全文获取类型
收费全文 | 374篇 |
免费 | 25篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 10篇 |
大气科学 | 40篇 |
地球物理 | 106篇 |
地质学 | 118篇 |
海洋学 | 44篇 |
天文学 | 59篇 |
自然地理 | 23篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 12篇 |
2020年 | 13篇 |
2019年 | 10篇 |
2018年 | 22篇 |
2017年 | 19篇 |
2016年 | 27篇 |
2015年 | 18篇 |
2014年 | 15篇 |
2013年 | 23篇 |
2012年 | 19篇 |
2011年 | 38篇 |
2010年 | 20篇 |
2009年 | 31篇 |
2008年 | 27篇 |
2007年 | 18篇 |
2006年 | 10篇 |
2005年 | 14篇 |
2004年 | 9篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1995年 | 2篇 |
1991年 | 1篇 |
1986年 | 1篇 |
1979年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有400条查询结果,搜索用时 109 毫秒
131.
Urban and artificial structures are increasingly added to the world’s coasts during a time in which changing climate is forecast to drive shifts in naturally occurring habitats. We ask whether the role of artificial structures as marine habitats will increase in importance relative to their natural counterparts, particularly as natural habitats are negatively affected by ocean warming and acidification. To evaluate this model, we contrasted use of natural (kelp forest and turfing algae) and artificial habitat (plastic pier-piling) by a nest-building amphipod (Cymadusa pemptos) under current and future climate conditions of CO2 and temperature. Under future conditions, amphipod populations in mesocosms increased, but this did not lead to greater proportional colonization of kelp and turf. Instead, colonization doubled in artificial habitats, and there was increasing production and occupation of nests on artificial habitats relative to natural habitats. In an age when human modification of natural substrata is increasingly cited as an agent of wildlife decline, understanding the future role of artificial habitats as replacement dwellings for natural habitats is critical. We pioneer an understanding of the future role of natural and artificial habitats, identifying the possibility that the role of urban structures as marine habitats may only increase. 相似文献
132.
Along‐strike evolution of folding,stretching and breaching of supra‐salt strata in the Plataforma Burgalesa extensional forced fold system (northern Spain)
下载免费PDF全文
![点击此处可从《Basin Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The Plataforma Burgalesa is a partly exposed extensional forced fold system with an intermediate salt layer, which has developed along the southern portion of the Basque‐Cantabrian Basin from Malm to Early Cretaceous as part of the Bay of Biscay‐Pyrenean rift system. Relationships between syn‐ and pre‐rift strata of the supra‐salt cover sequence and distribution of intra‐cover second‐order faults are observed both along seismic sections and at the surface. These relationships indicate an along‐strike variability of the extensional structural style. After a short period of salt mobilization and forced folding, high slip rates in the central portion of the major basement faults have rapidly promoted brittle behaviour of the salt layer, preventing further salt mobilization and facilitating the propagation of the fault across the salt layer. In contrast, at the tip regions of basement faults, slower slip rates have facilitated ductile salt behaviour, ensuring its further evaporite evacuation, preventing fault propagation across the salt layer and, in essence, allowing for a long‐living forced folding process. Our results indicate the important effect of along‐strike variation in displacement and displacement rates in controlling evaporite behaviour in extensional basins. Amount of displacement and displacement rates are key factors controlling the propagation of basement faults across evaporite layers. In addition, growth strata patterns are recognized as a powerful tool for constraining the up‐dip propagation history of basement faults in extensional fault‐related fold systems with intermediate décollement levels. 相似文献
133.
134.
135.
Juan Antonio Pascual Aguilar Vicente Andreu Pablo Vázquez Yolanda Picó 《Environmental Earth Sciences》2014,71(1):31-37
The Mediterranean wetlands are unique in biological diversity and provide multiple benefits, constituting a great water reserve for the planet and producing biomass and nutrients for the trophic chain. However, the increasing human impact and socio-economic development in recent decades have caused important losses in these ecosystems. This work was carried out in the Natural Park of L’Albufera (Valencia, Spain), which includes a coastal lagoon, marshlands, dunes and pinewoods, surrounded by rice fields and orchard in its non-urbanized part. Despite this great ecological value, it suffers impacts derived from the high human and industrial occupation and the hydrological contributions of the connected irrigation systems. The study focused on the development of a combined methodology, based on environmental forensics principles, with the aim of identifying the presence, flow paths and spatial distribution of illicit drugs entering the Natural Park. It is organized around two major procedures: analysis of 16 water samples and application of Geographical Information Systems (GIS) integrating different sources and data formats, as analysis of 14 drugs of abuse by Liquid Chromatography-Mass Spectrometry techniques, and social and environmental data in either GIS layers or tabular digital formats. Results show that, at present, most analyzed drugs have been identified in all sample points. Besides the population distribution pattern, the traditional irrigation system connected to sewage treatment plant (STP) locations is the way by which illicit substances are introduced into the Natural Park waters. 相似文献
136.
Ingo J. Hahn Pablo M. Vergara Julia Baumeister Gerardo E. Soto Uwe Römer 《Natural Hazards》2014,71(1):987-993
Natural catastrophes could damage island biodiversity and ecosystems, and their effects could become devastating if combined with human disturbances. In this study, we determined the effects of the tsunami occurred in Robinson Crusoe Island (Chile) on 27 February 2010 on an endangered soil–plant system. Using data of endemic Cabbage Trees (Dendroseris litoralis Skottsb.) and soil attributes taken before and after the 2010 event, we developed thematic maps to assess the changes in population size and soil substrate of Cabbage Trees caused by the tsunami. We determined that from 153 pre-tsunami (2009) standing Cabbage Trees, only 66 (43 %) survived in 2011, mostly in elevations above 25 m a.s.l. Before the tsunami, 86 (56 %) of Cabbage Trees were established in humus-rich soil sites whereas after the tsunami, this number declined to 53 (35 %). These results represent the first report of a severe population decline after a tsunami and indicate that tsunamis are an important source of species extinction in small oceanic islands not only by reducing the population size but also by reducing the quality of sites for plant growth. 相似文献
137.
Pinheiro Maria Eduarda O. de Oliveira Pablo E. S. Acevedo Otávio C. 《Boundary-Layer Meteorology》2022,183(1):79-96
Boundary-Layer Meteorology - Vertical profiles of temperature, water vapour, and carbon dioxide ( $$\mathrm {CO}_{2}\,$$ ) densities are analyzed, together with the respective turbulent fluxes of... 相似文献
138.
Ana I. Gómez?de?Castro Jesús Maíz Pablo Rodriguez Maite Gómez Juan A. Larruquert José A. Méndez Tomas Belenguer Victor Rodrigo-Gudiel Fátima López-Martínez Paola Sestito 《Astrophysics and Space Science》2011,335(1):283-289
ISSIS is the Imaging and Slitless Spectroscopy Instrument for the World Space Observatory-Ultraviolet (WSO-UV) mission. ISSIS
is a multipurpose instrument designed to carry out high resolution (<0.1 arcsec) imaging in the far UV with fields of view
≥2×2 arcmin2. ISSIS has two acquisition channels: the High Sensitivity Channel (HSC) and the Channel for Surveys (CfS). The HSC is equipped
with an MCP-type detector to guarantee high sensitivity in the 1150–1750 ? range and high rejection of lower energy radiation.
The CfS is equipped with a large CCD detector (4k×4k) to obtain images from the far UV to the red (1150–8500 ?); the CfS is
implemented to allow observing UV bright sources such as reflection nebulae or nearby massive star forming regions. The design
drivers and the current status of the instrument are described in this contribution. 相似文献
139.
Alexander Henderson Edison Liang Pablo Yepes Hui Chen Scott Wilks 《Astrophysics and Space Science》2011,336(1):273-277
Irradiating high-Z targets such as gold with ultra-intense lasers creates electron-positron pairs. In particular, the positron
density in the plasma created by this procedure is higher than that obtained via other laboratory-based methods, with theoretical
maximum densities exceeding 1018 cm−3. All of the significantly contributing processes are well-known and hence we can study this phenomenon using Monte Carlo
simulation. We focus on the latter part of this procedure, the passage of high-energy electrons through the target creating
pairs. In particular, we discuss the usefulness of CERN’s GEANT4 Monte Carlo code in simulating this process. Once this code
is successfully calibrated, we will use it to perform parameter studies, and design future targets to optimize the positron
yield. 相似文献
140.
David Orejana Carlos Villaseca Pablo Valverde-Vaquero Elena A. Belousova Richard A. Armstrong 《International Journal of Earth Sciences》2012,101(7):1789-1815
The Spanish Central System (SCS) batholith, located in the Central Iberian Zone, is one of the largest masses of granite in the European Variscan Belt. This batholith is a composite unit of late- and post-kinematic granitoids dominated by S- and I-type series granite, with subordinate leucogranite and granodiorite. Zircon trace element contents, from two representative S-type and three I-type granitoids from the eastern portion of the SCS batholith, indicate a heterogeneous composition due to magma differentiation and co-crystallisation of other trace element-rich accessory phases. In situ, U–Pb dating of these zircons by SHRIMP and LA-ICP-MS shows 479–462-Ma inherited zircon ages in the I-type intrusions, indicating the involvement of an Ordovician metaigneous protolith, while the S-type intrusions exclusively contain Cadomian and older zircon ages. The zircon crystallisation ages show that these granites have been emplaced at ca. 300?Ma with a time span between 303?±?3?Ma and 298?±?3?Ma. Precise dating by CA-ID-TIMS reveals a pulse at 305.7?±?0.4?Ma and confirms the major pulse at 300.7?±?0.6?Ma. These ages match the Permo-Carboniferous age for granulite-facies metamorphism of the lower crust under the SCS batholith and coincide with a widespread granitic event throughout the Southern Variscides. Ti-in zircon thermometry indicates temperatures between 844 and 784°C for both the S- and I-type granites, reinforcing the hypothesis that these granites are derived from deep crustal sources. 相似文献