全文获取类型
收费全文 | 271篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 6篇 |
大气科学 | 37篇 |
地球物理 | 58篇 |
地质学 | 57篇 |
海洋学 | 66篇 |
天文学 | 40篇 |
综合类 | 3篇 |
自然地理 | 11篇 |
出版年
2021年 | 1篇 |
2019年 | 4篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 10篇 |
2013年 | 9篇 |
2012年 | 9篇 |
2011年 | 6篇 |
2010年 | 16篇 |
2009年 | 5篇 |
2008年 | 9篇 |
2007年 | 14篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 10篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 13篇 |
1985年 | 3篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 2篇 |
1972年 | 4篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有278条查询结果,搜索用时 17 毫秒
271.
Thomas Hobiger Seiichi Shimada Shingo Shimizu Ryuichi Ichikawa Yasuhiro Koyama Tetsuro Kondo 《Journal of Atmospheric and Solar》2010,72(2-3):262-270
Space geodetic applications require to model troposphere delays as good as possible in order to achieve highly accurate positioning estimates. However, these models are not capable to consider complex refractivity fields which are likely to occur during extreme weather situations like typhoons, storms, heavy rain-fall, etc. Thus it has been investigated how positioning results can be improved if information from numerical weather models is taken into account. It will be demonstrated that positioning errors can be significantly reduced by the usage of ray-traced slant delays. Therefore, meso-scale and fine-mesh numerical weather models are utilized and their impact on the positioning results will be measured. The approach has been evaluated during a typhoon passage using global positioning service (GPS) observations of 72 receivers located around Tokyo, proving the usefulness of ray-traced slant delays for positioning applications. Thereby, it is possible reduce virtual station movements as well as improve station height repeatabilities by up to 30% w.r.t. standard processing techniques. Additionally the advantages and caveats of numerical weather models will be discussed and it will be shown how fine-mesh numerical weather models, which are restricted in their spatial extent, have to be handled in order to provide useful corrections. 相似文献
272.
Geneses of Two Types of Mafic Rocks to Carry Placer‐Magnetite Ores in the Sanin Granitic Belt,SW Japan 下载免费PDF全文
Two types of mafic rocks from the central Sanin district, and their mafic minerals, were studied chemically and microscopically. They are classified into pyroxene‐containing gabbroid and hornblende–biotite quartz diorite. The gabbroid had higher color index but lower magnetite content; while the quartz diorite had lower color index, but higher magnetite content. The magnetite contents are also related to the amounts of hydrous mafic silicates. The gabbroic magma having pyroxene–amphibole assemblage, originated in the upper mantle, was considered essentially anhydrous, but became partly hydrous on the way to the site of solidification in the continental crust, and crystallized some magnetites with hypersthene and amphibole. The quartz dioritic magma was formed by partial melting of possibly subducting ocean‐floor basalts, once exposed to the sea‐floor then altered; thus the magmas became hydrous and oxidized originally, and precipitated abundant magnetite and hydrous mafic silicates from the early crystallization stage onward. Their weathered parts provided the most placer magnetite ores in the history. 相似文献
273.
Eiji Ohtani Naohisa Hirao Tadashi Kondo Masayoshi Ito Takumi Kikegawa 《Physics and Chemistry of Minerals》2005,32(1):77-82
We observed a direct reaction of metallic iron with water to form iron hydride and iron oxide, 3Fe + H2O–>2FeHx + FeO, at pressures from 6 GPa to 84 GPa and temperatures above 1,000 K in diamond anvil cell (DAC). Iron hydride is dhcpFeHx or -FeHx, and iron oxide has the rhombohedral or B1 structure at pressures at least up to 37 GPa. The formation of an assembly composed of dhcpFeHx and FeO with the B8 structure was observed at 84 GPa. In primordial Earth, water formed by dehydration of the low temperature primitive materials reacts with metallic iron in the high temperature component to form iron hydride FeHx and iron oxide FeO. The former would be incorporated in the iron forming the core. Thus hydrogen could be an important element of the Earths core. This reaction would be essential for transport of hydrogen into the core in the accretion stage of the Earth. 相似文献
274.
Thomas Hobiger Tetsuro Kondo Yasuhiro Koyama Kazuhiro Takashima Harald Schuh 《Journal of Geodesy》2007,81(6-8):389-401
The usage of Very Long Baseline Interferometry (VLBI) fringe-phase information in geodetic VLBI is a new field of research,
which can be used for the detection of short-period (i.e., several minutes) variations (scintillations) of the ionosphere.
This paper presents a method for the extraction of such disturbances and discusses how dispersive influences can be separated
from intra-scan delay variations. A proper functional and stochastic model for the separation of the different effects is
presented and the algorithms are applied to real measurements. In an example, it is shown that a traveling ionospheric disturbance
in Antarctica can be detected very precisely. A possible physical origin and the propagation properties of the disturbance
are presented and the results are compared with GPS measurements. The benefit of this method for other applications is also
discussed. 相似文献
275.
Hideo Aochi Ariane Ducellier Fabrice Dupros Mickael Delatre Thomas Ulrich Florent de Martin Masayuki Yoshimi 《Pure and Applied Geophysics》2013,170(1-2):43-64
Finite difference simulations of seismic wave propagation are performed in the Niigata area, Japan, for the 2007 Mw 6.6 Niigata-ken Chuetsu-Oki earthquake at low frequencies. We test three 3D structural models built independently in various studies. First aftershock simulations are carried out. The model based on 3D tomography yields correct body waves in the near field, but later phases are imperfectly reproduced due to the lack of shallow sediment layers; other models based on various 1D/2D profiles and geological interpretation provide good site responses but generate seismic phases that may be shifted from those actually observed. Next, for the mainshock simulations, we adopt two different finite source models that differ in the near-field ground motion, especially above the fault plane (but under the sea) and then along the coastline. Each model is found to be calibrated differently for the given stations. For engineering purposes, the variations observed in simulated ground motion are significant, but for seismological purposes, additional parameter calibrations would be possible for such a complex 3D case. 相似文献
276.
Deep flows on the slope inshore of the Kuril-Kamchatka Trench southeast off Cape Erimo, Hokkaido were observed for about five years from June 1989 to March 1995, using a mooring system with two current meters. In 1991 and 1993 directionally stable southwestward flows were observed at the upper layer (1000 m). These appear to be typical of the Oyashio because the characteristics of the flows were high mean kinetic energy, low eddy energy and high stability. However, the magnitudes of other mean flows at the upper layer, except for 1991 and 1993, were less than their standard deviations. This suggests that the Oyashio was observed for only a limited period of time. On the other hand, at the lower layer (3000 m) the magnitudes of the mean flows for 10–11 months were 1–3 cm s-1 and ellipses of their eddy kinetic energy were extremely flattened in the direction of the local isobath. The directions of the mean flows in 1990, 1991 and 1993 were southwestward along the local isobath. The relationships between the upper and the lower flows are discussed in terms of monthly change of kinetic energy, since the low-frequency fluctuations longer than 30-day are predominant from the eddy kinetic energy spectra. The results show that there are cases when the kinetic energy of the monthly mean flows at the lower layers are larger than those at the upper layers. This suggests the possibility that the lower flows are in part a southward deep western boundary current. 相似文献
277.
278.
Thomas Hobiger Tadahiro Gotoh Jun Amagai Yasuhiro Koyama Tetsuro Kondo 《GPS Solutions》2010,14(2):207-216
Off-the-shelf graphics processing units provide low-cost massive parallel computing performance, which can be utilized for
the implementation of a GPS software receiver. In order to realize a real-time capable system the crucial stages of the receiver
should be optimized to suit the requirements of a parallel processor. Moreover, the receiver should be capable to provide
wider correlation functions and provide easy access to the spectral domain of the signals. Thus, the most suitable correlation
algorithm, which forms the core part of each receivers should be chosen and implemented on the graphics processor. Since the
sampling rate of the received signal limits the real-time capabilities of the software radio it is necessary to determine
an optimum value, considering that the precision of the observable varies with sampling bandwidth. We are going to discuss
details and present our single frequency multi-channel implementation, which is capable of operating in real-time mode. Our
implementation differs from other solutions by the wideness of the correlation function and allows simple handling of data
in the spectral domain. Comparison with output from a commercial hardware receiver, which shares the antenna with the software
radio, confirms the consistency and accuracy of our development. 相似文献