全文获取类型
收费全文 | 284篇 |
免费 | 11篇 |
国内免费 | 12篇 |
专业分类
测绘学 | 5篇 |
大气科学 | 40篇 |
地球物理 | 57篇 |
地质学 | 83篇 |
海洋学 | 72篇 |
天文学 | 37篇 |
综合类 | 9篇 |
自然地理 | 4篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 19篇 |
2015年 | 13篇 |
2014年 | 13篇 |
2013年 | 22篇 |
2012年 | 13篇 |
2011年 | 20篇 |
2010年 | 26篇 |
2009年 | 21篇 |
2008年 | 11篇 |
2007年 | 13篇 |
2006年 | 23篇 |
2005年 | 18篇 |
2004年 | 5篇 |
2003年 | 14篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1980年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有307条查询结果,搜索用时 15 毫秒
91.
Kwanho Kim Kyuhyup Oh Yeong Kyu Lee SungHo Kim 《International journal of geographical information science》2014,28(9):1781-1801
Identifying zones and movement patterns of people is crucial to understanding adjacent regions and the relationship in urban areas. Most previous studies addressed zones or movement patterns separately without analysing simultaneously the two issues. In this article, we propose an integrated approach to discover directly both zones and movement patterns among the zones, referred to as movement patterns between zones (MZPs), from historical boarding behaviours of passengers in subway networks by using an agglomerative clustering method. In addition, evaluation measures of MZPs are suggested in terms of coverage and accuracy. The effectiveness of the proposed approach is finally demonstrated through a real-world data set obtained from smart cards on a subway network in Seoul, Korea. 相似文献
92.
Marine macroalgae can absorb carbon and play an important role in carbon sequestration. As an important economic macroalga, Gracilariopsis lemaneiformis has the potential to significantly affect carbon absorption and storage in wave-sheltered intertidal reef systems. However, detailed knowledge on seasonal biomass changes and carbon storage of G. lemaneiformis is lacking, especially in many small and scattered ecosystems. Considering the influence of human activities on wild distribution of G. lemaneiformis, the understanding of seasonal dynamics of an economically important species in nature is necessary. In this study, we first investigated seasonal variations in biomass, coverage area, and carbon storage during low tide from August 2011 to July 2012 in Zhanshan Bay, Qingdao, China. Furthermore, we estimated the carbon storage potential of wild G. lemaneiformis using light use efficiency(LUE). The results show that the standing biomass and coverage area changed significantly with season. However, seasonal variations in carbon content and water content were not obvious, with an average content of 35.1% and 83.64%, respectively. Moreover, carbon storage in individual months varied between 0.67 and 47.03 g C/m 2, and the value of carbon storage was the highest in August and June and the lowest in February. In Zhanshan Bay, LUE of G. lemaneiformis was only 0.23%. If it is increased to the theoretical maximum(5%–6%), the carbon storage will have an increase of at least 21 times compared with the current, which suggested that carbon storage of wild G. lemaneiformis had a high enhancement potential. The study will help to assess a potential role of G. lemaneiformis in reducing atmospheric CO2. 相似文献
93.
This paper proposes and tests a method of producing macrofauna habitat potential maps based on a weights-of-evidence model (a probabilistic approach) for the Hwangdo tidal flat, Korea. Samples of macrobenthos were collected during field work, and we considered five mollusca species for habitat mapping. A weights-of-evidence model was used to calculate the relative weights of 10 control factors that affect the macrobenthos habitat. The control factors were compiled as a spatial database from remotely sensed data combined with GIS analysis. The relative weight of each factor was integrated as a species potential index (SPI), which produced habitat potential maps. The maps were compared with the surveyed habitat locations, revealing a strong correlation between the potential maps and species locations. The combination of a GIS-based weights-of-evidence model and remote sensing techniques is an effective method in determining areas of macrobenthos habitat potential in a tidal flat setting. 相似文献
94.
Effects of the Changjiang river discharge on sea surface warming in the Yellow and East China Seas in summer 总被引:2,自引:0,他引:2
Taewook Park Chan Joo Jang Johann H. JungclausHelmuth Haak Wonsun ParkIm Sang Oh 《Continental Shelf Research》2011,31(1):15-22
This study explores the effects of the Changjiang (also called the Yangtze River) river discharge (CRD) on the density stratifications and associated sea surface temperature (SST) changes using a global ocean general circulation model with regional focus on the Yellow and East China Seas (YECS). It is found that CRD increases the SST in summer through a barrier layer (BL) formation that tends to enhance stratification at the mixed layer base, and thus reduces both vertical mixing and entrainment. This process is effective, particularly in August, after the CRD reaches its maximum in July. The SST difference between the composites of flood and drought years confirms that the surface warming is related to surface freshening by the CRD. This result suggests that the BL induced by the CRD is an important contributor to the surface heat budget in the YECS. 相似文献
95.
Changhwan Oh Julien Legrand Kyungsik Kim Marc Philippe In SungPaik 《Journal of Asian Earth Sciences》2011,40(3):710-721
Mesozoic fossil floras are distributed over eastern Asia (China, Mongolia, Siberia, Korea and Japan) according to a regular latitudinal pattern. Two floras are usually distinguished, a northern type and a southern type, the distribution of which oscillated during the Mesozoic. In Japan, this regular pattern is disrupted by a sharp inflexion of the boundary between the two floras. Two competing hypotheses have been proposed to explain this disruption. One hypothesis advocates later tectonic motion clouding the original pattern, while the other hypothesis proposes that a warm oceanic current allowed the southern flora to grow much further north in coastal areas. We used fossil wood, a biotic component that has not previously been used, for a palaeobiogeographical study of the region. The observed fossil wood diversity at the generic level does not fit with the hypothesis of a warm oceanic current, unless this hypothesis is modified to include alternating warm northbound and cold southbound oceanic currents. Our results provide new evidence for the palaeoecology of the Mesozoic continental biota in Far-East Asia. 相似文献
96.
Sensitivity analysis for the GIS-based mapping of the ground subsidence hazard near abandoned underground coal mines 总被引:3,自引:3,他引:0
Ground subsidence around abandoned underground coal mines can cause much loss of life and property. We analyze factors that
can affect ground subsidence around abandoned mines in Jeongahm in Kangwon-do by sensitivity analysis in geographic information
system (GIS). Spatial data for the subsidence area, topography and geology and various ground engineering data were collected
and used to make a factor raster database for a ground subsidence hazard map. To determine the importance of extracted subsidence-related
factors, frequency ratio model and sensitivity analysis were employed. Sensitivity analysis is a method for comparing the
combined effects of all factors except one. Sensitivity analysis and its verification showed that using all factors provided
91.61% accuracy. The best accuracy was achieved by not considering the groundwater depth (92.77%) and the worst by not considering
the lineament (85.42%). The results show that the distance from the lineament and the distance from the drift highly affected
the occurrence of ground subsidence, and the groundwater depth, land use and rock mass rating had the least effects. Thus,
we determined causes of ground subsidence in the study area and this information could help in the prediction of ground subsidence
in other areas. 相似文献
97.
Seok Lee Heung-Jae Lie Cheol-Ho Cho Sok Kuh Kang William J. Teague Kyung-Il Chang Kyu-Min Song Kyung-Hee Oh 《Ocean Science Journal》2011,46(2):73-84
The vertical structure of the M2 tidal current in the Yellow Sea is analyzed from data acquired using an acoustic Doppler current profiler. The observed vertical
profiles of the M2 tidal current are decomposed into two rotating components of counter-clockwise and clockwise, and restructured using a simple
one-point model with a constant vertical eddy viscosity. The analyzed results show that the internal fictional effect dominates
the vertical structure of the tidal current in the bottom boundary layer. In the Yellow Sea, the effect of the bottom friction
reduces the current speed by about 20–40% and induces the bottom phase advance by about 15–50 minutes. In the shallower coastal
regions, the effects of bottom topography are more prominent on the vertical structure of tidal currents. The vertical profile
of the tidal current in summer, when the water column is strongly stratified, is disturbed near the pycnocline layer. The
stratification significantly influences the vertical shear and distinct seasonal variation of the tidal current. 相似文献
98.
Spindel R.C. Jungyul Na Dahl P.H. Suntaek Oh Eggen C. Young Gyu Kim Akulichev V.A. Morgunov Y.N. 《Oceanic Engineering, IEEE Journal of》2003,28(2):297-302
A pilot experiment was conducted in the Sea of Japan (also called the East Sea) in September-October 1999, to assess the possibility of using acoustic tomographic techniques for monitoring water mass structure and dynamics. Acoustic m-sequence signals at various frequencies between 250 and 634 Hz were transmitted from bottom-mounted acoustic sources in shallow water off the coast of Vladivostok to vertical-array receiving systems deployed off the north coast of Ulleung-Do island (S. Korea), 558 km to the south. The data are analyzed for temporal correlation, time spread, and transmission loss and are interpreted in terms of a tomographic system for monitoring the East Sea. 相似文献
99.
100.