全文获取类型
| 收费全文 | 507篇 |
| 免费 | 301篇 |
| 国内免费 | 349篇 |
专业分类
| 测绘学 | 2篇 |
| 大气科学 | 723篇 |
| 地球物理 | 45篇 |
| 地质学 | 222篇 |
| 海洋学 | 80篇 |
| 天文学 | 45篇 |
| 综合类 | 17篇 |
| 自然地理 | 23篇 |
出版年
| 2024年 | 5篇 |
| 2023年 | 21篇 |
| 2022年 | 24篇 |
| 2021年 | 26篇 |
| 2020年 | 36篇 |
| 2019年 | 42篇 |
| 2018年 | 35篇 |
| 2017年 | 36篇 |
| 2016年 | 34篇 |
| 2015年 | 42篇 |
| 2014年 | 58篇 |
| 2013年 | 64篇 |
| 2012年 | 53篇 |
| 2011年 | 65篇 |
| 2010年 | 49篇 |
| 2009年 | 53篇 |
| 2008年 | 57篇 |
| 2007年 | 75篇 |
| 2006年 | 62篇 |
| 2005年 | 53篇 |
| 2004年 | 39篇 |
| 2003年 | 24篇 |
| 2002年 | 36篇 |
| 2001年 | 28篇 |
| 2000年 | 27篇 |
| 1999年 | 28篇 |
| 1998年 | 11篇 |
| 1997年 | 13篇 |
| 1996年 | 16篇 |
| 1995年 | 12篇 |
| 1994年 | 9篇 |
| 1993年 | 12篇 |
| 1992年 | 4篇 |
| 1991年 | 4篇 |
| 1990年 | 2篇 |
| 1989年 | 1篇 |
| 1987年 | 1篇 |
排序方式： 共有1157条查询结果，搜索用时 15 毫秒
31.
32.
The present study validated the capability of the AM2.1, a model developed at NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL), in reproducing the fundamental features of the East Asian Subtropical Westerly Jet Stream (EASWJ). The main behaviors of the EASWJ are also investigated through the reanalysis of observational NCEP/NCAR data. The mean state of the EASWJ, including its intensity, location, structure, and seasonal evolution is generally well-portrayed in the model. Compared with the observation, the model tends to reproduce a weaker jet center. And, during summer, the simulated jet center is northward-situated. Results also demonstrate the model captures the variability of EASWJ during summer well. The results of the empirical orthogonal function (EOF) applied on the zonal wind at 200 hPa (U200) over East Asia for both the observation and simulation indicate an inter-decadal shift around the late 1970s. The correlation coefficient between the corresponding principle components is as great as 0.42 with significance at the 99% confidence level. 相似文献
33.
Weakening of Interannual Variability in the Summer East Asian Upper-tropospheric Westerly Jet since the Mid-1990s 总被引：4，自引：1，他引：3
In this study,we found that the intensity of interannual variability in the summer upper-tropospheric zonal wind has significantly weakened over Northeast Asia and the subtropical western North Pacific(WNP) since the mid-1990s,concurrent with the previously documented decrease of the westerly jet over North China and Northwest China.Corresponding to this weakening of zonal wind variability,the meridional displacement of the East Asian westerly jet(EAJ) manifested as the leading mode of zonal wind variability over the WNP and East Asia(WNP-EA) before the mid-1990s but not afterward.The energetics of the anomalous pattern associated with the meridional displacement of the EAJ suggests that barotropic energy conversion,from basic flow to anomalous patterns,has led to the weakening of the variability in the EAJ meridional displacement and to a change in the leading dominant mode since the mid-1990s.The barotropic energy conversion efficiently maintained the anomalies associated with the variability in the EAJ meridional displacement during 1979-1993 but acted to dampen the anomalies during 1994-2008.A further investigation of the energetics suggests that the difference in the patterns of the circulation anomaly associated with either the first leading mode or the meridional displacement of the EAJ,i.e.,a southwest-northeast tilted pattern during 1979-1993 and a zonally oriented pattern during 1994-2008,has contributed greatly to the change in barotropic energy conversion. 相似文献
34.
35.
四川省武都水库右岸EL574 m灌浆平洞揭露出厚度2.3～9.8 m的粉细砂层,普通水泥高压灌浆无法形成可靠的防渗帷幕。采用高压旋喷、湿磨细水泥、化学灌浆的组合处理方式,取得了较好的施工效果。通过钻孔压水、大功率声波CT、单孔声波、钻孔全景数字成像等方法检测,表明达到了设计防渗要求。 相似文献
36.
37.
38.
高压喷射注浆于1968年首创于日本。我国于20世纪70年代初相继引进并开始研究高压喷射注浆技术。目前,高压旋喷工艺应用最为广泛,工艺技术最为成熟。对旋喷桩成桩质量及单桩承载力进行研究分析,为旋喷桩在地基与基础工程、水利水电工程、止水、加固工程中的应用提供设计参考依据。该试验在陕西省延安市某建成小区内选三个试验点,按不同旋喷桩施工工艺成桩,通过对桩身完整性检测、单桩承载力试验,分析旋喷桩成桩质量及单桩承载力。 相似文献
39.
利用1961—2005年逐候资料对东亚副热带西风急流初夏至盛夏变化与江淮出梅的关系进行了分析。结果表明,多年平均7月初夏至盛夏急流中心由西太平洋地区西跳至青藏高原的同时我国东部地区急流北跳至37.5°N以北,比梅雨结束早1候;急流北跳使得我国东部高空强辐散中心北移至华北地区,江淮地区上空辐散显著减弱,上升运动减弱,从而使得江淮梅雨结束,雨带北移;而急流中心的西跳仅使得我国东部地区高空辐散中心减弱,降水减弱,有利于雨带北移。我国东部急流北跳与江淮地区梅雨结束时间显著正相关,在北跳偏早(晚)年份梅雨结束早(晚),长江中下游地区降水偏少(多),而急流中心西跳早晚对我国华北北部地区和淮河附近地区降水有较大影响。可见,我国东部急流北跳与梅雨结束关系密切,可作为梅雨结束的先期信号。 相似文献
40.
Chaofan LI Riyu LU Nick DUNSTONE Adam A.SCAIFE Philip E.BETT Fei ZHENG 《大气科学进展》2021,38(12):2055-2066
During June and July of 2020, the Yangtze River basin suffered from extreme mei-yu rainfall and catastrophic flooding. This study explores the seasonal predictability and associated dynamical causes for this extreme Yangtze River rainfall event, based on forecasts from the Met Office GloSea5 operational forecast system. The forecasts successfully predicted above-average rainfall over the Yangtze River basin, which arose from the successful reproduction of the anomalous western North Pacific subtropical high (WNPSH). Our results indicate that both the Indian Ocean warm sea surface temperature (SST) and local WNP SST gradient were responsible for the westward extension of the WNPSH, and the forecasts captured these tropical signals well. We explore extratropical drivers but find a large model spread among the forecast members regarding the meridional displacements of the East Asian mid-latitude westerly jet (EAJ). The forecast members with an evident southward displacement of the EAJ favored more extreme Yangtze River rainfall. However, the forecast Yangtze River rainfall anomaly was weaker compared to that was observed and no member showed such strong rainfall. In observations, the EAJ displayed an evident acceleration in summer 2020, which could lead to a significant wind convergence in the lower troposphere around the Yangtze River basin, and favor more mei-yu rainfall. The model forecast failed to satisfactorily reproduce these processes. This difference implies that the observed enhancement of the EAJ intensity gave a large boost to the Yangtze River rainfall, hindering a better forecast of the intensity of the event and disaster mitigation. 相似文献