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491.
Crystal chemistry of Fe-containing sphalerites 总被引:2,自引:0,他引:2
Cell dimensions and solvus properties of Fe-containing sphalerites, depending on temperature and sulfur fugacity, were investigated
using equilibrated powdered materials synthesized from elements and binary sulfides under vacuum. The Fe solvus in sphalerite,
determined by optical microscopy and microprobe analysis, are directly correlated with increasing temperature and decreasing
sulfur fugacity controlled by solid-state buffers. The increase of lattice parameters with Fe correlates with an increase
of FeS independent of sulfur fugacity up to 10 mol% FeS within ZnS. Above about 10 mol% the lattice parameters are strongly
depending on the sulfur fugacity controlled Fe3+/Fe2+ ratios. The Fe3+/Fe2+ ratios determined by Moessbauer spectroscopy and involving metal vacancies depend on the sulfur fugacity. The critical Fe2+ content determined by experimental simulations as well as the minimal Fe3+/ Fe2+ ratios agree with the required minimal Fe content for CuFeS2-DIS in sphalerite. The critical Fe2+ content also agrees with the change of Moessbauer signal from a singlet to a doublet for Fe2+ containing sphalerite. Pyrrhotite exsolutions in sphalerite caused by higher sulfur fugacity show orientationally intergrown
with the sphalerite matrix. Density data calculated from lattice parameters and composition are compared with experimental
density measurements.
Received: 25 April 2001 / Accepted: 14 February 2003 相似文献
492.
493.
水岩体系Eh-pH法及其在砂岩型铀矿体定位研究中的应用——以新疆伊犁盆地512铀矿床为例 总被引:5,自引:0,他引:5
512铀矿床不同氧化还原环境水岩体系Eh和pH值的研究结果表明:同一氧化还原环境的水岩体系Eh平均值极为接近;不同氧化还原环境的水岩体系Eh值差异明显,即从氧化带到还原带,水岩体系Eh值明显下降;不同氧化还原环境,其水岩体系pH值也有所不同,氧化带和还原带处于弱碱性介质环境,过渡带(矿化地段)处于中性介质环境;水岩体系Eh和pH值可以作为划分含矿层氧化还原环境分带及圈定铀矿体位置的依据。 相似文献
494.
后江桥铅锌矿具有多源,多阶段成矿特点,成矿主要与泥盆纪地层及热液作用有关,对其矿床地质特征,同位素地质学,矿床成因等方面研究,认为成矿物质来源具双重性,既有来源于地层,又有来自壳幔源岩浆,成因类型属于沉积改造型铅锌矿床。 相似文献
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497.
Development of Cu and Zn Isotope MC-ICP-MS Measurements: Application to Suspended Particulate Matter and Sediments from the Scheldt Estuary 总被引:1,自引:0,他引:1
Jérôme C.J. Petit Jeroen de Jong Lei Chou Nadine Mattielli 《Geostandards and Geoanalytical Research》2008,32(2):149-166
The present study evaluates several critical issues related to precision and accuracy of Cu and Zn isotopic measurements with application to estuarine particulate materials. Calibration of reference materials (such as the IRMM 3702 Zn) against the JMC Zn and NIST Cu reference materials were performed in wet and/or dry plasma modes (Aridus I and DSN‐100) on a Nu Plasma MC‐ICP‐MS. Different mass bias correction methods were compared. More than 100 analyses of certified reference materials suggested that the sample‐calibrator bracketing correction and the empirical external normalisation methods provide the most reliable corrections, with long term external precisions of 0.06 and 0.07‰ (2SD), respectively. Investigation of the effect of variable analyte to spike concentration ratios on Zn and Cu isotopic determinations indicated that the accuracy of Cu measurements in dry plasma is very sensitive to the relative Cu and Zn concentrations, with deviations of δ65Cu from ?0.4‰ (Cu/Zn = 4) to +0.4‰ (Cu/Zn = 0.2). A quantitative assessment (with instrumental mass bias corrections) of spectral and non‐spectral interferences (Ti, Cr, Co, Fe, Ca, Mg, Na) was performed. Titanium and Cr were the most severe interfering constituents, contributing to inaccuracies of ?5.1‰ and +0.60‰ on δ68/64Zn, respectively (for 500 μg l?1 Cu and Zn standard solutions spiked with 1000 μg l?1 of Ti or Cr). Preliminary isotopic results were obtained on contrasting sediment matrices from the Scheldt estuary. Significant isotopic fractionation of zinc (from 0.21‰ to 1.13‰ for δ66Zn) and copper (from ?0.38‰ to 0.23‰ for δ65Cu), suggest a control by physical mixing of continental and marine water masses, characterized by distinct Cu and Zn isotopic signatures. These results provide a stepping‐stone to further evaluate the use of Cu and Zn isotopes as biogeochemical tracers in estuarine environments. 相似文献
498.
499.
500.
Pb-Zn-Ag-bearing M anganoan Skarns of China 总被引:2,自引:0,他引:2
ZHAO Yiming LI Daxin Institute of Mineral Resources Chinese Academy of Geological Sciences Beijing 《《地质学报》英文版》2004,78(2):524-528
Manganoan skarns consist of special Mn (Ca, Mg, Fe, Al) silicate metasomatic minerals and are usually associated with Pb-Zn(Ag) mineralization. They occur chiefly along the lithologic contacts or faults and fractures of carbonate wall rocks distal from the intrusive contact zone, and are combined with Fe, Cu, W, Sn and Cu-bearing calcic or magnesian skarns occurring in the contact zones to constitute certain metasomatic zoning. Manganoan skarns are formed later than calcic or magnesian skarns. Their rock-forming temperatures are lower than those of calcic or magnesian skarns. The mineral assemblages of manganoan skarns occurring in different carbonate rocks (limestone or dolomite) are notably different. 相似文献