全文获取类型
收费全文 | 389篇 |
免费 | 27篇 |
国内免费 | 50篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 89篇 |
地球物理 | 180篇 |
地质学 | 89篇 |
海洋学 | 19篇 |
综合类 | 15篇 |
自然地理 | 70篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 11篇 |
2019年 | 20篇 |
2018年 | 19篇 |
2017年 | 12篇 |
2016年 | 9篇 |
2015年 | 12篇 |
2014年 | 23篇 |
2013年 | 46篇 |
2012年 | 14篇 |
2011年 | 10篇 |
2010年 | 18篇 |
2009年 | 15篇 |
2008年 | 15篇 |
2007年 | 14篇 |
2006年 | 13篇 |
2005年 | 15篇 |
2004年 | 16篇 |
2003年 | 11篇 |
2002年 | 17篇 |
2001年 | 17篇 |
2000年 | 12篇 |
1999年 | 9篇 |
1998年 | 12篇 |
1997年 | 11篇 |
1996年 | 12篇 |
1995年 | 19篇 |
1994年 | 8篇 |
1993年 | 11篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有466条查询结果,搜索用时 15 毫秒
121.
根据目前地震科普防震知识宣传工作存在的现实问题,认为,要想切实搞好此项工作,并能深入持久地开展下去,使之卓有成效,首先应在地震管理体系中制定出明确的责任目标,并要有保证目标实现的措施,第二在此基础上尽快将此项工作纳入社会宣传的总体规划,实现社会化管理,组织起社会多种宣传力量,齐抓共管。 相似文献
122.
The Meseta and Fuego volcanoes closely overlap and collectively are known as the Fuego Volcanic Complex. Historic activity occurs exclusively at Fuego, the southern center, and consists of high-Al basalts. Meseta, the inactive northern center, is predominantly composed of basaltic andesites with minor basalt and andesite. A thick sequence of lava flows and dikes is exposed by a steep collapse escarpment on the east flank of Meseta. The upper 75% of the sequence was sampled from three interfingering stratigraphic sections consisting of 27, 10 and 4 lavas, respectively. Temporal geochemical trends of each section indicates a complex evolutionary history. A major trend toward more evolved compositions upward in the section is consistent with crystal fractionation. This trend is sharply interrupted by the youngest lavas which become distinctly more mafic in composition. Magma mixing is apparently the dominant magmatic evolution process that generated these lavas. The two trends have distinct Sr signatures that suggest a change in parental magma compositions. This abrupt change in composition is interpreted to signal high input rates of mafic magma into the subvolcanic magma chamber. These changes eventually led to sector collapse of Meseta volcano and deposition of the Escuintla debris avalanche. Eruptive activity then migrated to the Fuego volcano where historic activity is similar to that of Meseta immediately prior to its collapse. 相似文献
123.
124.
2001年7月28日夜山西省运城市出现了地震谣传,为从此次事件中吸取教训,对山西省运城市地震局在平息此次地震谣传过程中所采取的措施进行了回顾,分析了地震谣传产生的原因,查找了防震减灾工作中的不足,指出了今后工作中的努力方向。 相似文献
125.
126.
Using the SST data series in tropical ocean(20°N-20°S,50°E-80°W)during 1951-1997 to calculate its monthly mean square deviation,the work obtains results showing that interannual SST variability of the Pacific is more significant than that of the Indian Ocean.Especially near the central and eastern equatorial Pacific(165°W-90°W,6°N-6°S)。where it ranges from 2℃ to 4℃.The interannual SST variability is obvious in November and December but small in March and April.The interannual variabiltiy of “warm pool“SST is not so obvious as that of the eastern equatorial Pacific,Howerver,interannual SST variability of the Indian Ocean ranges from 1℃to 2℃ or so,being smaller than that of the Pacific,In the Indian ocean.Interannual SST variability of the Southern Hemisphere is more obvious than that of the Northern Hemisphere,According to above characterstics of interannual SST variability,the key sectors are determined. 相似文献
127.
结合山东省地震局科技档案管理模式的现状,阐述了地震科技档案信息服务模式改革的必要性和重要性;结合信息社会发展的特点,指出了未来地震科技档案发展的方向。 相似文献
128.
129.
H. Jacob Carlson 《Urban geography》2018,39(5):726-745
Bangalore is held up as a model for how cities, particularly in the global south, should develop in the globalized information age, in which entrepreneurs with new access to international capital fuel service-sector-driven development. Expanding market forces cultivate cities of skilled middle-class workers whose increased consumption generates broad developmental benefits. Now known as the “Silicon Valley of India,” Bangalore was previously the capital of India’s public sector enterprises (PSEs), which laid important groundwork for the city of today, including the IT sector. I show how, by providing access to homeownership along with high wages and benefits tied to secure employment, Bangalore’s PSEs created the foundation for the city today and its middle-class character. The skilled workforce that PSEs created helped the IT sector emerge in the city. By examining this erased history, we see the role of the state in development projects, and consider alternative models for urban change. 相似文献
130.
Aisling Gallagher 《New Zealand geographer》2017,73(1):15-24
There has been a significant growth in childcare in New Zealand (NZ) since 2006. Shaped by debates around the marketisation of childcare, this paper will make some key observations about the NZ childcare market. I will argue that the landscape of childcare has changed in favour of a burgeoning private sector and consider the recent impetus for corporatisation. Finally, I will examine the discourse of parental ‘choice’ which pervades policy discussions around ECE in New Zealand and how this plays out in the face of an expanding private for‐profit sector. 相似文献