全文获取类型
收费全文 | 136篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 20篇 |
地球物理 | 43篇 |
地质学 | 41篇 |
海洋学 | 11篇 |
天文学 | 26篇 |
自然地理 | 4篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 8篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 12篇 |
2015年 | 7篇 |
2014年 | 14篇 |
2013年 | 11篇 |
2012年 | 11篇 |
2011年 | 10篇 |
2010年 | 11篇 |
2009年 | 8篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 5篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1997年 | 1篇 |
排序方式: 共有147条查询结果,搜索用时 15 毫秒
1.
Katharina Marger Matthieu Harlaux Andrea Rielli Lukas P. Baumgartner Andrea Dini Barbara L. Dutrow Anne‐Sophie Bouvier 《Geostandards and Geoanalytical Research》2020,44(3):593-615
Six tourmaline samples were investigated as potential reference materials (RMs) for boron isotope measurement by secondary ion mass spectrometry (SIMS). The tourmaline samples are chemically homogeneous and cover a compositional range of tourmaline supergroup minerals (primarily Fe, Mg and Li end‐members). Additionally, they have homogeneous boron delta values with intermediate precision values during SIMS analyses of less than 0.6‰ (2s). These samples were compared with four established tourmaline RMs, that is, schorl IAEA‐B‐4 and three Harvard tourmalines (schorl HS#112566, dravite HS#108796 and elbaite HS#98144). They were re‐evaluated for their major element and boron delta values using the same measurement procedure as the new tourmaline samples investigated. A discrepancy of about 1.5‰ in δ11B was found between the previously published reference values for established RMs and the values determined in this study. Significant instrumental mass fractionation (IMF) of up to 8‰ in δ11B was observed for schorl–dravite–elbaite solid solutions during SIMS analysis. Using the new reference values determined in this study, the IMF of the ten tourmaline samples can be modelled by a linear combination of the chemical parameters FeO + MnO, SiO2 and F. The new tourmaline RMs, together with the four established RMs, extend the boron isotope analysis of tourmaline towards the Mg‐ and Al‐rich compositional range. Consequently, the in situ boron isotope ratio of many natural tourmalines can now be determined with an uncertainty of less than 0.8‰ (2s). 相似文献
2.
What controls submarine channel development and the morphology of deltas entering deep-water fjords?
Jenny A. Gales Peter J. Talling Matthieu J.B. Cartigny John Hughes Clarke Gwyn Lintern Cooper Stacey Michael A. Clare 《地球表面变化过程与地形》2019,44(2):535-551
River deltas and associated turbidity current systems produce some of the largest and most rapid sediment accumulations on our planet. These systems bury globally significant volumes of organic carbon and determine the runout distance of potentially hazardous sediment flows and the shape of their deposits. Here we seek to understand the main factors that determine the morphology of turbidity current systems linked to deltas in fjords, and why some locations have well developed submarine channels while others do not. Deltas and associated turbidity current systems are analysed initially in five fjord systems from British Columbia in Canada, and then more widely. This provides the basis for a general classification of delta and turbidity current system types, where rivers enter relatively deep (>200 m) water. Fjord-delta area is found to be strongly bimodal. Avalanching of coarse-grained bedload delivered by steep mountainous rivers produces small Gilbert-type fan deltas, whose steep gradient (11°–25°) approaches the sediment's angle of repose. Bigger fjord-head deltas are associated with much larger and finer-grained rivers. These deltas have much lower gradients (1.5°–10°) that decrease offshore in a near exponential fashion. The lengths of turbidity current channels are highly variable, even in settings fed by rivers with similar discharges. This may be due to resetting of channel systems by delta-top channel avulsions or major offshore landslides, as well as the amount and rate of sediment supplied to the delta front by rivers. © 2018 John Wiley & Sons, Ltd. 相似文献
3.
4.
Although meteorites are now considered as scientific objects, they still bear a strong and powerful symbolic meaning due to their extraterrestrial provenance. The present article focuses on their legal status, in other words the collection of rules, very diverse in nature, which are applicable to them. Despite a growing international market, the question of meteorites is often ignored or regarded as a detail in international relations and is rarely taken explicitly into account in negotiations and treaties. This relative neglect explains why a non‐State player, the Meteoritical Society, has taken methodological initiatives into meteoritic science and has effectively become a regulator of meteorite naming and acceptance, with a global scope. We show that to understand the legal status of meteorites, it is necessary to consider them under the prism of public international law, transnational law, and national law. We conclude that, despite the universality of meteorites as extraterrestrial objects, the variability of legal rules applicable to meteorites depending onto which territory they fall or where they are found. We note, however, that there is a trend toward regulatory uniformity in the scientific analysis of meteorites, which frames the practices of researchers and regulates traders’ activities. Finally, we contend that a meteorite remains a badly defined legal object, because it can be viewed under many angles: as an object susceptible to private appropriation, as a “common thing” (res communis), or as an element of national heritage. 相似文献
5.
Philipp R. Heck Christopher Herd Jeffrey N. Grossman Dmitry Badjukov Audrey Bouvier Emma Bullock Hasnaa Chennaoui‐Aoudjehane Vinciane Debaille Tasha L. Dunn Denton S. Ebel Ludovic Ferrire Laurence Garvie Jrme Gattacceca Matthieu Gounelle Richard Herd Trevor Ireland Emmanuel Jacquet Robert J. Macke Tim McCoy Francis M. McCubbin Takashi Mikouchi Knut Metzler Mathieu Roskosz Caroline Smith Meenakshi Wadhwa Linda Welzenbach‐Fries Toru Yada Akira Yamaguchi Ryan A. Zeigler Michael Zolensky 《Meteoritics & planetary science》2019,54(7):1397-1400
6.
7.
A new elastoplastic model called loading memory surface based on the critical state concept and the multi‐surface framework is proposed for geomaterials. The model uses a hypoelastic formulation and two plastic mechanisms. The formulations of the model are made in three‐dimensional stress–strain space and work under both monotonic and cyclic loadings. A newly introduced formalism makes it possible to obtain the cyclic response directly from the monotonic loading one. This formalism gives a three‐dimensional generalization of the well‐known Masing rule. The model has been validated against test results of Hostun sand under several conditions: monotonic and cyclic, drained and undrained, tests in compression and in extension, and at different confining pressures and different densities. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
8.
Jennifer Vandenhecke Matthieu Waeles Jean-Yves Cabon Cédric Garnier Ricardo D. Riso 《Estuarine, Coastal and Shelf Science》2010
Over this one-year study, the variations of inorganic As species were examined monthly along the salinity gradient of the Penzé estuary (NW France) in relation with different biogeochemical parameters. In most cases, dissolved As exhibited a non-conservative behaviour which resulted from the competition between two major processes. In the upstream section of the estuary, a strong input of both total inorganic As and As(III) occurred. Then, the removal of the same species, under precipitation of iron oxides/oxyhydroxides, was observed in the low-salinity range (S < 10). Using our experimental data, the fluxes of the various As species were estimated for the first time in estuarine waters. Inputs from the river were mainly constituted of particulate As (∼70%). Conversely, dissolved species were predominant in the net fluxes (∼65%) and As(III) accounted for ∼15% of the dissolved net flux. 相似文献
9.
10.
Mathieu Causse Aurore Laurendeau Matthieu Perrault John Douglas Luis Fabian Bonilla Philippe Guéguen 《Bulletin of Earthquake Engineering》2014,12(2):755-768
Nonlinear dynamic analysis of existing or planned structures often requires the use of accelerograms that match a target design spectrum. Here, our main concern is to generate a set of motions with a good level of fit to the Eurocode 8 design spectra for France. Synthetic time series are generated by means of a non-stationary stochastic method. To calibrate the input parameters in the stochastic approach, we select a reference set of accelerograms for a Eurocode 8 type B site category from the PEER Ground-Motion Database, which are then adjusted to the target spectrum through wavelet addition. Then, we compute nonlinear seismic responses of a soil column, including pore pressure effects, and brittle and ductile structures to the stochastic time-series, the natural accelerograms and time-series generated using stationary stochastic approaches. The results of these calculations reveal considerable variability in response despite the similarities in terms of spectral acceleration. 相似文献