全文获取类型
收费全文 | 123篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 4篇 |
地球物理 | 28篇 |
地质学 | 57篇 |
海洋学 | 14篇 |
天文学 | 25篇 |
自然地理 | 3篇 |
出版年
2023年 | 1篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 8篇 |
2014年 | 3篇 |
2013年 | 9篇 |
2012年 | 3篇 |
2011年 | 14篇 |
2010年 | 9篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 10篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1972年 | 1篇 |
排序方式: 共有132条查询结果,搜索用时 0 毫秒
101.
Anthony?C.?HarrisEmail author Charlotte?M.?Allen Scott?E.?Bryan Ian?H.?Campbell Rodney?J.?Holcombe J.?Michael?Palin 《Mineralium Deposita》2004,39(1):46-67
ELA-ICP-MS U–Pb zircon geochronology has been used to show that the porphyritic intrusions related to the formation of the Bajo de la Alumbrera porphyry Cu–Au deposit, NW Argentina, are cogenetic with stratigraphically well-constrained volcanic and volcaniclastic rocks of the Late Miocene Farallón Negro Volcanic Complex. Zircon geochronology for intrusions in this deposit and the host volcanic sequence show that multiple mineralized porphyries were emplaced in a volcanic complex that developed over 1.5 million years. Volcanism occurred in a multi-vent volcanic complex in a siliciclastic intermontane basin. The complex evolved from early mafic-intermediate effusive phases to a later silicic explosive phase associated with mafic intrusions. Zircons from the basal mafic-intermediate lavas have ages that range from 8.46±0.14 to 7.94±0.27 Ma. Regionally extensive silicic explosive volcanism occurred at ~8.0 Ma (8.05±0.13 and 7.96±0.11 Ma), which is co-temporal with intrusion of the earliest mineralized porphyries at Bajo de la Alumbrera (8.02±0.14 and 7.98±0.14 Ma). Regional uplift and erosion followed during which the magmatic-hydrothermal system was probably unroofed. Shortly thereafter, dacitic lava domes were extruded (7.95±0.17 Ma) and rhyolitic diatremes (7.79±0.13 Ma) deposited thick tuff blankets across the region. Emplacement of large intermediate composition stocks occurred at 7.37±0.22 Ma, shortly before renewed magmatism occurred at Bajo de la Alumbrera (7.10±0.07 Ma). The latest porphyry intrusive event is temporally associated with new ore-bearing magmatic-hydrothermal fluids. Other dacitic intrusions are associated with subeconomic deposits that formed synchronously with the mineralized porphyries at Bajo de la Alumbrera. However, their emplacement continued (from 7.10± 0.06 to 6.93±0.07 Ma) after the final intrusion at Bajo de al Alumbrera. Regional volcanism had ceased by 6.8 Ma (6.92±0.07 Ma). The brief history of the volcanic complex hosting the Bajo de la Alumbrera Cu–Au deposit differs from that of other Andean provinces hosting porphyry deposits. For example, at the El Salvador porphyry copper district in Chile, magmatism related to Cu mineralization was episodic in regional igneous activity that occurred over tens of millions of years. Bajo de la Alumbrera resulted from the superposition of multiple porphyry-related hydrothermal systems, temporally separated by a million years. It appears that the metal budget in porphyry ore deposits is not simply a function of their longevity and/or the superposition of multiple porphyry systems. Nor is it a function of the duration of the associated cycle of magmatism. Instead, the timing of processes operating in the parental magma body is the controlling factor in the formation of a fertile porphyry-related ore system.Electronic Supplementary Material Electronic supplementary material to this paper can be obtained by using the Springer Link server located at Editorial handling: N. White 相似文献
102.
Arthur W. Wells J. Rodney Diehl Grant Bromhal Brian R. Strazisar Thomas H. Wilson Curt M. White 《Applied Geochemistry》2007
Geological sequestration of CO2 in depleted oil reservoirs is a potentially useful strategy for greenhouse gas management and can be combined with enhanced oil recovery. Development of methods to estimate CO2 leakage rates is essential to assure that storage objectives are being met at sequestration facilities. Perfluorocarbon tracers (PFTs) were added as three 12 h slugs at about one week intervals during the injection of 2090 tons of CO2 into the West Pearl Queen (WPQ) depleted oil formation, sequestration pilot study site located in SE New Mexico. The CO2 was injected into the Permian Queen Formation. Leakage was monitored in soil–gas using a matrix of 40 capillary adsorbent tubes (CATs) left in the soil for periods ranging from days to months. The tracers, perfluoro-1,2-dimethylcyclohexane (PDCH), perfluorotrimethylcyclohexane (PTCH) and perfluorodimethylcyclobutane (PDCB), were analyzed using thermal desorption, and gas chromatography with electron capture detection. Monitoring was designed to look for immediate leakage, such as at the injection well bore and at nearby wells, and to develop the technology to estimate overall CO2 leak rates based on the use of PFTs. Tracers were detected in soil–gas at the monitoring sites 50 m from the injection well within days of injection. Tracers continued to escape over the following years. Leakage appears to have emanated from the vicinity of the injection well in a radial pattern to about 100 m and in directional patterns to 300 m. Leakage rates were estimated for the 3 tracers from each of the 4 sets of CATs in place following the start of CO2 injection. Leakage was fairly uniform during this period. As a first approximation, the CO2 leak rate was estimated at about 0.0085% of the total CO2 sequestered per annum. 相似文献
103.
There are fundamental links between population health, environment and economic development. The ultimate goal of economic
development is to improve the quality of human life and increase people's longevity. This goal cannot be achieved without
a clean and prosperous Earth. There has been increasing evidence showing that the expansion of economic activities can have
significant impacts on the environment and can cause large-scale and sometimes irreversible environmental changes. It is beyond
reasonable doubt that these changes will have serious public health consequences. How to tackle these issues is a unprecedented
challenge to scientists and policy-makers.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
104.
105.
A study of the distribution of bacteria in relation to particle concentration and type was conducted over a spring-neap tidal cycle in the Tamar Estuary, southwest England. Three groups of bacteria were recognized: free-living; those attached to permanently suspended particles; and those attached to particles which undergo tidally controlled resuspension and sedimentation. The total activity and the activity of all three groups of bacteria increase in the turbidity maximum region. The bacteria associated with the permanently suspended particles, which have a larger mean size and organic carbon content than those in the resuspended sediments, contribute the major part of this increased activity. This is a significant finding as it had been previously thought that the increase in bacterial activity at the turbidity maximum was due to bacteria attached to resuspended sediments. However, resuspension still plays an important role because the increase in bacterial activity is consistently coincident with the turbidity maximum. 相似文献
106.
Aenigmatite, sodic pyroxene and arfvedsonite occur as interstitial minerals in metaluminous to weakly peralkaline syenite patches in alkali dolerite, Morotu, Sakhalin. Aenigmatite is zoned from Ca, Al, Fe3+-rich cores to Ti, Na, Mn, Si-rich rims reflecting the main substitutions Fe2+Ti4+Fe3+, NaSiCaAl and Mn2+Fe2+. Aenigmatite replaces aegirine and ilmenite supporting the existence of a no-oxide field in
— T space. In one case aenigmatite has apparently formed by reaction between ilmenite and arfvedsonite. Titanian aegirine (up to 3.0 wt% TiO2) and Fe-chlorite may replace aenigmatite. Sodic pyroxene occurs as zoned crystals with cores of aegirine-augite rimmed by aegirine and in turn by pale green aegirine containing 93 mol% NaFe3+Si2O6. Additional substitution of the type NaAlCaFe2+ is indicated by significant amounts (up to 6 mol%) of NaAlSi2O6. Arfvedsonite is zoned with rims enriched in Na, Fe and depleted in Ca which parallels the variation of these elements in the sodic pyroxenes.The high peralkalinity of the residual liquid from which the mafic phases formed resulted from the early crystallization of microperthite (which makes up the bulk of the syenites) leading to an increase in the Na2O/(Na2O+K2O) and (Na2O+K2O)/Al2O3 ratios of the remaining interstitial liquid which is also enriched in Ti, Fe, and Mn. Bulk composition of the melt,
, temperature and volatile content were all important variables in determining the composition and stability of the peralkaline silicates.
in the residual liquid appears to have been buffered by arfvedsonite-aegirine and later by the arfvedsonite-aenigmatite and aenigmatite-aegirine equilibria under
conditions of a no-oxide field. An increase in
, above that of the alkali buffer reactions, is inferred by an increase of Ti and Mn in aenigmatite rims. The latest postmagmatic vapour crystallization stage of the syenites is marked by extremely low
which may have been facilitated by exsolution of a gas phase. Low
is supported by the replacement of aenigmatite by titanian aegirine, and the formation of rare Ti-rich garnet with a very low (Ti4++Fe3+)/(Ti+Fe) ratio of 0.51, associated with leucoxene alteration of ilmenite. 相似文献
107.
108.
对来自华南多个花岗岩体的暗色微粒包体样品进行了系统的矿物组成和微结构研究,发现包体中不管是造岩矿物还是副矿物,均存在新、老两个不同世代;包体的微结构大部分情况下也不是“火成结构”,而是以熔融结构为主,并且常多种结构共存,揭示包体是岩石部分熔融的残余物而并非来自岩浆的结晶。不同包体或同一包体从中心到边缘的矿物组成与微结构的差异,反映原岩部分熔融程度的不同,揭示其处于不同的演化阶段。 相似文献
109.
110.