全文获取类型
收费全文 | 89篇 |
免费 | 3篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 7篇 |
地球物理 | 29篇 |
地质学 | 11篇 |
海洋学 | 20篇 |
天文学 | 15篇 |
综合类 | 1篇 |
自然地理 | 7篇 |
出版年
2021年 | 2篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 5篇 |
2012年 | 3篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 8篇 |
2008年 | 6篇 |
2007年 | 2篇 |
2006年 | 6篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有92条查询结果,搜索用时 0 毫秒
71.
Takahito Kazama Hideaki Hayakawa Toshihiro Higashi Shingo Ohsono Shunsuke Iwanami Tomoko Hanyu Harumi Ohta Koichiro Doi Yuichi Aoyama Yoichi Fukuda Jun Nishijima Kazuo Shibuya 《Polar Science》2013,7(3-4):260-277
Absolute gravity values were measured with a portable absolute gravimeter A10 in East Antarctica, for the first time by the Japanese Antarctic Research Expedition. This study aims to investigate regional spatiotemporal variations of ice mass distributions and associated crustal deformations around Syowa Station by means of repeated absolute gravity measurements, and we obtained the first absolute gravity value in Southern Langhovde on the Antarctic Continent. The average absolute gravity value at the newly installed benchmark AGS01 in Langhovde (obtained on 3 February 2012) was 982535584.2 ± 0.7 μgal (1 [μgal] = 1 × 10?8 [m/s2]), which was in agreement with the gravity values obtained by the past relative gravity measurements within 1 mgal. In addition, the average absolute gravity value obtained at AGSaux in Syowa Station was consistent with both previous absolute gravity values and those obtained by simultaneous measurements using an FG5 gravimeter, owing to adequate data corrections associated with tidal effects and time variations in atomic clock frequencies. In order to detect the gravity changes associated with the ice mass changes and other tectonic phenomena, we plan to conduct absolute gravity measurements at AGS01 again and at other campaign sites around Syowa Station as well in the near future, with careful attention paid to the impacts of severe environmental conditions in Antarctica on gravity data collection. 相似文献
72.
Toshihiro Kasuga Jun-Ichi Watanabe Mikiya Sato 《Monthly notices of the Royal Astronomical Society》2006,373(3):1107-1111
The asteroid 3200 Phaethon is suggested as a candidate for direct impact research. The object is considered to be an extinct comet and the parent of the Geminid meteor shower. One could say that this provides a possible argument for a space mission. Based on such a mission, this paper proposes to investigate the nature of the extinct comet and the additional interesting possibility of artificially generated meteor showers.
Dust trail theory can calculate the distribution of a bundle of trails and be used to show in which years artificial meteors would be expected. Results indicate that meteor showers will be seen on Earth about 200 yr after the event, on 2022 April 12. 相似文献
Dust trail theory can calculate the distribution of a bundle of trails and be used to show in which years artificial meteors would be expected. Results indicate that meteor showers will be seen on Earth about 200 yr after the event, on 2022 April 12. 相似文献
73.
Naoto Takahata Yuji Sano Keika Horiguchi Kotaro Shirai Toshitaka Gamo 《Journal of Oceanography》2008,64(2):293-301
We have collected fifty-five seawater samples at seven stations at various depths in the Yamato and Japan Basins of the Japan
Sea and measured their helium isotopic ratios. The 3He/4He ratios vary from 0.997 Ratm to 1.085 Ratm where Ratm is the atmospheric ratio. The maximum 3He excesses about 8%, are observed at mid-depth (1000 m), and these values are significantly lower than those observed in
deep Pacific waters. This implies that mantle-derived helium in deep Pacific water cannot enter the Japan Sea since it is
an almost landlocked marginal sea. The observed 8% excess 3He may be attributable to the decay product of tritium. Slightly higher 3He/4He ratios in the Bottom Water were observed in the Yamato Basin than in the Japan Basin. The ventilation ages of seawater
shallower than 1000 m are calculated as about 5 to 20 years, which is consistent with the CFC ages reported in the literature.
There is a positive correlation between the apparent oxygen utilization and 3H-3He ages. The estimated oxygen utilization rate from the correlation in a layer between 500 m and 1000 m is about 3 μmol/kg/yr, which is similar to that in the eastern subtropical North Atlantic. 相似文献
74.
75.
Tomoki Nakamura Aiko Nakato Hatsumi Ishida Shigeru Wakita Takaaki Noguchi Michael E. Zolensky Masahiko Tanaka Makoto Kimura Akira Tshuchiyama Toshihiro Ogami Takahito Hashimoto Mitsuru Konno Masayuki Uesugi Toru Yada Kei Shirai Akio Fujimura Ryuji Okazaki Scott. A. Sandford Yukihiro Ishibashi Masanao Abe Tatsuaki Okada Munetaka Ueno Junichiro Kawaguchi 《Meteoritics & planetary science》2014,49(2):215-227
The mineralogy and mineral chemistry of Itokawa dust particles captured during the first and second touchdowns on the MUSES‐C Regio were characterized by synchrotron‐radiation X‐ray diffraction and field‐emission electron microprobe analysis. Olivine and low‐ and high‐Ca pyroxene, plagioclase, and merrillite compositions of the first‐touchdown particles are similar to those of the second‐touchdown particles. The two touchdown sites are separated by approximately 100 meters and therefore the similarity suggests that MUSES‐C Regio is covered with dust particles of uniform mineral chemistry of LL chondrites. Quantitative compositional properties of 48 dust particles, including both first‐ and second‐touchdown samples, indicate that dust particles of MUSES‐C Regio have experienced prolonged thermal metamorphism, but they are not fully equilibrated in terms of chemical composition. This suggests that MUSES‐C particles were heated in a single asteroid at different temperatures. During slow cooling from a peak temperature of approximately 800 °C, chemical compositions of plagioclase and K‐feldspar seem to have been modified: Ab and Or contents changed during cooling, but An did not. This compositional modification is reproduced by a numerical simulation that modeled the cooling process of a 50 km sized Itokawa parent asteroid. After cooling, some particles have been heavily impacted and heated, which resulted in heterogeneous distributions of Na and K within plagioclase crystals. Impact‐induced chemical modification of plagioclase was verified by a comparison to a shock vein in the Kilabo LL6 ordinary chondrite where Na‐K distributions of plagioclase have been disturbed. 相似文献
76.
77.
Toru Kobari Hiroyasu Akamatsu Masato Minowa Toshihiro Ichikawa Kazuo Iseki Ryuji Fukuda Masataka Higashi 《Journal of Oceanography》2010,66(5):673-684
Seasonal changes in the shape and size composition of fecal pellets were investigated with sediment trap samples from 50 and
150 m in Kagoshima Bay to evaluate how the mesozooplankton community affects fecal pellet flux. Deep vertical mixing was evident
in March, and thermal stratification was developed above 50 m in June, August and November. Chlorophyll a, suspended particulate organic carbon (POC) and copepod abundance were uniform throughout the water column during the seasonal
mixing and concentrated above 50 m in the stratified seasons. Calanoids were the most predominant copepods in March and poecilostomatoids
composed more than 45% of the copepod community in June, August and November. Fecal pellet fluxes at 50 and 150 m were the
highest in March, nearly half of POC flux. The relative contribution declined considerably in the other months, especially
for less than 4% of POC flux in August. The decline was corresponded to the predominance of cyclopoids and poecilostomatoids.
Cylindrical pellets dominated the fecal matters at both depths throughout the study period, while larger cylindrical pellets
nearly disappeared at 150 m in June, August and November. Copepod incubation revealed that cylindrical and oval pellets were
egested by calanoids and the other copepods, respectively. We suggest that cylindrical fecal pellets produced by calanoid
copepods contribute to feces flux but the predominance of poecilostomatoids and/or cyclopoids decreases feces flux via the
increase of oval pellets and fragmentation of larger cylindrical pellets. 相似文献
78.
Hiroshi Adachi Hiroya Yamano Toshihiro Miyajima Masahiro Nakaoka 《Journal of Oceanography》2010,66(6):865-872
This article describes a simple, quick, and inexpensive procedure for coring unconsolidated sediment in shallow water (<30
m from water surface). A ∼1 m core is retrieved by a PVC pipe that penetrates sediment in response to the percussive force
of a hand-operated hammering tool or air hammer. After retrieving the first core segment, a casing is inserted to allow access
to deeper sediment layers. Pulverized sediment produced during coring is removed by a water-lubrication system that is powered
by an electric pump attached to a generator. Using this system and procedure, five 2-m-long cores with excellent quality were
retrieved. 相似文献
79.
A simple trap model of solar hard X-ray bursts is discussed in which nonthermal electrons trapped in a magnetic bottle precipitate into the lower chromosphere through the resonant scattering by whistlers. In such a model, the X-ray spectra produced from trapped and precipitating electrons have different spectral shape, and both of the spectra will initially soften with time, provided the precipitation dominates over collisional degradation. 相似文献
80.
Toshihiro Suzuki Syun-iti Akimoto Yuh Fukai 《Physics of the Earth and Planetary Interiors》1984,36(2):135-144
The system iron-enstatite-water was investigated at pressures around 5 GPa and at temperatures ranging from 1000 to 1200°C, using several different kinds of starting materials. Quenched samples showed the coexistence of iron, olivine and pyroxene. Synthesis of the Fe-containing olivine in the run products proves that a series of reactions, Fe + H2O → FeHx + FeO and FeO + MgSiO3 → (Mg, Fe)2SiO4, have taken place. Spherical “balls of iron” were observed in the 1200°C run. This strongly indicates that the melting temperature of iron decreased by ~ 500 K by the possible dissolution of hydrogen. Following geophysical implications are derived from these experimental results. If water was retained in the hydrous minerals in the primordial material, the iron-water reaction is expected to occur throughout the core-formation process. The reaction product FeHx will melt and then sink to form a proto-core and iron oxide will be dissolved in the Earth's mantle. The dissolution of hydrogen in the Earth's core is a natural consequence of the core-formation process. 相似文献