全文获取类型
收费全文 | 170篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 7篇 |
地球物理 | 22篇 |
地质学 | 44篇 |
海洋学 | 11篇 |
天文学 | 50篇 |
自然地理 | 41篇 |
出版年
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 6篇 |
2015年 | 2篇 |
2013年 | 9篇 |
2012年 | 3篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 10篇 |
2004年 | 14篇 |
2003年 | 9篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 9篇 |
1999年 | 7篇 |
1998年 | 11篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1924年 | 1篇 |
排序方式: 共有176条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
The behaviour of quartz during metamorphism is studied based on two case studies from the Barrovian terrains of Sulitjelma in arctic Scandinavia and Loch Tay in the Central Highlands Dalradian of Scotland. Both terrains preserve evidence for metamorphism in pelites involving nucleation and growth of garnet at different times in the deformation history. Data are presented on the size, shape and crystallographic orientation of quartz preserved as inclusions in garnet and as grains in the surrounding matrix. While quartz-grains remain small and dispersed between mica grains, deformation appears to be dominated by grain-boundary sliding accommodated by dissolution–precipitation. At amphibolite facies, textural coarsening occurs by dissolution of small quartz grains and growth of larger quartz grains, coupled with segregation of quartz from mica. As a result, quartz deforms by dislocation creep, developing crystallographic preferred orientations (CPO) consistent with both coaxial and non-coaxial strain. Quartz CPOs with <0001> axes lying parallel to foliation and stretching direction are commonly developed, and best explained by mechanical rotation of inequant (detrital?) quartz grains. There is no evidence for selective entrapment of quartz inclusions in garnet on the basis of quartz crystallographic orientation. 相似文献
7.
Offsets from isotopic equilibrium in biogenic carbonates have complicated paleoclimate reconstructions for decades. A new archive of climate, deep-sea corals, is used to evaluate the calcification processes, independent of photosynthesis, that contribute to these offsets. Carbon and oxygen stable isotope data from six modern deep-sea corals show strong linear trends between δ13C and δ18O. Slopes of these trends between samples are similar and range between 1.9 to 2.6 for Δδ13C/Δδ18O. Linear trends intersect isotopic equilibrium for δ18O and are slightly depleted for δ13C. Variations in the isotopic ratios are strongly correlated with the density banding structure. Isotopically depleted aragonite is associated with light, quickly precipitating bands, whereas isotopically enriched points correspond to slowly accumulating, less dense aragonite. The densest white band at the trabecular center is furthest from isotopic equilibrium for both carbon and oxygen. Data from this region fall off the linear trend between δ18O and δ13C. This deviation, where δ13C remains constant while the δ18O continues to decrease, does not support “vital effect” mechanisms that call upon kinetic fractionation to explain offsets from isotopic equilibrium. We propose a new mechanism for vital effects in these deep-sea corals that is based on a thermodynamic response to a biologically induced pH gradient in the calcifying region. 相似文献
8.
Edward A. Boyle 《Geochimica et cosmochimica acta》2005,69(21):5165-5166
9.
10.
ABSTRACTThe sinking of the MV Rena on Astrolabe Reef (Otaiti) in the Bay of Plenty, New Zealand, resulted in the release of oil and ship debris, including dangerous goods carried as cargo. Two key questions of concern to the public and environmental managers were posed immediately: what was the impact of the Rena oil spill and how long would it take for the marine environment to recover? The research that began immediately after the ship grounded provided answers, as documented in this special issue. 相似文献