全文获取类型
| 收费全文 | 959篇 |
| 免费 | 32篇 |
| 国内免费 | 22篇 |
专业分类
| 测绘学 | 16篇 |
| 地球物理 | 100篇 |
| 地质学 | 96篇 |
| 海洋学 | 199篇 |
| 天文学 | 543篇 |
| 综合类 | 4篇 |
| 自然地理 | 55篇 |
出版年
| 2024年 | 1篇 |
| 2023年 | 2篇 |
| 2022年 | 5篇 |
| 2021年 | 10篇 |
| 2020年 | 10篇 |
| 2019年 | 5篇 |
| 2018年 | 10篇 |
| 2017年 | 15篇 |
| 2016年 | 14篇 |
| 2015年 | 13篇 |
| 2014年 | 14篇 |
| 2013年 | 49篇 |
| 2012年 | 19篇 |
| 2011年 | 35篇 |
| 2010年 | 23篇 |
| 2009年 | 79篇 |
| 2008年 | 88篇 |
| 2007年 | 71篇 |
| 2006年 | 74篇 |
| 2005年 | 64篇 |
| 2004年 | 59篇 |
| 2003年 | 55篇 |
| 2002年 | 50篇 |
| 2001年 | 53篇 |
| 2000年 | 35篇 |
| 1999年 | 26篇 |
| 1998年 | 45篇 |
| 1997年 | 10篇 |
| 1996年 | 13篇 |
| 1995年 | 10篇 |
| 1994年 | 13篇 |
| 1993年 | 8篇 |
| 1992年 | 3篇 |
| 1991年 | 5篇 |
| 1990年 | 5篇 |
| 1989年 | 2篇 |
| 1988年 | 6篇 |
| 1986年 | 2篇 |
| 1985年 | 2篇 |
| 1984年 | 1篇 |
| 1982年 | 3篇 |
| 1981年 | 3篇 |
| 1980年 | 1篇 |
| 1979年 | 1篇 |
| 1978年 | 1篇 |
排序方式： 共有1013条查询结果，搜索用时 62 毫秒
921.
922.
Quentin A. Parker A. Acker D. J. Frew M. Hartley A. E. J. Peyaud F. Ochsenbein S. Phillipps D. Russeil S. F. Beaulieu M. Cohen J. Köppen B. Miszalski D. H. Morgan R. A. H. Morris M. J. Pierce A. E. Vaughan 《Monthly notices of the Royal Astronomical Society》2006,373(1):79-94
We present the Macquarie/AAO/Strasbourg Hα Planetary Nebula Catalogue (MASH) of over 900 true, likely and possible new Galactic planetary nebulae (PNe) discovered from the AAO/UKST Hα survey of the southern Galactic plane. The combination of depth, resolution, uniformity and areal coverage of the Hα survey has opened up a hitherto unexplored region of parameter space permitting the detection of this significant new PN sample. Away from the Galactic bulge the new PNe are typically more evolved, of larger angular extent, of lower surface brightness and more obscured (i.e. extinguished) than those in most previous surveys. We have also doubled the number of PNe in the Galactic bulge itself and although most are compact, we have also found more evolved examples. The MASH catalogue represents the culmination of a seven-year programme of identification and confirmatory spectroscopy. A key strength is that the entire sample has been derived from the same, uniform observational data. The 60 per cent increase in known Galactic PNe represents the largest ever incremental sample of such discoveries and will have a significant impact on many aspects of PN research. This is especially important for studies at the faint end of the PN luminosity function which was previously poorly represented. 相似文献
923.
Crustal lineament control on magmatism and mineralization in northwestern Argentina: geological, geophysical, and remote sensing evidence 总被引：2，自引：0，他引：2
The relationship between long-lived deep crustal lineaments and the locations of magmatic centers and associated mineral deposits has been investigated in the Puna region of northwestern Argentina, through the analysis of regional aeromagnetic surveys, Landsat images, and geological information. The good exposure and excellent preservation of basement and supracrustal geology in this region makes it particularly suitable for such a study. At a regional scale, several contrasting magnetic domains are recognized, which correlate with crustal geology. Two basement domains are separated by a NNE-trending boundary, which is believed to correlate with a Paleozoic suture zone between the Pampia (to the southeast) and Arequipa–Antofalla terranes (to the northwest). Locally overlying these basement terranes is the Cenozoic magmatic domain, which is best developed in the N–S-trending volcanic arc at the western edge of the Puna (the Cordillera Occidental). In addition, four southeast-trending volcanic zones extend for several hundred kilometers across the Puna. Many important mineral deposits and areas of hydrothermal alteration are associated with these volcanic breakouts, and we have selected three such areas for more detailed study: Bajo de la Alumbrera (Argentina's largest porphyry copper deposit), Cerro Galán (the largest ignimbrite caldera in Argentina, with associated hydrothermal alteration zones), and El Queva (a historic polymetallic district located within a major volcanic range). A comparison of lineament maps generated from aeromagnetic and Landsat TM images reveals broad correlation between these different remote sensing techniques, which respectively highlight subsurface magnetic and surface geological features. In addition, the locations of magmatic and hydrothermal centers can be related to the interpreted structural framework, and are seen to occur near the intersections of major lineament zones. It is suggested that in three dimensions, such intersection zones form trans-lithospheric columns of low strength and high permeability during transpressional or transtensional tectonic strain, and may thereby serve as conduits for magma ascent to the shallow crust. Pooling of large volumes of deeply derived magma in shallow crustal magma chambers may then result in voluminous devolatilization and the formation of hydrothermal mineral deposits. It is important to note that in this model, structural intersections serve as facilitators for magma ascent and volatile exsolution, but do not in themselves cause this process—other factors such as magma supply rate and tectonic stress are essential primary ingredients, and local magmatic and volcanic processes affect the ultimate potential for ore formation. Nevertheless, we suggest that lineament analysis provides a valuable framework for guiding the early stages of mineral exploration; other regional and local geological considerations must then be applied to identify priority targets within this framework. 相似文献
924.
在前人研究的基础上，通过化探工作，比较确切地查明了平冈断裂在覆盖区的具体部位。对比测值发现，该断裂南西段的规模大于北东段。对断裂的近期活动性．作了尝试性的探讨 相似文献
925.
926.
928.
929.
为了研究蓬莱西庄海岸侵蚀原因、揭示泥沙运移规律，利用萤光示踪砂和染色砾石进行侵蚀岸段的泥沙示踪研究．其主要结果如下：１．海滩泥沙运动完全由波浪控制，泥沙运移的速度和方向取决于破波的大小和方向．２．海滩泥沙以群体形式沿岸输移．３．在平直海岸上，泥沙可超越粘土质海蚀平台进入另一砂质海滩。 相似文献
930.