全文获取类型
收费全文 | 513篇 |
免费 | 43篇 |
国内免费 | 12篇 |
专业分类
测绘学 | 6篇 |
大气科学 | 37篇 |
地球物理 | 165篇 |
地质学 | 191篇 |
海洋学 | 45篇 |
天文学 | 86篇 |
自然地理 | 38篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 25篇 |
2020年 | 27篇 |
2019年 | 19篇 |
2018年 | 40篇 |
2017年 | 28篇 |
2016年 | 23篇 |
2015年 | 31篇 |
2014年 | 29篇 |
2013年 | 41篇 |
2012年 | 23篇 |
2011年 | 30篇 |
2010年 | 26篇 |
2009年 | 28篇 |
2008年 | 19篇 |
2007年 | 16篇 |
2006年 | 17篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 12篇 |
2001年 | 2篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有568条查询结果,搜索用时 31 毫秒
151.
Copper isotope fractionation in the Meiduk porphyry copper deposit,Northwest of Kerman Cenozoic magmatic arc,Iran
下载免费PDF全文
![点击此处可从《地学学报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The Meiduk deposit possesses three different Cu reservoirs each with a unique Cu isotope signature. δ65Cu for the leached cap minerals ranges from ?2.5 to +0.49‰ to ?0.45 to +0.3‰ for hypogene minerals and from +1.3 to +4.4‰ for supergene enrichment minerals. Oxidation of hypogene sulphides and effective trapping of copper (from solutions derived from the leached cap) in the supergene enrichment zone caused this relationship. A systematic pattern of low Cu isotope values close to the surface and higher isotope values with depth reveals a palaeo‐fluid pathway in the northwest–southeast direction over the deposit. Thus, the copper isotope data from leached cap and enrichment minerals can be used to monitor copper migration during supergene weathering at the Meiduk deposit. 相似文献
152.
Quantifying groundwater–surface water interactions in a proglacial valley,Cordillera Blanca,Peru
下载免费PDF全文
![点击此处可从《水文研究》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Lauren D. Somers Ryan P. Gordon Jeffrey M. McKenzie Laura K. Lautz Oliver Wigmore AnneMarie Glose Robin Glas Caroline Aubry‐Wake Bryan Mark Michel Baraer Thomas Condom 《水文研究》2016,30(17):2915-2929
A myriad of downstream communities and industries rely on streams fed by both groundwater discharge and glacier meltwater draining the Cordillera Blanca, Northern Peruvian Andes, which contains the highest density of glaciers in the tropics. During the dry season, approximately half the discharge in the region's proglacial streams comes from groundwater. However, because of the remote and difficult access to the region, there are few field methods that are effective at the reach scale to identify the spatial distribution of groundwater discharge. An energy balance model, Rhodamine WT dye tracing, and high‐definition kite‐borne imagery were used to determine gross and net groundwater inputs to a 4‐km reach of the Quilcay River in Huascaran National Park, Peru. The HFLUX computer programme ( http://hydrology.syr.edu/hflux.html ) was used to simulate the Quilcay River's energy balance using stream temperature observations, meteorological measurements, and kite‐borne areal photography. Inference from the model indicates 29% of stream discharge at the reach outlet was contributed by groundwater discharge over the study section. Rhodamine WT dye tracing results, coupled with the energy balance, show that approximately 49% of stream water is exchanged (no net gain) with the subsurface as gross gains and losses. The results suggest that gross gains from groundwater are largest in a moraine subreach but because of large gross losses, net gains are larger in the meadow subreaches. These insights into pathways of groundwater–surface water interaction can be applied to improve hydrological modelling in proglacial catchments throughout South America. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
153.
154.
155.
Solar flare gamma-ray emissions from energetic ions and electrons have been detected and measured to GeV energies since 1980. In addition, neutrons produced in solar flares with 100 MeV to GeV energies have been observed at the Earth. These emis-sions are produced by the highest energy ions and electrons accelerated at the Sun and they provide our only direct (albeit secondary) knowledge about the properties of the acceler-ator(s) acting in a solar flare. The solar flares, which have direct evidence for pion-decaygamma-rays, are unique and are the focus of this paper. We review our current knowl-edge of the highest energy solar emissions, and how the characteristics of the acceleration process are deduced from the observations. Results from the RHESSI, INTEGRAL and CORONAS missions will also be covered. The review will also cover the solar flare ca-pabilities of the new mission, FERMI GAMMA RAY SPACE TELESCOPE, launched on 2008 June 11. Finally, we discuss the requirements for future missions to advance this vital area of solar flare physics. 相似文献
156.
Variation of Mo isotopes from molybdenite in high-temperature hydrothermal ore deposits 总被引:1,自引:0,他引:1
Ryan Mathur S. Brantley A. Anbar F. Munizaga V. Maksaev R. Newberry J. Vervoort G. Hart 《Mineralium Deposita》2010,45(1):43-50
Measurable molybdenum isotope fractionation in molybdenites from different ore deposits through time provides insights into
ore genesis and a new technique to identify open-system behavior of Re–Os in molybdenites. Molybdenite samples from six porphyry
copper deposits, one epithermal polymetallic vein deposit, four skarns, and three Fe-oxide Cu–Au deposits were analyzed. The
δ97Mo‰ (where ) for all samples varied from 1.34 ± 0.09‰ to −0.26 ± 0.04‰. This is the largest molybdenum isotopic variation in molybdenite
from high-temperature ore deposits recorded to date. δ97Mo‰ of molybdenite varies as a function of the deposit type and the rhenium and osmium concentrations of the samples. Isotope
values for Mo also vary within the individual deposits. In general, molybdenites from porphyry copper deposits have the lightest
values averaging 0.07 ± 0.23‰ (1σ). Molybdenites from the other deposit types average 0.49 ± 0.26‰ (1σ). The variations could be related to the fractionation of Mo into different mineral phases during the ore-forming processes.
A comparison of the Mo isotope ratios and the Re–Os ages obtained from the same aliquot may possess a geochronological evaluation
tool. Samples that yielded robust ages have different Mo isotopic compositions in comparison to samples that yielded geologically
unreasonable ages. Another observed relationship between the Re–Os and Mo isotope data reveals a weak correspondence between
Re concentration and Mo isotope composition. Molybdenites with higher concentrations of Re correspond to lighter Mo isotope
values. 相似文献
157.
Kieran M. Ryan D. Michael Williams Drew S. Coleman Staci Loewy 《Geological Journal》2010,45(4):467-480
The western Ireland Ordovician stratigraphy has been previously used to constrain the timing of docking of an island arc and its fore‐arc basin with the margin of Laurentia for the British and Irish Caledonides. New field relationships and age data indicate that one of the key formations, the Rosroe Formation (459.2 ± 0.8 and 465.1 ± 2.1 Ma), and its supposed lateral equivalent, the Maumtrasna Formation are younger than previously interpreted. New age data for a tuff band in the Maumtrasna Formation (468.9 ± 1.3 Ma) also support previous studies showing it can be correlated to the adjacent Mweelrea Formation. The new field evidence, age data and geochemistry contradict some previous studies and show that the Maumtrasna, Rosroe and Derrylea formations can no longer be considered lateral equivalents. Based on the new stratigraphy a revised tectonic model is required with sedimentation in this part of the Caledonides taking place in a fore‐arc basin outboard of a continental arc and the oceanic arc was an along‐strike equivalent of this arc situated in an embayment of the Laurentian margin. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
158.
Ryan A. Boller Scott A. Braun Jadrian Miles David H. Laidlaw 《Earth Science Informatics》2010,3(1-2):119-126
We present an application of uncertainty visualization to air parcel trajectories generated from a global meteorological model. We derive an approximation of advection uncertainty due to interpolation and incorporate this uncertainty into our visualization of trajectories. Our work enables efficient visual pruning of unlikely results, especially in regions of atmospheric shear, potentially reducing erroneous interpretations. Finally, we apply these methods to a real-world meteorological problem to demonstrate its use. 相似文献
159.
John P. Ryan Andrew M. Fischer Raphael M. Kudela James F.R. Gower Stephanie A. King Roman Marin Francisco P. Chavez 《Continental Shelf Research》2009,29(5-6):785-795
It has recently been shown that inner shelf waters of NE Monterey Bay, California function as an “extreme bloom incubator”, frequently developing dense “red tide” blooms that can rapidly spread. Located within the California Current upwelling system, this open bay is strongly influenced by oceanographic dynamics resulting from cycles of upwelling favorable winds and their relaxation and/or reversal. Different wind forcing causes influx of different water types that originate outside the bay: cold nutrient-rich waters during upwelling and warm nutrient-poor waters during relaxation. In this study, we examine how the bay's bloom incubation area can interact with highly variable circulation to cause red tide spreading, dispersal and retention. This examination of processes is supported by satellite, airborne and in situ observations of a major dinoflagellate bloom during August and September of 2004. Remote sensing of high spatial, temporal and spectral resolution shows that the bloom originated in the NE bay, where it was highly concentrated in a narrow band along a thermal front. Upwelling circulation rapidly spread part of the bloom, mixing cool waters of an upwelling filament with warm bloom source waters as they spread. Vertical migration of the dinoflagellate populations was mapped by autonomous underwater vehicle surveys through the spreading bloom. Following bloom expansion, a two-day wind reversal forced intrusion of warm offshore waters that dispersed much of the bloom. Upwelling winds then resumed, and the bloom was further dispersed by an influx of cold water. Throughout these oceanographic responses to changing winds, an intense bloom persisted in sheltered waters of the NE bay, where extreme blooms are most frequent and intense. Microscopic examination of surface phytoplankton samples from the central bay showed that spreading of the bloom from the NE bay and mixing with regional water masses resulted in significantly increased abundance of dinoflagellates and decreased abundance of diatoms. Similar dinoflagellate bloom incubation sites are indicated in other areas of the California Current system and other coastal upwelling systems. Through frequent bloom development and along-coast transports, relatively small incubation sites may significantly influence larger regions of the coastal marine ecosystems in which they reside. 相似文献
160.
Trace elements in garnets and chromites: Diamond formation in the Siberian lithosphere 总被引:1,自引:0,他引:1
W.L. Griffin N.V. Sobolev C.G. Ryan N.P. Pokhilenko T.T. Win E.S. Yefimova 《Lithos》1993,29(3-4):235-256
Proton-microprobe analyses of trace elements in garnet and chromite inclusions in diamonds (DI) from the Mir, Udachnaya, Aikhal and Sytykanskaya kimberlites in Yakutia, CIS, provide new insights into the processes that form diamond. Equivalent data on garnet and chromite concentrates from these pipes yield information on the thermal state and chemical stratification of the Siberian lithosphere. Peridotite-suite diamonds from Yakutia have formed over a temperature interval of ca. 600°C, as measured by Ni and Zn thermometry on garnet and chromite inclusions in diamonds. Individual diamonds contain inclusions recording temperature intervals of >400°C; ranges of >100°C are common. Diamond formation followed a severe depletion event(s), and a separate enrichment in Sr. Comparison of temperatures on DI garnet and spinel with temperatures derived from diamondiferous harzburgites, exposed inclusions in boart and concentrate minerals suggests that the diamond-containing part of the lithosphere has cooled significantly since the Siberian diamonds crystallized. The peridotite-suite diamonds probably formed mainly in response to one or more relatively short-lived thermal events, related to magmatic intrusion. The northern part of the Daldyn-Alakit district may have had a typical cratonic geotherm at the time of diamond formation, and during kimberlite intrusion. The southern part of the district, and the Malo-Botuobiya kimberlite field, probably had a relatively low geotherm (ca. 35 mW/m2). The vertical distribution of garnet and chromite types indicates that the mantle above 120 km depth is dominated by lherzolites, whereas the deeper parts of the lithosphere are a mixture of lherzolites and more depleted harzburgites and dunites. 相似文献