全文获取类型
收费全文 | 83篇 |
免费 | 13篇 |
国内免费 | 8篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 1篇 |
地球物理 | 69篇 |
地质学 | 17篇 |
海洋学 | 8篇 |
天文学 | 3篇 |
综合类 | 3篇 |
自然地理 | 1篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 5篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 7篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 8篇 |
2004年 | 1篇 |
2003年 | 7篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
排序方式: 共有104条查询结果,搜索用时 17 毫秒
61.
全球板块的分割和漂移并非杂乱无章,它们被力学性质各异的构造网络组合在同一应力场中构成全球扭转构造体系。本文从分析结构要素的力学属性入手来鉴定这个体系。该体系由一个NWW向螺旋型扭转压裂带为主干要素及NNE向张裂带、经向扭劈裂带和纬向扭割裂带等配套要素组成。 相似文献
62.
M. Ciccotti N. Negri L. Sassi G. Gonzato F. Mulargia 《Journal of Volcanology and Geothermal Research》2000,98(1-4)
The results of a series of experiments aimed at characterizing the elastic and failure parameters of lava specimens from Mount Etna, Vulcano and Stromboli volcanos is presented. The double torsion—constant configuration—load relaxation method has been employed to obtain the behavior of the stress intensity factor versus mode I subcritical crack velocity. The experimental technique has been optimized in several respects. First, a very stiff machine, expressly designed and built, has been used. Second, all samples have been carefully machined to low tolerance. Third, the experimental conditions have been carefully controlled, with temperature variations within 1°C and humidity within 10%. Fourth, high resolution electronic measuring systems have been used together with a pulse stacking procedure. Fifth, the length of the prefracture has been optically checked. This optimization allowed us to measure the slope of the subcritical fracture propagation curve in the III region, which extends from velocities of 10−7 m/s to catastrophic, with a standard deviation around 20%, suggesting that the results can be effectively used for modeling purposes. As a by-product, we could measure the elastic parameters with an accuracy of a few percent. 相似文献
63.
The most straightforward method to mitigate seismic pounding damage to adjacent structures is to provide adequate separation distance between them to completely preclude pounding during strong shaking. Many studies on the necessary separation distance between adjacent structures have been reported recently. Seismic codes around the world also specify the minimum required separation distances. However, all those required separations were derived by considering only the lateral responses of structures. For asymmetric structures with coupled torsional–lateral responses, the required separations are not well investigated. This paper presents some parametric study results on the relative displacement of adjacent asymmetric structures by considering their coupled torsional–lateral responses. Random vibration method is employed in the analysis. Both elastic and inelastic responses are considered. Effects of vibration frequencies, torsional stiffness and eccentricities of adjacent structures on their relative displacements are investigated. Numerical results are presented in dimensionless form and are discussed with respect to the current code specifications. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
64.
A comprehensive approach is developed to estimate relevant design quantities—lateral deformations and axial forces—in isolation systems composed of lead–rubber bearings. The approach, applicable to symmetric and asymmetric‐plan systems, includes the effects of bidirectional excitation, rocking, and torsion; and is the culmination of previous work on this topic. The approach is based on nonlinear response history analysis of an isolated block using an advanced bearing model that incorporates the interaction between axial force and lateral response of the bearing, known as axial‐load effects. The rocking response of the system and peak axial forces are shown to depend on the isolation period, the normalized strength—or yield strength normalized by peak ground velocity, the ratios of rocking frequency about each horizontal axis to vertical frequency, and the normalized stiffness eccentricity. In an attempt to develop results widely applicable to asymmetric‐plan systems, eccentricity is introduced by varying the stiffnesses and strengths of individual bearings in an idealized, rectangular plan. This idealized system approach is shown to have limited success; when applied to actual asymmetric‐plan systems the design equations to estimate response are accurate for lateral deformations but err by up to 25% for axial forces. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
65.
The inelastic earthquake response of eccentric, multistorey, frame‐type, reinforced concrete buildings is investigated using three‐ and five‐storey models, subjected to a set of 10, two‐component, semi‐artificial motions, generated to match the design spectrum. Buildings designed according to the EC8 as well as the UBC‐97 code were included in the investigation. It is found that contrary to what the simplified one‐storey, typical, shear‐beam models predict, the so‐called ‘flexible’ side frames exhibit higher ductility demands than the ‘stiff’ side frames. The substantial differences in such demands between the two sides suggest a need for reassessment of the pertinent code provisions. This investigation constitutes one of the first attempts to study the problem of inelastic torsion by means of realistic, multistorey inelastic building models. Additional studies with similar or even more refined idealizations will certainly be required to arrive at definite results and recommendations for possible code revisions. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
66.
This paper addresses some key issues which have been the subject of dispute in recent years in studying the seismic torsional response of asymmetric structures. These issues include the interpretation of the code accidental torsional provision, and the influence of the force reduction factor and of the uncoupled lateral period, on the torsional response of asymmetric structures. The responses of single-storey torsionally unbalanced structural models, designed in accordance with the torsional provisions of seismic building codes in Europe, the United States and Canada, and subjected to seismic ground motions corresponding to both the serviceability and ultimate limit states, are studied analytically. On the basis of a better understanding of the above issues as achieved in this study, the performance of code-designed torsionally unbalanced structures for both limit states is assessed. © 1997 John Wiley & Sons, Ltd. 相似文献
67.
68.
69.
不对称大底板多塔楼隔震结构的地震响应分析 总被引:1,自引:0,他引:1
针对不对称大底板多塔楼隔震结构体系,通过建立地震响应的动力分析简化模型,推导出不对称大底板多塔楼隔震结构体系地震作用下的运动方程。对一实际的不对称大底板多塔楼隔震结构进行地震响应仿真分析,探讨塔楼质量偏心率和塔楼质量比对结构周期比、位移比和层剪力比的影响。结果显示,不对称大底板多塔楼隔震结构扭转角主要由隔震层产生;与不隔震结构相比,不对称大底板多塔楼隔震体系的扭转角减小,可取得较好的减震效果;塔楼与底板的位置分布和质量分布会影响体系的扭转效应和减震效果,应尽量使塔楼的质心与底板质心重合,塔楼质量分布均匀,以减小结构的扭转效应,提高减震效果。 相似文献
70.
This paper studies the effect of coherency loss and wave passage on the seismic torsional response of three‐dimensional, multi‐storey, multi‐span, symmetric, linear elastic buildings. A model calibrated against statistical analyses of ground motion records in Mexico City is used for the coherency function. The structural response is assessed in terms of shear forces in structural elements. Incoherence and wave passage effects are found to be significant only for columns in the ground level of stiff systems. The increase of column shears in the ground level is much higher for soft than for firm soil conditions. For the torsionally stiff systems considered, it is found that incoherent and phase‐delayed ground motions do not induce a significant rotational response of the structure. The use of a code eccentricity to account for torsion due to ground motion spatial variation is assessed. On firm soil, the use of a base shear along with an accidental eccentricity results in highly overestimated shear forces; however, for soft soil conditions, code formulations may result in underestimated shear forces. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献