全文获取类型
收费全文 | 348篇 |
免费 | 102篇 |
国内免费 | 87篇 |
专业分类
测绘学 | 29篇 |
大气科学 | 122篇 |
地球物理 | 169篇 |
地质学 | 125篇 |
海洋学 | 45篇 |
天文学 | 1篇 |
综合类 | 20篇 |
自然地理 | 26篇 |
出版年
2024年 | 4篇 |
2023年 | 12篇 |
2022年 | 10篇 |
2021年 | 14篇 |
2020年 | 15篇 |
2019年 | 24篇 |
2018年 | 21篇 |
2017年 | 23篇 |
2016年 | 18篇 |
2015年 | 29篇 |
2014年 | 26篇 |
2013年 | 42篇 |
2012年 | 26篇 |
2011年 | 20篇 |
2010年 | 24篇 |
2009年 | 17篇 |
2008年 | 19篇 |
2007年 | 18篇 |
2006年 | 29篇 |
2005年 | 21篇 |
2004年 | 10篇 |
2003年 | 16篇 |
2002年 | 7篇 |
2001年 | 9篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1997年 | 11篇 |
1996年 | 7篇 |
1995年 | 13篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 9篇 |
1990年 | 2篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有537条查询结果,搜索用时 343 毫秒
21.
飞机颠簸对飞机运行安全及旅客舒适度具有很大危害,提高飞机颠簸的预报准确率对于减轻人员伤害和财产损失具有重要意义,且一直是航空气象研究的重点领域。随着观测手段的丰富和科学技术的进步,飞机颠簸预报也取得了长足发展。本文首先从定性预报和定量预报的角度对国内外飞机颠簸预报的主要方法,特别是人工智能(AI)方法在其中的最新应用进行了综述。在此基础上,归纳总结出AI用于飞机湍流预报存在的主要问题和未来的重点研究方向:1)飞机实况数据的开放共享以及多源湍流数据的融合构建问题;2)基于人工智能构建飞机颠簸预报模型的可解释性及物理机制问题;3)基于人工智能构建飞机颠簸的集合预报问题。最后,提出了气象领域未来第三代人工智能的发展思路。 相似文献
22.
Yasaman Jafariavval 《Marine Georesources & Geotechnology》2020,38(2):214-222
AbstractLiquefaction of loose saturated soil deposits is a hazardous type of ground failure occurring under earthquake excitations. Therefore, an accurate estimation of liquefaction potential is extremely important in geotechnical engineering. In the current study, a new model is proposed which estimates the level of strain energy needed for liquefaction initiation. A compiled database containing cyclic tests gathered from previously published works was used to develop new models to predict liquefaction potential. M5′ algorithm was used to find the best correlation between parameters. It was shown that not only the derived formulas are acceptably accurate but also they feature a very simple structure in comparison with available formulas in the literature. The proposed equations are accurate, physically sound and uncomplicated. Furthermore, safety factors were given for different levels of risk, which can be useful for engineering practice. In addition, the influence of different predictors on the liquefaction potential was evaluated and also the significance of input variables was assessed via sensitivity analysis. Finally, a new model was introduced for preliminary estimation of liquefaction potential. 相似文献
23.
24.
加强目标观测,服务防灾减灾 总被引:3,自引:0,他引:3
以深入浅出的方式介绍了目标观测的定义、历史、确定目标观测敏感区的方法,以及实施目标观测与防灾减灾的关系;并以欧洲中期天气预报中心目标观测业务化为例,简明地概括了目标观测的实施过程;结合国内目标观测研究现状,对中国目标观测的未来提出了看法。 相似文献
25.
In river bank filtration, impurities present in the river water travel with the bank filtrate towards the pumping well. During this passage, certain types of impurities, such as turbidity, total coliform, and so forth, may get attenuated; however, it is interesting to note that some of the instant raw river water quality parameters, such as alkalinity and electrical conductivity, increase after the passage of water through the porous medium. This occurs because water, when passing through the soil pores, absorbs many of the solutes that cause an increase in alkalinity and electrical conductivity. Measurements at a river bank filtration site for a year showed that alkalinity of 116–32 mg l?1 in river water increased to 222.4–159.9 mg l?1 in the river bank filtered water. Likewise, the electrical conductivity increased from 280–131 μS cm?1 to 462–409.6 μS cm?1. This study uses a probabilistic approach for investigating the variation of alkalinity and electrical conductivity of source water that varies with the natural logarithm of the concentration of influent water. The probabilistic approach has the potential of being used in simulating the variation of alkalinity and electrical conductivity in river bank filtrate. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
26.
Kyungcho Bae Recent PhD graduate in Mineral Economics DeVerle Harris 《Natural Resources Research》1995,4(4):325-339
Monthly consumption forecasts for U.S. oil, natural gas, and coal are made using state space and multiple regression applied to the same data. These forecasts are compared with actual consumption for a test period. The forecasts made using state space are preferred to those made using multiple regression models for both expost and exante cases. The state space forecasts track data cycles better than do the regression forecasts. Average absolute forecast errors are less for the state space models than they are for the multiple regression models. 相似文献
27.
利用Threat Score方法,对1991年6月12—15日,6月29日—7月12日江淮持续暴雨的定量预报进行了检验。结果表明,对于大雨和暴雨预报,目前主观预报优于客观预报。数值预报在降雨定量预报的某些方面有了一定突破。 相似文献
28.
29.
An AMT-model,consisting of a trajectory model and a one-dimensional boundary layer model,is tested fortrajectories arriving in Taiyuan to study the possibility of using it in Taiyuan.The sensitivity of the model tothe different processes was studied.Some parameters of the model were modified for the purpose of forecast-ing in specific mountainous terrain and dry climate conditions.Results of examples which we have workedout for Taiyuan circumstances for the periods of July(summer)1985 and January(winter)1986,show that the12h runs of the AMT-model are able to reproduce(on historical data)the sounding of Taiyuan.The AMT-modelcontributes fruitfully to short-range weather forecasts(12—36h ahead)during periods of severe air pollution andwhen cold waves occur. 相似文献
30.
Statistical analysis of time-dependent earthquake occurrence and its impact on hazard in the low seismicity region Lower Rhine Embayment 总被引:1,自引:0,他引:1
Licia Faenza Sebastian Hainzl Frank Scherbaum Céline Beauval 《Geophysical Journal International》2007,171(2):797-806
The time-dependence of earthquake occurrence is mostly ignored in standard seismic hazard assessment even though earthquake clustering is well known. In this work, we attempt to quantify the impact of more realistic dynamics on the seismic hazard estimations. We include the time and space dependences between earthquakes into the hazard analysis via Monte Carlo simulations. Our target region is the Lower Rhine Embayment, a low seismicity area in Germany. Including aftershock sequences by using the epidemic type aftershock-sequence (ETAS) model, we find that on average the hypothesis of uncorrelated random earthquake activity underestimates the hazard by 5–10 per cent. Furthermore, we show that aftershock activity of past large earthquakes can locally increase the hazard even centuries later. We also analyse the impact of the so-called long-term behaviour, assuming a quasi-periodic occurrence of main events on a major fault in that region. We found that a significant impact on hazard is only expected for the special case of a very regular recurrence of the main shocks. 相似文献