全文获取类型
收费全文 | 78篇 |
免费 | 2篇 |
国内免费 | 36篇 |
专业分类
大气科学 | 1篇 |
地球物理 | 7篇 |
地质学 | 96篇 |
海洋学 | 8篇 |
天文学 | 1篇 |
综合类 | 2篇 |
自然地理 | 1篇 |
出版年
2023年 | 2篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 6篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2013年 | 5篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 13篇 |
2008年 | 9篇 |
2007年 | 8篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2004年 | 8篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1993年 | 2篇 |
排序方式: 共有116条查询结果,搜索用时 31 毫秒
41.
42.
Yan Tao Chusi Li Ruizhong Hu Edward M. Ripley Andao Du Hong Zhong 《Contributions to Mineralogy and Petrology》2007,153(3):321-337
The Jinbaoshan ultramafic intrusion is a sheet-like body with a thick wehrlite unit in the center and thin pyroxenite units
at the margins. PGE are enriched in several disseminated sulfide zones in the intrusion. Olivine from the intrusion has low
Fo and depleted Ni contents compared to olivine from coeval Emeishan picrites. Whole rock major and trace element concentrations
suggest that the Jinbaoshan wehrlites originally contained <30% trapped liquid. The total amount of sulfide in the rocks exceeds
that which could have been dissolved in the trapped liquid. The Jinbaoshan wehrlites are interpreted to represent residual
assemblages formed by dissolution of plagioclase by passing magma. No clear evidence of crustal contamination is indicated
by S, Nd and Os isotopes. We envision that sulfide saturation occurred at depth due to olivine and chromite crystallization.
Immiscible sulfide droplets were transported to the Jinbaoshan conduit where they accumulated and reacted with magma successively
passing through the conduit to achieve high PGE concentrations. 相似文献
43.
Groundwater and sediment samples (∼ 1 m depth) at sites representative of different groundwater pathways were collected to determine the aqueous speciation of sulfur and the fractionation of sulfur isotopes in aqueous and solid phases. In addition, selected sediment samples at 5 depths (from oxic to anoxic layers) were collected to investigate the processes controlling sulfur biogeochemistry in sedimentary layers. Pyrite was the dominant sulfur-bearing phase in the capillary fringe and groundwater zones where anoxic conditions are found. Low concentrations of pyrite (< 5.9 g kg− 1) coupled with high concentrations of dissolved sulfide (4.81 to 134.7 mg L− 1) and low concentrations of dissolved Fe (generally < 1 mg L− 1) and reducible solid-phase Fe indicate that availability of reactive Fe limits pyrite formation. The relative uniformity of down-core isotopic trends for sulfur-bearing mineral phases in the sedimentary layers suggests that sulfate reduction does not result in significant sulfate depletion in the sediment. Sulfate availability in the deeper sediments may be enhanced by convective vertical mixing between upper and lower sedimentary layers due to evaporative concentration. The large isotope fractionation between dissolved sulfate and sedimentary sulfides at Owens Lake provides evidence for initial fractionation from bacterial sulfate reduction and additional fractionation generated by sulfide oxidation followed by disproportionation of intermediate oxidation state sulfur compounds. The high salinity in the Owens Lake brines may be a factor controlling sulfate reduction and disproportionation in hypersaline conditions and results in relatively constant values for isotope fractionation between dissolved sulfate and total reduced sulfur. 相似文献
44.
Toxicity identification evaluation (TIE) of pore water of contaminated marine sediments collected from Hong Kong waters 总被引:2,自引:0,他引:2
Marine sediment can function both as a source and as a sink of marine chemical contaminants. The toxicity of contaminated marine sediment can be assessed by toxic evaluation of its pore water, the inter-particle water of sediment, because toxicants in the pore water may be bioavailable to marine organisms. In this study, the toxicity identification evaluation (TIE) was performed to identify the major toxicants in the pore water of marine sediment collected in Hong Kong waters. In Phase 1 TIE, the suspected toxicants were characterized as anions or organic compounds that are either oxidizable or filterable in alkaline medium. In Phase 2 TIE, the suspected toxicants were identified as sulfide (S2−) based on the reduction of toxicity due to lowering of sulfide concentrations by experimental manipulations. The mass balance and spiking analyses in Phase 3 confirmed that S2− was one of the major toxicants and that some non-toxic unknown compounds measured by LC–MS, which was removed by C18 solid phase extraction, enhanced the toxicity of S2− in the pore water samples. 相似文献
45.
46.
南海北部渔场表层沉积物中的硫化物 总被引:1,自引:0,他引:1
为了给南海北部渔场的资源和环境保护提供基础数据,用碘量法测定了南海北部陆架区表层沉积物中硫化物含量.结果表明,全部28份样品中硫化物含量为3.3~42.2mg/kg(干重,下同),平均为12.1mg/kg,符合外海含量低的一般规律,明显低于沿岸海湾的含量,远低于日本渔业环境质量标准(200mg/kg)和安全下限值(400mg/kg).硫化物含量在测站间和不同区域间存在一定差异,南北方向呈近岸(13.1mg/kg)略高于离岸(12.1mg/kg)、离岸略高于远岸(11.1mg/kg)的梯度分布,但梯度差异不显著(p>0.10);东西方向的分布特点是粤西海域(23.7mg/kg)>海南岛以东(15.3mg/kg)>台湾浅滩(9.4mg/kg)≈粤东海域(8.7mg/kg)≈珠江口外海域(8.6mg/kg).空间分布不太均匀主要是受沉积物类型的影响,与陆源硫化物输入的关系不大. 相似文献
47.
LA-(MC)-ICPMS和(Nano)SIMS硫化物微量元素和硫同位素原位分析与矿床形成的精细过程 总被引:8,自引:3,他引:5
硫化物微区原位分析技术包括LA-ICPMS定点微量元素分析、LA-ICPMS和(Nano) SIMS微量元素面扫描分析,以及SIMS、Nano SIMS和LA-MC-ICPMS原位硫同位素点分析和面扫描。这些分析方法可以有效地获取不同期次硫化物微量元素含量、丰度分布图像、硫同位素比值和分布特征,结合微区时间分辨信号谱图、微量元素相关性分析等,在矿床学的成矿元素行为与赋存状态、成矿元素置换反应、成矿流体与硫的来源、矿石矿物的化学分带性、矿床成因模型等研究中有着重要的应用前景,以探讨矿床的精细成矿过程。硫化物原位微量元素和同位素LA-(MC)-ICPMS和(Nano) SIMS分析,需要降低仪器和分析方法的系统误差,克服严重的基体效应和同位素分馏效应。 相似文献
48.
新疆东天山黄山东岩体橄榄石成因意义探讨 总被引:12,自引:6,他引:6
黄山东岩体位于新疆东天山造山带中段,由四次岩浆侵入形成:第一次侵入形成了岩体上部的橄榄辉长岩、角闪辉长岩和闪长岩,构成岩体的主体;第二次侵入形成辉长苏长岩,呈岩墙状分布于岩体西端和西北部;第三次侵入岩石为斜长二辉橄榄岩,位于岩体下部,为主要的赋矿岩石;第四次侵入岩石为底部角闪辉长岩。橄榄石为第三次侵入的斜长二辉橄榄岩和第一次侵入的橄榄辉长岩主要造岩矿物之一,橄榄石的镁橄榄石牌号(Fo)值介于68.5~82.5之间。其中含硫化物斜长二辉橄榄岩中的橄榄石具有较高的Fo值(79.7~82.5);斜长二辉橄榄岩中橄榄石的Fo值为78.3~79.9;而基性程度较低的橄榄辉长岩中橄榄石具有较低的Fo值(68.5~72.2)。利用橄榄石矿物成分计算得出黄山东岩体母岩浆Mg#(Mg2+/(Mg2++Fe2+))为0.59,为原生玄武质岩浆经历结晶分异作用形成。模拟计算结果显示黄山东岩体不含矿岩石中橄榄石是母岩浆经过2%的橄榄石结晶分异且硫达到饱和后,在硫化物熔离的同时岩浆发生橄榄石结晶而形成,并且橄榄石︰硫化物≈50︰1,部分橄榄石成分投点在橄榄石结晶和硫化物熔离的模拟曲线右下侧,指示它们可能受到晶间硅酸盐熔浆作用的影响。含硫化物斜长二辉橄榄岩中Fo值与Ni含量呈负相关关系,说明橄榄石与硫化物熔体之间发生了Fe-Ni交换反应。 相似文献
49.
河南省栾川县西沟铅锌银矿床单矿物铷-锶同位素组成特征 总被引:9,自引:7,他引:2
河南栾川西沟铅锌银矿床位于华北克拉通南缘栾川断裂北侧,为赋存于中-晚元古代浅变质碳酸盐建造中的层控矿床,被认为是晚元古代的热水沉积型矿床.从成矿早阶段至晚阶段,矿物共生组合依次为;细粒黄铁矿、粗粒黄铁矿-闪锌矿-白云石-石英组合、多金属硫化物-白云石-石英组合、黄铁矿-石英-碳酸盐组合.本文对其矿石硫化物和黑云母进行了单颗粒矿物Rb-Sr同位素分析和研究.1件赋矿钙质二云片岩样品的5个黑云母颗粒样品给出Rb-Sr等时线年龄为366.0±10Ma,代表赋矿围岩的区域变质年龄.由于黄铁矿-碳酸盐细脉切穿了钙质二云片岩的片理,闪锌矿细脉切穿大理岩条带,矿体未遭受区域变质作用,可推断矿化发生于366Ma之后.考虑到区域内的构造变形事件和大规模花岗岩类侵入和成矿作用的年龄数据集中在156~134Ma,峰值在138 Ma左右,认为西沟铅锌银矿床形成于晚侏罗世-早白垩世.5件成矿早阶段细粒黄铁矿具有较低的I_(Sr-138Ma0值(按138Ma计算的锶同位素初始比值),变化范围为0.7100~0.7151,平均0.7127,该值略高于晚侏罗-早白垩斑岩类和花岗岩基,明显低于太古代太华群变质基底、中元古代熊耳群安山质火山盖层和中-晚元古代栾川群和官道口群的片岩地层,但与赋矿围岩栾川群大理岩地层接近,表明碳酸盐地层变质脱水和晚侏罗-早白垩岩浆岩均有可能为早阶段成矿提供成矿流体.相比之下,主成矿阶段硫化物则更加富含放射成因锶;14个主成矿阶段粗粒黄铁矿测点的I_(Sr-138Ma)值范围为0.7152~0.7344,平均0.7247,13个闪锌矿测点的I_(Sr-138Ma)值范围为0.7108~0.7398,平均0.7283,这些硫化物I_(Sr-138Ma)值接近于或低于太古宙太华群、中元古代熊耳群和中-晚元古代官道口群和栾川群,表明这些地层的锶都有可能混入成矿流体.因此,上述研究表明成矿早阶段流体主要为壳源岩石的变质脱水流体或燕山期岩浆热液,而在主成矿阶段,通过水岩相互作用与浅源循环的大气水或建造水的混入,浅部盖层栾川群地层的成分较多地加入了成矿系统. 相似文献
50.
Mineralogical study of base metal tailings with various sulfide contents, oxidized in laboratory columns and field lysimeters 总被引:7,自引:0,他引:7
S. C. Shaw L. A. Groat J. L. Jambor D. W. Blowes C. J. Hanton-Fong R. A. Stuparyk 《Environmental Geology》1998,33(2-3):209-217
Oxidation of a flotation-derived, low-sulfide tailings containing approximately 0.4 wt.% S was compared with simultaneously
oxidized tailings containing 1.0 wt.% S and 2.5 wt.% S to assess their acid generating characteristics. Each tailings type
was exposed to oxidation for three years in laboratory columns and in lysimeter pits in the field. In these tailings the sulfide
mineral of principal concern with respect to acid generation is pyrrhotite (Fe
1-x
S). In past studies the alteration of pyrrhotite has been characterized by initial replacement with marcasite (FeS2) and ferric iron sulfates, which are followed by development of ferric oxyhydroxides such as goethite and lepidocrocite.
Macroscopic characterization of the tailings shows varying and progressive degrees of oxidation correlative with the three
different sulfur contents. As expected, the tailings with the lowest sulfur content are the least oxidized, and those with
the highest sulfur content have reacted the most. The column tests, which represent accelerated reaction conditions relative
to those for the lysimeter pits, show much higher degrees of oxidation, and a markedly more distinct boundary between the
oxidized and unoxidized zones; as well, differences among the three tailings types are more pronounced.
Received: 31 October 1997 · Accepted: 27 May 1997 相似文献