全文获取类型
| 收费全文 | 66篇 |
| 免费 | 4篇 |
| 国内免费 | 1篇 |
专业分类
| 测绘学 | 3篇 |
| 大气科学 | 9篇 |
| 地球物理 | 11篇 |
| 地质学 | 19篇 |
| 海洋学 | 24篇 |
| 天文学 | 2篇 |
| 自然地理 | 3篇 |
出版年
| 2021年 | 2篇 |
| 2020年 | 1篇 |
| 2019年 | 1篇 |
| 2018年 | 3篇 |
| 2017年 | 2篇 |
| 2016年 | 4篇 |
| 2015年 | 3篇 |
| 2014年 | 5篇 |
| 2013年 | 4篇 |
| 2012年 | 6篇 |
| 2011年 | 6篇 |
| 2010年 | 4篇 |
| 2009年 | 7篇 |
| 2008年 | 7篇 |
| 2007年 | 1篇 |
| 2006年 | 3篇 |
| 2005年 | 4篇 |
| 2004年 | 1篇 |
| 2003年 | 1篇 |
| 2001年 | 2篇 |
| 1996年 | 2篇 |
| 1993年 | 1篇 |
| 1973年 | 1篇 |
排序方式： 共有71条查询结果，搜索用时 15 毫秒
61.
62.
A sample of coastal marine fulvic acids (mfua) was studied and its binding site structures that form stable complexes with metal ions were identified. A previously developed self-modeling methodology, based on the coupling of synchronous fluorescence (SyF) spectroscopy with evolving factor analysis (EFA), was used for the analysis of the interactions between mfua and two metal ions that act as probes for binding sites, namely Be(II) and Al(III). Two types of binding site structures were detected, probably of the salicylic acid and catechol types. The values of the conditional stability constants between mfua and the two metal ions were: for Be(II), at pH = 6, log K = 5.32(8); for Al(III), at pH = 4, log K = 5.1(2). The concentration of the corresponding binding sites was found to be less than one half of those found for soil fulvic acid samples. 相似文献
63.
Atsamon Limsakul Toshiro Saino Takashi Midorikawa Joaquim I. Goes 《Progress in Oceanography》2001,49(1-4)
An examination of large archives (1950–1997) of the oceanographic and atmospheric data from the northwestern North Pacific Subtropical Gyre has revealed clear linkages between atmospheric forcing factors, physical processes and biological events. Large changes in the winter and spring biomass of phytoplankton and macroplankton observed over annual, decadal and inter-decadal time scales could clearly be attributed to climate-related changes in oceanographic processes. Interannual changes in the intensity of the winter-time East Asian Monsoon had a significant impact on the extent of convective overturning, on nitrate inputs into the euphotic zone and the concentrations of chlorophyll a in winter and during the following spring. A prolonged period of deeper winter mixed layers observed from the mid-1970s to the mid-1980s led to a sizeable increase in winter mixed-layer nitrate concentrations. This change resulted in a decrease in winter-time phytoplankton biomass. Spring-time chlorophyll a, in contrast, showed a steady increase during this period. The decline in winter phytoplankton biomass could be attributed to the depths of mixed layer. A deeper mixed layer prevents phytoplankton from remaining in the euphotic zone for long enough to photosynthesize and grow, leaving substantial amounts of nutrients unutilised. However, as a result of stratification of the water column in spring following each of these winters, phytoplankton could take advantage of the enhanced ambient concentrations of nutrients and increase its biomass. Another noteworthy observation for the period from the mid-1970s to the early 1980s is that the western subtropical gyre progressively became phosphate limited. The period of diminishing mixed-layer phosphate concentrations was observed in our study area from the early 1990s onwards was consistent with recent observations at Station ALOHA in the eastern subtropical gyre. 相似文献
64.
The salt mist present in the coastal shoreline constitutes an important weathering agent of the building materials applied in these regions. Portugal has an extensive coastline, which has a high population density. It holds a long tradition in the use of stone as a building material, due to the abundance of this natural resource, but also because of its durability and beauty. Considering the main ornamental stones mined in Portugal, limestones are the most susceptible to the action of saline atmospheric aerosol, because, in most cases, they present open porosities higher than those of other stone types. This feature facilitates the penetration of saline aerosol in their structures. Six widely applied Portuguese limestones, with different technological properties, were selected for this study. After accessing their petrographic and main technological features, the limestones were submitted to salt mist test. The test method, established in the respective European standard, was complemented with further determinations (variation on water absorption and flexural strength after salt mist cycling). The results allowed evaluating the limestones’ suitability for the main types of applications and for specific usage conditions, within each one. Thus, it was possible to set the recommended uses for each limestone, in order to maximize its durability. Salt mist testing made possible to determine the limestones’ resistance to the climatic conditions of coastal areas. The detailed analysis of the salt mist results strengthens the knowledge that the open porosity plays a decisive role in the limestones’ behaviour to this test. 相似文献
65.
Stefan Zacharias Mark Reyers Joaquim G. Pinto Jan H. Schween Susanne Crewell Michael Kerschgens 《Meteorology and Atmospheric Physics》2012,117(1-2):47-61
High-resolution simulations with a mesoscale model are performed to estimate heat and moisture budgets of a well-mixed boundary layer. The model budgets are validated against energy budgets obtained from airborne measurements over heterogeneous terrain in Western Germany. Time rate of change, vertical divergence, and horizontal advection for an atmospheric column of air are estimated. Results show that the time trend of specific humidity exhibits some deficiencies, while the potential temperature trend is matched accurately. Furthermore, the simulated turbulent surface fluxes of sensible and latent heat are comparable to the measured fluxes, leading to similar values of the vertical divergence. The analysis of different horizontal model resolutions exhibits improved surface fluxes with increased resolution, a fact attributed to a reduced aggregation effect. Scale-interaction effects could be identified: while time trends and advection are strongly influenced by mesoscale forcing, the turbulent surface fluxes are mainly controlled by microscale processes. 相似文献
66.
The role of small prey in human subsistence strategies from Early Upper Palaeolithic sites in Iberia: the rabbits from the Evolved Aurignacian level of Arbreda Cave 
下载免费PDF全文
下载免费PDF全文 67.
Alfredo L. Aretxabaleta Keston W. Smith Dennis J. McGillicuddy Joaquim Ballabrera-Poy 《Ocean Modelling》2011,36(3-4):219-227
A simple improvement to objective analysis of hydrographic data is proposed to eliminate spatial aliasing effects in tidally energetic regions. The proposed method consists of the evaluation of anomalies from observations with respect to circulation model fields. The procedure is run iteratively to achieve convergence. The method is applied in the Bay of Fundy and compared with traditional objective analysis procedures and dynamically adjusted climatological fields. The hydrographic skill (difference between observed and model temperature and salinity) of the dynamically adjusted objective analysis is significantly improved by reducing bias and correcting the vertical structure. Representation of the observed velocities is also improved. The resulting flow is consistent with the known circulation in the Bay. 相似文献
68.
69.
70.