全文获取类型
收费全文 | 54篇 |
免费 | 1篇 |
专业分类
地球物理 | 23篇 |
地质学 | 18篇 |
海洋学 | 7篇 |
天文学 | 3篇 |
自然地理 | 4篇 |
出版年
2020年 | 1篇 |
2019年 | 2篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2014年 | 1篇 |
2013年 | 5篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2001年 | 2篇 |
1999年 | 7篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1992年 | 4篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1956年 | 1篇 |
1954年 | 1篇 |
1949年 | 1篇 |
排序方式: 共有55条查询结果,搜索用时 15 毫秒
11.
In studies of temporal variation in dust activity, rainfall recorded at the same location as the dust events (local rainfall) has commonly been used as a climatic control variable. The main objectives of this note are to test the validity of using local rainfall and to determine the improvement in the relationship between rainfall and dust activity that could be achieved by using regional rainfall in the dust source area. For the period 1960-1989 at Mildura, Australia, the likely dust source area was identified by analysing wind direction during dust events. It was found that a marked improvement in the correlation between dust activity and antecedent rainfall can be achieved by using the regional source area rainfall rather than local rainfall. The improved correlation suggests that widespread drought is more important than local below-average rainfall in intensifying dust activity. 相似文献
12.
Fish assemblages that included known predators of benthic crustaceans were compared between kelp and barren habitats in northeastern New Zealand using baited underwater video census methods. The benthic-feeding fish were observed in winter, spring/summer and autumn, as well as during night-time in spring/summer. Overall, the fish assemblages varied between barren and kelp habitat, being most marked in winter. Individual benthic-feeding species, such as grey mao mao (Scorpis lineolatus) and leatherjacket (Meuschenia scaber) were associated with barren habitat, while the spotted wrasse (Notolabrus celidotus) was more strongly associated with kelp habitat. The results suggest that changes in habitats on coastal reefs affect populations of species that are benthic predators, which may in turn influence the distribution and abundance of their prey species, such as juvenile spiny lobsters. 相似文献
13.
14.
The occurrence of gas hydrates in deep-water sections of the continental margins predicted from anomalous acoustic reflectors on seismic profiles has been confirmed by recent deep-sea drilling results. On the Pacific continental slope off Guatemala gas hydrates were brought up for the first time from two holes (497, 498A) drilled during Leg 67 of the DSDP in water depths of 2360 and 5500 m, respectively. The hydrates occur in organic matter-rich Pleistocene to Miocene terrigenous sediments. In the hydrate-bearing zone a marked decrease in interstitial water chlorinities was observed starting at about 10–20 m subbottom depth. Pore waters at the bottom of the holes (near 400 m subbottom) have as little as half the chlorinity of seawater (i.e. 9‰). Similar, but less pronounced, trends were observed during previous legs of the DSDP in other hydrate-prone segments of the continental margins where recharge of fresh water from the continent can be excluded (e.g. Leg 11). The crystallization of hydrates, like ice, excludes salt ions from the crystal structure. During burial the dissolved salts are separated from the solids. Subsidence results in a downward motion of the solids (including hydrates) relative to the pore fluids. Thawing of hydrates during recovery releases fresh water which is remixed with the pore fluid not involved in hydrate formation. The volume of the latter decreases downhole thus causing downward decreasing salinity (chlorinity). Hydrate formation is responsible for oxygen isotope fractionation with18O-enrichment in the hydrate explaining increasingly more positive δ18O values in the pore fluids recovered (after hydrate dissociation) with depth. 相似文献
15.
The characterization of refractory organic substances (ROS) is very complicated because of their heterogeneous structure. Size-exclusion chromatography with continuous detection of dissolved nitrogen (LC-DN), dissolved organic carbon (LC-DOC), and UV-absorbance (LC-UV) is a very useful analytical tool for the characterization of changes of ROS in natural aquatic systems and in technological treatment. The effect of natural, oxidative, and biochemical processes on formation and removal of ROS is described. Additionally the role of hydrolysable carbohydrates in the composition of ROS is presented. 相似文献
16.
17.
18.
Ocean Dynamics - Net deposition in estuaries is often linked to the estuarine turbidity maximum zones, in which fine, cohesive sediments accumulate due to residual transport by the estuarine... 相似文献
19.
20.
J.A. Esposito E.R. Christian V.K. Balasubrahmanyan L.M. Barbier J.F. Ormes R.E. Streitmatter B. Acharya B. Luzietti A. Hesse U. Heinbach W. Heinrich M. Henkel C. Pfeifer M. Simon 《Astroparticle Physics》1992,1(1)
A Large Isotopic Composition Experiment (ALICE) is a balloon-borne spectrometer which can determine the elemental and isotopic composition of galactic cosmic rays with energies near 1 GeV/nucleon. ALICE was flown from Prince Albert, Canada in August 1987, and remained at float altitude (120000 feet) for 14.7 hours. In this paper, we describe the experimental methods and analysis which will be used for subsequent isotopic analysis. We obtained very precise charge resolution over the entire designed range: 0.10 and 0.16 charge units at neon and iron, respectively. Results on the galactic cosmic ray abundances and absolute fluxes of the elements from neon through nickel are reported. 相似文献