全文获取类型
收费全文 | 356篇 |
免费 | 26篇 |
国内免费 | 18篇 |
专业分类
测绘学 | 23篇 |
大气科学 | 53篇 |
地球物理 | 98篇 |
地质学 | 93篇 |
海洋学 | 87篇 |
天文学 | 20篇 |
综合类 | 8篇 |
自然地理 | 18篇 |
出版年
2022年 | 2篇 |
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 13篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 14篇 |
2014年 | 12篇 |
2013年 | 18篇 |
2012年 | 19篇 |
2011年 | 20篇 |
2010年 | 17篇 |
2009年 | 20篇 |
2008年 | 26篇 |
2007年 | 21篇 |
2006年 | 12篇 |
2005年 | 10篇 |
2004年 | 15篇 |
2003年 | 12篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1959年 | 1篇 |
1954年 | 1篇 |
1953年 | 1篇 |
1942年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有400条查询结果,搜索用时 234 毫秒
111.
Shiang-Kueen Hsu 《Hydrogeology Journal》1998,6(3):405-415
In Taiwan, rapid economic growth, rising standards of living, and an altered societal structure have in recent years put
severe demands on water supplies. Because of its stable quantity and quality, groundwater has long been a reliable source
of water for domestic, agricultural, and industrial users, but the establishment of a management program that integrates groundwater
and surface-water use has been hampered by the lack of groundwater data. In 1992, the Department of Water Resources (DWR)
initiated a program entitled "Groundwater Monitoring Network Plan in Taiwan." Under this program, basic groundwater data,
including water-level and water-quality data, are being collected, and a reliable database is being established for the purpose
of managing total water resources. This paper introduces the goals, implementation stages, and scope of that plan. The plan
calls for constructing 517 hydrogeologic survey stations and 990 groundwater monitoring wells within 17 years. Under this
program, water-level fluctuations are continuously monitored, whereas water-quality samples are taken for analysis only at
the initial drilling stage and, subsequently, at the time when a monitoring well is being serviced. In 1996, the DWR and the
Water Resources Planning Commission were merged to form today's Water Resources Bureau.
Received, July 1997 · Revised, February 1998 · Accepted, January 1998 相似文献
112.
113.
We studied the mineralogy, mineral chemistry, and compositions of 48 interior silicate inclusions and a large K-rich surface inclusion from the Colomera IIE iron meteorite. Common minerals in the interior silicate inclusions are Cr diopside and Na plagioclase (albite). They are often enclosed by or coexist with albitic glasses with excess silica and minor Fe-Mg components. This mineral assemblage is similar to the “andesitic” material found in the Caddo County IAB iron meteorite for which a partial melt origin has been proposed. The fairly uniform compositions of Cr diopside (Ca44Mg46Fe10) and Na plagioclase (Or2.5Ab90.0An7.5 to Or3.5Ab96.1An0.4) in Colomera interior inclusions and the angular boundaries between minerals and metal suggest that diopside and plagioclase partially crystallized under near-equilibrium conditions from a common melt before emplacement into molten metal. The melt-crystal assemblage has been called “crystal mush.” The bulk compositions of the individual composite inclusions form an array between the most diopside-rich inclusion and plagioclase. This is consistent only with a simple mechanical mixing relationship, not a magmatic evolution series. We propose a model in which partly molten metal and crystal mush were mixed together by impact on the IIE parent body. Other models involving impact melting of the chondritic source material followed by growth of diopside and plagioclase do not easily explain near equilibrium growth of diopside and Na plagioclase, followed by rapid cooling. In the K-rich surface inclusion, K feldspar, orthopyroxene, and olivine were found together with diopside for the first time. K feldspar (sanidine, Or92.7Ab7.2An0.1 to Or87.3Ab11.0An1.7) occurs in an irregular veinlike region in contact with large orthopyroxene crystals of nearly uniform composition (Ca1.3Mg80.5Fe17.8 to Ca3.1Mg78.1Fe18.9) and intruding into a relict olivine with deformed-oval shape. Silica and subrounded Cr diopside are present within such K-feldspar regions. Some enrichments of the albite component have been detected at the end of curved elongated nodules of K feldspar intruded into the mafic silicates. The textural relationships suggest that a K-rich melt was present. A K-rich melt is neither the first melt of a chondritic system nor a differentiation product of a Na-rich partial melt of chondritic material. The K-rich material may have originated as a fluid phase that leached K from surrounding materials and segregated by a mechanism similar to that proposed for the Na-rich inclusions. 相似文献
114.
Based on a two dimensional linear water wave theory, the boundary element method (BEM) is developed and applied to study the heave and the sway problem of a floating rectangular structure in water to finite depth with one side of the boundary is a vertical sidewall and the other boundary is an open boundary. Numerical results for the added mass and radiation damping coefficients are presented. These coefficients are not only depend on the submergence and the width of the structure, but also depend on the clearance between structure and sidewall. Negative added mass and sharp peaks in the damping and added mass coefficients have been found when the clearance with a value close to integral times of half wave length of wave generated by oscillation structure. The important effect of the clearance on the added mass and radiation damping coefficients are discussed in detail. An analytical solution method is also presented. The BEM solution is compared with the analytical solution, and the comparison shows good agreement. 相似文献
115.
Yan Zhiyong Chen Lin Xiong Xiong Wang Kai Xie Renxian Hsu Hou Tze 《中国科学:地球科学(英文版)》2020,63(8):1069-1091
Flat subduction refers to low-angle(10°) or sub-horizontal subduction of oceanic slabs. Flat subduction is only recognized in ~10% of present-day subduction zones, but its impact on the behavior of the overriding plate is particularly strong.For example, flat subduction zones are typically associated with stronger earthquakes. The deformation caused by typical flat subduction will transfer from the trench to the overriding continental interior and form a broad magma belt. The formation mechanism of flat subduction has been linked to the relative buoyancy of subducted oceanic plateaus, overthrusting of the overriding plate, hydrodynamic suction, and trench retreat. However, these mechanisms remain debated. This paper systematically analyzes and summarizes previous studies on flat subduction, and outlines the possible geological effects of flat subduction, such as intracontinental orogeny and magmatism. Using examples from numerical modeling, we discuss the possible formation mechanisms. The most important factors that control the formation of flat subduction are associated with overthrusting of the overriding plate and the arrival of an oceanic plateau at the subduction zone. In addition, trench retreat is necessary to enable flat subduction. Hydrodynamic suction contributes to the reduction of the slab dip angle, but is insufficient to form flat subduction. Future numerical modeling of flat subduction should carry out three-dimensional high-resolution thermo-mechanical simulation, considering the influence of crustal eclogitization(negative buoyancy) and mantle serpentinization(positive buoyancy) of oceanic lithosphere, in combination with geological and geophysical data. 相似文献
116.
Bing-Ru Wu Nai-Chi Hsiao Pei-Yang Lin Ting-Yu Hsu Chiou-Yun Chen Shieh-Kung Huang Hung-Wei Chiang 《Journal of Seismology》2017,21(1):165-180
An earthquake early warning (EEW) system with integration of regional and onsite approaches was installed at nine demonstration stations in several districts of Taiwan for taking advantages of both approaches. The system performance was evaluated by a 3-year experiment at schools, which experienced five major earthquakes during this period. The blind zone of warning was effectively reduced by the integrated EEW system. The predicted intensities from EEW demonstration stations showed acceptable accuracy compared to field observations. The operation experience from an earthquake event proved that students could calmly carry out correct action before the seismic wave arrived using some warning time provided by the EEW system. Through successful operation in practice, the integrated EEW system was verified as an effective tool for disaster prevention at schools. 相似文献
117.
To understand the importance of picoeukaryotes in the biogeochemical cycle in the subtropical Kuroshio Current, a year-round survey of the hydrography and the distribution of picoeukaryotes were conducted in four oceanographic cruises from October 2012 to July 2013. In comparison with other seasons, the highest abundancy of photosynthetic picoeukaryotes, with concentrations >104 cells/ml, was observed around the eastern boundary of the Kuroshio in the winter. Accordingly, the composition of picoeukaryotes in this cold season was further studied by a metabarcoding analysis of the 18S rRNA gene. The majority of picoeukaryotes comprised Alveolata, followed by Haptophyta and Stramenopiles. Their composition was diverse in the waters affected by the Kuroshio and in the offshore province. For Haptophyta, in contrast to clade A prevailing in the Kuroshio waters, clade B1, which was considered the host of uncultivated diazotrophic cyanobacterium group A (UCYN-A), appeared only in the offshore area. Similarly, in Stramenopiles, Pseudo-nitzschia spp. and MAST-1D, respectively, dominated in the Kuroshio-influenced and offshore areas. While Alveolata was the most abundant group, the distributions of all lineages were similar. The association between picoeukaryote succession and hydrographic change is yet to be fully understood. Our results will assist future studies on the community composition of picoplankton and their relationship with marine ecology in the region. 相似文献
118.
Lin Liang-Fu Hsu Ho-Han Liu Char-Shine Chao Kuo-Han Ko Chia-Chun Chiu Shye-Dong Hsieh Hsin-Sung Ma Yu-Fang Chen Song-Chuen 《Marine Geophysical Researches》2019,40(4):619-633
Marine Geophysical Research - Strong ocean current influences a marine seismic survey and forces the streamer off-course from the survey line. The sideway drift of the streamer results in that the... 相似文献
119.
Nathaniel G. Plant Kacey L. Edwards James M. Kaihatu Jayaram Veeramony Larry Hsu K. Todd Holland 《Coastal Engineering》2009
Nearshore wave and flow model results are shown to exhibit a strong sensitivity to the resolution of the input bathymetry. In this analysis, bathymetric resolution was varied by applying smoothing filters to high-resolution survey data to produce a number of bathymetric grid surfaces. We demonstrate that the sensitivity of model-predicted wave height and flow to variations in bathymetric resolution had different characteristics. Wave height predictions were most sensitive to resolution of cross-shore variability associated with the structure of nearshore sandbars. Flow predictions were most sensitive to the resolution of intermediate scale alongshore variability associated with the prominent sandbar rhythmicity. Flow sensitivity increased in cases where a sandbar was closer to shore and shallower. Perhaps the most surprising implication of these results is that the interpolation and smoothing of bathymetric data could be optimized differently for the wave and flow models. We show that errors between observed and modeled flow and wave heights are well predicted by comparing model simulation results using progressively filtered bathymetry to results from the highest resolution simulation. The damage done by over smoothing or inadequate sampling can therefore be estimated using model simulations. We conclude that the ability to quantify prediction errors will be useful for supporting future data assimilation efforts that require this information. 相似文献
120.
The authors are grateful to the derivation and correction addressed by Shi and Kirby (2008) for the calculation of the wave setup and setdown induced by obliquely incident waves. The mathematical equations for the expression of setup and setdown are rederived in which the velocity potential is expanded to the second-order on the still water lever. The correct form of setdown presented by Shi and Kirby is confirmed in the present paper. 相似文献