全文获取类型
收费全文 | 1481篇 |
免费 | 268篇 |
国内免费 | 390篇 |
专业分类
测绘学 | 162篇 |
大气科学 | 52篇 |
地球物理 | 675篇 |
地质学 | 946篇 |
海洋学 | 165篇 |
天文学 | 9篇 |
综合类 | 77篇 |
自然地理 | 53篇 |
出版年
2024年 | 3篇 |
2023年 | 19篇 |
2022年 | 49篇 |
2021年 | 46篇 |
2020年 | 58篇 |
2019年 | 75篇 |
2018年 | 71篇 |
2017年 | 64篇 |
2016年 | 75篇 |
2015年 | 55篇 |
2014年 | 87篇 |
2013年 | 107篇 |
2012年 | 121篇 |
2011年 | 99篇 |
2010年 | 74篇 |
2009年 | 72篇 |
2008年 | 77篇 |
2007年 | 102篇 |
2006年 | 133篇 |
2005年 | 114篇 |
2004年 | 89篇 |
2003年 | 89篇 |
2002年 | 70篇 |
2001年 | 60篇 |
2000年 | 70篇 |
1999年 | 52篇 |
1998年 | 49篇 |
1997年 | 29篇 |
1996年 | 23篇 |
1995年 | 13篇 |
1994年 | 23篇 |
1993年 | 5篇 |
1992年 | 15篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有2139条查询结果,搜索用时 46 毫秒
991.
992.
消能支撑-方钢管混凝土框架结构抗震性能的试验研究 总被引:4,自引:0,他引:4
本文设计了一榀消能支撑框架,方钢管混凝土通过不同频率、不同位移幅值下的水平低周反复荷载试验,验证了消能支撑框架优异的消能能力,提出了相关连接构造的设计建议,为中高层钢结构住宅提供了一种新的抗震设计思路。 相似文献
993.
层间隔震技术评述 总被引:37,自引:5,他引:32
祁皑 《地震工程与工程振动》2004,24(6):114-120
层间隔震结构是隔震技术的新发展,它将隔震层设置在建筑物某层柱子和楼板之间进行结构的地震反应控制。层间隔震结构在减震机理、振动特性以及设计方法等诸多方面有别于基础隔震结构和屋盖隔震结构。本文对层间隔震结构的适用范围、优点以及其在实际工程中的应用情况进行了综述,最后,指出了层问隔震结构需要进一步研究的问题。现有的研究成果和工程应用情况表明,层间隔震结构具有明确的减震效果,施工方便,是一种具有发展前途的减震体系。 相似文献
994.
995.
Yoshiki Ikeda 《地震工程与结构动力学》2016,45(13):2185-2205
This study proposes a new design method for an active mass damper (AMD) that is based on auto‐regressive exogenous models of a building structure. The proposed method uses the results of system identification in the field of active structural control. The uncontrolled structure is identified as auto‐regressive exogenous models via measurements under earthquake excitation and forced vibration. These models are linked with an equation of motion for the AMD to introduce a state equation and output equation for the AMD–structure interaction system in the discrete‐time space; the equations apply modern control theories to the AMD design. In the numerical applications of a 10‐degree‐of‐freedom building structure, linear quadratic regulator control is used to understand the fundamental characteristics of the proposed design procedure. The feedback control law requires the AMD's acceleration, velocity and stroke; the structure's acceleration; and the ground acceleration as vibration measurements. The numerical examples confirm the high applicability and control effectiveness of the proposed method. One remarkable advantage of the proposed method is that an equation of motion for the structure becomes unnecessary for designing controllers. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
996.
Investigation of the seismic response of high‐rise buildings supported on tension‐resistant elastomeric isolation bearings
下载免费PDF全文
![点击此处可从《地震工程与结构动力学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In many applications of seismic isolation, such as in high‐rise construction, lightweight construction, and structures with large height‐to‐width aspect ratios, significant tension forces can develop in bearings, raising concerns about the possible rupture of elastomeric bearings and the uplift of sliding bearings. In this paper, a novel tension‐resistant lead plug rubber bearing (TLRB) with improved tension‐resisting capabilities is developed and experimentally and numerically assessed. This TLRB consists of a common lead plug rubber bearing (LRB) and several helical springs. After describing the theory underlying the behavior of the TLRB, the mechanical properties of reduced‐scale prototype bearings are investigated through extensive horizontal and vertical loading tests. The test results indicate that TLRBs can improve the shear stiffness and tension resistance capacity even under significant tensile loads. A series of shaking table tests on scaled models of high‐rise buildings with different aspect ratios were conducted to investigate the dynamic performance of the TLRB and the seismic responses of base‐isolated high‐rise buildings. Three different cases were considered in the shaking table tests: a fixed base condition and the use of TLRB and LRB isolation systems. The results of the shaking table test show that (a) base‐isolated systems are effective in reducing the structural responses of high‐rise buildings; (b) an isolated structure's aspect ratio is an important factor influencing its dynamic response; (c) TLRBs can endure large tensile stresses and avoid rupture on rubber bearings under strong earthquakes; and (d) the experimental and numerical results of the responses of the models show good agreement. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
997.
Probabilistic collapse resistance and residual drift assessment of buildings with fluidic self‐centering systems
下载免费PDF全文
![点击此处可从《地震工程与结构动力学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The seismic performance of three‐ and six‐story buildings with fluidic self‐centering system is probabilistically assessed. The fluidic self‐centering systems consist of devices that are based on the technology of fluid viscous dampers but built in a way that pressurization of the devices results in preload that is explored to reduce or eliminate residual drift. The design of these buildings followed a procedure that parallels the design for structures with damping systems in ASCE 7 but modified to include the preload effect. Reference conventional buildings were also designed per ASCE 7 for comparison. These buildings were then analyzed to examine and compare their seismic collapse resistance and residual drift, where the residual drift limits of 0.2, 0.5, 1.0 and 2.0% of story height were selected as important thresholds. The study further calculated the mean annual frequency of collapse and corresponding exceedance probability over 50 years, and the mean annual frequency of exceeding the threshold residual story drift limits and the corresponding exceedance probability over 50 years. Variations in the design procedures by considering increased displacement capacity or damping or preload of the devices, different types of damping, increased ultimate strength of the self‐centering device–brace systems and increased frame strength were considered. It was found that increasing either the ultimate force capacity of the self‐centering device–brace system or the frame strength results in important improvements in the collapse resistance and in minimizing residual drift, whereas the variation of other design parameters has minor effects. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
998.
Damping reduction factors and code‐based design equation for structures using semi‐active viscous dampers
下载免费PDF全文
![点击此处可从《地震工程与结构动力学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nikoo Kh. Hazaveh Geoffrey W. Rodgers Stefano Pampanin J. Geoffrey Chase 《地震工程与结构动力学》2016,45(15):2533-2550
This study uses a semi‐active viscous damper with three different control laws to reshape the structural hysteresis loop and mitigate structural response, referred to as 1–4, 1–3 and 2–4 devices, respectively. The 1–4 control law provides damping in all four quadrants of the force‐displacement graph (it behaves like a standard viscous damper), the 1–3 control law provides resisting forces only in the first and third quadrants, and the 2–4 control law provides damping in the second and fourth quadrants. This paper first outlines the linear single degree of freedom structural performance when the three types of semi‐active viscous dampers are applied. The results show that simultaneous reduction in both displacement and base‐shear demand is only available with the semi‐active 2–4 device. To enable guidelines for adding a 2–4 device into the design procedure, damping reduction factors (RFξs) are developed, as they play an important role and provide a means of linking devices to design procedures. Three methods are presented to obtain RFξ and equivalent viscous damping of a structure with a 2–4 semi‐active viscous damper. In the first method, the relationship between RFξ and the damping of a semi‐active structure can be obtained by calculating the area under the force‐deformation diagram. The second and third method modified the Eurocode8 formula of RFξ and smoothed results from analysis, respectively. Finally, a simple method is proposed to incorporate the design or retrofit of structures with simple, robust and reliable 2–4 semi‐active viscous dampers using standard design approaches. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
999.
1000.
在海洋平台摇摆墙体系基础上,在摇摆墙底部的铰接点处安装一粘弹性转角阻尼器,进行被动消能结构振动控制,利用ANSYS进行地震荷载作用下的抗震性能验算,并对阻尼器的刚度和阻尼参数进行了分析。结果表明,在摇摆墙底部施加的转角阻尼器能显著降低结构的地震反应。 相似文献