全文获取类型
收费全文 | 6585篇 |
免费 | 354篇 |
国内免费 | 48篇 |
专业分类
测绘学 | 185篇 |
大气科学 | 484篇 |
地球物理 | 2365篇 |
地质学 | 2272篇 |
海洋学 | 484篇 |
天文学 | 847篇 |
综合类 | 37篇 |
自然地理 | 313篇 |
出版年
2023年 | 28篇 |
2022年 | 61篇 |
2021年 | 132篇 |
2020年 | 141篇 |
2019年 | 109篇 |
2018年 | 285篇 |
2017年 | 274篇 |
2016年 | 415篇 |
2015年 | 301篇 |
2014年 | 359篇 |
2013年 | 432篇 |
2012年 | 354篇 |
2011年 | 392篇 |
2010年 | 335篇 |
2009年 | 350篇 |
2008年 | 301篇 |
2007年 | 222篇 |
2006年 | 223篇 |
2005年 | 167篇 |
2004年 | 186篇 |
2003年 | 155篇 |
2002年 | 129篇 |
2001年 | 116篇 |
2000年 | 79篇 |
1999年 | 84篇 |
1998年 | 106篇 |
1997年 | 71篇 |
1996年 | 51篇 |
1995年 | 54篇 |
1994年 | 59篇 |
1993年 | 43篇 |
1992年 | 48篇 |
1991年 | 56篇 |
1990年 | 67篇 |
1989年 | 46篇 |
1988年 | 30篇 |
1987年 | 37篇 |
1986年 | 41篇 |
1984年 | 40篇 |
1983年 | 32篇 |
1982年 | 33篇 |
1981年 | 32篇 |
1980年 | 27篇 |
1979年 | 29篇 |
1978年 | 28篇 |
1977年 | 27篇 |
1976年 | 28篇 |
1974年 | 31篇 |
1973年 | 34篇 |
1971年 | 43篇 |
排序方式: 共有6987条查询结果,搜索用时 781 毫秒
641.
642.
643.
644.
645.
646.
647.
648.
649.
J.?García-SerranoEmail author V.?Guemas F.?J.?Doblas-Reyes 《Climate Dynamics》2015,44(9-10):2539-2555
Identifying regions sensitive to external radiative changes, including anthropogenic (sulphate aerosols and greenhouse gases) and natural (volcanoes and solar variations) forcings, is important to formulate actionable information at multi-year time-scales. Internally-generated climate variability can overcome this radiative forcing, especially at regional level, so that detecting the areas for this potential dominance is likewise critical for decadal prediction. This work aims to clarify where each contribution has the largest effect on North Atlantic sea surface temperature (SST) predictions in relation to the Atlantic multi-decadal variability (AMV). Initialized decadal hindcasts and radiatively-forced historical simulations from the fifth phase of the Climate Model Intercomparison Project are analysed to assess multi-year skill of the AMV. The initialized hindcasts reproduce better the phase of the AMV index fluctuations. The radiatively-forced component consists of a residual positive trend, although its identification is ambiguous. Initialization reduces the inter-model spread when estimating the level of AMV skill, thus reducing its uncertainty. Our results show a skilful performance of the initialized hindcasts in capturing the AMV-related SST anomalies over the subpolar gyre and Labrador Sea regions, as well as in the eastern subtropical basin, and the inability of the radiatively-forced historical runs to simulate the horseshoe-like AMV signature over the North Atlantic. Initialization outperforms empirical predictions based on persistence beyond 1–4 years ahead, suggesting that ocean dynamics play a role in the AMV predictability beyond the thermal inertia. The initialized hindcasts are also more skilful at reproducing the observed AMV teleconnection to the West African monsoon. The impact of the start date frequency is also described, showing that the standard of 5-year interval between start dates yields the main features of the AMV skill that are robustly detected in hindcasts with yearly start date sampling. This work updates previous studies, complementing them, and concludes that skilful initialized multi-model forecasts of the AMV-related climate variability can be formulated, improving uninitialized projections, until 3–6 years ahead. 相似文献
650.
J. A. Combi J. F. Albacete Colombo L. Pellizza J. López-Santiago G. E. Romero J. Martí A. J. Muñoz-Arjonilla E. Sánchez-Ayaso P. L. Luque-Escamilla J. R. Sánchez-Sutil 《Astrophysics and Space Science》2011,331(1):53-61
We present a catalog of cross-correlated radio, infrared and X-ray sources using a very restrictive selection criteria with
an IDL-based code developed by us. The significance of the observed coincidences was evaluated through Monte Carlo simulations
of synthetic sources following a well-tested protocol. We found 3320 coincident radio/X-ray sources with a high statistical
significance characterized by the sum of error-weighted coordinate differences. For 997 of them, 2MASS counterparts were found.
The percentage of chance coincidences is less than 1%. X-ray hardness ratios of well-known populations of objects were used
to provide a crude representation of their X-ray spectrum and to make a preliminary diagnosis of the possible nature of unidentified
X-ray sources. The results support the fact that the X-ray sky is largely dominated by Active Galactic Nuclei at high galactic
latitudes (|b|≥10°). At low galactic latitudes (|b|≤10°) most of unidentified X-ray sources (∼94%) lie at |b|≤2°. This result suggests that most of the unidentified sources found toward the Milky Way plane are galactic objects. Well-known
and unidentified sources were classified in different tables with their corresponding radio/infrared and X-ray properties.
These tables are intended as a useful tool for researchers interested in particular identifications. 相似文献