全文获取类型
收费全文 | 182篇 |
免费 | 4篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 5篇 |
大气科学 | 13篇 |
地球物理 | 48篇 |
地质学 | 47篇 |
海洋学 | 37篇 |
天文学 | 26篇 |
综合类 | 2篇 |
自然地理 | 13篇 |
出版年
2023年 | 1篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 6篇 |
2013年 | 8篇 |
2012年 | 8篇 |
2011年 | 11篇 |
2010年 | 7篇 |
2009年 | 14篇 |
2008年 | 6篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 6篇 |
2004年 | 10篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1993年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有191条查询结果,搜索用时 15 毫秒
181.
Masachika Maeda 《Journal of Oceanography》1980,36(3):167-176
This article summarizes the author's current work on microbial degradation of nucleic acid. The aim of this work is to elucidate parts of the saprogenic process in the marine ecosystem through the study of the behavior of nucleic acid-hydrolyzing bacteria inhabiting seawater and sediments.Considerably large population of nucleic acid-hydrolyzing bacteria was found to occur in seawater and sediments. The main genera of these microbes areVibrio spp. in coastal seas, andPseudomonas spp. in the oceanic waters. As a result of microbial attack, nucleic acid components are released into seawater. The properties of extracellular nuclease produced by a marineVibrio sp. are well adapted to the seawater environment; consequently this enzyme has high activity and stability in seawater. By determining nuclease activity in seawater and sediments, the intensities of nucleic acid-hydrolysisin situ were evaluated.Distribution patterns of marine bacteria are also discussed in reference to the occurrence of phytoplankton in seawater. 相似文献
182.
183.
Numerical calculations for the electric current in the polar ionosphere have been made by assuming some realistic distributions of the electric field and conductivity. Two dynamo actions are taken into account; one of which is induced by ionospheric winds and the other by the solar wind. For the solar wind dynamo action, it is found that the secondary polarization field caused by non-uniform distribution of ionospheric conductivity is much larger than the primary field induced by the solar wind, suggesting its important effect on charged particles in the magnetosphere, and that the irrotational current having a source and sink is of the same order of magnitude as the solenoidal current closing its circuit in the ionosphere. It is also found that the solar wind is, in general, more effective than the ionospheric winds in producing polar current systems such as DP 1 and 2, but in some cases the ionospheric winds have a significant effect on the current distribution. 相似文献
184.
Masa-Yuki Yamamoto Masayuki Toda Yoshihiro Higa Kouji Maeda Jun-Ichi Watanabe 《Earth, Moon, and Planets》2004,95(1-4):279-287
Observations of persistent meteor trains are limited because of the extreme rarity of the phenomenon. The altitudinal distribution
of persistent trains has previously been investigated via limited instances of simultaneous observation from multiple sites,
however, a statistical study of persistent trains has yet to be realized. The meteor train observation (METRO) campaign was
established in Japan in 1998 to obtain images of persistent trains. From 1998 to 2002, the METRO campaign, involving Japanese
amateur collaborators, captured more than 400 image sequences of persistent trains, resulting in 53 simultaneous multi-site
observations. Several Japanese observers were involved in imaging persistent trains prior to the METRO campaign, producing
6 simultaneous observations over the period 1988–1997. In this paper, simultaneous multi-site observations of high spatial
and temporal resolution are used to determine, via triangulation, the altitudinal distribution of persistent trains for 20
events. The altitudinal range of 2 Orionid trains was slightly higher than that of 18 Leonid trains. The Leonid train data
reveal no clear dependence of upper and lower altitude on the brightness of the associated fireball. The upper altitude of
the 18 observed Leonid trains were almost invariant with respect to local time (LT) of observation, however, a possible dependence
of lower altitude on LT of observation was also found, indicating a near-constant penetrating path-length in the upper atmosphere
for each train. The average upper altitude of persistent Leonid trains was 99.8 km, while the average central altitude was
93.0 km. These trends are probably determined by atmospheric conditions such as the abundance of O and O3. 相似文献
185.
186.
187.
188.
Neoproterozoic India within East Gondwana: Constraints from recent geochronologic data from Himalaya 总被引:2,自引:0,他引:2
Recent geochronologic data of detrital zircons and neodymium isotopic signatures of the Himalaya, Arabian–Nubian Shield, and Western Australia–East Antarctica (the Pinjarra Orogen/Circum-East Antarctic Orogen) are assessed to estimate the location of Neoproterozoic basement of the Himalaya.
The protolith of the Higher Himalayan Gneisses is considered to have been derived from the Pinjarra Orogen/Circum-East Antarctic Orogen of Western Australia–East Antarctica, and not from the Indian Craton to the south. This conclusion strongly suggests the juxtaposition of the Indian Craton, which forms the basement of the Himalaya, with the Circum-East Antarctic Orogen during the Neoproterozoic when the protolith of the Higher Himalayan Gneisses deposited. 相似文献
189.
Surface electronic structures of metal oxides such as MgO, TiO2, SrTiO3, ReO3 and transition-metal monoxides are discussed based on the first-principles DV-Xα cluster and slab methods. Particular attention is paid to the origin and properties of intrinsic and extrinsic surface states. A close correlation between the surface structure and electronic states is confirmed. Some exotic properties of polar oxide surfaces, for example the formation of a two-dimensional metallic band, are predicted. 相似文献
190.
This study has developed sampling downscaling (SmDS), in which dynamical downscaling (DDS) is executed for a few of period selected from a long-term integration by general circulation model based on an observed statistical relationship between large-scale climate and regional-scale precipitation. SmDS expectedly produces climatology and frequency distribution of precipitation over a nested region with reducing computational cost, if a global-scale climate pattern mostly controls regional-scale weather statistics. Here SmDS was attempted for wintertime precipitation over Hokkaido, Japan, because a linkage between snowfall and sea-level pressure patterns has been known by Japanese synopticians and it can be detected by singular value decomposition (SVD) analysis on wintertime inter-annual variability during the period from 1980/1981 to 2009/2010 for precipitation over Hokkaido and moisture flux convergence around there. DDS for the full period over the same domain was also performed for comparison with SmDS. SmDS selected two winters from the top and two winters from the bottom of the projection onto the first SVD mode. It was found that, comparing with the full DDS, SmDS indeed provided unbiased statistics for average but exaggerated extreme statistics such as heavy rainfall frequency. It was also shown that the sampling in the SmDS method was much more effective than the random sampling. 相似文献