全文获取类型
收费全文 | 107912篇 |
免费 | 1601篇 |
国内免费 | 1110篇 |
专业分类
测绘学 | 2763篇 |
大气科学 | 7688篇 |
地球物理 | 21214篇 |
地质学 | 38469篇 |
海洋学 | 9559篇 |
天文学 | 24573篇 |
综合类 | 352篇 |
自然地理 | 6005篇 |
出版年
2022年 | 630篇 |
2021年 | 1109篇 |
2020年 | 1209篇 |
2019年 | 1268篇 |
2018年 | 2898篇 |
2017年 | 2734篇 |
2016年 | 3451篇 |
2015年 | 1962篇 |
2014年 | 3300篇 |
2013年 | 5761篇 |
2012年 | 3484篇 |
2011年 | 4693篇 |
2010年 | 3981篇 |
2009年 | 5225篇 |
2008年 | 4706篇 |
2007年 | 4535篇 |
2006年 | 4302篇 |
2005年 | 3350篇 |
2004年 | 3301篇 |
2003年 | 3111篇 |
2002年 | 2929篇 |
2001年 | 2636篇 |
2000年 | 2520篇 |
1999年 | 2028篇 |
1998年 | 2160篇 |
1997年 | 2010篇 |
1996年 | 1724篇 |
1995年 | 1690篇 |
1994年 | 1451篇 |
1993年 | 1318篇 |
1992年 | 1294篇 |
1991年 | 1192篇 |
1990年 | 1333篇 |
1989年 | 1094篇 |
1988年 | 1053篇 |
1987年 | 1214篇 |
1986年 | 1058篇 |
1985年 | 1307篇 |
1984年 | 1453篇 |
1983年 | 1315篇 |
1982年 | 1279篇 |
1981年 | 1120篇 |
1980年 | 1033篇 |
1979年 | 978篇 |
1978年 | 973篇 |
1977年 | 849篇 |
1976年 | 817篇 |
1975年 | 796篇 |
1974年 | 764篇 |
1973年 | 749篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Falconer David A. Jordan Stuart D. Brosius Jeffrey W. Davila Joseph M. Thomas Roger J. Andreatta Vicenzo Hara Hirohisa 《Solar physics》1998,180(1-2):179-191
We investigate the possibility that strong EUV lines observed with the Goddard Solar EUV Rocket Telescope and Spectrograph (SERTS) provide good proxies for estimating the total coronal flux over shorter wavelength ranges. We use coordinated SERTS and Yohkoh observations to obtain both polynomial and power-law fits relating the broad-band soft X-ray fluxes to the intensities of Fexvi 335 Ú and 361 Ú, Fexv 284 Ú and 417 Ú, and Mgix 368 Ú measured with SERTS. We found that the power-law fits best cover the full range of solar conditions from quiet Sun through active region, though not surprisingly the cooler Mgix 368 Ú line proves to be a poor proxy. The quadratic polynomial fits yield fair agreement over a large range for all but the Mgix line. However, the linear fits fail conspicuously when extrapolated into the quiet-Sun regime. The implications of this work for the Heii 304 Ú line formation problem are also briefly considered. 相似文献
993.
Bianchi type V cosmological models are studied that contain a relativistic ideal Boltzmann gas. The effect of a cosmological constant upon the space-time geometry is also considered. In both high and low temperature limit the general solution of the Einstein gravitational field equations can be expressed in an exact closed parametric form. At final stages, depending on the presence or absence of the cosmological constant, cosmologies are driven to an isotropic inflationary open de Sitter type Universe or to an isotropic open Friedmann era. 相似文献
994.
Mouradian Z. Soru-Escaut I. Hiei E. McALLISTER A. H. Shibasaki K. Ohyama M. Khan J. I. Uchida Y. 《Solar physics》1998,180(1-2):313-329
The 7 May 1992 filament disappearance in the low corona is analyzed. The cool and hot components of this event are studied, using H, soft X-ray and radio data. We first show the general effect of the disparition brusque (DB) on the life of the filament, which was a quiescent filament in the vicinity of an active region, and then give the history of the development of the 7 May event. The main stages of the event are: (i) the formation of hot arches spanning the cool filament; (ii) rise of the filament, with plasma ejection into the corona, in which we note some spreading of loops from the main body, with two distinct rising velocity phases of the H filament; (iii) formation of X-ray arches below the filament, the foot points of the arcades being two-ribbon H flare patches. The dynamics of H and X-rays features are given. 相似文献
995.
996.
The relationship between the RMS amplitudes of the wind wave spectral components and the wind speed has been studied at ten frequencies in the band of 0.65–23 Hz. To measure the parameters of the high-frequenci waves, a resistance elevation wave gauge was operated, which was deployed in the Black See on an oceanographic platform near Katsively. The correlation between the wave amplitudes and the wind velocity at high frequencies of 5–23 Hz, corresponding to gravitation-capillary ripples, was found to reach a value of 0.8. At lower frequencies of 0.65–4.3 Hz, corresponding to short gravity waves, it dropped to 0.5–0.7. The response of spectral components to the wind speed variations in the gravity-capillary range is higher than in the range of short gravity waves. The results obtained differ from Phillips' idea about a saturated range for the frequency form of the spectrum of high-frequency gravity waves, since a linear dependence of the spectral amplitudes on the wind speed is established at a wind of force 1–8.Translated by Mikhail M. Trufanov. 相似文献
997.
Nonlinear axisymmetric oscillations of a warm baroclinic eddy are considered within the framework of an reduced-gravity model of the dynamics of a multilayer ocean. A class of exact analytical solutions describing pure inertial oscillations of an eddy formation is found. The thicknesses of layers in the eddy vary according to a quadratic law, and the horizontal projections of the velocity in the layers depend linearly on the radial coordinate. Owing to a complicated structure of the eddy, weak limitations on the vertical distribution of density, and an explicit form of the solution, the latter can be treated as a generalization of the exact analytical solutions of this form that were previously obtained for homogeneous and baroclinic eddies in the ocean. 相似文献
998.
999.
1000.