全文获取类型
收费全文 | 671篇 |
免费 | 31篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 15篇 |
大气科学 | 47篇 |
地球物理 | 153篇 |
地质学 | 314篇 |
海洋学 | 30篇 |
天文学 | 116篇 |
综合类 | 7篇 |
自然地理 | 22篇 |
出版年
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 10篇 |
2018年 | 19篇 |
2017年 | 13篇 |
2016年 | 36篇 |
2015年 | 26篇 |
2014年 | 43篇 |
2013年 | 80篇 |
2012年 | 19篇 |
2011年 | 35篇 |
2010年 | 47篇 |
2009年 | 31篇 |
2008年 | 29篇 |
2007年 | 9篇 |
2006年 | 20篇 |
2005年 | 15篇 |
2004年 | 10篇 |
2003年 | 14篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 12篇 |
1998年 | 13篇 |
1997年 | 16篇 |
1996年 | 5篇 |
1994年 | 4篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1982年 | 6篇 |
1980年 | 6篇 |
1978年 | 7篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1972年 | 3篇 |
1970年 | 3篇 |
1969年 | 4篇 |
1968年 | 3篇 |
1965年 | 3篇 |
1964年 | 3篇 |
1957年 | 3篇 |
1956年 | 4篇 |
1951年 | 3篇 |
1948年 | 5篇 |
排序方式: 共有704条查询结果,搜索用时 31 毫秒
1.
Journal of Oceanology and Limnology - The aim of this study was to determine the species composition, biodiversity and, relative abundance of epiphytic algae and their relationship with... 相似文献
2.
3.
A survey is made of the present constraints on cosmological parameters from Cosmic Microwave Background Anisotropies.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
5.
We have investigated the evolutionary behaviour of intermediate mass (2, 3, 4, 5, and 7M
) Population I stars, assuming two different rates of rotation at the threshold of stability.In the first part of the study, stars are assumed to start with a critical rotation (fast rotation model) and to progress to the point of rotational instability. The stars evolve by losing mass and become rotationally unstable before they reach the zero-age Main Sequence. It is argued that multiple star systems might be formed through the evolution of rapidly rotating stars. An expression for the rotational mass loss rate is derived as a function of the physical parameters of stars.In the second part of the study, stars are assumed to rotate at a rate below the critical value (slow rotation model). The evolution of slowly rotating stars is followed as far as zero-age Main Sequence on the theoretical Hertzsprung-Russell diagram and compared with that of normal stars. The evolutionary paths are found to be more or less similar to those of normal stars; but their positions on the Main Sequence are characterized by effective temperatures and luminosities lower than those of normal stars. The zero-age Main-Sequence times of these stars are longer than those of normal stars. The rotational rates obtained for the zero-age Main Sequence are in good agreement with observed values. 相似文献
6.
Adnan Özdemir 《Environmental Geology》2008,53(8):1695-1710
This study examines the local geological conditions and soil structure as possible causes of the collapse of the Zümrüt Building
2 February 2004. This catastrophe resulted in 92 fatalities and 35 injuries. This study also examines other views which claim
weak soil structure, elastic and consolidation settlement of soil and excessive groundwater extraction as well as subsidence
resulting from the underground silt erosion as possible factors. Zümrüt Building was constructed on normally consolidated,
low plasticity clay. The underground water table was 30 m in depth. The internal friction angle of soil was 8°–30°, its cohesion
was between 34 and 127 kN/m2 and standard penetration test numbers varied between 11 and 50. The underground water level beneath Zümrüt Building had risen
4.5 m since its construction. Therefore the claim that subsidence resulting from the decrease of underground water level contributed
to the collapse is incorrect. Secondly the settlement, resulting from the filling up of the pores created by the silt receding
with the underground water, was 4.4 mm in total, and attributing this as the primary cause of the collapse is also incorrect.
Soil properties, in situ and laboratory test results showed that the existing and/or expected settlement and the differential
ground settlement in the Zümrüt building vicinity had the potential to cause structural damage. The tensile stresses caused
by differential settlements recorded here are thought to be an indicator, but not the main cause contributing to the collapse
of the building. The Zümrüt Building collapse was due to several compounding mistakes during the construction phase. These
were geotechnical and other project faults and the use of low quality construction materials. The resulting catastrophe caused
92 fatalities, 35 injuries and a material loss of approximately US$7 million. 相似文献
7.
8.
9.
Atίla Özgüç 《Solar physics》1989,123(2):381-383
After re-examination of data presented by Verma (1984), some misuse of solar parameteres published in Solar Geophysical Data is presented. Consequently some conclusions made by Verma (1984, 1986) on about the longitudinal distribution of cool solar surges based on these misuses are discussed. 相似文献
10.
Haubold Herbert Scholger Robert Kondopoulou Despina Mauritsch Hermann J. 《Geologie en Mijnbouw》1997,76(1-2):45-55
Various Oligocene formations from NE Greece (ignimbrites from the Medousa area, rhyolites from Zagradenia, granodiorites from Elatia) show discordant paleomagnetic signatures, in each case indicating small cw (clockwise) rotation and also inclination flattening. Marls from Pithion were partly remagnetized in a present-day field. Samples that contain ancient magnetization components also indicate small cw rotation and inclination flattening. However, the magnetization of andesites from Peplos reflects a considerably larger rotation, likely owing to local tectonics. In the context of previous work in the area, these results are used to propose a subdivision of NE Greece into four structural zones of distinctive rotational behaviour (from east to west): sites in zone 1, east of the Kavala-Xanthi-Komotini fault (KXK), show various cw and ccw (counterclockwise) rotation angles owing to complex kinematics resulting from the interaction of the KXK and the north-Anatolian fault zone. However, zone 2, between the KXK and the Strymon valley, is structurally homogeneous ( 10° cw rotation). The paleomagnetic signature of the Vertiskos massif (zone 3) implies a larger (> 30°) cw rotation, whereas sites in the Vardar basin (zone 4) contain a paleomagnetic signature similar to that of zone 2. This suggests a motion of the Vertiscos massif, a meta-ophiolitic nappe, relative to underlying strata. Indeed, zones 2 and 4 may be parts of the same structural unit which underlies this nappe. 相似文献