全文获取类型
收费全文 | 73篇 |
免费 | 11篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 3篇 |
地球物理 | 47篇 |
地质学 | 25篇 |
海洋学 | 4篇 |
天文学 | 3篇 |
综合类 | 1篇 |
自然地理 | 2篇 |
出版年
2021年 | 3篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 5篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 3篇 |
2009年 | 6篇 |
2008年 | 4篇 |
2007年 | 2篇 |
2006年 | 6篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1990年 | 2篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有88条查询结果,搜索用时 0 毫秒
81.
One of the challenges associated with Eurocode 8 and AASHTO-LRFD is predicting the failure of irregular bridges supported by piers of unequal heights. EC8 currently uses “moment demand-to-moment capacity” ratios to somewhat guarantee simultaneous failure of piers on bridges, while AASHTO-LRFD relies on the relative effective stiffness of the piers. These conditions are not entirely valid, in particular for piers with a relative height of 0.5 or less, where a possible combination of flexure and shear failure mode may occur. In this case, the shorter piers often result in brittle shear failure, while the longer piers are most likely to fail due to flexure, creating a combination of different failure modes experienced by the bridge. To evaluate the adequacy of EC8 design procedures for regular seismic behavior, various irregular bridges are simulated through a non-linear pushover analysis using shear-critical fiber-based beam-column elements. The paper investigates the behavior of irregular monolithic and bearing-type bridges experiencing different failure modes, and proposes different methods for regularizing the bridge performance to balance damage. The ultimate aim is to obtain a simultaneous or near-simultaneous failure of all piers irrespective of the different heights and failure mode experienced. 相似文献
82.
83.
Geopolymer formation and its unique properties 总被引:3,自引:0,他引:3
The characteristic property of naturally-occurring geopolymers is a high content of humic materials that are recognized by the nitrogen function. Through a simulated geopolymerization, biopolymers with non-nitrogen function, such as xanthan gum, were found to have the characteristics of humic acid by means of UV–Vis spectrometry. This fact ascertains that any kind of biopolymer may naturally transform to a geopolymer. A geopolymer is a type of crosslinked long-chain compound, built in three-dimensional structures whose property is immune to microbial degradation. A crosslinked biopolymer was shown to have the same characterization as a geopolymer that has a long life due to its crosslinking capacity and anti-microbial properties. In this study, the formation of petroleum-based geopolymers (e.g., kerogen) was introduced. This study may elucidate the structure of geomacromolecules and the mechanism of their formation, closely related with crosslink reaction between inorganic and organic molecules. This will further change the conventional definition of geopolymer that involves only the inorganic geopolymer. 相似文献
84.
Chin-Lien Yen Chin-Hsiung Loh Liang-Chun Chen Liang-Yung Wei Wen-Cheng Lee Hsin-Ya Ho 《Natural Hazards》2006,37(1-2):3-21
In order to improve the efficiency of disaster reduction, the government of Taiwan has taken a number of initiatives in the
development of disaster reduction technology since 1982, including the 1st, 2nd and 3rd 5-year plans for hazards prevention
research, and the National Science and Technology Program for Hazards Mitigation (NAPHM). In this article, the contents and
achievements of the 5-year plans and the NAPHM are briefly reviewed. On the one hand, the 5-year plans have produced meaningful
research results; on the other hand, the NAPHM has provided a mechanism for integrating and translating the research results
into technologies that can be implemented. The NAPHM was transformed in 2003 into the National Science and Technology Center
for Disaster Reduction (NCDR) to further enhance the development and implementation of disaster technology. The mission and
major future works of the NCDR are discussed. 相似文献
85.
In August 2009,Typhoon Morakot brought a large amount of rainfall with both high intensity and long duration to a vast area of Taiwan.Unfortunately,this resulted in a catastrophic landslide in Hsiaolin Village,Taiwan.Meanwhile,large amounts of landslides were formed in the Jiaopu Stream watershed near the southeast part of the Hsiaolin Village.The Hsiaolin Village access road(Provincial Highway No.21 and Bridge No.8) was completely destroyed by the landslide and consequent debris flow.The major scope of this study is to apply a debris flow model to simulate the disaster caused by the debris flow that occurred in the Jiaopu Stream during Typhoon Morakot.According to the interviews with local residents,this study applied the destruction time of Bridge No.8 and Chen's house to verify the numerical debris flow model.By the spatial rainfall distributions information,the numerical simulations of the debris flow are conducted in two stages.In the first stage(before the landslide-dam failure),the elevation of the debris flow and the corresponding potential damages toward residential properties were investigated.In the second stage(after the landslidedam failure),comparisons of simulation results between the longitudinal and cross profiles of the Jiaopu Stream were performed using topographic maps and satellite imagery.In summary,applications of the adopted numerical debris flow model have shown positive impact on supporting better understanding of the occurrence and movement of debris flow processes. 相似文献
86.
Abstract Submarine trenching for pipeline installation in potentially unstable sediments has recently been of increasing concern. Although typical pipeline depths are less than 3 or 4 m, trenching operations generally cause local stress concentrations within the sediments and induce excess pore pressures. The result of these stress concentrations and pore pressure increases may be spreading of submarine slumps that can endanger pipelines or other nearby installations. A simplified analytical approach is described to estimate the extent of slump spreading caused by trenching. It is shown that the spreading potential is affected by many geotechnical characteristics of the sediments in addition to geomorphic processes and the oceanographic regimes governing the area. The primary geotechnical factors that influence spreading include the porepressure parameter Af , the degree of consolidation, the coefficient of earth pressure at rest, and the strength characteristics of the soil. Dimensionless parameters are developed to illustrate graphically the functional relationships among these parameters. A Gulf of Mexico soil profile is used to quantify the spreading phenomenon. 相似文献
87.
88.
Chun-Chieh Hsiao J. Y. Liu K.-I. Oyama N. L. Yen Y. A. Liou S. S. Chen J. J. Miau 《GPS Solutions》2010,14(1):83-89
The seismo-ionospheric precursor prior to the Mw7.9 earthquake near Wenchuan, China, on 12 May 2008 was observed by the FORMOSAT-3/COSMIC
satellite constellation. By binning radio occultation observations, the three-dimensional ionospheric structure can be obtained
to monitor the ionospheric electron density variation prior to the earthquake. It has been determined that near the epicenter
the F2-peak height, hmF2, descends about 25 km and the F2-peak electron density, NmF2, decreases about 2 × 105 el/cm3 around noon within 5 days prior to the earthquake. The integrated electron content decreases more than 2 TECU between 250
and 300 km altitude. 相似文献