全文获取类型
收费全文 | 131篇 |
免费 | 9篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 7篇 |
大气科学 | 17篇 |
地球物理 | 19篇 |
地质学 | 54篇 |
海洋学 | 13篇 |
天文学 | 19篇 |
综合类 | 1篇 |
自然地理 | 12篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 7篇 |
2012年 | 4篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2009年 | 7篇 |
2008年 | 11篇 |
2007年 | 7篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 2篇 |
1999年 | 3篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有142条查询结果,搜索用时 15 毫秒
81.
Alexis Hannart Michael Ghil Jean-Louis Dufresne Philippe Naveau 《Climatic change》2013,119(3-4):585-601
How will our estimates of climate uncertainty evolve in the coming years, as new learning is acquired and climate research makes further progress? As a tentative contribution to this question, we argue here that the future path of climate uncertainty may itself be quite uncertain, and that our uncertainty is actually prone to increase even though we learn more about the climate system. We term disconcerting learning this somewhat counter-intuitive process in which improved knowledge generates higher uncertainty. After recalling some definitions, this concept is connected with the related concept of negative learning that was introduced earlier by Oppenheimer et al. (Clim Change 89:155–172, 2008). We illustrate disconcerting learning on several real-life examples and characterize mathematically certain general conditions for its occurrence. We show next that these conditions are met in the current state of our knowledge on climate sensitivity, and illustrate this situation based on an energy balance model of climate. We finally discuss the implications of these results on the development of adaptation and mitigation policy. 相似文献
82.
With the increasing precision of the GRAIL gravity field models and topography from LOLA, it is possible to investigate the substructure beneath crater Clavius. An admittance between gravity and topography data is commonly used to estimate selenophysical parameters, including load ratio, crustal thickness and density, and elastic thickness. Not only a surface load, but also a subsurface load is considered in estimation. The algorithm of particle swarm optimization(PSO) with a swarm size of 400 is employed as well.Results indicate that the observed admittance is best-fitted by the modeled admittance based on a spherical shell model, which was proved to be unsatisfactory in the previous study. The best-fitted load ratio f is around-0.194. Such a small load ratio conforms to the direct proportion between the nearly uncompensated topography and its corresponding negative gravity anomaly. It also indicates that a surface load dominates all the loads. Constrained within 2σSTD, a small crustal thickness(~30 km) and a crustal density of ~2587 kg m-3are found, quite close to the results from previous GRAIL research. Considering the well constrained crustal thickness and density, the best-fitted elastic thickness(~7 km) is rational. This result is slightly smaller than the previous study(~12 km). Such difference can be attributed to the difference in crustal density used and the precision of gravity and topography data. Considering that the small difference between the modeled gravity anomaly and observations is quite small, a parameter inversed here could be an indicator of the subsurface structure beneath Clavius. 相似文献
83.
84.
This paper presents a wavelet analysis of temporal and spatial variations of the Earth’s gravitational potential based on
tensor product wavelets. The time-space wavelet concept is realized by combining Legendre wavelets for the time domain and
spherical wavelets for the space domain. In consequence, a multiresolution analysis for both temporal and spatial resolution
is formulated within a unified concept. The method is then numerically realized by using first synthetically generated data
and finally two real data sets. 相似文献
85.
利用MODIS资料遥感香港地区高分辨率气溶胶光学厚度 总被引:28,自引:2,他引:28
在美国国家航空和宇航局(NASA)利用中分辨率成像光谱仪(MODIS)遥感大气气溶胶业务算法的基础上, 提出了一个1 km高分辨率气溶胶光学厚度反演方法, 并应用于香港地区的反演. 与地面太阳光度计的长期对比相对偏差大约为20%以内, 显示这一方法在香港地区的试用具有较高的精度.将该产品应用于空气污染个例, 并与香港地区14个站的地面污染物PM10(直径在10 μm以下的气溶胶颗粒物)质量浓度的变化进行了比较, 结果显示气溶胶光学厚度产品可以用来描绘城市尺度的气溶胶污染分布, 提供了更好地研究大气环境污染的新信息. 相似文献
86.
Alexis S. Templeton Kung-Hui Chu Lisa Alvarez-Cohen 《Geochimica et cosmochimica acta》2006,70(7):1739-1752
Carbon isotope fractionation factors reported for aerobic bacterial oxidation of CH4(αCH4-CO2) range from 1.003 to 1.039. In a series of experiments designed to monitor changes in the carbon isotopic fractionation of CH4 by Type I and Type II methanotrophic bacteria, we found that the magnitude of fractionation was largely due to the first oxidation step catalyzed by methane monooxygenase (MMO). The most important factor that modulates the (αCH4-CH3OH) is the fraction of the total CH4 oxidized per unit time, which strongly correlates to the cell density of the growth cultures under constant flow conditions. At cell densities of less than 0.1 g/L, fractionation factors greater than 1.03 were observed, whereas at cell densities greater than 0.5 g/L the fractionation factors decreased to as low as 1.002. At low cell densities, low concentrations of MMO limit the amount of CH4 oxidized, while at higher cell densities, the overall rates of CH4 oxidation increase sufficiently that diffusion of CH4 from the gaseous to dissolved state and into the cells is likely the rate-determining step. Thus, the residual CH4 is more fractionated at low cell densities, when only a small fraction of the total CH4 has been oxidized, than at high cell densities, when up to 40% of the influent CH4 has been utilized. Therefore, since Rayleigh distillation behavior is not observed, δ13C values of the residual CH4 cannot be used to infer the amount oxidized in either laboratory or field-studies. The measured (αCH4-CH3OH) was the same for both Type I and Type II methanotrophs expressing particulate or soluble MMO. However, large differences in the δ13C values of biomass produced by the two types of methanotrophs were observed. Methylosinus trichosporium OB3b (Type II) produced biomass with δ13C values about 15‰ higher than the dissimilated CO2, whereas Methylomonas methanica (Type I) produced biomass with δ13C values only about 6‰ higher than the CO2. These effects were independent of the magnitude of the initial carbon isotope fractionation caused by MMO and were relatively constant despite changing ratios of assimilatory to dissimilatory carbon transformation by the organisms. This suggests that the difference in biomass carbon isotopes is primarily due to differences in the fractionation effect at the formaldehyde branch point in the metabolic pathway, rather than assimilation of CO2 by Type II methanotrophs. 相似文献
87.
88.
Annie Souriau Matthieu Sylvander Valérie Maupin Jean-François Fels Alexis Rigo 《Comptes Rendus Geoscience》2002,334(3):155-161
This study presents a detailed analysis of the seismic records of a strong explosion that occurred on 21 September 2001 at a chemical complex located south of Toulouse, France, and provoked important damages. The explosion, which is equivalent to a 3.4 magnitude earthquake, has been recorded at most of the stations of the National Seismological Network, as well as at a station under test at the ‘Observatoire Midi-Pyrénées’, 4.2 km away from the epicentre. The main seismic phases are interpreted using the known crustal structures, and a modelling with synthetic seismograms is performed. To cite this article: A. Souriau et al., C. R. Geoscience 334 (2002) 155–161. 相似文献
89.
90.