全文获取类型
收费全文 | 442篇 |
免费 | 11篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 18篇 |
地球物理 | 111篇 |
地质学 | 104篇 |
海洋学 | 89篇 |
天文学 | 113篇 |
综合类 | 3篇 |
自然地理 | 16篇 |
出版年
2023年 | 2篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 12篇 |
2018年 | 4篇 |
2017年 | 13篇 |
2016年 | 8篇 |
2015年 | 8篇 |
2014年 | 25篇 |
2013年 | 14篇 |
2012年 | 15篇 |
2011年 | 17篇 |
2010年 | 23篇 |
2009年 | 23篇 |
2008年 | 26篇 |
2007年 | 19篇 |
2006年 | 26篇 |
2005年 | 14篇 |
2004年 | 15篇 |
2003年 | 11篇 |
2002年 | 16篇 |
2001年 | 13篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1977年 | 6篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1963年 | 1篇 |
排序方式: 共有457条查询结果,搜索用时 406 毫秒
21.
Nakamura Hitomi Iwamori Hikaru Morikawa Noritoshi Kharitonova Natalia Chelnokov Georgy Bragin Ivan Chang Qing 《Aquatic Geochemistry》2021,27(4):269-282
Aquatic Geochemistry - Spring waters with high-pCO2 content are widely distributed in the Sikhote-Alin region in Russia. Mukhen spa is one such spring located in the northern Sikhote-Alin region.... 相似文献
22.
A PRELIMINARY ANALYSIS ON THE CHARACTERISTICS OF THE KUROSHIO FRONTAL EDDY IN THE EAST CHINA SEA IN SPRING 总被引:3,自引:0,他引:3
The Kuroshi'o front eddy's surface and sectional isothermal distribution characteristics were analyzed on the basis of observation data obtained in April 13-16 of 1989 in the East China Sea. It was found from the similarity between these isothermal distributions with those in January and beginning of June for the years 1986-1990 that the Kuroshio front eddy often occurred from March to the beginning of June. The Kuroshio front eddy movement in the East China Sea in spring was along two routes: the Okinawa Trough route, and the continental shelf slope route. The two moving routes both in the surface layer and in the section are described, their causes are discussed, and differences are compared. 相似文献
23.
We applied an image correlation method to Japanese Earth Resources Satellite-1 (JERS-1) synthetic aperture radar (SAR) data obtained from 1996 to 1998 to examine flow velocity within Shirase Glacier, Antarctica. From the grounding line to the downstream region of the glacier, the obtained ice-flow velocity was systematically higher on the western streamline than the eastern. The differences between the two streamlines were 0.31 km/a in 1996 and 0.37 km/a in 1998, significantly larger than the error estimate of 0.03 km/a. The direction of ice flow was about 312° at the grounding line and changed to 327° at 10 km, 346° at 20 km and 2° at 30 km downstream from the grounding line. The total accumulated deflection is 50° to the east. Under the assumption of the conservation of ice mass across the glacier, the observed eastward change in flow direction can be explained by an asymmetric deepening of bedrock topography, that is, across the 8 km width of the glacier, the eastern side is 50 m (10%) deeper than the western side. This eastward turning of flow direction appears to be accelerated by tributary inlets, that flow to the north and northeast at 60–75% of the velocity of inlets on the western streamline. 相似文献
24.
H. Nakamura 《Theoretical and Applied Climatology》1996,55(1-4):19-32
Summary Interannual variability in the activity of fluctuations with subseasonal time scales is investigated based upon observed data of the extratropical Northern Hemisphere circulation over the recent 38 winters. Their activity is represented in the root mean square (RMS) field of filtered geopotential height in which the fluctuations with time scales between 10 days and a season are retained. The singular value decomposition (SVD) was applied to the covariance matrix between the seasonal mean and RMS fields for the 500-hPa height.The leading SVD mode for the north Pacific represents the strong relationship between the polarity of the Pacific/North American (PNA) pattern in the seasonal-mean anomalies and the amplitude of a meridionally-oriented dipole-like oscillation within the season. It tends to be more active when the seasonal-mean jet stream is strongly diffluent over the central Pacific than when the jet is extended zonally across the Pacific. The leading SVD mode for the north Atlantic is indicative of stronger intraseasonal fluctuations near Greenland in the presence of anticyclonic seasonal-mean anomalies associated with the North Atlantic Oscillation (NAO).The intraseasonal variability in the extratropics is strongly correlated with the underlying sea surface temperature (SST) anomalies, and that in the north Pacific also exhibits significant but rather weak correlation with SST anomalies in the equatorial Pacific. The activity of the atmospheric intraseasonal fluctuations is found to be modulated in accordance with interdecadal variability in the seasonal-mean circulation and SST.On leave from Department of Earth & Planetary Physics, University of Tokyo.With 12 Figures 相似文献
25.
Observation of human-induced large-amplitude lateral vibration of an actual pedestrian bridge in an extremely congested condition is reported. Walking motions of pedestrians recorded by a video camera are analysed. It is found that walking among 20 per cent or more of the pedestrians on the bridge was synchronized to the girder lateral vibration. With this synchronization, the total lateral force from the pedestrians to the girder is evidently increased and it acts as a resonant force on the girder lateral vibration. 相似文献
26.
The CQC rule for modal combination is extended to include the quasi-static contribution of truncated modes and the effects of input narrow-bandedness and cut-off frequency. A simple measure of the error in approximating a high-frequency modal response by its quasi-static contribution is derived. The extended rule is applicable to structures with high-frequency modes and to seismic inputs which may not be regarded as wide band. Numerical examples demonstrate the significance of input bandwidth and cut-off frequency on modal cross-correlation coefficients, and on the error resulting from truncation of high-freqeuncy modes. 相似文献
27.
Arata Sugimura Tokihiko Matsuda Kiyotaka Chinzei Kazuaki Nakamura 《Bulletin of Volcanology》1963,26(1):125-140
The late Cenozoic orogeny in Japan is briefly reviewed. Amounts of volcanic materials in the three periods of the orogeny are estimated at: early Neogene 150 × 103 km3 (mafic 40 %, salic 60 %), middle and late Neogene 20 × 103 km3 (mafic 70 %, salic 30 %), Quaternary 5 × 103 km3 (mafic 80 %, salic 20 %). The largest volume per unit time is in the early Neogene, and the smallest in the middle and late Neogene. Volume per unit area becomes larger towards the southeastern margin or «front» of the volcanic belt. Thermal energy transported by volcanic materials is compared with the terrestrial heat flow in the belt. 相似文献
28.
The compositions of five different coexisting pyroxenes hypersthene, pigeonite and augite in groundmass and bronzite and augite of phenocryst in a tholeiitic andesite from Hakone Volcano, Japan have been determined by the electron probe microanalyser. It is shown that there is a compositional gap of about 25 mole per cent CaSiO3 between groundmass pigeonite and augite, compared with 35 per cent CaSiO3 between phenocrystic augite and bronzite. Subcalcic augite or pigeonitic augite was not found. The groundmass augite, which occurs only as thin rims of pigeonite and hypersthene, is less calcic and more iron-rich than the phenocryst augite. It is also shown that the groundmass pigeonite is 3–4 mole per cent more CaSiO3-rich than the coexisting groundmass hypersthene. The Fe/(Mg + Fe) ratios of these coexisting hypersthene and pigeonite are about 0.31 and 0.33, respectively. It is suggested from these results that a continuous solid solution does not exist between augite and pigeonite of the Fe/(Mg + Fe) ratio at least near 0.3 under the conditions of crystallization of groundmass of the tholeiitic andesite. It is suggested from the Mg-Fe partition and the textural relation that the groundmass augite crystallized from a liquid more iron-rich than that from which groundmass hypersthene and pigeonite crystallized. 相似文献
29.
Akimasa Masuda Noboru Nakamura Tsuyoshi Tanaka 《Contributions to Mineralogy and Petrology》1971,32(4):295-306
Two foliated metagabbros from the Mid-Atlantic Ridge near 30° N were analyzed for rare earth elements. The chondrite-normalized rare earth pattern for one of them is quite similar to those for abyssal tholeiites. The pattern for another sample, however, is somewhat different from the above one. A new set of bulk partition coefficients for rare earth elements has been estimated correspondingly. This set throws a new light on the interpretation that many alkali olivine basalts were produced by a zone melting or partial melting of primary-liquid-type material. Also the same partition coefficients lead us to an inference that the high-temperature peridotite intrusion in the Lizard area, Cornwall, England, is a secondary-solid-type material which was once in equilibrium with a primary-solid-type material, whereas the pyroxenite, Canyon Mountain, Oregon, is a primary-solid-type material.Both of the metagabbros studied show positive europium anomaly. 相似文献
30.
Kenji Kashiwaya Masayuki Ryugo Masae Horii Hideo Sakai Toshio Nakamura Takayoshi Kawai 《Journal of Paleolimnology》1999,21(2):143-150
The St.16 core obtained from the Academician Ridge of Lake Baikal in eastern Siberia may span about 260 000 years, and some physical properties of the core samples are closely related to aquatic paleoproductivity and climatic change. The median of grain size, grain density, and water content fluctuate synchronously. They also are connected with change in the abundance of biogenic silica (diatoms). The physical parameters indicate that there were high aquatic productivity periods around interglacial periods (MIS 5 and 7; 70 000-125 000 yr B.P. and 180 000-250 000 yr B.P.). Comparatively large clastics were transported from outside of the lake through various routes (ice rafting, etc.) in addition to fluvial routes during the glacials or 'stadials. There are ca. 20 000 yr, 40 000 yr and 100 000 yr periods in the variations of physical properties. These are related to the three Milankovitch parameters of solar insolation. 相似文献