全文获取类型
收费全文 | 175篇 |
免费 | 3篇 |
专业分类
测绘学 | 4篇 |
大气科学 | 13篇 |
地球物理 | 23篇 |
地质学 | 47篇 |
海洋学 | 72篇 |
天文学 | 15篇 |
综合类 | 1篇 |
自然地理 | 3篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 8篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 6篇 |
2012年 | 5篇 |
2011年 | 9篇 |
2010年 | 9篇 |
2009年 | 18篇 |
2008年 | 10篇 |
2007年 | 12篇 |
2006年 | 11篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1996年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有178条查询结果,搜索用时 31 毫秒
51.
Ryuichi Kurosawa Tim J. Harries Neil H. Symington 《Monthly notices of the Royal Astronomical Society》2005,358(2):671-683
We present time-series echelle spectra of the Paβ line of the T Tauri star SU Aur, observed over three consecutive nights. The line shows strong variability (∼10 per cent) over the velocity range 100–420 km s−1 in the red broad absorption component, and weaker variability (∼2 per cent) over the velocity range −200–0 km s−1 in the blue wing. The variability in the velocity range −200–0 km s−1 is correlated with that in 200–400 km s−1 , and the variability in these velocity ranges anticorrelates with that in 0–100 km s−1 . The mean spectrum from the second night shows the suggestion of a blueshifted absorption component at about −150 km s−1 , similar to that found in the Hα and Hβ lines. We find the position of the subpeak in the red absorption component changes steadily with time, and its motion modulates at half the rotational period. We also find that the modulation of the line equivalent width is possibly associated with a half and a third of the rotational period, which is consistent with the surface Doppler images of SU Aur. Radiative transfer models of a rotationally modulated Paβ line, produced in the shock-heated magnetospheric accretion flow, are also presented. Models with a magnetic dipole offset reproduce the overall characteristics of the observed line variability, including the line equivalent width and the motion of the subpeak in the red absorption trough. 相似文献
52.
Osamu Seki Takeshi Nakatsuka Kimitaka Kawamura Sei-Ichi Saitoh Masaaki Wakatsuchi 《Marine Chemistry》2007,104(3-4):253-265
C37–C39 alkenones were measured in time-series sediment trap samples collected from August 1998 to June 2000 at two depths in the seasonal sea ice region of the western Sea of Okhotsk, off Sakhalin, in order to investigate alkenone production and water-column processes in the region. Measurable export fluxes of alkenones are ranged from < 0.1 to 5.8 μg/m2/day and clearly showed that the alkenone production was restricted to autumn. In 1998, maximum export flux of alkenones occurred in September when surface water column was well stratified with low nutrients in the surface mixing layer. In the next year, the maximum flux is observed in October. Comparison between alkenone temperature and satellite based sea surface temperature (SST) shows that the estimated alkenone temperatures in August 1998 were found to be 10 °C lower than the temporal satellite SST, suggesting that alkenones are produced in surface to subsurface thermocline layers during the period. Annual mean flux of alkenones is lower in the lower traps than that of the upper traps, suggesting rapid degradation of alkenones in water column, but the UK37′ value is not significantly altered. This study indicates that UK37′ values preserved in the surface sediments off Sakhalin reflect the seasonal temperature signal of near surface water, rather than annual mean surface temperature. 相似文献
53.
Ryuichi Sugisaki 《Lithos》1976,9(1):17-30
The chemical compositions of Quaternary volcanic products which occur along the closing boundary of plates vary systematically with the closing rate of the plates. It is probable that the amount of water provided to the wedge of the mantle from the descending plate controls the abundance of andesite, while the temperature distribution under volcanoes regulates the alkalinity of magmas. Both the water supply to the mantle and the temperature distribution are controlled by the closing rate of the plates. 相似文献
54.
Polyunsaturated fatty acids (C18:2 and C18:3ω3 were analyzed in the upper 20m layer of a 200 m long sediment core taken from Lake Biwa. Concentration maxima occur in layers at depths of 0.2, 1–5, 11–12, and 16m. The vertical changes in the ratio appear to correlate with paleoclimatic condition suggested from palynological evidence. On the basis of ratios, it was suggested that it has been colder at 200, 1000–4000, 15,000 and 20,000 yr BP than at other times. 相似文献
55.
The fine structure of laboratory wind-wave surfaces was investigated using an optical method. Several characteristic structures, closely associated with wind speed and the stage of development of the waves, are described. A parallel light, incident on the wind-wave surface, was backscattered by specular facets perpendicular to the incident angle. These specular facets, which represented the fine structures, were photographed and quantitatively analyzed by image processing techniques.For wind speeds ranging from 3.6 to 13.6 m s–1, different types of small-scale undulations appeared: a three-dimensional rhombic structure; a train of capillary waves on the forward face with wavelengths gradually decreasing with distance from the crest, and a streaky structure on the backward face in the direction of the wind; and random and wide-spreading irregularities covering the whole wind-wave surface. The spatial scales and temporal variation of the undulations are described. 相似文献
56.
Fatty acids (FAs), β- and ω-hydroxy acids, α,ω-dicarboxylic acids and n-alkanes were studied in a 200 m sediment core taken from Lake Biwa, Japan. FAs showed bimodal distribution with peaks at C16 and C22-C28. Their distribution patterns clearly changed with depth from lower molecular weight (C12-C19) predominance to higher molecular weight (C20-C32) predominance in the upper 20 m interval. Analyses of related compounds (β- and ω-hydroxy acids and α, ω-dicarboxylic acids) suggest that β- and ω-oxidative degradation of C12-C19 FAs has occurred in the sediments.The ratio of bound C12-C19 to unbound FAs increases with depth in the upper 0–1 m sediments, suggesting that unbound FAs are more labile. However, the ratio varies significantly in deeper sections and may be associated with water temperature.In the sediments deeper than 20 m in depth, C12-C19 FAs gradually decrease. On the other hand, higher molecular weight FAs (HFAs: C20-C32), which were probably derived from terrestrial plants, increase in concentration from 20 m to 100 m, suddenly decrease at 100 m and show progressively lower concentration in deeper sediments. These fluctuations are interpreted in relation to paleolimnological changes of the lake and the drainage basin. ω-Hydroxy C20-C30 acids and C20-C30α, ω-dicarboxylic acids show a distribution pattern similar to HFAs. Branched chain FAs, ω-hydroxy acids and C9-C19α,ω-dicarboxylic acids show a major peak around 3–15 m in depth. This peak is probably caused by increased bacterial activity in the water column and surface sediments in the past, which may be associated with an increase in primary production of the lake. 相似文献
57.
The West Philippine basin (WPB) is a currently inactive marginal basin belonging to Philippine Sea plate, which has a complex formation history and various crust structures. Based on gravity, magnetic and seismic data, the tectonics in West Philippine basin is characterized by amagnma spreading stage and strike slip fractures. NNE trending Okinawa-Luzon fracture zone is a large fracture zone with apparent geomorphology and shows a right-handed movement. The results of joint gravity-magnetic-seismic inversion suggest that the Okinawa-Luzon fracture zone has intensive deformation and is a transform fault. Western existence of the NW trending fractures under Ryukyu Islands Arc is the main cause of the differences between south and north Okinawa Trough. The Urdaneta plateau is not a remained arc, but remnant of mantle plume although its lava chemistry is similar to oceanic island basalt (OIB). 相似文献
58.
Wirasatriya Anindya Kawamura Hiroshi Helmi Muhammad Sugianto Denny Nugroho Shimada Teruhisa Hosoda Kohtaro Handoyo Gentur Putra Yoppik Disma Girindra Koch Magaly 《Ocean Dynamics》2020,70(6):771-786
Ocean Dynamics - The short-lived events of high SST are called hot events (HEs) and can only be generated under the conditions of large daily heat gain due to strong solar radiation and weak wind.... 相似文献
59.
Hideyuki Kawamura Toshimichi Ito Naoki Hirose Tetsutaro Takikawa Jong-Hwan Yoon 《Journal of Oceanography》2009,65(4):439-454
The branches of the Tsushima Warm Current (TWC) are realistically reproduced using a three-dimensional ocean general circulation
model (OGCM). Simulated structures of the First Branch and the Second Branch of the TWC (FBTWC and SBTWC) in the eastern Japan
Sea are mainly addressed in this study, being compared with measurement in the period September–October 2000. This is the
first numerical experiment so far in which the OGCM is laterally exerted by real volume transports measured by acoustic Doppler
current profiler (ADCP) through the Tsushima Straits and the Tsugaru Strait. In addition, sea level variation measured by
tide-stations along the Japanese coast as well as satellite altimeters is assimilated into the OGCM through a sequential data
assimilation method. It is demonstrated that the assimilation of sea level variation at the coastal tide-stations is useful
in reproducing oceanic conditions in the nearshore region. We also examine the seasonal variation of the branches of the TWC
in the eastern Japan Sea in 2000. It is suggested as a consequence that the FBTWC is continuous along northwestern Honshu
Island in summertime, while it degenerates along the coast between the Sado Strait and the Oga Peninsula in other seasons.
On the other hand, a mainstream of the SBTWC exists with meanders and eddies in the offshore region deeper than 1000 m to
the north of the Sado Island throughout the year. 相似文献
60.
A Review on the Currents in the South China Sea: Seasonal Circulation, South China Sea Warm Current and Kuroshio Intrusion 总被引:43,自引:4,他引:43
Researches on the currents in the South China Sea (SCS) and the interaction between the SCS and its adjacent seas are reviewed. Overall seasonal circulation in the SCS is cyclonic in winter and anticyclonic in summer with a few stable eddies. The seasonal circulation is mostly driven by monsoon winds, and is related to water exchange between the SCS and the East China Sea through the Taiwan Strait, and between the SCS and the Kuroshio through the Luzon Strait. Seasonal characteristics of the South China Sea Warm Current in the northern SCS and the Kuroshio intrusion to the SCS are summarized in terms of the interaction between the SCS and its adjacent seas. 相似文献