全文获取类型
| 收费全文 | 1546篇 |
| 免费 | 234篇 |
| 国内免费 | 335篇 |
专业分类
| 测绘学 | 91篇 |
| 大气科学 | 290篇 |
| 地球物理 | 395篇 |
| 地质学 | 715篇 |
| 海洋学 | 169篇 |
| 天文学 | 129篇 |
| 综合类 | 167篇 |
| 自然地理 | 159篇 |
出版年
| 2024年 | 8篇 |
| 2023年 | 23篇 |
| 2022年 | 78篇 |
| 2021年 | 85篇 |
| 2020年 | 57篇 |
| 2019年 | 95篇 |
| 2018年 | 66篇 |
| 2017年 | 77篇 |
| 2016年 | 85篇 |
| 2015年 | 60篇 |
| 2014年 | 95篇 |
| 2013年 | 68篇 |
| 2012年 | 69篇 |
| 2011年 | 70篇 |
| 2010年 | 93篇 |
| 2009年 | 92篇 |
| 2008年 | 93篇 |
| 2007年 | 82篇 |
| 2006年 | 58篇 |
| 2005年 | 65篇 |
| 2004年 | 25篇 |
| 2003年 | 40篇 |
| 2002年 | 35篇 |
| 2001年 | 41篇 |
| 2000年 | 68篇 |
| 1999年 | 79篇 |
| 1998年 | 55篇 |
| 1997年 | 44篇 |
| 1996年 | 57篇 |
| 1995年 | 45篇 |
| 1994年 | 42篇 |
| 1993年 | 33篇 |
| 1992年 | 21篇 |
| 1991年 | 18篇 |
| 1990年 | 16篇 |
| 1989年 | 23篇 |
| 1988年 | 16篇 |
| 1987年 | 7篇 |
| 1986年 | 6篇 |
| 1985年 | 4篇 |
| 1984年 | 2篇 |
| 1983年 | 5篇 |
| 1982年 | 5篇 |
| 1981年 | 1篇 |
| 1979年 | 3篇 |
| 1978年 | 1篇 |
| 1977年 | 2篇 |
| 1958年 | 2篇 |
排序方式： 共有2115条查询结果，搜索用时 15 毫秒
191.
Dai Zhenwei Zhang Yanjun Zhang Chenyang Luo Jianhua Yao Wang 《Geotechnical and Geological Engineering》2022,40(9):4551-4561
Geotechnical and Geological Engineering - The periodic reservoir water level (RWL) fluctuation on bank slopes during water impoundment in Three Gorges Reservoir (TGR) may lead to the reactivation... 相似文献
192.
193.
194.
In a warming climate, atmospheric wave activity and associated weather patterns may change, although conflicting results have been reported on this topic. Additionally, atmospheric wave changes in a future climate have mainly focused on waves of a specified spatial scale, rather than a particular spatiotemporal scale. Here, changes in the variability of Rossby waves of multiple spatiotemporal scales are analyzed using the wavenumber-frequency power spectrum, a tool commonly applied to analyze atmospheric equatorial waves. Daily 500 hPa geopotential height data over 40°–60°N from historical (1950–2005) and future (2006–2099) simulations from 20 models in the Coupled Model Intercomparison Project Phase 5 (CMIP5) under the RCP8.5 scenario were analyzed. When compared to the historical period, the late 21st century climate projections showed a decline in spectral power for both eastward and westward propagating waves with wavenumbers greater than 8 that spanned over all frequencies in all seasons, but an increase in mean power for eastward propagating waves with wavenumbers 1–7 over all frequencies was shown in winter and spring. This increase in power was accompanied by increased variance, i.e., an increased meridional extent of 500 hPa ridges and troughs, and was the result of increases in the mean number of high amplitude events and duration of activity within this wave band. These results indicate that large-scale (~ 104 km) eastward propagating weather systems may intensify with higher amplitudes for ridges and troughs, while short-scale (102–103 km) weather systems may decrease in their intensity due to reduced variability in the late 21st century under the high emissions scenario. Potential mechanisms for these changes are discussed, including enhanced Arctic warming and midlatitude-tropical interactions. 相似文献
195.
Dai Aiguo Huang Danqing Rose Brian E. J. Zhu Jian Tian Xiangjun 《Climate Dynamics》2020,54(11):4515-4543
Climate Dynamics - Equilibrium climate sensitivity (ECS) refers to the total global warming caused by an instantaneous doubling of atmospheric CO2 from the pre-industrial level in a climate system.... 相似文献
196.
利用常规观测资料、探空资料、多普勒天气雷达基本产品及导出产品,分析了2017年8月中旬萍乡地区雷暴大风天气过程,并选取了其中最强的一次过程进行了细致的分析。结果表明,“北低槽、南副高”的环流形势是此次长时间雷暴大风的环流背景,萍乡受“上下一致”的西南急流控制,中低层切变线、西南急流导致了强对流不稳定;低层逆温、“上干冷、下暖湿”以及风垂直切变的垂直结构,为雷暴大风的产生提供了层结条件和能量条件;地面热低压和地面辐合线、干线等是此次雷暴大风的触发机制。飑线过境,气象要素变化剧烈,在“人”字形回波附近,回波断裂处等区域容易产生强雷暴大风天气。强回波高度迅速下降、拖曳作用、动量下传、中层干暖空气的夹卷及蒸发作用、一定强度的中层径向辐合等多种因素导致了此次地面大风。垂直累积液态含水量、最大反射率因子、风暴顶高的持续下降,对地面大风天气的预报具有一定的指示意义。 相似文献
197.
江西生态优势明显,森林覆盖率居全国前列,研究植被生态系统碳汇价值是应对气候变化和生态文明建设的具体体现。基于森林资源清查资料,研究了2001—2016年江西省森林碳汇价值;基于卫星遥感数据反演获取植被生态系统净初级生产力(NPP),评估了2000—2016年江西各设区市(县)植被碳汇分布特征。结果表明:1)2016年江西省森林碳储量价值为980.30亿元,植被和森林碳汇价值均呈上升趋势。2)江西省植被碳汇价值增加率为4.55亿元/a,2016年约为823.53亿元,每公顷所创造的碳汇经济价值为4930.67元,比2000年增加了11%。3)2016年各设区市植被碳汇价值排名前三位的分别是赣州、吉安和上饶,排名后三位的是新余、鹰潭和萍乡,单位面积固碳价值排名前三位的为赣州、吉安和抚州,排名后三位的是南昌、九江和鹰潭,其排名与森林面积和森林覆盖率有较大关系。 相似文献
198.
Aiguo Dai 《Climate Dynamics》2013,41(3-4):633-646
Precipitation over the contiguous United States exhibits large multi-decadal oscillations since the early twentieth century, and they often lead to dry (e.g., 1946–1976 and 1999-present) and wet (e.g., 1977–1998) periods and apparent precipitation trends (e.g., from the 1950s to 1990s) over most of the western and central US. The exact cause of these inter-decadal variations is not fully understood. Using observational and reanalysis data and model simulations, this paper examines the influence of the Inter-decadal Pacific Oscillation (IPO) on US precipitation. The IPO is a leading mode of sea surface temperatures (SSTs) seen mostly in the Pacific Ocean. It is found that decadal precipitation variations over much of the West and Central US, especially the Southwest, closely follow the evolution of the IPO (r = 0.85 during 1923–2010 for the Southwest US), and the dry and wet periods are associated, respectively, with the cold and warm phases of the IPO. In particular, the apparent upward trend from the 1950s–1990s and the dry decade thereafter in precipitation over much of the West and Central US are largely caused by the IPO cycles, which switched to a warm phase around 1977 and back to a cold phase around 1999. An atmospheric model forced with observed SSTs reproduces much of this association of US precipitation with the IPO (r = 0.95 between smoothed observed and simulated Southwest US precipitation during 1950–2009 and r = 0.88 between the simulated Southwest US precipitation and the IPO). Atmospheric reanalysis and model data both show a strong high (low) pressure center and anti-cyclonic (cyclonic) anomaly circulation over the North Pacific in the lower troposphere during cold (warm) phases of the IPO, which lead to dry and cold northwesterly and northerly winds and below-normal precipitation over much of the West US during IPO cold periods. The IPO induced changes are most pronounced during the boreal cold season. The results reinforce the notion that tropical Pacific SSTs (and the accompanying SST anomalies in the North Pacific) have large impacts on US precipitation and highlight the need to understand and simulate the IPO for decadal prediction of US precipitation. 相似文献
199.
The Beijing meteorological tower is located in an area of Beijing, China, which has developed from a suburban to an inner city setting over the past 30 years. The impacts of this urbanization process on both the vertical profile and diurnal cycles of air temperature are investigated using hourly data collected from a series of monitoring levels (up to 325 m high) on the Beijing meteorological tower since 1984. We find that the inter-decadal temperature has increased gradually, and that a more significant increase occurred during the 1980s and 1990s due to the effects of urbanization. A well-defined change in temperature stratification was also observed over this period. The height of the temperature inversion layer decreased from the 1980s to the 2000s. A well-defined nighttime temperature inversion developed below 50 m during the summer in the 1980s, but this near-surface inversion is not seen in data from the 1990s and 2000s. This change can be related to an increase in turbulent mixing caused by urban roughness and surface heat storage that disturbs the near-surface temperature inversion layer. In addition, the diurnal change in temperature in the city in summer shows a maximum increase from sunrise to the early afternoon, which is mainly caused by the nature variability and global warming in both the summer and winter. The urbanization mainly contributes to the temperature increase in the afternoon and nighttime. Moreover the urbanization dominates the increase in daily mean near-surface temperature. 相似文献
200.