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421.
The sulphide-bearing rocks of the Upper Cretaceous Germav Formation in southeastern Turkey (Bozova–Urfa) and the morphologically varied sulphide occurrences they contain have been investigated. Pyrite and marcasite are the main sulphide minerals; lesser bravoite and millerite also occur. Pyritised branches and leaves, trace fossils, and animal microfossils and macrofossils are abundant. Most of the concretionary and authigenic concretionary pyrite occurrences are probably related to burrows. The concretionary pyrites have low Co and high Ni contents and low Co:Ni ratios. The pyrite-rich lithostratigraphic sequences were deposited in a deep-sea environment, and pyrite mineralization developed in syn-sedimentary, early diagenetic and epigenetic stages under anoxic conditions. To cite this article: C. Bölücek, B. Ilhan, C. R. Geoscience 338 (2006). 相似文献
422.
M. Vespa R. Dhn D. Grolimund M. Harfouche E. Wieland A.M. Scheidegger 《Journal of Geochemical Exploration》2006,88(1-3):77
Cement-based materials play an important role in multi-barrier concepts developed worldwide for the safe disposal of industrial and radioactive waste in underground repositories. In this study, synchrotron based-techniques (micro X-ray spectroscopy (XAS) and micro X-ray fluorescence (XRF)) were used to investigate Co and Ni uptake by Hardened Cement Paste (HCP) with the aim of improving our understanding of the immobilization process of heavy metals in cement at the molecular level. For Ni and Co, XRF mapping revealed a highly heterogeneous element distribution as far as the concentration is concerned. The XAS studies further showed that Ni(II) forms predominantly layered double hydroxide (LDH) phases. In contrast to Ni, Co was found to be present in the oxidation states II and III. Co(II) is predominately incorporated into newly formed Co(II) hydroxide-like phases (Co(OH)2), Co-LDH or Co-phyllosilicates, whereas Co(III) tends to be incorporated into a Co(III)O(OH)-like phase or a Co-phyllomanganate. 相似文献
423.
新疆东天山白石泉铜镍矿床基性-超基性岩体锆石U-Pb同位素年龄、地球化学特征及其对古亚洲洋闭合时限的制约 总被引:26,自引:24,他引:26
白石泉铜镍硫化物矿床位于中天山北缘,阿齐库都克-沙泉子断裂带南侧,产于同源侵入基性-超基性复式岩体中。采用锆石激光剥蚀法(LA-ICP-MS)获得矿化辉长岩中锆石U-Pb年龄为281.2±0.9Ma。辉长岩和橄榄岩的地球化学数据表明白石泉含矿杂岩体具高Mg特征。岩石富集大离子亲石元素(Rb、Ba、K、Sr)、LREE和高场强元素(U、Pb),而具有Ce负异常和亏损高场强元素(Th、Nb、Ta、Zr、Hf)的特征。这些表明白石泉含矿杂岩体具有幔源特征和岛弧岩浆特征。结合对白石泉岩体地质特征和区域地质背景的综合分析,本文推断白石泉岩体形成于岛弧环境或活动陆缘环境,即早二叠世期间在东天山地区还存在俯冲作用,因而古亚洲洋至少应在早二叠世晚期或以后才闭合。 相似文献
424.
María Eugenia Pérez González María del Pilar García Rodríguez Vanesa González-Quiñones Raimundo Jiménez Ballesta 《Environmental Geology》2006,51(1):143-149
The spatial variability of the quality of the soil on the shores of a lagoon affected by hydromorphy and/or salinity can be identified (Laguna de Villacañas, Castilla La Mancha) by the use of multitemporal Landsat images in order to analyse these changes. For this purpose, TM and ETM images along with field observations and certain edaphic laboratory parameters are used. In order to identify saline-hydromorphic soils, the spatial variability of chemical and physical properties of a transect, which includes from Solonchaks to Regosols and Cambisols, have been correlated with the Normalised Difference Vegetation Index (NDVI). This index, chosen for specific dates, has proven to be very useful in detecting halophytic vegetation and relating it to the variability of the quality of these soils. 相似文献
425.
1 INTRODUCTION The ocean is a very important source of heat and water vapor for the atmosphere. Its changes in state are mainly reflected by SST, which varies in high frequency (or called the ENSO variability) and low frequency (or known as interdecadal variability). Studies[1] have shown that the spatial structure for low frequency is much similar to that for high frequency, which is also known as ENSO-like mode. Called “teleconnection”, the anomalous link between the El Ni?o phen… 相似文献
426.
Takeshi Izumo 《Ocean Dynamics》2005,55(2):110-123
The equatorial undercurrent (EUC), the shallow meridional overturning cells feeding it, and their role in El Niño and decadal variability in the equatorial Pacific are studied using both in situ data and an ocean general circulation model. Using temperature and current data from the TAO/TRITON moorings at the equator, their data gaps are filled and it was shown that continuous time series of mass transport, temperature, depth, and kinetic energy of the EUC could be constructed for the period 1980–2002 with an excellent accuracy. This dataset was analysed and used to validate the output from an oceanic general circulation model (OGCM). The OGCM was then used to find that variations in the strength of the EUC, shallow meridional overturning (pycnocline convergence and surface divergence), and equatorial upwelling had the same variations in mass transport on interannual and longer time scales within the period 1951–1999. These variations are all caused by variations of the zonal wind stress zonally integrated, in agreement with simple linear and steady dynamics theories. Impact of these mass transport variations and of temperature variations on heat budgets in the entire equatorial band of the Pacific and in its eastern part are quantified. 相似文献
427.
V. A. Valencia J. Ruiz F. Barra G. Geherls M. Ducea S. R. Titley L. Ochoa-Landin 《Mineralium Deposita》2005,40(2):175-191
Uranium–lead zircon (laser ablation multi-collector ICP-MS spot analysis) ages from La Caridad porphyry copper deposit in
the Nacozari District, Northeastern Sonora, Mexico, suggest a short period of magmatism, between 55.5 and 52.6 Ma. Two U–Pb
ages from the mineralized quartz monzonite unit, showing different textural characteristics, yielded indistinguishable crystallization
ages (~54 Ma), and indicate that the intrusion responsible for the mineralization occurred as a single large complex unit,
instead of multiple pulses of magmatism. Some zircons analyzed also show inherited ages in cores recording dates of 112–124 Ma,
141–166 Ma and 1.4 Ga. The Re–Os molybdenite ages from the potassic and phyllic hydrothermal alteration veins yielded identical
ages within error, 53.6±0.3 Ma and 53.8±0.3 Ma, respectively (weighted average of 53.7±0.21 Ma), supporting a restricted period
for the mineralization. The geochronological data thus indicate a short-lived magmatic and hydrothermal system. The inherited
zircons of Precambrian and Late Jurassic-Mid Cretaceous age found in the intrusive rocks of La Caridad deposit, can be explained
considering two possible scenarios within the tectonic/magmatic evolution of the area. The first scenario considers the presence
of a Precambrian anorogenic granitic basement that is intruded by Mesozoic (Jurassic–Cretaceous) units present beneath the
La Caridad deposit. The second scenario suggests that the Mesozoic Glance Conglomerate Formation of Arizona underlies the
Paleocene volcanic-igneous pile in the La Caridad area. 相似文献
428.
429.
利用Nio 3指数,把ENSO循环不同位相的夏季划分为四类并进行聚类分析,发现E1 Nio发展期和La Nia衰减期可以聚为一类;E1 Nio衰减期和La Nia发展期可以聚为一类。而后经过比较分析,考虑ENSO循环对江、淮地区降水的不同影响,定义了新的东亚副热带夏季风强度指数。并利用该指数研究了夏季风异常和ENSO循环与江、淮地区夏季降水年际变化的关系和成因。结果发现,ENSO年,淮河和长江中下游地区夏季降水的年际变化是ENSO和夏季风共同作用的结果。ENSO的不同位相对雨带的南北位置有重要影响,夏季风异常主要对雨量的偏多偏少起重要作用。而与ENSO无关的年份,易出现强夏季风,这种年份长江和淮河地区经常是一致的干旱。 相似文献
430.