全文获取类型
收费全文 | 255篇 |
免费 | 5篇 |
国内免费 | 13篇 |
专业分类
测绘学 | 7篇 |
大气科学 | 23篇 |
地球物理 | 61篇 |
地质学 | 102篇 |
海洋学 | 22篇 |
天文学 | 40篇 |
综合类 | 4篇 |
自然地理 | 14篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 7篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 13篇 |
2015年 | 12篇 |
2014年 | 21篇 |
2013年 | 16篇 |
2012年 | 7篇 |
2011年 | 14篇 |
2010年 | 20篇 |
2009年 | 16篇 |
2008年 | 13篇 |
2007年 | 16篇 |
2006年 | 11篇 |
2005年 | 8篇 |
2004年 | 12篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1993年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有273条查询结果,搜索用时 0 毫秒
81.
In this paper, we focus on a conservative momentum advection discretisation in the presence of z-layers. While in the 2D case conservation of momentum is achieved automatically for an Eulerian advection scheme, special
attention is required in the multi-layer case. We show here that an artificial vertical structure of the flow can be introduced
solely by the presence of the z-layers, which we refer to as the staircase problem. To avoid this staircase problem, the z-layers have to be remapped in a specific way. The remapping procedure also deals with the case of an uneven number of layers
adjacent to a column side, thus allowing one to simulate flooding and drying phenomena in a 3D model. 相似文献
82.
83.
For the first time, the structure of the meiobenthos community and marine nematodes in particular was investigated in the
different intertidal zones of Jeju Island (South Sea of Korea). A relationship was found between the density of meiobenthic
communities and the type of the bottom sediment. In addition, in the silty sediments, nematodes were dominant, while in the
sandy sediments harpacticoids and ostracods were dominant groups. Sixty eight species belonging to 60 genera and 19 families
of nematodes were found in the whole area. Four different nematode taxocenosis were distinguished using a cluster analysis.
Dominant feeding groups were omnivores (2B) and epistratum-feeders (2A). The highest number of non-selective deposit-feeders
(1B) was detected in the lagoon with the bottom silty sediments. 相似文献
84.
Nikolay Tikhonov Olga Galazutdinova Olga Sholukhova Antoniya Valcheva Petko Nedialkov Olga Merkulova 《天文和天体物理学研究(英文版)》2021,(4):186-192
This paper introduces a technique for searching for bright massive stars in galaxies beyond the Local Group.To search for massive stars,we processed the results of stellar photometry from the Hubble Space Telescope(HST) images using the DAOPHOT and DOLPHOT packages.The results of such searches are demonstrated with examples of the galaxies DDO 68,M94 and NGC 1672.In the galaxy DDO 68,the LBV star changes its brightness,and massive stars in M94 can be identified by excess in the Ha band.For the galaxy NGC 1672,we measure the distance for the first time by the TRGB method,which enabled determining the luminosities of the brightest stars,likely hypergiants,in the young star formation region.So far,we have performed stellar photometry on HST images of 320 northern sky galaxies located at a distance less than 12 Mpc.This allowed us to identify 53 galaxies with probable hypergiants.Further photometric and spectral observations of these galaxies are planned to search for massive stars. 相似文献
85.
Albina I. Kuznetsova Olga V. Zarubina Olga A. Sklyarova 《Geostandards and Geoanalytical Research》2007,31(3):251-259
Reference samples of soils from the Institute of Applied Physics, Irkutsk (RIAP), the Institute of Geochemistry, Irkutsk (IGI) and the United States Geological Survey, Reston (USGS) were analysed with the aim of determining Ag, B, Ge, Mo, Sn, Tl and W abundances by an atomic emission method with air-stabilised D.C. arc excitation. Two series of reference samples of soils and bottom sediments, GSS-1-8 and GSD-1-12 (IGGE), were used to ensure the traceability link for the analytical results. Traceability was also demonstrated through the comparison of measured results by AES and ICP-MS methods. It is shown that the reference samples GSS-1-8 and GSD-1-12 satisfied the "fitness-for-purpose" criterion (uncertainty U of the certified value should be one-third to one-tenth the magnitude of routine laboratory data uncertainty S (S/U > 3-10)) and can be applied for calibrating AES techniques. 相似文献
86.
An attempt to detect the finest white-light coronal features observed with a large optical telescope was made at the July 11, 1991 Solar Total Eclipse. A few selected results taken from the video-CCD high speed observations obtained at the prime focus of the Canada-France-Hawaï-Telescope (CFHT) with a red coronal interference filter are presented. The smallest (sub-arsec) detected and/or resolved coronal features are shown. The methods that were used to extract them from the noisy and seeing-limited images taken from video frames are described. 相似文献
87.
88.
Marina KOLPAKOVA Stepan SHVARTSEV Vitalyi ISUPOV Sodov ARIUNBILEG Alexander VLADIMIROV Olga GASKOVA 《《地质学报》英文版》2014,88(Z1):142-144
正All the lakes are accumulative systems for the various chemical elements.However,the ratios of the elements in different lake types are very different.It is generally accepted that the composition of lake water determined by 相似文献
89.
Ludger Timmen Olga Gitlein Volker Klemann Detlef Wolf 《Pure and Applied Geophysics》2012,169(8):1331-1342
The Nordic countries Norway, Sweden, Finland and Denmark are a key study region for research of glacial isostasy. In addition, such research offers a unique opportunity for absolute gravimetry to show its capability as a geodetic tool for geophysical research. Within a multi-national cooperation, annual absolute gravity measurements have been performed in Fennoscandia by IfE since 2003. For the Hanover gravimeter FG5-220, overall accuracy of ±30?nm/s2 is indicated for a single station determination. First results of linear gravity changes are derived for ten stations in the central and southern part of the uplift area. Comparing with the rates predicted by glacial rebound modelling, the gravity trends of the absolute measurements differ by 3.8?nm/s2 per year (root-mean-square discrepancy) from the uplift model. The mean difference between observed and predicted rates is 0.8?nm/s2 per year only. A proportionality factor of ?1.63?±?0.20?nm/s2 per mm has been obtained, which describes the mean ratio between the observational gravity and height rates. 相似文献
90.
Johanna K. Spiegel Nina Buchmann Olga L. Mayol-Bracero Luis A. Cuadra-Rodriguez Carlos J. Valle Díaz Kimberly A. Prather Stephan Mertes Werner Eugster 《Pure and Applied Geophysics》2014,171(9):2443-2459
We investigated cloud properties of warm clouds in a tropical montane cloud forest at Pico del Este (1,051 m a.s.l.) in the northeastern part of Puerto Rico to address the question of whether cloud properties in the Caribbean could potentially be affected by African dust transported across the Atlantic Ocean. We analyzed data collected during 12 days in July 2011. Cloud droplet size spectra were measured using the FM-100 fog droplet spectrometer that measured droplet size distributions in the range from 2 to 49 µm, primarily during fog events. The droplet size spectra revealed a bimodal structure, with the first peak (D < 6 µm) being more pronounced in terms of droplet number concentrations, whereas the second peak (10 µm < D < 20 µm) was found to be the one relevant for total liquid water content (LWC) of the cloud. We identified three major clusters of characteristic droplet size spectra by means of hierarchical clustering. All clusters differed significantly from each other in droplet number concentration ( \(N_{\rm tot}\) ), effective diameter (ED), and median volume diameter (MVD). For the cluster comprising the largest droplets and the lowest droplet number concentrations, we found evidence of inhomogeneous mixing in the cloud. Contrastingly, the other two clusters revealed microphysical behavior, which could be expected under homogeneous mixing conditions. For those conditions, an increase in cloud condensation nuclei—e.g., from processed African dust transported to the site—is supposed to lead to an increased droplet concentration. In fact, one of these two clusters showed a clear shift of cloud droplet size spectra towards smaller droplet diameters. Since this cluster occurred during periods with strong evidence for the presence of long-range transported African dust, we hypothesize a link between the observed dust episodes and cloud characteristics in the Caribbean at our site, which is similar to the anthropogenic aerosol indirect effect. 相似文献