全文获取类型
收费全文 | 294篇 |
免费 | 7篇 |
国内免费 | 11篇 |
专业分类
测绘学 | 12篇 |
大气科学 | 6篇 |
地球物理 | 60篇 |
地质学 | 81篇 |
海洋学 | 53篇 |
天文学 | 75篇 |
综合类 | 5篇 |
自然地理 | 20篇 |
出版年
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 10篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 8篇 |
2013年 | 14篇 |
2012年 | 8篇 |
2011年 | 9篇 |
2010年 | 11篇 |
2009年 | 17篇 |
2008年 | 19篇 |
2007年 | 15篇 |
2006年 | 17篇 |
2005年 | 19篇 |
2004年 | 12篇 |
2003年 | 16篇 |
2002年 | 12篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1974年 | 1篇 |
1973年 | 4篇 |
1970年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有312条查询结果,搜索用时 15 毫秒
11.
南海东沙海域的陆坡台地区, 浅表断裂及生物礁发育众多, 浅层新生界多为碳酸盐岩层, 中深层的中生界内部构造复杂, 断裂较多, 常规单船窄方位地震剖面显示中深层反射品质较差。利用双船可以设计灵活的观测系统, 形成双方位角地震探测方式, 对于地下同一反射点的照明, 可以获得比窄方位角探测更好的效果, 也可以改善高速屏蔽层下方、高陡倾角斜层等区域的成像质量。文章通过重点技术的攻关研发, 进行了单源激发、双缆接收的双方位角采集试验, 成功实现该方法在南海海域中深层地震勘探中的应用。 相似文献
12.
D. Minniti P.W. Lucas J.P. Emerson R.K. Saito M. Hempel P. Pietrukowicz A.V. Ahumada M.V. Alonso J. Alonso-Garcia J.I. Arias R.M. Bandyopadhyay R.H. Barbá B. Barbuy L.R. Bedin E. Bica J. Borissova L. Bronfman G. Carraro M. Catelan J.J. Clariá G. Pietrzynski 《New Astronomy》2010,15(5):433-443
We describe the public ESO near-IR variability survey (VVV) scanning the Milky Way bulge and an adjacent section of the mid-plane where star formation activity is high. The survey will take 1929 h of observations with the 4-m VISTA telescope during 5 years (2010–2014), covering ~109 point sources across an area of 520 deg2, including 33 known globular clusters and ~350 open clusters. The final product will be a deep near-IR atlas in five passbands (0.9–2.5 μm) and a catalogue of more than 106 variable point sources. Unlike single-epoch surveys that, in most cases, only produce 2-D maps, the VVV variable star survey will enable the construction of a 3-D map of the surveyed region using well-understood distance indicators such as RR Lyrae stars, and Cepheids. It will yield important information on the ages of the populations. The observations will be combined with data from MACHO, OGLE, EROS, VST, Spitzer, HST, Chandra, INTEGRAL, WISE, Fermi LAT, XMM-Newton, GAIA and ALMA for a complete understanding of the variable sources in the inner Milky Way. This public survey will provide data available to the whole community and therefore will enable further studies of the history of the Milky Way, its globular cluster evolution, and the population census of the Galactic Bulge and center, as well as the investigations of the star forming regions in the disk. The combined variable star catalogues will have important implications for theoretical investigations of pulsation properties of stars. 相似文献
13.
In order to examine the applicability of remotely-sensed ocean color for the estimation of phytoplankton biomass and primary
production in the Oyashio region, the western subarctic Pacific, vertical distributions of chlorophylla concentration and primary production were observed in April and May 1997. Spring bloom was observed in both April and May,
and the surface concentration of chlorophylla exceeded 40 mg m−3. The relationship between the standing stocks of chlorophylla within the layer from the sea surface to one optical depth (0–1/k layer) and the surface chlorophylla concentration is expressed as a Michaelis-Menten equation. The mean ratio of the standing stock of chlorophylla in the euphotic layer to that in the 0–1/k layer was 4.41, this ratio did not significantly differ from 4.61 which was obtained at homogeneous distribution of chlorophylla within the euphotic layer. These facts suggest that the distribution of chlorophylla could be assumed to be homogeneous in the euphotic layer during the spring bloom. Results of primary production measurements
by simulatedin situ method were compared with those by an algorithm with two variables; chlorphylla and non-spectral PAR. Daily primary production in the euphotic layer estimated by the algorithm varied in a range of 38–274%
of that estimated by incubation, although the primary productions by the algorithm agreed with those by the incubation at
a half of stations. Primary production within the euphotic layer calculated using simply the surface data was the same as
that estimated using vertical distribution of chlorophylla. These results show that the primary production in the euphotic layer may be estimated from the remote sensed measurements
during the spring bloom in the Oyashio region. 相似文献
14.
15.
16.
本文在大量实际调查资料的基础上,详细论述了天山南北麓库车山前拗陷和乌鲁木齐山前拗陷在第四纪时期主要的构造变动及形成的最新构造形迹,并利用石油地质研究的最近成果对山前拗陷中最新构造的形成、演化以及褶皱构造与基底断裂活动的关系进行了讨论。 相似文献
17.
18.
R. Spence J.-C. Komorowski K. Saito A. Brown A. Pomonis G. Toyos P. Baxter 《Journal of Volcanology and Geothermal Research》2008
This paper describes the development and application of an impact model for a future hypothetical sub-Plinian eruption of La Soufrière of Guadeloupe. The model was designed to assess the impact from either a single or multiple eruption scenarios, each defined in terms of a map of the intensity of three volcanic hazards; volcanogenic earthquake, tephra fallout and pyroclastic density currents. The impact from the three hazards can be assessed independently or alternatively the joint impact of the three hazards can be assessed. The outputs that are produced from the model are; the number of buildings with collapsed roofs, and the number of fatal and non-fatal casualties. 相似文献
19.
Acta Geotechnica - Most studies investigating the effect of cyclic loading on soil properties have been conducted for saturated soils. Embankments such as fill dams, roads and railways are usually... 相似文献
20.
A metabasalt dredged at a junction of the median valley with the Atlantis fracture zone (30°01/tN, 42°04/tW) in the Mid-Atlantic Ridge shows complete recrystallization under a metasomatic condition, though the original igneous texture of a coarse-grained basalt is still recognizable. There is strong circumstantial evidence suggesting that this rock is not an ice-rafted erratic, but an authentic Mid-Atlantic Ridge rock. The 40Ar-39Ar age of this sample is 169 m.y. (Jurassic) which should represent the time of recrystallization. The initial value (87Sr/86Sr)O is 0.720, far above the values previously observed in oceanfloor basalts, including both tholeiitic and alkalic rocks (0.701–0.704). Sr with such a high isotopic ratio is considered to have been introduced by metasomatism during metamorphism by a solution coming from a continental mass or masses which were then located very close to the Mid-Atlantic Ridge. The 40Ar−39Ar age of sample AM50 may approximate the time of the commencement of the opening of the Atlantic. All these data support the possible existence of ancient rock masses in the Mid-Atlantic Ridge, as was formerly claimed by Bonatti, Melson and others. 相似文献