全文获取类型
| 收费全文 | 5733篇 |
| 免费 | 835篇 |
| 国内免费 | 863篇 |
专业分类
| 测绘学 | 342篇 |
| 大气科学 | 316篇 |
| 地球物理 | 946篇 |
| 地质学 | 2339篇 |
| 海洋学 | 468篇 |
| 天文学 | 1541篇 |
| 综合类 | 274篇 |
| 自然地理 | 1205篇 |
出版年
| 2024年 | 12篇 |
| 2023年 | 42篇 |
| 2022年 | 123篇 |
| 2021年 | 147篇 |
| 2020年 | 155篇 |
| 2019年 | 188篇 |
| 2018年 | 156篇 |
| 2017年 | 155篇 |
| 2016年 | 189篇 |
| 2015年 | 191篇 |
| 2014年 | 223篇 |
| 2013年 | 317篇 |
| 2012年 | 247篇 |
| 2011年 | 231篇 |
| 2010年 | 205篇 |
| 2009年 | 382篇 |
| 2008年 | 419篇 |
| 2007年 | 449篇 |
| 2006年 | 434篇 |
| 2005年 | 363篇 |
| 2004年 | 337篇 |
| 2003年 | 315篇 |
| 2002年 | 297篇 |
| 2001年 | 260篇 |
| 2000年 | 231篇 |
| 1999年 | 243篇 |
| 1998年 | 231篇 |
| 1997年 | 131篇 |
| 1996年 | 113篇 |
| 1995年 | 113篇 |
| 1994年 | 93篇 |
| 1993年 | 95篇 |
| 1992年 | 78篇 |
| 1991年 | 48篇 |
| 1990年 | 55篇 |
| 1989年 | 43篇 |
| 1988年 | 25篇 |
| 1987年 | 31篇 |
| 1986年 | 25篇 |
| 1985年 | 11篇 |
| 1984年 | 5篇 |
| 1983年 | 2篇 |
| 1981年 | 3篇 |
| 1980年 | 2篇 |
| 1979年 | 2篇 |
| 1977年 | 4篇 |
| 1976年 | 3篇 |
| 1975年 | 1篇 |
| 1972年 | 1篇 |
| 1954年 | 4篇 |
排序方式： 共有7431条查询结果，搜索用时 46 毫秒
51.
52.
牛福增 《广东海洋大学学报》2003,23(2):57-64
行政腐败和行政作弊现象使政府行政的合法性受到人们的置疑 ,深入推行的廉政建设责任制反映了政府在这一问题上理论认识的巨大进步与从严治政的重大决心。公共选择理论认为 ,官僚的经济人属性不会因其成为政府官僚而改变 ,其目标不是公共利益也不是机构效率 ,而是个人效用 ;西方国家的“三权分立”学说及其实践对于公共行政的监督具有重大的历史进步意义 ,但其精致架构的私有制基础决定了这种民主可能只具有形式主义的性质 ,它只是一种富人之间的游戏规则与表现形式。毛泽东的“双平行制约”理论与方法是中国共产党人对公共行政理论与实践的巨大贡献 ,效果奇特却存在着一系列致命的弊端。对上述理论与实践的比较研究 ,为我国当前广泛展开的廉政建设提出了一些深层次的启发性思考 相似文献
53.
54.
Fabio Fontanot Pierluigi Monaco Stefano Borgani 《Monthly notices of the Royal Astronomical Society》2003,341(2):692-706
We apply the ztrace algorithm to the optical NOG and infrared PSC z galaxy catalogues to reconstruct the pattern of primordial fluctuations that have generated our local Universe. We check that the density fields traced by the two catalogues are well correlated, and consistent with a linear relation [either in δ or in log (1 +δ) ] with relative bias (of NOG with respect to PSC z ) b rel = 1.1 ± 0.1 . The relative bias relation is used to fill the optical zone of avoidance at | b | < 20° using the PSC z galaxy density field.
We perform extensive testing on simulated galaxy catalogues to optimize the reconstruction. The quality of the reconstruction is predicted to be good at large scales, up to a limiting wavenumber klim ≃ 0.4 h Mpc−1 beyond which all information is lost. We find that the improvement arising from the denser sampling of the optical catalogue is compensated by the uncertainties connected to the larger zone of avoidance.
The initial conditions reconstructed from the NOG catalogue are found (analogously to those from the PSC z ) to be consistent with a Gaussian paradigm. We use the reconstructions to produce sets of initial conditions ready to be used for constrained simulations of our local Universe. 相似文献
We perform extensive testing on simulated galaxy catalogues to optimize the reconstruction. The quality of the reconstruction is predicted to be good at large scales, up to a limiting wavenumber k
The initial conditions reconstructed from the NOG catalogue are found (analogously to those from the PSC z ) to be consistent with a Gaussian paradigm. We use the reconstructions to produce sets of initial conditions ready to be used for constrained simulations of our local Universe. 相似文献
55.
The paper provides a new stereo‐analytical method, which is a combination of the stereographic method and analytical methods, to separate finite removable blocks from the infinite and tapered blocks in discontinuous rock masses. The methodology has applicability to both convex and concave blocks. Application of the methodology is illustrated through examples. Addition of this method to the existing block theory procedures available in the literature improves the capability of block theory in solving practical problems in rock engineering. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
56.
57.
Ramona Núñez-López Anton Lipovka Vladimir Avila-Reese 《Monthly notices of the Royal Astronomical Society》2006,369(4):2005-2012
Possible detection of signatures of structure formation at the end of the 'dark age' epoch ( z ∼ 40–20) is examined. We discuss the spectral–spatial fluctuations in the cosmic microwave background radiation (CMBR) temperature produced by elastic resonant scattering of CMBR photons on deuterated hydrogen (HD) molecules located in protostructures moving with peculiar velocity. Detailed chemical kinematic evolution of HD molecules in the expanding homogeneous medium is calculated. Then, the HD abundances are linked to protostructures at their maximum expansion, whose properties are estimated by using the top-hat spherical approach and the Λ cold dark matter (ΛCDM) cosmology. We find that the optical depths in the HD three lowest pure rotational lines for high-peak protohaloes at their maximum expansion are much higher than those in LiH molecule. The corresponding spectral–spatial fluctuation amplitudes, however, are probably too weak to be detected by current and forthcoming millimetre telescope facilities. We extend our estimates of spectral–spatial fluctuations to gas clouds inside collapsed CDM haloes by using results from a crude model of HD production in these clouds. The fluctuations for the highest peak CDM haloes at redshifts ∼20–30 could be detected in the future. Observations will be important to test model predictions of early structure formation in the Universe. 相似文献
58.
59.
60.