全文获取类型
收费全文 | 262篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 18篇 |
大气科学 | 19篇 |
地球物理 | 63篇 |
地质学 | 101篇 |
海洋学 | 11篇 |
天文学 | 40篇 |
自然地理 | 16篇 |
出版年
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 10篇 |
2012年 | 18篇 |
2011年 | 17篇 |
2010年 | 5篇 |
2009年 | 22篇 |
2008年 | 14篇 |
2007年 | 17篇 |
2006年 | 16篇 |
2005年 | 21篇 |
2004年 | 19篇 |
2003年 | 17篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 9篇 |
1999年 | 5篇 |
1998年 | 11篇 |
1997年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1984年 | 3篇 |
1981年 | 1篇 |
1976年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有268条查询结果,搜索用时 46 毫秒
261.
The Guelb Moghrein Fe oxide–Cu–Au–Co deposit, with a total resource of 23.6 Mt at 1.88% Cu, 1.41 g/t Au, and 143 g/t Co, is hosted by an extensive metacarbonate body. However, it is restricted to up to 30-m wide tabular breccia zones developed parallel to discrete shear zones that transect the host metacarbonates. The Fe–Mg clinoamphibole–chlorite schists represent up to 1-m thick interlayer metasediments and localized viscous shearing in these shear zones. Siderite of the metacarbonate body was deformed into a breccia and was replaced by an ore and alteration assemblage comprised of Fe–Mg clinoamphibole, magnetite, pyrrhotite, chalcopyrite, graphite, Fe–Co–Ni arsenides, arsenopyrite, cobaltite, uraninite, and Bi–Au–Ag–Te minerals. In contact with wall rock amphibolites, the metacarbonate body is enveloped by an alteration halo up to 40 m wide, consisting of biotite, actinolite, grunerite, chlorite, calcite, albite, and quartz. The Guelb Moghrein ore body is structurally controlled by shear zones that developed in the footwall of a regional thrust zone. This thrust separates greenschist facies quartz–sericite schists and biotite–garnet–quartz schists of the Sainte Barbe volcanic unit in the hanging wall from amphibolite facies metavolcanic rocks, metacarbonates, and the Guelb Moghrein ore body of the Akjoujt metabasalt unit in the footwall. Peak temperatures of the latter unit are estimated by hornblende–plagioclase thermometry at 580±40°C. Thrusting was retrograde for the Akjoujt metabasalt unit, but prograde for the Sainte Barbe volcanic unit at P–T conditions of about 410±30°C and 2–3 kbar (garnet–biotite thermometry). Structural and petrological evidences suggest that the ore fluids migrated along the shear zones and reacted with the siderite in the metacarbonate. This evolution and the setting of Guelb Moghrein in the fold-and-thrust belt of the Pan-African to Variscan Mauritanides (Mauritania, West Africa) resemble Proterozoic Fe oxide–Cu–Au–Co deposits such as examples from the Tennant Creek and Mount Isa Inliers, Australia.Electronic Supplementary Material Supplementary material is available for this article at 相似文献
262.
Bruno Merz Jana Friedrich Markus Disse Jochen Schwarz Johann G. Goldammer Jochen Wächter 《Natural Hazards》2006,38(1-2):3-20
The German Research Network for Natural Disasters (DFNK) linked 15 partners with scientific expertise in the field of natural
hazards. Main objectives were the development and provision of the scientific fundamentals for an advanced risk management
of important natural disasters in Germany, i.e., floods, earthquakes, storms and wildland fires. This included risk analyses,
the development of information systems for supporting disaster management, and recommendations for risk reduction measures.
This paper gives an overview of DFNK and summarises its experiences concerning multidisciplinarity and user-orientation. It
illustrates the concept of risk chains, causally linking the different processes from hazard to risk. The step from hazard
to risk requires interdisciplinary research teams. The experiences show that integrative concepts allow results not achievable
with mono-disciplinary approaches. Integrative approaches pave the way to harmonised safety considerations taking into account
the different hazards in a region within a common framework. User-orientation, policy advice and development of operational
tools are key issues of disaster research. The experiences of DFNK illustrate the limitations of a research network in bridging
the gap between research and application within rather short-term projects. Successful cooperation with users could be established
by those activities where, at the beginning of the project, a user was identified who had a strong interest in solving an
urgent problem. 相似文献
263.
Zeming Zhang Yilin Xiao Jochen Hoefs J. G. Liou Klaus Simon 《Contributions to Mineralogy and Petrology》2006,152(4):421-441
The main hole (MH) of the Chinese Continental Scientific Drilling Project (CCSD) in southern Sulu has penetrated into an ultrahigh-pressure (UHP) metamorphic rock slice which consists of orthogneiss, paragneiss, eclogite, ultramafic rock and minor schist. Recovered eclogites have a UHP metamorphic mineral assemblage of garnet + omphacite + rutile ± phengite ± kyanite ± coesite ± epidote. Ultramafic rocks contain garnet + olivine + clinopyroxene + orthopyroxene ± Ti-clinohumite ± phlogopite. Gneisses and schists contain an amphibolite-facies paragenesis, but their zircons have coesite, garnet, omphacite (or jadeite) and phengite inclusions, indicating that eclogites and gneisses have been subjected to in situ UHP metamorphism. Using available geothermobarometers, P–T estimates of 3.1–4.4 GPa and 678–816°C for eclogites were obtained. If surface outcrops and neighboring shallow drill holes are considered together, we suggest that a huge supracrustal rock slab (> 50 km long × 100 km wide × 5 km deep) was subducted to a depth > 100 km and then exhumed to the surface. The depth interval (0–2,050 m) of the CCSD-MH can be divided into six lithological units. Unit 1 consists of alternating layers of quartz-rich and rutile-rich eclogites, with thin interlayers of gneiss and schist. Eclogites of unit 1 are characterized by Nb, Ta, Sr and Ti depletions, low Mg number and general LREE enrichment. Unit 2 comprises rutile- and ilmenite-rich eclogite and minor “normal” eclogite and is characterized by high TiO2, total Fe, V, Co and Sr, and very low SiO2, alkali, Zr, Ba, Nb, Ta and total REE contents, and LREE-depleted REE patterns with slightly positive Eu anomalies. Unit 3 contains ultramafic rock and minor MgO-rich eclogite. Protoliths of UHP rocks from units 1, 2 and 3 represent a layered mafic to ultramafic intrusion at crustal depth. Units 4 and 6 consist of interlayered eclogite and paragneiss; the eclogites are characterized by Th, U, Nb, Ta and Ti depletion and K enrichment and LREE-enriched REE patterns. Paragneisses show Nb, Ta, Sr and Ti depletions and LREE-enriched REE patterns occasionally with slightly negative Eu anomalies, indicating that their protoliths represent metamorphic supracrustal series. Unit 5 consists mainly of orthogneisses, showing distinct Nb, Ta, Sr and Ti depletions, and LREE-enriched REE patterns with pronounced negative Eu anomalies, suggesting granitic protoliths. In conclusion it is proposed that the southern Sulu UHP belt consists of a series of meta-supracrustal rocks, a layered mafic–ultramafic complex and granites. 相似文献
264.
Tobias Diehl Nicholas Deichmann John Clinton Stephan Husen Toni Kraft Katrin Plenkers Benjamin Edwards Carlo Cauzzi Clotaire Michel Philipp Kästli Stefan Wiemer Florian Haslinger Donat Fäh Urs Kradolfer Jochen Woessner 《Swiss Journal of Geoscience》2013,106(3):543-558
This report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during 2012. During this period, 497 earthquakes and 88 quarry blasts were detected and located in the region under consideration. With a total of only 13 events with ML ≥ 2.5, the seismic activity in the year 2012 was far below the average over the previous 37 years. Most noteworthy were the earthquake sequence of Filisur (GR) in January with two events of ML 3.3 and 3.5, the ML 4.2 and ML 3.5 earthquakes at a depth of 32 km below Zug in February and the ML 3.6 event near Vallorcine in October. The epicentral intensity of the ML 4.2 event close to Zug was IV, with a maximum intensity of V reached in a few areas, probably due to site amplification effects. 相似文献
265.
266.
Rastislav Milovský Alfons van den Kerkhof Jochen Hoefs Vratislav Hurai Walter Prochaska 《International Journal of Earth Sciences》2012,101(2):535-554
Basal hydraulic breccias of alpine thin-skinned Muráň nappe were investigated by means of cathodoluminescence petrography,
stable isotope geochemistry and fluid inclusions analysis. Our study reveals an unusual dynamic fluid regime along basal thrust
plane during final episode of the nappe emplacement over its metamorphic substratum. Basal thrusting fluids enriched in 18O, silica, alumina, alkalies and phosphates were generated in the underlying metamorphosed basement at epizonal conditions
corresponding to the temperatures of 400–450°C. The fluids fluxed the tectonized nappe base, leached evaporite-bearing formations
in hangingwall, whereby becoming oversaturated with sulphates and chlorides. The fluids further modified their composition
by dedolomitization and isotopic exchange with the host carbonatic cataclasites. Newly formed mineral assemblage of quartz,
phlogopite, albite, potassium feldspar, apatite, dravite tourmaline and anhydrite precipitated from these fluids on cooling
down to 180–200°C. Finally, the cataclastic mush was cemented by calcite at ambient anchizonal conditions. Recurrent fluid
injections as described above probably enhanced the final motion of the Muráň nappe. 相似文献
267.
Isotopic reference materials are essential to enable reliable and comparable isotope data. In the case of boron only a very limited number of such materials is available, thus preventing adequate quality control of measurement results and validation of analytical procedures. To address this situation a unique set of two boron isotope reference materials (ERM‐AE102a and ‐AE104a) and three offset δ11B reference materials (ERM‐AE120, ‐AE121 and ‐AE122) were produced and certified. The present article describes the production and certification procedure in detail. The isotopic composition of all the materials was adjusted by mixing boron parent solutions enriched in 10B or 11B with a boron parent solution having a natural isotopic composition under full gravimetric control. All parent solutions were analysed for their boron concentration as well as their boron isotopic composition by thermal ionisation mass spectrometry (TIMS) using isotope dilution as the calibration technique. For all five reference materials the isotopic composition obtained on the basis of the gravimetric data agreed very well with the isotopic composition obtained from different TIMS techniques. Stability and homogeneity studies that were performed showed no significant influence on the isotopic composition or on the related uncertainties. The three reference materials ERM‐AE120, ERM‐AE121 and ERM‐AE122 are the first reference materials with natural δ11B values not equal to 0‰. The certified δ11B values are ?20.2‰ for ERM‐AE120, 19.9‰ for ERM‐AE121 and 39.7‰ for ERM‐AE122, each with an expanded uncertainty (k = 2) of 0.6‰. These materials were produced to cover about three‐quarters of the known natural boron isotope variation. The 10B enriched isotope reference materials ERM‐AE102a and ERM‐AE104a were produced for industrial applications utilising 10B for neutron shielding purposes. The certified 10B isotope abundances are 0.29995 for ERM‐AE102a and 0.31488 for ERM‐AE104a with expanded uncertainties (k = 2) of 0.00027 and 0.00028, respectively. Together with the formerly certified ERM‐AE101 and ERM‐AE103 a unique set of four isotope reference materials and three offset δ11B reference materials for boron isotope determination are now available from European Reference Materials. 相似文献
268.
A multi-method approach to quantify groundwater/surface water-interactions in the semi-arid Hailiutu River basin,northwest China 总被引:1,自引:0,他引:1
Identification and quantification of groundwater and surface-water interactions provide important scientific insights for managing groundwater and surface-water conjunctively. This is especially relevant in semi-arid areas where groundwater is often the main source to feed river discharge and to maintain groundwater dependent ecosystems. Multiple field measurements were taken in the semi-arid Bulang sub-catchment, part of the Hailiutu River basin in northwest China, to identify and quantify groundwater and surface-water interactions. Measurements of groundwater levels and stream stages for a 1-year investigation period indicate continuous groundwater discharge to the river. Temperature measurements of stream water, streambed deposits at different depths, and groundwater confirm the upward flow of groundwater to the stream during all seasons. Results of a tracer-based hydrograph separation exercise reveal that, even during heavy rainfall events, groundwater contributes much more to the increased stream discharge than direct surface runoff. Spatially distributed groundwater seepage along the stream was estimated using mass balance equations with electrical conductivity measurements during a constant salt injection experiment. Calculated groundwater seepage rates showed surprisingly large spatial variations for a relatively homogeneous sandy aquifer. 相似文献