全文获取类型
收费全文 | 582篇 |
免费 | 29篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 36篇 |
地球物理 | 151篇 |
地质学 | 286篇 |
海洋学 | 46篇 |
天文学 | 59篇 |
综合类 | 3篇 |
自然地理 | 30篇 |
出版年
2022年 | 3篇 |
2021年 | 8篇 |
2020年 | 2篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 16篇 |
2016年 | 21篇 |
2015年 | 14篇 |
2014年 | 17篇 |
2013年 | 32篇 |
2012年 | 30篇 |
2011年 | 25篇 |
2010年 | 30篇 |
2009年 | 40篇 |
2008年 | 22篇 |
2007年 | 33篇 |
2006年 | 30篇 |
2005年 | 38篇 |
2004年 | 37篇 |
2003年 | 31篇 |
2002年 | 29篇 |
2001年 | 14篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有615条查询结果,搜索用时 6 毫秒
501.
Fabrizio Alfano Costanza Bonadonna Alain C. M. Volentik Charles B. Connor Sebastian F. L. Watt David M. Pyle Laura J. Connor 《Bulletin of Volcanology》2011,73(5):613-630
On May 1st 2008 Mount Chaitén (southern Chile) interrupted a long period of quiescence, generating a sequence of explosive
eruptions and causing the evacuation of Chaitén town located a few kilometers south of the volcano. The activity was characterized
by several explosive events each associated with plumes which reached up to about 19 km above sea level. The products were
dispersed across a wide area, with the finest ash reaching the Atlantic coast of Argentina. Our field observations in the
proximal-medial area (3–25 km from the vent) indicate that the May 2008 tephra deposit consists of numerous layers, most of
which can be correlated with individual eruptive events. These layers vary from extremely fine-grained ash to layers of lapilli
and blocks, composed of both juvenile and lithic material. Here we describe the stratigraphy and physical characteristics
of the May 2008 deposits, and propose a reconstruction of the timing of the May 2008 events. The deposits are mainly associated
with the three main explosive phases which occurred on 1st–2nd May, 3rd–5th May and 6th May, with an estimated bulk tephra
volume of 0.5–1.0 km3 (integration of both exponential and power-law fitting). For the 6th May event, represented by a layer composed mainly of
lithic lapilli and blocks (>2 mm), an isopleth map was compiled from which a 19 km plume height was determined, which is in
good agreement with satellite observations. 相似文献
502.
Holocene salt‐marsh sedimentary infilling and relative sea‐level changes in West Brittany (France) using foraminifera‐based transfer functions 下载免费PDF全文
Pierre Stéphan Jérôme Goslin Yvan Pailler Rose Manceau Serge Suanez Brigitte Van Vliet‐Lanoë Alain Hénaff Christophe Delacourt 《Boreas: An International Journal of Quaternary Research》2015,44(1):153-177
In order to reconstruct former sea‐levels and to better characterize the history of Holocene salt‐marsh sedimentary infillings in West Brittany (western France), local foraminifera‐based transfer functions were developed using weighted‐average‐partial‐least‐squares (WAPLS) regression, based on a modern data set of 26 and 51 surface samples obtained from salt‐marshes in the bay of Tresseny and the bay of Brest, respectively. Fifty cores were retrieved from Tresseny, Porzguen, Troaon and Arun salt‐marshes, which were litho‐ and biostratigraphically analysed in order to reconstruct palaeoenvironmental changes. A total of 26 AMS 14C age determinations were performed within the sediment successions. The Holocene evolution of salt‐marsh environments can be subdivided into four stages: (i) a development of brackish to freshwater marshes (from c. 6400 to 4500 cal. a BP); (ii) salt‐marsh formation behind gravel barriers in the bay of Brest (from 4500 to 2900 cal. a BP); (iii) salt‐marsh erosion and rapid changes of infilling dynamics due to the destruction of coastal barriers by storm events (c. 2900?2700 cal. a BP); (iv) renewed salt‐marsh deposition and small environmental changes (from 2700 cal. a BP to present). From the application of transfer functions to fossil assemblages, 14 new sea‐level index points were obtained, indicating a mean relative sea‐level rise of around 0.90±0.12 mm a?1 since 6300 cal. a BP. 相似文献
503.
504.
505.
Julien Thiesson Gabrielle RousselleFrançois Xavier Simon Alain Tabbagh 《Journal of Applied Geophysics》2011,75(4):731-737
Electromagnetic induction (EMI) is one of the geophysical techniques widely used in soil studies, the slingram devices being held horizontally over the soil surface, i.e. with the coils located at the same height above the ground surface. Our study aims assessing the abilities of slingram devices when held vertically. 1D and 3D modelling have been achieved in order to compare the theoretical responses of vertical devices to the horizontal ones. Some comparative surveys were also undertaken in archaeological contexts to confirm the reliability of theoretical conclusions. Both approaches show that vertical slingram devices are suitable for survey and can constitute an alternative to the usual horizontal orientation. We give a table in Appendix A which contains the calibration coefficient allowing transforming of the values given by some of commercially available devices which would be advantageous to use in vertical orientation 相似文献
506.
对巢湖北部地区以碳酸盐岩为主的寒武系—下三叠统海相地层的黏土矿物分析及伊利石结晶度测定的结果表明:伊利石是本区海相地层的主体矿物,平均体积分数为73%。黏土矿物的成岩转化特征表现为蒙皂石的伊利石化。按照伊利石结晶度的成岩-浅变质程度划分,本区寒武系—下三叠统的成岩作用已达到最高成岩阶段。伊利石结晶度的纵向变化总体上可分为上、下两部分:下部寒武系至志留系的结晶度为0.41~0.60°Δ2θ,结晶度与埋深具有一定的相关性,成岩作用是下部地层黏土矿物特征的主控因素;上部泥盆系至下三叠统的结晶度为0.45~0.77°Δ2θ,呈波动变化,蒙皂石连续出现,地层没有被显著埋藏,沉积因素是上部地层黏土矿物特征的主控因素。下三叠统地层中蒙皂石的分布特征以及上泥盆统五通组顶部高岭石的普遍富集具有重要的古气候研究意义。 相似文献
507.
Philippe Drobinski Alain M. Dabas Christian Haeberli Pierre H. Flamant 《Boundary-Layer Meteorology》2001,99(2):277-296
Flow splitting in the Rhine valley has been observed with a transportable wind lidar (TWL) during a shallow-foehn event in the framework of the Mesoscale Alpine Programme (MAP). The Doppler lidar recorded in detail flow splitting, foehn wind gusts, and flow reversal. Such structures have not previously been observed with comparable detail by conventional in-situinstruments. In addition to the TWL, boundary-layer processes have been documented by means of rawinsondes and surface stations. This paper presents an analysis of the processes giving birth to flow splitting between the Seez and Rhine valleys during Intensive Observation Period (IOP) 5 (1–3 October 1999) by combining the collected data with hydraulic theory. The study shows thatthe splitting of the channelled flow is associated with (1) the existence of a stagnation point at the intersection of the Seez and Rhine valleys, and (2) the deflection of the flow by the lateral sidewalls of the valleys. 相似文献
508.
509.
510.
RésuméÀ l’échelle du Maghreb, la Kabylie (Algérie) est considérée comme une région asismique. L’étude détaillée des données de la sismicité historique et instrumentale de cette région montre une activité sismique modérée depuis au moins un siècle et demi (M1 = 5,0). Les observations géomorphologiques faites sur le versant sud du massif kabyle, s’appuyant sur l’analyse d’images satellites, de photos aériennes et de la topographie, nous ont permis de démontrer la présence d’une activité tectonique quaternaire le long de la rupture de pente au sud de ces massifs. Elle correspond à la réactivation de chevauchements d’âge miocène qui se manifestent par des escarpements d’au moins 10 m affectant le glacis d’âge quaternaire ainsi que les cônes de déjection. Ces escarpements sont interprétés comme des ruptures probablement associées à une succession de séismes de forte magnitude. Les observations que nous décrivons se situent dans la région de Tazmalt et de Boüira où ces déformations sont les plus spectaculaires. L’ampleur des déformations quaternaires qui affectent l’ensemble de cette région considérée jusqu’à l’heure actuelle comme asismique ou faiblement sismique pose, comme dans la plupart des régions intracontinentales, le problème de la période de retour des séismes de forte magnitude. © Elsevier, Paris 相似文献