全文获取类型
收费全文 | 188篇 |
免费 | 12篇 |
国内免费 | 7篇 |
专业分类
测绘学 | 7篇 |
大气科学 | 16篇 |
地球物理 | 38篇 |
地质学 | 67篇 |
海洋学 | 23篇 |
天文学 | 42篇 |
综合类 | 5篇 |
自然地理 | 9篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 3篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 16篇 |
2015年 | 8篇 |
2014年 | 16篇 |
2013年 | 10篇 |
2012年 | 13篇 |
2011年 | 10篇 |
2010年 | 9篇 |
2009年 | 16篇 |
2008年 | 7篇 |
2007年 | 8篇 |
2006年 | 6篇 |
2005年 | 11篇 |
2004年 | 2篇 |
2003年 | 9篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1998年 | 3篇 |
1995年 | 2篇 |
1994年 | 1篇 |
排序方式: 共有207条查询结果,搜索用时 15 毫秒
31.
Anton Varlamov Natalia Smirnova Masashi Hayakawa Kiyohumi Yumoto 《Acta Geophysica》2012,60(3):928-941
Fractal analysis of magnetic records (1 Hz sampling rate) of 5 stations (Guam, Moshiri, Paratunka, Magadan, and Chokurdakh)
located along the 210 magnetic meridian (210 MM) has been performed using the Higuchi method. The period of 22 months (October
1992 to July 1994) that embodies the date of the strong Guam earthquake of 8 August1993 has been considered. A comparison
of the ULF emissions scaling parameters (spectral exponents β and fractal dimensions D) obtained at different latitudes has been made. Dependence of β and D on the Kp index of geomagnetic activity has been analyzed for each of the 24 local time intervals. It is revealed that D decreases ( β increases) with increasing geomagnetic activity at all stations, but the rates of decrease (increase) are different at different
stations and in different time intervals. It is shown that the evening, night and early morning hours are preferable to study
magnetospheric effects, whereas the noon hours are the most suitable for the analysis of lithospheric effects. A possibility
of using the data of the 210 MM stations as reference materials for the Guam seismically active area is discussed. 相似文献
32.
Slavica Matijević Natalia Bojanić Grozdan Kušpilić Živana Ninčević Gladan 《Environmental Earth Sciences》2009,59(4):853-866
Phosphorus (P) species concentrations in 0–2 cm surface sediment layer were investigated monthly from November 2001 to December
2002 at the bay, channel and open sea stations in the middle Adriatic. Modified SEDEX method was used for inorganic phosphorus
species determination [P in biogenic (P-FD), authigenic (P-AUT), detrital apatite (P-DET) and P adsorbed on to iron oxides
and hydroxides (P–Fe)], and organic phosphorus (P-ORG). P-FD, P-AUT and P-DET concentration ranges (1.5–5.4, 0–2.7 and 0.4–3.4 μmol g−1, respectively) were similar at all stations, and showed no obvious common trend of seasonal changes. P–Fe ranged from 1.9
to 11.9 μmol g−1 with the highest values at bay station and higher seasonal oscillations than other inorganic P forms. P-ORG ranged from 0.3
to 18.7 μmol g−1 with higher concentrations at stations of fine-sized sediments and showed increased concentrations in warm part of the year
at all stations. Correlation between concentrations of P–Fe in the surface sediment layer and orthophosphate sediment-water
interface concentration gradients at bay and channel stations indicated to P–Fe importance in the orthophosphate benthic flux.
For the bay station, linkage between sediment P-ORG and chlorophyll a concentrations, primary production and microzooplankton abundance was established, indicating a 1 month delay of sediment
response to production fluctuations in the water column. 相似文献
33.
Natalia Fedorova Vladimir Levit Aliton Oliveira da Silva Deydila Michele Bonfim dos Santos 《Pure and Applied Geophysics》2013,170(4):689-709
Visibility analysis and forecast at the Maceio International Airport in the Brazilian Northeast (NEB) was the principal goal of this investigation. Surface meteorological data of the Maceio International Airport were used for low visibility frequency study. Low visibility in NEB was provoked more frequently by light fog (LF) formation (1,098 or 92 h month?1 on average). Haze and fog were very rare (81 h and one event per year, respectively on average). Light fog with a visibility less than 2 km usually was detected together with rain or drizzle. Low visibility was observed more frequently at night and during the rainy season. Applications of the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model for light fog forecast were tested. Thermodynamic processes were studied by vertical profile, elaborated by: (1) National Centers for Environmental Prediction (NCEP) reanalysis data for Maceio (because of some radiosonde absence) and (2) forecast vertical temperature and humidity profiles were produced, using Air Parcels Trajectories of the HYSPLIT model at the pattern levels. The synoptic situations before and during low visibility phenomena were analyzed using different products of NCEP reanalysis, the high resolution (10 km) ETA model and infrared satellite images. Wave disturbance in the trade winds field, localized on the northwest periphery of the South Atlantic subtropical High, usually accompanied the phenomena. A humidity advection, weak ascendant movement and thermal inversion absence at the low levels were created by these waves. The middle level’s descendent movement provoked the humidity accumulation at levels below. Satisfactory results of the HYSPLIT model applications for light fog forecast were obtained with 12 h antecedence. In particular, stable level forecast by the ETA model was forecast satisfactorily with 12 h antecedence; vertical movements were predicted better with up to 48 h antecedence. The PSU/NCAR mesoscale model (MM5) and PAFOG models were tested for analysis and forecast of an intensive fog event. Intensive fog provoked a fatal accident of a small airplane near the Maceio Airport in 2007. These fog formation processes were studied by NCEP reanalysis data, the high resolution regional model MM5, and satellite and radar data. Fog formation was simulated by PAFOG model and satisfactory results were obtained with 10 h antecedence. 相似文献
34.
Gama Andre B. Perondi Daniel Dewdney Megan M. Fraisse Clyde W. Small Ian M. Peres Natalia A. 《Theoretical and Applied Climatology》2022,149(1-2):83-99
Theoretical and Applied Climatology - Disease alert systems (DAS) of the AgroClimate platform are intended to facilitate grower decision-making when planning fungicide applications. These DAS... 相似文献
35.
Finn Løvholt Sylfest Glimsdal Carl B. Harbitz Natalia Zamora Farrokh Nadim Pascal Peduzzi Hy Dao Helge Smebye 《Earth》2012,110(1-4):58-73
In the aftermath of the 2004 Indian Ocean tsunami, a large increase in the activity of tsunami hazard and risk mapping is observed. Most of these are site-specific studies with detailed modelling of the run-up locally. However, fewer studies exist on the regional and global scale. Therefore, tsunamis have been omitted in previous global studies comparing different natural hazards. Here, we present a first global tsunami hazard and population exposure study. A key topic is the development of a simple and robust method for obtaining reasonable estimates of the maximum water level during tsunami inundation. This method is mainly based on plane wave linear hydrostatic transect simulations, and validation against results from a standard run-up model is given. The global hazard study is scenario based, focusing on tsunamis caused by megathrust earthquakes only, as the largest events will often contribute more to the risk than the smaller events. Tsunamis caused by non-seismic sources are omitted. Hazard maps are implemented by conducting a number of tsunami scenario simulations supplemented with findings from literature. The maps are further used to quantify the number of people exposed to tsunamis using the Landscan population data set. Because of the large geographical extents, quantifying the tsunami hazard assessment is focusing on overall trends. 相似文献
36.
Joseph G. Meert Anatoly S. Gibsher Natalia M. Levashova Warren C. Grice George D. Kamenov Alexander B. Ryabinin 《Gondwana Research》2011,19(4):867-880
The Cambrian explosion, c. 530–515 Ma heralded the arrival of a diverse assembly of multicellular life including the first hard-shelled organisms. Fossils found in Cambrian strata represent the ancestors of most modern animal phyla. In contrast to the apparent explosiveness seen in the Cambrian fossil record, studies of molecular biology hint that the diversification observed in Cambrian strata was rooted in ancestry extending back into the Ediacaran (635–542 Ma). Fossil evidence for this mostly cryptic phase of evolution is derived from the soft-bodied fossils of the Ediacaran biota found throughout the world and bilaterian embryos found in the Doushantuo lagerstätte in South China. The first appearance of Ediacara fauna is thought to have followed the last of the ~ 750–635 Ma Neoproterozoic glacial episodes by 20–30 million years. In this paper, we present evidence for the oldest discovery of the ‘Ediacara’ discoidal fossils Nimbia occlusa and Aspidella terranovica (?) that predate the early Cryogenian glaciations by more than fifty million years. There is considerable disagreement over the significance of discoidal Ediacaran fossils, but our findings may support earlier suggestions that metazoan life has roots extending deeper into the Proterozoic Eon. We also confirm the presence of a Late Cryogenian (e.g. “Marinoan”) glaciation on the Lesser Karatau microcontinent including dropstones and striated clasts within the glacial strata. 相似文献
37.
Dieter Stöffler Natalia A. Artemieva Kai Wünnemann W. Uwe Reimold Juliane Jacob Birgit K. Hansen Iona A. T. Summerson 《Meteoritics & planetary science》2013,48(4):515-589
We report results of an interdisciplinary project devoted to the 26 km‐diameter Ries crater and to the genesis of suevite. Recent laboratory analyses of “crater suevite” occurring within the central crater basin and of “outer suevite” on top of the continuous ejecta blanket, as well as data accumulated during the past 50 years, are interpreted within the boundary conditions imposed by a comprehensive new effort to model the crater formation and its ejecta deposits by computer code calculations (Artemieva et al. 2013). The properties of suevite are considered on all scales from megascopic to submicroscopic in the context of its geological setting. In a new approach, we reconstruct the minimum/maximum volumes of all allochthonous impact formations (108/116 km3), of suevite (14/22 km3), and the total volume of impact melt (4.9/8.0 km3) produced by the Ries impact event prior to erosion. These volumes are reasonably compatible with corresponding values obtained by numerical modeling. Taking all data on modal composition, texture, chemistry, and shock metamorphism of suevite, and the results of modeling into account, we arrive at a new empirical model implying five main consecutive phases of crater formation and ejecta emplacement. Numerical modeling indicates that only a very small fraction of suevite can be derived from the “primary ejecta plume,” which is possibly represented by the fine‐grained basal layer of outer suevite. The main mass of suevite was deposited from a “secondary plume” induced by an explosive reaction (“fuel‐coolant interaction”) of impact melt with water and volatile‐rich sedimentary rocks within a clast‐laden temporary melt pool. Both melt pool and plume appear to be heterogeneous in space and time. Outer suevite appears to be derived from an early formed, melt‐rich and clast‐poor plume region rich in strongly shocked components (melt ? clasts) and originating from an upper, more marginal zone of the melt pool. Crater suevite is obviously deposited from later formed, clast‐rich and melt‐poor plumes dominated by unshocked and weakly shocked clasts and derived from a deeper, central zone of the melt pool. Genetically, we distinguish between “primary suevite” which includes dike suevite, the lower sublayer of crater suevite, and possibly a basal layer of outer suevite, and “secondary suevite” represented by the massive upper sublayer of crater suevite and the main mass of outer suevite. 相似文献
38.
39.
Ioannis A. Daglis Georgios Balasis Natalia Ganushkina Fiori-Anastasia Metallinou Minna Palmroth Risto Pirjola Ioanna Tsagouri 《Acta Geophysica》2009,57(1):141-157
Comprehensive understanding of the dynamics of the coupled solar wind-magnetosphere-ionosphere system is of utmost interest,
both from the perspective of solar system astrophysics and geophysics research and from the perspective of space applications.
The physical processes involved in the dynamical evolution of this complex coupled system are pertinent not only for the Sun-Earth
connection, but also for major phenomena in other astrophysical systems. Furthermore, the conditions in geospace collectively
termed space weather affect the ever increasing technological assets of mankind in space and therefore need to be understood,
quantified and efficiently forecasted. The present collaborative paper communicates recent advances in geospace dynamic coupling
research through modeling, simulations and data analysis and discusses future directions. 相似文献
40.
Bartosz Czernecki Marek Półrolniczak Leszek Kolendowicz Michał Marosz Sebastian Kendzierski Natalia Pilguj 《Journal of Atmospheric Chemistry》2017,74(1):115-139
This study investigates atmospheric conditions’ influence on the mean and extreme characteristics of PM10 concentrations in Poznań during the period 2006–2013. A correlation analysis was carried out to identify the most important meteorological variables influencing the seasonal dynamics of PM10 concentrations. The highest absolute correlation values were obtained for planetary boundary layer height (r = ?0.57), thermal (daily minimum air temperature: r = ?0.51), anemological (average daily wind speed: r = ?0.37), and pluvial (precipitation occurrence: r = ?0.36) conditions, however the highest correlations were observed for temporal autocorrelations (1 day lag: r = 0.70). As regulated by law, extreme events were identified on the basis of daily threshold value i.e. 50 μg m?3. On average, annually there are approximately 71.3 days anywhere in the city when the threshold value is exceeded, 46.6 % of those occur in winter. Additionally, 83.7 % of these cases have been found to be continuous episodes of a few days, with the longest one persisting for 22 days. The analysis of the macro-scale circulation patterns led to the identification of an easy-to-perceive seasonal relations between atmospheric fields that favour the occurrence of high PM10 concentration, as well as synoptic situations contributing to the rapid air quality improvement. The highest PM10 concentrations are a clear reaction to a decrease in air temperature by over 3 °C, with simultaneous lowering of PBL height, mean wind speed (by around 1 m s?1) and changing dominant wind directions from western to eastern sectors. In most cases, such a situation is related to the expansion of a high pressure system over eastern Europe and weakening of the Icelandic Low. Usually, air quality conditions improve along with an intensification of westerlies associated with the occurrence of low pressure systems over western and central Europe. Opposite relations are distinguishable in summer, when air quality deterioration is related to the inflow of tropical air masses originating over the Sahara desert. 相似文献