008年 | 219篇 |
2007年 | 220篇 |
2006年 | 179篇 |
2005年 | 173篇 |
2004年 | 133篇 |
2003年 | 127篇 |
2002年 | 110篇 |
2001年 | 100篇 |
2000年 | 90篇 |
1999年 | 68篇 |
1998年 | 63篇 |
1997年 | 50篇 |
1996年 | 31篇 |
1995年 | 51篇 |
1994年 | 26篇 |
1993年 | 25篇 |
1992年 | 19篇 |
1991年 | 19篇 |
1990年 | 15篇 |
1989年 | 16篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 1篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有3867条查询结果,搜索用时 15 毫秒
991.
992.
This paper describes the modification of a two-dimensional finite element long wave hydrodynamic model in order to predict the net current and water levels attributable to the influences of waves. Tests examine the effects of the application of wave induced forces, including comparisons to a physical experiment. An example of a real river system is presented with comparisons to measured data, which demonstrate the importance of simulating the combined effects of tides and waves upon hydrodynamic behavior. 相似文献
993.
994.
为了揭示沿岸海区冬季垂直环流及其温盐结构的分布特征和变化规律,利用三维斜压流体动力学模型,对具有岸界坡度变化、河流入海、海湾、岛屿和海槽的理想海区冬季的垂直环流及其温盐结构进行了数值模拟。其环流的数值结果表明,冬季沿岸海区的垂直环流普遍呈逆时针流动。在近表层为向岸流,沿岸为下降流,近表层以下为离岸流;近表层以下的离岸流在外海有明显的上升趋势;沿岸下降流自表层至底层逐渐由强变弱;就整个海区而言,随着自南往北海区水深的逐渐变浅和岸界地形坡度的由大变小,其沿岸下降流则由强变弱。 相似文献
995.
Distinctive diatom assemblages may be associated with tsunami sediments and may often contrast with the assemblages found within sediments underlying the tsunami deposit as well as those associated with the modern coastal environment. Sediments associated with the 1998 tsunami that destroyed much of the Sissano lagoon area in northern Papua New Guinea have been investigated. Surface sediments from three transects across the sediment spit near Warapu have been examined for diatom content and preservation. The preservation is variable, and the data show an, often chaotic, assemblage that can be attributed to the tsunami waves incorporating and depositing diatoms from distinctive habitat zones during their runup and subsequent backwash. The diatoms identified within the Warapu sediments indicate an origin from within the inter-tidal and offshore area rather than from the beach–sand spit complex. The sand deposits disclose a high percentage, in excess of 75%, of broken diatom valves, and a predominance of centric (circular) species due to preferential preservation. The study demonstrates that the application of diatom biostratigraphy to modern tsunami deposits can be used in conjunction with other stratigraphical lines of evidence to interpret the source and provenance of historical and palaeo-tsunami deposits. 相似文献
996.
997.
海岸带开发的可持续性探讨 总被引:2,自引:0,他引:2
以海带为研究对象,探讨了影响岸带环境系统可持续性的相关因素,在将人类社会经济活动纳入统一的海岸带生态系统范范畴的前提下,提出了海岸带开发的可持续性判定因子。指出,实现海岸带的可持续发展,必须树立新的社会经济-生态环境观,以海岸带社会,经济,环境的协调发展为基础理念,实施一体化管理,依赖科技进步,确保环境资源的消耗与补给达到动态平衡,通过动态规划和及时的反馈调整,最终走出持续发展之路。 相似文献
998.
Coastal wetlands present particular challenges for coastal governance and for the implementation of the Ramsar Convention, not least because coastal areas are focal points of human activity and of governance ambiguity. Through the evaluation of Ramsar delivery at both national and local levels in Japan and England, the relationship between Ramsar implementation and coastal governance was examined. In England, Ramsar status is primarily treated as a nature conservation designation which limits the wider opportunities inherent in the designation. In contrast, in Japan, the Ramsar Convention is used as a policy driver at the national level and as a leverage to encourage citizen engagement, economic benefit, and wetland conservation at the local level. It was concluded that through the implementation of the Ramsar Convention in important coastal wetland areas, significant steps can be taken towards delivering integrated approaches to coastal governance. 相似文献
999.
1000.
Pengfei LIN Zhipeng YU Hailong LIU Yongqiang YU Yiwen LI Jirong JIANG Wei XUE Kangjun CHEN Qian YANG Bowen ZHAO Jilin WEI Mengrong DING Zhikuo SUN Yaqi WANG Yao MENG Weipeng ZHENG Jinfeng MA 《大气科学进展》2020,37(3):239-249
The datasets of two Ocean Model Intercomparison Project(OMIP) simulation experiments from the LASG/IAP Climate Ocean Model, version 3(LICOM3), forced by two different sets of atmospheric surface data, are described in this paper. The experiment forced by CORE-II(Co-ordinated Ocean–Ice Reference Experiments, Phase II) data(1948–2009) is called OMIP1, and that forced by JRA55-do(surface dataset for driving ocean–sea-ice models based on Japanese 55-year atmospheric reanalysis) data(1958–2018) is ca... 相似文献