全文获取类型
| 收费全文 | 287565篇 |
| 免费 | 10864篇 |
| 国内免费 | 10690篇 |
专业分类
| 测绘学 | 9433篇 |
| 大气科学 | 25607篇 |
| 地球物理 | 61563篇 |
| 地质学 | 104321篇 |
| 海洋学 | 25177篇 |
| 天文学 | 56529篇 |
| 综合类 | 4516篇 |
| 自然地理 | 21973篇 |
出版年
| 2022年 | 2575篇 |
| 2021年 | 3664篇 |
| 2020年 | 3808篇 |
| 2019年 | 4258篇 |
| 2018年 | 5494篇 |
| 2017年 | 5109篇 |
| 2016年 | 7696篇 |
| 2015年 | 5788篇 |
| 2014年 | 8796篇 |
| 2013年 | 16019篇 |
| 2012年 | 8385篇 |
| 2011年 | 9916篇 |
| 2010年 | 9119篇 |
| 2009年 | 11506篇 |
| 2008年 | 10207篇 |
| 2007年 | 9544篇 |
| 2006年 | 10837篇 |
| 2005年 | 8881篇 |
| 2004年 | 8494篇 |
| 2003年 | 7984篇 |
| 2002年 | 7536篇 |
| 2001年 | 6879篇 |
| 2000年 | 6966篇 |
| 1999年 | 6639篇 |
| 1998年 | 6352篇 |
| 1997年 | 6103篇 |
| 1996年 | 5670篇 |
| 1995年 | 5287篇 |
| 1994年 | 4858篇 |
| 1993年 | 4431篇 |
| 1992年 | 4053篇 |
| 1991年 | 3958篇 |
| 1990年 | 3937篇 |
| 1989年 | 3624篇 |
| 1988年 | 3419篇 |
| 1987年 | 3849篇 |
| 1986年 | 3388篇 |
| 1985年 | 4205篇 |
| 1984年 | 4718篇 |
| 1983年 | 4371篇 |
| 1982年 | 4285篇 |
| 1981年 | 3892篇 |
| 1980年 | 3620篇 |
| 1979年 | 3464篇 |
| 1978年 | 3450篇 |
| 1977年 | 3227篇 |
| 1976年 | 2970篇 |
| 1975年 | 2900篇 |
| 1974年 | 2863篇 |
| 1973年 | 3060篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
991.
J. CAMPSIE M. H. RASMUSSEN L. C. KOVACS F. DITTMER J. C. BAILEY N. O. HANSEN J. LAURSEN L. JOHNSON 《Polar research》1990,8(2):237-243
New aeromagnetic data, K-Ar age determinations of dredged marine igneous rocks, as well as other geophysical evidence have shed light on the chronology, nature and evolution of the northern Iceland Plateau. Correspondence between seismic refraction profiles taken on the Jan Mayen Ridge and westward through Jan Mayen Island, suppressed aeromagnetic anomalies, earthquake surface wave studies, and ages of dredged igneous rocks suggest these strata may form an extended region of thickened crust, possibly of Caledonian age, extending westward toward the Kolbeinsey Ridge and northwest to the south wall of the Jan Mayen Fracture Zone. 相似文献
992.
The oscillatory, conjugate and asymptotic behaviours of the principal and non-principal solutions of the Blasius and corresponding heat transfer equations governing the compressible laminar boundary-layer flow over a semi-infinite flat plate with heat flux have been studied; the results of the discussion being based on the asymptotic integrations of second-order linear differential equations. 相似文献
993.
The Indian team at ISRO has been part of the Whole Earth Telescope (WET) team since 1988 when we first participated in the
campaign on V471 Tau. We have been part of many other observing campaigns over the last decade. This presentation traces the
circumstances leading to our joining the WET team and how useful the coverage from the Indian longitude has been. The results
of several pulsators from the WET runs during which we participated are also described. These include PG1159-035 the prototype
of the GW Vir type of stars, RE J 0751+14 a cataclysmic variable, PG 1336-018 a binary with an sdB pulsator and finally HR
1217 a roAp star. The paper concludes with what the limitations are in our observations and how we can overcome them in the
future. 相似文献
994.
995.
996.
997.
P. A. M. Van Hoof M. E. Foord R. F. Heeter J. E. Bailey H.-K. Chung M. E. Cuneo W. H. Goldstein V. Jonauskas F. P. Keenan R. Kisielius D. A. Liedahl C. Ramsbottom S. J. Rose P. T. Springer R. S. Thoe 《Astrophysics and Space Science》2005,298(1-2):147-153
In experiments at the high-power Z-facility at Sandia National Laboratory in Albuquerque, New Mexico, we have been able to
produce a low density photoionized laboratory plasma of Fe mixed with NaF. The conditions in the experiment allow a meaningful
comparison with X-ray emission from astrophysical sources. The charge state distributions of Fe, Na and F are determined in
this plasma using high resolution X-ray spectroscopy. Independent measurements of the density and radiation flux indicate
unprecedented values for the ionization parameter ξ = 20–25 erg cm s−1 under nearly steady-state conditions. First comparisons of the measured charge state distributions with X-ray photoionization
models show reasonable agreement, although many questions remain. 相似文献
998.
999.