全文获取类型
收费全文 | 960篇 |
免费 | 93篇 |
国内免费 | 244篇 |
专业分类
测绘学 | 100篇 |
大气科学 | 227篇 |
地球物理 | 64篇 |
地质学 | 189篇 |
海洋学 | 106篇 |
天文学 | 539篇 |
综合类 | 38篇 |
自然地理 | 34篇 |
出版年
2024年 | 6篇 |
2023年 | 5篇 |
2022年 | 31篇 |
2021年 | 35篇 |
2020年 | 26篇 |
2019年 | 25篇 |
2018年 | 27篇 |
2017年 | 36篇 |
2016年 | 30篇 |
2015年 | 43篇 |
2014年 | 44篇 |
2013年 | 50篇 |
2012年 | 37篇 |
2011年 | 35篇 |
2010年 | 34篇 |
2009年 | 80篇 |
2008年 | 59篇 |
2007年 | 93篇 |
2006年 | 106篇 |
2005年 | 73篇 |
2004年 | 79篇 |
2003年 | 76篇 |
2002年 | 42篇 |
2001年 | 45篇 |
2000年 | 42篇 |
1999年 | 38篇 |
1998年 | 33篇 |
1997年 | 7篇 |
1996年 | 17篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1297条查询结果,搜索用时 15 毫秒
151.
J.Delabrouille G.Patanchon E.Audit 《Monthly notices of the Royal Astronomical Society》2002,330(4):807-816
For the most sensitive present and future experiments dedicated to cosmic microwave background (CMB) anisotropy observations, the identification and separation of signals coming from different sources is an important step in the data analysis. This problem of the restitution of signals from the observation of their mixture is classically called 'component separation' in CMB mapping. In this paper, we address the general problem of separating, for millimetre-wave sky-mapping applications, components which include not only astrophysical emissions in two-dimensional maps, but also one-dimensional instrumental effects in the data streams. We show that component separation methods can be adapted to separate simultaneously both astrophysical emissions and components coming from time-dependent foreground signals which originate from the instrument itself. Such general methods can be used for the optimal processing of low-redundancy observations where multi-channel observations are a precious tool to remove systematic effects, as may be the case for the Planck mission. 相似文献
152.
153.
154.
M. Shimon Y. Rephaeli B. W. O'Shea M. L. Norman 《Monthly notices of the Royal Astronomical Society》2006,368(2):511-511
Scattering of the cosmic microwave background (CMB) in clusters of galaxies polarizes the radiation. We explore several polarization components which have their origin in the kinematic quadrupole moments induced by the motion of the scattering electrons, either directed or random. Polarization levels and patterns are determined in a cluster simulated by the hydrodynamical enzo code. We find that polarization signals can be as high as ∼1 μK , a level that may be detectable by upcoming CMB experiments. 相似文献
155.
Fast heuristically weighted, or pseudo-Cℓ, estimators are a frequently used method for estimating power spectra in CMB surveys with large numbers of pixels. Recently, Challinor and Chon showed that the E–B mixing in these estimators can become a dominant contaminant at low noise levels, ultimately limiting the gravity wave signal which can be detected on a finite patch of sky. We define a modified version of the estimators which eliminates E–B mixing and is near-optimal at all noise levels. 相似文献
156.
A. Dinculescu 《Astrophysics and Space Science》2007,310(3-4):237-239
Starting from the assumption that the radiation source at the origin of the cosmic microwave background (CMB) could not have a luminosity larger than the maximum energy in ordinary matter divided by the minimum time allowed by causality,
one arrives at an expression that gives the energy density of CMB as a function of the main cosmological parameters. Also, by defining a radiation charge as the hypothetical charge that opposes
the congregation of a cloud of particles around a source of electromagnetic radiation, on arrives at another expression for
the energy density of CMB that agrees exactly with the measured value for a value of the Hubble constant equal to 72.09 km s−1 Mpc−1. Both expressions are independent of the redshift. 相似文献
157.
158.
Robert A. Watson Pedro Carreira Kieran Cleary Rod D. Davies Richard J. Davis Clive Dickinson Keith Grainge † Carlos M. Gutiérrez Michael P. Hobson Michael E. Jones Rüdiger Kneissl Anthony Lasenby Klaus Maisinger Guy G. Pooley Rafael Rebolo José Alberto Rubiño-Martin ‡ Ben Rusholme § Richard D. E. Saunders Richard Savage Paul F. Scott Ane Slosar Pedro J. Sosa Molina Angela C. Taylor David Titterington Elizabeth Waldram Althea Wilkinson 《Monthly notices of the Royal Astronomical Society》2003,341(4):1057-1065
159.
D. Schwan F. Bertoldi S. Cho M. Dobbs R. Guesten N. W. Halverson W. L. Holzapfel E. Kreysa T. M. Lanting A. T. Lee M. Lueker J. Mehl K. Menten D. Muders M. Myers T. Plagge A. Raccanelli P. Schilke P. L. Richards H. Spieler M. White 《New Astronomy Reviews》2003,47(11-12):933
The APEX-SZ experiment is a sky survey designed to discover galaxy clusters via the Sunyaev–Zel’dovich effect at millimeter wavelengths. We describe the components of the instrument, including the 12 m Atacama Pathfinder Experiment telescope, optics, Transition-edge sensor bolometer array and SQUID readout. APEX-SZ will begin observations in 2004. 相似文献
160.