全文获取类型
收费全文 | 76篇 |
免费 | 4篇 |
国内免费 | 3篇 |
专业分类
大气科学 | 6篇 |
地球物理 | 15篇 |
地质学 | 43篇 |
海洋学 | 1篇 |
天文学 | 18篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 12篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 2篇 |
2012年 | 5篇 |
2011年 | 4篇 |
2010年 | 9篇 |
2009年 | 4篇 |
2008年 | 2篇 |
2007年 | 8篇 |
2006年 | 6篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2002年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有83条查询结果,搜索用时 140 毫秒
61.
Zoran Micovic Desmond N. D. Hartford Melvin G. Schaefer Bruce L. Barker 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(2):559-581
The traditional and still prevailing approach to characterization of flood hazards to dams is the inflow design flood (IDF). The IDF, defined either deterministically or probabilistically, is necessary for sizing a dam, its discharge facilities and reservoir storage. However, within the dam safety risk informed decision framework, the IDF does not carry much relevance, no matter how accurately it is characterized. In many cases, the probability of the reservoir inflow tells us little about the probability of dam overtopping. Typically, the reservoir inflow and its associated probability of occurrence is modified by the interplay of a number of factors (reservoir storage, reservoir operating rules and various operational faults and natural disturbances) on its way to becoming the reservoir outflow and corresponding peak level—the two parameters that represent hydrologic hazard acting upon the dam. To properly manage flood risk, it is essential to change approach to flood hazard analysis for dam safety from the currently prevailing focus on reservoir inflows and instead focus on reservoir outflows and corresponding reservoir levels. To demonstrate these points, this paper presents stochastic simulation of floods on a cascade system of three dams and shows progression from exceedance probabilities of reservoir inflow to exceedance probabilities of peak reservoir level depending on initial reservoir level, storage availability, reservoir operating rules and availability of discharge facilities on demand. The results show that the dam overtopping is more likely to be caused by a combination of a smaller flood and a system component failure than by an extreme flood on its own. 相似文献
62.
63.
64.
Anna M. Nobili Gian Luca Comandi Suresh Doravari Donato Bramanti Rajeev Kumar Francesco Maccarrone Erseo Polacco Slava G. Turyshev Michael Shao John Lipa Hansjoerg Dittus Claus Laemmerzhal Achim Peters Jurgen Mueller C. S. Unnikrishnan Ian W. Roxburgh Alain Brillet Christian Marchal Jun Luo Jozef van der Ha Vadim Milyukov Valerio Iafolla David Lucchesi Paolo Tortora Paolo De Bernardis Federico Palmonari Sergio Focardi Dino Zanello Salvatore Monaco Giovanni Mengali Luciano Anselmo Lorenzo Iorio Zoran Knezevic 《Experimental Astronomy》2009,23(2):689-710
“Galileo Galilei” (GG) is a small satellite designed to fly in low Earth orbit with the goal of testing the Equivalence Principle—which
is at the basis of the General Theory of Relativity—to 1 part in 1017. If successful, it would improve current laboratory results by 4 orders of magnitude. A confirmation would strongly constrain
theories; proof of violation is believed to lead to a scientific revolution. The experiment design allows it to be carried
out at ambient temperature inside a small 1-axis stabilized satellite (250 kg total mass). GG is under investigation at Phase
A-2 level by ASI (Agenzia Spaziale Italiana) at Thales Alenia Space in Torino, while a laboratory prototype (known as GGG)
is operational at INFN laboratories in Pisa, supported by INFN (Istituto Nazionale di fisica Nucleare) and ASI. A final study
report will be published in 2009. 相似文献
65.
One deposit and four occurrences of uranium minerals in the Permo-Triassic sedimentary rocks of the Stara Planina in eastern Serbia were ascertained using data from years of multidisciplinary geological research. The minerals are the fissure-filling type, and were assigned to the exogenic mineralization group, being mostly epigene in nature. Relevant geological information was used to derive a genetic model of uranium mineralization in the Permo-Triassic sedimentary rocks of the Stara Planina. The model explains the formation of Permo-Triassic rocks and three stages of the complex process of U mineralization. The genetic model treats: (1) the primary sources of the uranium; (2) the mobility of uranium; and (3) accessory metals from the parent rocks to their deposition in host rocks and the postmineral change in ore bodies. A geochemical barrier zone was identified in the sedimentary rocks that contained uranium mineral ore. This geochemical barrier area included crescent-shaped, flat-lens, or vein-like ore bodies. The U-containing mineral described is comparable with those from the relatively common fissure-filling uranium minerals found around the world. 相似文献
66.
Spatial and temporal analysis of dry spells in Croatia 总被引:3,自引:1,他引:2
Systematic statistical analysis of dry day sequences, which are defined according to 0.1, 1, 5 and 10 mm of precipitation-per-day thresholds, is performed on seasonal and yearly basis. The data analysed come from 25 Croatian meteorological stations and cover the period 1961–2000. Climatological features of the mean and maximum dry spell durations, as well as the frequency of long dry spells (>20 days) are discussed. The results affirm the three main climatological regions in Croatia, with the highlands exhibiting shorter dry spells than the mainland, and the coastal region exhibiting longer dry spells. The prevailing positive trend of both mean and maximal durations is detected during winter and spring seasons, while negative trend dominate in autumn for all thresholds. Positive field significant trends of mean dry spell duration with 5 and 10 mm thresholds are found during spring and the same is valid for annual maximum dry spell duration with a 10 mm threshold. It is found that the Discrete Autoregressive Moving Average (DARMA(1,1)) model can be used to estimate the probabilities of dry spells in Croatia that are up to 20–30 days long. 相似文献
67.
The concentrations of air pollutants depend on meteorological conditions and pollutant emission level. From the statistical properties of air pollutants the number of times the daily average concentrations exceed the assigned air quality standard (AQS) can be estimated, as well as the level of reduction of particle matter emission sources required to meet the AQS. In this paper three statistical distributions (lognormal, Weibull and type V Pearson distribution) were used to fit the complete set of PM10 data for the Belgrade urban area during a three-year period (2003–2005). The method of moments and the method of least squares were both used to estimate the parameters of the three theoretical distributions. The type V Pearson distribution represented the PM10 daily average concentration most closely. However, the parent distributions sometimes diverged in predicting a high PM10 concentration and therefore asymptotic distributions of extreme values were used to fit the high PM10 concentration distribution more correctly. This method can successfully predict the return period and exceedances over a critical concentration in succeeding years. The estimated emission source reduction of PM10 to meet the assigned standard varied from 53% to 63% in the Belgrade urban area. The results provide useful information for air quality management and could be used to examine the similarities and differences among air pollution types in diverse areas. 相似文献
68.
Darka Marković Bojan Jokić Zoran Šaponjić Branislav Potkonjak Petar Jovančić Maja Radetić 《洁净——土壤、空气、水》2013,41(10):1002-1009
This paper discusses the possibility of immobilization of TiO2 nanoparticles onto recycled wool‐based nonwoven material, which can be utilized for removal of dyes from wastewater. The photocatalytic activity of TiO2 nanoparticles deposited on the nonwoven material was evaluated in the aqueous solution of direct dye C.I. Direct Blue 78 under the UV illumination. Nonwoven material modified with TiO2 nanoparticles provides complete removal of dye from the solution already after 4–6 h of UV illumination. However, photodegradation of the dye adsorbed on the nonwoven material was obtained within 24 h of UV illumination. The rate of dye adsorption and photodegradation depends on the amount of deposited TiO2 nanoparticles. The increase of initial dye concentration induced decrease in photocatalytic efficiency of immobilized TiO2 nanoparticles. The highest photodegradation rate was achieved in acidic conditions. Elevated temperatures positively affected the removal of dye from solution. Photocatalytic activity of TiO2 nanoparticles deposited on nonwoven material was preserved after three photodegradation cycles. 相似文献
69.
Massimiliano Guzzo Zoran Knežević Andrea Milani 《Celestial Mechanics and Dynamical Astronomy》2002,83(1-4):121-140
We apply the spectral formulation of the Nekhoroshev theorem to investigate the long-term stability of real main belt asteroids. We find numerical indication that some asteroids are in the so-called Nekhoroshev stability regime, that is they are on chaotic orbits but their motion is stable over very long times. We have analyzed the motion of bodies in different regions of the belt, to assess the sensitivity of our method. We found that it allows us to clearly discriminate between different dynamical regimes, such as the one described by the Nekhoroshev stability, the one well described by the KAM theory, and the unstable chaotic regime in which diffusion in phase space can be detected over time spans much shorter than the age of the solar system. 相似文献
70.