全文获取类型
收费全文 | 2558篇 |
免费 | 179篇 |
国内免费 | 26篇 |
专业分类
测绘学 | 81篇 |
大气科学 | 231篇 |
地球物理 | 803篇 |
地质学 | 962篇 |
海洋学 | 207篇 |
天文学 | 310篇 |
综合类 | 24篇 |
自然地理 | 145篇 |
出版年
2024年 | 6篇 |
2023年 | 7篇 |
2022年 | 26篇 |
2021年 | 67篇 |
2020年 | 60篇 |
2019年 | 58篇 |
2018年 | 103篇 |
2017年 | 114篇 |
2016年 | 160篇 |
2015年 | 123篇 |
2014年 | 151篇 |
2013年 | 226篇 |
2012年 | 170篇 |
2011年 | 166篇 |
2010年 | 145篇 |
2009年 | 136篇 |
2008年 | 126篇 |
2007年 | 82篇 |
2006年 | 95篇 |
2005年 | 76篇 |
2004年 | 62篇 |
2003年 | 54篇 |
2002年 | 68篇 |
2001年 | 39篇 |
2000年 | 22篇 |
1999年 | 28篇 |
1998年 | 35篇 |
1997年 | 27篇 |
1996年 | 16篇 |
1995年 | 22篇 |
1994年 | 19篇 |
1993年 | 18篇 |
1992年 | 7篇 |
1991年 | 23篇 |
1990年 | 15篇 |
1989年 | 12篇 |
1987年 | 16篇 |
1986年 | 7篇 |
1985年 | 15篇 |
1984年 | 20篇 |
1983年 | 14篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 14篇 |
1976年 | 6篇 |
1975年 | 9篇 |
1974年 | 9篇 |
1973年 | 11篇 |
1969年 | 7篇 |
排序方式: 共有2763条查询结果,搜索用时 31 毫秒
991.
Joaquín Ferreras Cadierno Manuel Ignacio Guerra Romero Andrés Juan Valdés Julia Mª Morán del Pozo Julia García González Desirée Rodríguez Robles José Vallepuga Espinosa 《Geotechnical and Geological Engineering》2014,32(2):439-452
One of the bases of sustainable development is the responsible management of natural resources, and this is the approach which has been adopted by developed countries as regards management of all kinds of waste, through the establishment of management strategies based on prevention, reuse and recycling. This article present the results of a physical, chemical and geotechnical characterization of colliery spoils stored in slag heaps in the Ciñera-Matallana coal mining area in León, Spain. The primary objectives of this research were to determine the suitability of this mining waste for use as granular material in rural and civil engineering infrastructures and to classify it according to national and international road construction standards. On the basis of the results obtained, they are proposed several possible uses (foundation and core layers in track and road embankments, granular sub-base for light traffic and top layers of embankments), although it should be noted the need for mechanical treatments as crushing or sieving and the recommendation of use of sulphate resistant cement to avoid the possible problems. 相似文献
992.
Vaduvescu O. Aznar Macias A. Wilson T. G. Zegmott T. Pérez Toledo F. M. Predatu M. Gherase R. Pinter V. Pozo Nunez F. Ulaczyk K. Soszyński I. Mróz P. Wrona M. Iwanek P. Szymanski M. Udalski A. Char F. Salas Olave H. Aravena-Rojas G. Vergara A. C. Saez C. Unda-Sanzana E. Alcalde B. de Burgos A. Nespral D. Galera-Rosillo R. Amos N. J. Hibbert J. López-Comazzi A. Oey J. Serra-Ricart M. Licandro J. Popescu M. 《Earth, Moon, and Planets》2022,126(2):1-26
Earth, Moon, and Planets - The Perseverance rover (Mars 2020) mission, the first step in NASA’s Mars Sample Return (MSR) program, will select samples for caching based on their potential to... 相似文献
993.
Amaral Genilda Canuto Pezzopane José Eduardo Macedo de Souza Nóia Júnior Rogério Martínez Manuel Fernández Fonseca Mariana Duarte Silva Gibson Elbya Leão Toledo João Vitor Pezzopane José Ricardo Macedo Klippel Valéria Hollunder Xavier Talita Miranda Teixeira 《Theoretical and Applied Climatology》2022,147(1-2):347-361
Theoretical and Applied Climatology - The climate change endangers many species of the Amazon Forest. An example, in the endangered medicinal species Pilocarpus microphyllus (popularly known as... 相似文献
994.
de Souza Luciana Sandra Bastos Silva Maiara Tatiane Lima Alba Elisiane de Moura Magna Soelma Beserra da Cruz Neto José Francisco de Souza Carlos André Alves da Silva Thieres George Freire 《Theoretical and Applied Climatology》2022,149(1-2):593-602
Theoretical and Applied Climatology - Analysing alternative methods for estimating reference evapotranspiration (ET0) is essential for improving the management of water resources, especially where... 相似文献
995.
José Francirlei Oliveira Michel Brossard Pedro Rodolfo Siqueira Vendrame Stanislas Mayi III Edemar Joaquim Corazza Robélio Leandro Marchão Maria de Fátima Guimarães 《Comptes Rendus Geoscience》2013,345(11-12):446-453
Vis–NIR spectroscopy is nowadays presented as a possible routine method for soil sample analysis. However, there is still no consensus on which is the best multivariate statistical method to use. We propose to use principal component analysis to complete the spectral data treatment. The soil samples came from a pedological cover made up of red–yellow Latosols: 88 samples of 11 soil profiles on four toposequences were collected; clay, organic matter, silica, iron, aluminum and titanium total contents were determined; the contents of goethite, hematite, gibbsite, and kaolinite were calculated. Diffuse reflectance Vis–NIR spectroscopy at wavelengths from 400 to 2400 nm combined with principal component analysis (PCA) was sufficiently sensitive to discriminate different Latosols. Wavelengths of 700 nm and 2200 to 2300 nm were influenced by content ratios of organic matter and iron oxides (700 nm), and kaolinite and gibbsite absorption (2200 and 2300 nm). The spectral responses were affected not only by the content of these constituents, but also by the composition of the minerals, so that the same class of Latosol may have different or similar spectral responses. The role of microaggregation is discussed. 相似文献
996.
This study describes a general liquefaction flow instability criterion for elastoplastic soils based on the concept of loss of uniqueness. We apply the criterion to the general case of axisymmetric loading and invoke the concepts of effective stresses and loss of controllability to arrive at a general criterion for the onset of liquefaction flow. The criterion is used in conjunction with an elastoplastic model for sands to generate numerical simulations. The numerical results are compared with experimental evidence to give the following insights into predicting liquefaction. (1) The onset of liquefaction flow is a state of instability occurring under both monotonic and cyclic tests, and coincides with loss of controllability. (2) The criterion proposed herein clearly and naturally differentiates between liquefaction flow (instability) and cyclic mobility. (3) Flow liquefaction not only depends on the potential of the material to generate positive excess pore pressures, but more importantly, it also depends on the current state of the material, which is rarely predicted by phenomenology. 相似文献
997.
Luis?PandoEmail author Javier?A.?Pulgar Manuel?Gutiérrez-Claverol 《Environmental Earth Sciences》2013,69(2):507-521
Within the TERENO initiative, four terrestrial observatories, collecting huge amounts of environmental data, are being set up since 2008. To manage, describe, exchange and publish these data, the distributed Spatial Data Infrastructure TEODOOR (http://www.tereno.net) was created. Each institution responsible for an individual observatory sets up its own local data infrastructure, which may communicate with each other to exchange data and metadata internally or to the public by OGC compliant Web services. The TEODOOR data portal serves as a database node to provide scientists and decision makers with reliable and well-accessible data and data products. Various tools like hierarchical search or Web-GIS functions allow a deeper insight into the different observatories, test sites and sensor networks. Sensor data can be queried and selected for measured parameters, stations and/or time periods, and can be visualized and downloaded according to a shared TERENO data policy. Currently, TEODOOR provides free access to data from more than 500 monitoring stations. 相似文献
998.
Mateus Barragana Luis Otavio Alvares 《International journal of geographical information science》2017,31(2):364-386
Unusual behavior detection has been of interest in video analysis, transportation systems, movement trajectories, and so on. In movement trajectories, only a few works identify unusual behavior of objects around pre-defined points of interest (POI), such as surveillance cameras, commercial buildings, etc., that may be interesting for several application domains, mainly for security. In this article, we define new types of unusual behaviors of moving objects in relation to POI, including surround, escape, and return. Based on these types of unusual behavior, we (i) present an algorithm to compute these behaviors, (ii) define a set of functions to weight the degree of unusual behavior of every moving object in the database, and (iii) rank the moving objects according to the degree of unusual behavior in relation to a set of POIs. We evaluate the proposed method with real trajectory data and show that the closest work does not detect the proposed behaviors and ranks objects considering only one type of unusual movement. 相似文献
999.
Massimiliano Tardio Francesca Sangiorgi Henk Brinkhuis Maria Letizia Filippi Marco Cantonati André F. Lotter 《Journal of Paleolimnology》2006,36(3):315-318
This paper documents the discovery of peridinioid organic walled dinoflagellate cysts in Holocene sediments of the freshwater, low-alkalinity, high mountain Lake Nero di Cornisello (Adamello mountain range, Trentino, Italy). Among the three main cyst morphotypes found in the samples, the dominant one is acavate, with a smooth and light brown colored wall, with a clear conical shape, elongated with a pointy to rounded end in the antapical-ventral part, with the epicyst broader than the hypocyst and displays a typical peridinioid archeopyle. Comparison with data available in literature, besides pointing out the general scarcity of observations on dinocysts in lakes sediments, suggested a strong morphological similarity with the marine genus Brigantedinium. This finding pinpoints the need for more detailed studies on cysts in freshwater environments offering a new tool for paleoenvironmental interpretations. 相似文献
1000.