全文获取类型
收费全文 | 397篇 |
免费 | 17篇 |
国内免费 | 6篇 |
专业分类
测绘学 | 8篇 |
大气科学 | 29篇 |
地球物理 | 132篇 |
地质学 | 110篇 |
海洋学 | 38篇 |
天文学 | 62篇 |
综合类 | 4篇 |
自然地理 | 37篇 |
出版年
2023年 | 2篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 18篇 |
2014年 | 9篇 |
2013年 | 14篇 |
2012年 | 10篇 |
2011年 | 25篇 |
2010年 | 8篇 |
2009年 | 18篇 |
2008年 | 27篇 |
2007年 | 25篇 |
2006年 | 29篇 |
2005年 | 19篇 |
2004年 | 23篇 |
2003年 | 13篇 |
2002年 | 13篇 |
2001年 | 4篇 |
2000年 | 11篇 |
1999年 | 5篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 2篇 |
排序方式: 共有420条查询结果,搜索用时 46 毫秒
61.
The scale factor of a superconducting gravimeter (SG) at the Esashi Earth Tides Station, Japan, was revised by repeating co-located absolute gravity measurements with an FG5 gravimeter. Although the calibration results from the absolute gravimeter (AG) show an apparent secular change in the scale factor of the SG (0.4% for the period 1993–2002), the relative scale factors, which are determined by tidal analysis with the response method, indicate that it has changed by no more than 0.01% during the above period. If the mean scale factor over the 10 years is adopted, a value of –56.082±0.029 Gal/V (1 Gal =10–8 m s–2) is obtained, which is about 0.4% smaller than that used in the global geodynamics project (GGP) database. Based on this newly determined scale factor, the tidal gravity factors at Esashi have been re-estimated. The observed tidal factors, corrected for the ocean tide effects with recent models, indicate that the theoretical gravity factors for an inelastic Earth model are more consistent with the observations than are those for an elastic model. 相似文献
62.
63.
Liu Rui-yuan Hu Hong-qiao Liu Yong-hua Xu Zhong-hua Sato N. Fraser B.J. 《Solar physics》2001,204(1-2):305-313
Simultaneous observations at Zhongshan Station, Antarctica, are presented for the interval of 13–17 July 2000 to show responses
of the polar ionosphere to the Bastille Day (14 July 2000) solar event. The polar ionosphere was highly disturbed, as shown
by frequently large deviations of the geomagnetic H-component, large riometer absorption events and strong ULF waves. Associated
with the huge solar proton event produced by the X5/3B flare, a polar cap absorption (PCA) was observed. It began at ∼ 10:40 UT
on 14 July and ended at ∼ 19:40 UT on 17 July. Superposed on it, there was a large absorption event with a peak of 26 dB,
starting at ∼ 03:00 UT and ending at ∼ 11:10 UT on 15 July. This kind of absorption was probably produced by an intense `cloud
of energetic electrons' during an auroral substorm. The ULF waves were very intense during the main phase and the recovery
phase of the severe magnetic storm on 15 and 16 July. The ionospheric absorption was so strong that the digisonde signal was
blacked out most of the time. The ionosphere returned to normal in the afternoon on 17 July. 相似文献
64.
The discovery of a planetary companion to the intermediate-mass late-type giant star HD173416 from precise Doppler surveys of G and K giants at Xingiong station and Okayama Astrophysical Observatory (OAO) is presented in this letter. The planet has a minimum mass of 2.7 MJ an eccentricity of 0.21, a semimajor axis of 1.16 AU and an orbital period of 324 days. 相似文献
65.
Kazunori Ogohara Toru Kouyama Hiroki Yamamoto Naoki Sato Masahiro Takagi Takeshi Imamura 《Icarus》2012,217(2):661-668
Japanese Venus Climate Orbiter, Akatsuki, is cruising to approach to Venus again although its first Venus orbital insertion (VOI) has been failed. At present, we focus on the next opportunity of VOI and the following scientific observations.We have constructed an automated cloud tracking system for processing data obtained by Akatsuki in the present study. In this system, correction of the pointing of the satellite is essentially important for improving accuracy of the cloud motion vectors derived using the cloud tracking. Attitude errors of the satellite are reduced by fitting an ellipse to limb of an imaged Venus disk. Next, longitude–latitude distributions of brightness (cloud patterns) are calculated to make it easy to derive the cloud motion vectors. The grid points are distributed at regular intervals in the longitude–latitude coordinate. After applying the solar zenith correction and a highpass filter to the derived longitude–latitude distributions of brightness, the cloud features are tracked using pairs of images. As a result, we obtain cloud motion vectors on longitude–latitude grid points equally spaced. These entire processes are pipelined and automated, and are applied to all data obtained by combinations of cameras and filters onboard Akatsuki. It is shown by several tests that the cloud motion vectors are determined with a sufficient accuracy. We expect that longitude–latitude data sets created by the automated cloud tracking system will contribute to the Venus meteorology. 相似文献
66.
Hisaaki Sato 《Marine Georesources & Geotechnology》2018,36(7):768-780
We propose a geochemical parameter, “metal flux” in evaluating hydrogenetic Co-rich ferromanganese crust deposits in the Pacific seamount area, that is based on physical, chemical, and geological characterization of the integrated growth piles of crusts. We calculated the metal flux for fifteen sites from different depths ranging between 900-6000m from different seamounts. The secular and areal variations of metal flux indicate a strong geological controls, and also can be a reliable tool for estimating an economic potential of the crusts. The Co flux decreases with increasing water depth, followed by almost constant flux of Ni and Mn. The Al and Fe fluxes vary with regions, indicating higher values in the western regions near the island arc probably related to a supply from the Asian continents. The results imply that Co, a redox sensitive metal element, is controlled by redox conditions of seawater, while Fe and Al are by terrigenous input. The metal flux reflects global and regional conditions and controls the compositional diversity of metals, thus consequently, the parameter can be a reliable powerful tool to estimate or single out more potential areas. 相似文献
67.
Theresa Tufuor Chizu Sato 《Norsk geografisk tidsskrift. Norwegian journal of geography》2017,71(1):46-59
In recent decades there has been a large migration stream of single women from the north to Accra in Ghana. Existing studies have focused on young migrant women’s livelihood strategies in their place of destination. However, once-married women – divorced and widowed women and neglected wives – also migrate, and their motivations for migration are less known. Drawing on qualitative and quantitative methods, the authors investigate the effects of gender norms, age, marital status, socio-economic status, and position in households on women’s decisions to migrate. The results revealed that migrant women from resource-poor households, regardless of age, marital status and position in households, commonly cited a gain in autonomy as an important motivation for their migration. From a differentiated perspective, young unmarried women aspired to prepare themselves for often expensive religious marriage ceremonies, whereas once-married women invest in their children’s education and build their own housing. By paying attention to the effects of gender norms, age, marital status, socio-economic status, and position in households on women’s decisions to migrate, the study illuminates the contradictory ways in which their migration practices are both shaped by and shape gender ideologies in parts of contemporary northern Ghana. 相似文献
68.
把细胞自动机和灰色局势决策结合起来对土地利用变换机制进行模拟。实验证明,基于灰色局势决策规则的细胞自动机是对土地利用变换机制从宏观和微观角度进行模拟的有效方法。 相似文献
69.
满洲里-新巴尔虎右旗斑岩系列矿床石英流体包裹体液相组分的PIXE分析和地质应用 总被引:1,自引:0,他引:1
PIXE(质子感应X射线分析)方法是目前国际上新的流体包裹体成分分析方法。在前人工作的基础上,尝试用PIXE方法分析了满洲里-新巴尔虎右旗斑岩系列多金属矿床石英流体包裹体的液相多元素化学组分,其结果反映了地质矿化规律。该方法对于多金属矿床石英流体包裹体成分研究非常有用。结合其他包裹体研究,提出甲乌拉与直干布拉根矿床流体组分和成矿物理化学条件均不同,初步认为不存在同一矿化中心;还提出了查干布拉根矿床西矿段深部可能存在乌奴格吐山式斑岩型Cu矿床,应引起注意。 相似文献
70.
Response of hybrid isolation system during a shake table experiment of a full‐scale isolated building 下载免费PDF全文
Keri L. Ryan Taichiro Okazaki Camila B. Coria Eiji Sato Tomohiro Sasaki 《地震工程与结构动力学》2018,47(11):2214-2232
A full‐scale 5‐story steel moment frame building was subjected to a series of earthquake excitations using the E‐Defense shake table in August, 2011. For one of the test configurations, the building was seismically isolated by a hybrid system of lead‐rubber bearings and low friction roller bearings known as cross‐linear bearings, and was designed for a very rare 100 000‐year return period earthquake at a Central and Eastern US soil site. The building was subject to 15 trials including sinusoidal input, recorded motions and simulated earthquakes, 2D and 3D input, and a range of intensities including some beyond the design basis level. The experimental program was one of the first system‐level full‐scale validations of seismic isolation and the first known full‐scale experiment of a hybrid isolation system incorporating lead‐rubber and low friction bearings. Stable response of the hybrid isolation system was demonstrated at displacement demands up to 550 mm and shear strain in excess of 200%. Torsional amplifications were within the new factor stipulated by the code provisions. Axial force was observed to transfer from the lead‐rubber bearings to the cross‐linear bearings at large displacements, and the force transfer at large displacements exceeded that predicted by basic calculations. The force transfer occurred primarily because of the flexural rigidity of the base diaphragm and the larger vertical stiffness of the cross‐linear bearings relative to the lead‐rubber bearings. 相似文献