全文获取类型
收费全文 | 3840篇 |
免费 | 346篇 |
国内免费 | 342篇 |
专业分类
电工技术 | 86篇 |
技术理论 | 6篇 |
综合类 | 837篇 |
化学工业 | 37篇 |
金属工艺 | 21篇 |
机械仪表 | 47篇 |
建筑科学 | 2122篇 |
矿业工程 | 190篇 |
能源动力 | 95篇 |
轻工业 | 10篇 |
水利工程 | 435篇 |
石油天然气 | 53篇 |
武器工业 | 6篇 |
无线电 | 42篇 |
一般工业技术 | 333篇 |
冶金工业 | 63篇 |
原子能技术 | 24篇 |
自动化技术 | 121篇 |
出版年
2024年 | 4篇 |
2023年 | 25篇 |
2022年 | 49篇 |
2021年 | 61篇 |
2020年 | 84篇 |
2019年 | 93篇 |
2018年 | 75篇 |
2017年 | 78篇 |
2016年 | 97篇 |
2015年 | 141篇 |
2014年 | 217篇 |
2013年 | 208篇 |
2012年 | 301篇 |
2011年 | 398篇 |
2010年 | 297篇 |
2009年 | 426篇 |
2008年 | 364篇 |
2007年 | 210篇 |
2006年 | 206篇 |
2005年 | 212篇 |
2004年 | 138篇 |
2003年 | 135篇 |
2002年 | 94篇 |
2001年 | 87篇 |
2000年 | 115篇 |
1999年 | 88篇 |
1998年 | 51篇 |
1997年 | 39篇 |
1996年 | 49篇 |
1995年 | 31篇 |
1994年 | 24篇 |
1993年 | 27篇 |
1992年 | 21篇 |
1991年 | 22篇 |
1990年 | 13篇 |
1989年 | 14篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1980年 | 5篇 |
1979年 | 3篇 |
排序方式: 共有4528条查询结果,搜索用时 15 毫秒
1.
边坡滑坡给社会经济和人民生命安全带来了巨大威胁,降雨和地震是边坡滑坡的两大诱因。以云南省某矿山边坡作为研究对象,取样后在室内进行岩石力学实验,得到后期工作所需的岩石力学参数,利用霍克布朗准则推导出岩体的力学参数,运用理论计算和数值模拟分析降雨和地震对边坡稳定性影响,结果表明:1)在降雨入渗作用下,边坡出现滑坡主要是静水压力造成的;2)在地震作用下,当地震峰值加速度为0.1g时,有效塑性区主要位于边坡中下部,当增大地震峰值加速度,其范围向坡脚移动,当加速度为0.3g时,塑性区出现贯通趋势。 相似文献
2.
Experimental and analytical investigation of the seismic out‐of‐plane behavior of unreinforced masonry walls In addition to the vertical and horizontal load‐bearing in‐plane, masonry must also withstand out‐of‐plane loads that occur in earthquake scenarios. The out‐of‐plane behavior of unreinforced masonry walls depends on a variety of parameters and is very complex due to the strong non‐linearity. Current design methods in German codes and various international codes have not been explicitly developed for out‐of‐plane behavior and contain considerable conservatism. In the present work, shaking‐table experiments with heat‐insulating masonry walls have been conducted to investigate the out‐of‐plane behavior of vertical spanning unreinforced masonry walls. As shown in previous numerical investigations, important parameters are neglected in existing design and analysis models and the out‐of‐plane capacity is underestimated significantly. In the conducted experiments the results of these numerical investigations are verified. Furthermore, the development of an analytical design model to determine the force‐displacement relationship and the out‐of‐plane load‐bearing capacity considering all significant parameters is presented. 相似文献
3.
Natural disasters greatly impact the environment of affected societies with often unknown consequences. In this study we examine the impact that the Canterbury Earthquakes of 2010–2011 had on the distribution of alcohol outlets in Christchurch, New Zealand. Specifically, we compare the distribution of both on-site and off-site alcohol outlets pre- (December 2009) and post-earthquake (December 2014) and use spatial regression models to identify whether any neighbourhood-level factors predict the observed redistributions. Overall, the number of alcohol outlets decreased by almost 13% after the Canterbury Earthquakes. However, we found a moderate increase in the clustering of both outlet types of outlets in the post-quake period. Increases in rates of both on-site and off-site alcohol outlets in neighbourhoods were positively associated with the percentage of residents who resided in their neighbourhood < 5 years and with neighbourhood crime rate change, while negative associations were found with percentage population aged between 15 and 29 years. The results suggest that the changing spatial distribution of alcohol outlets in Christchurch was not random but driven, in part, by the emergent demographic composition of neighbourhoods. The significant practical and policy implications of a redistribution of alcohol outlets are outlined providing a tangible link between empirical research and practice in an urban environment plagued with post-disaster spatial and social uncertainties. 相似文献
4.
目前,阻尼器在工程结构减隔震控制领域的应用已极为广泛,但存在中小地震作用下阻尼器的位移和速度等较小时,阻尼器难以充分发挥耗能能力的问题。因此近年来阻尼器响应放大技术得到了国内外学者的广泛重视,并利用连杆机构、齿轮机构、杠杆机构、跨层支撑等提出了多种阻尼器响应放大装置。全面综述国内外阻尼器响应放大技术的研究和应用进展,包括装置构造和作用机理等。同时,分析现有阻尼器响应放大技术在遭遇极罕遇地震作用时阻尼器更容易失效等方面的不足,指出响应放大技术的研究和发展方向,以期为阻尼器响应放大技术的发展和极罕遇地震作用下确保工程结构的安全提供有效思路。 相似文献
5.
6.
A diagrid structure fused with shear link (DSSL) is an innovative earthquake resilient structural system. The DSSL combines the steel diagrid structural system with shear links to dissipate the earthquake energy with the goal to minimize structural repair and downtime after strong earthquake shaking. The SLs are placed between diamond‐shaped grid units and decoupled from the gravity system. To facilitate the design of the proposed DSSL system, the performance‐based plastic design (PBPD) procedure is extended to design a prototype building utilizing DSSL. Detailed finite element model is developed to simulate the non‐linear dynamic response of the structure under a range of earthquake shaking intensities. The results of non‐linear dynamic analyses show that the DSSL has excellent seismic performance and can be efficiently designed using PBPD. Lastly, detailed collapse risk assessment of the prototype building is performed using the FEMA‐P695 methodology. The result shows that the PBPD‐designed DSSL has adequate margin against collapse. Hence, it can be used as an effective seismic force resisting system. 相似文献
7.
Hosein Ghaffarzadeh Amir Hossein Ghaffari T. Y. Yang 《The Structural Design of Tall and Special Buildings》2019,28(1)
In this paper, the effectiveness of the fuzzy sliding mode control strategy on three‐dimensional benchmark building with smart base isolation under seismic excitation has been examined. One of the appropriate control theories for such this nonlinear system is the sliding mode control theory; discontinuous sliding mode theory has weakness such as chattering phenomena. In this paper, we used a combination of fuzzy logic and sliding mode theory for the deletion of this defect. The proposed control theory has been scrutinized by applying on lately developed nonlinear three‐dimensional base‐isolated benchmark building. This building because of the three‐dimensional nature, coalescing of lateral and torsional responses, continuity of responses of the superstructure, and base is modeled with three degrees of freedom on every floor. In this building eight actuators assigned only at the base level and in the two directions (x, y). In other words, 16 actuators are located underneath the structure. Furthermore, the base isolation system has been modeled by considering lateral coupled equations for a better examination of the performance of the system. The results indicate that reduction of control performance is remarkable. Also, utilizing proposed control theory can decrease the responses of building in two main directions and, particularly, in the rotational degree of freedom. 相似文献
8.
An equivalent discrete model is developed for time domain dynamic analysis of uniform high‐rise shear wall‐frame buildings with fixed base and carrying any number of tuned mass dampers (TMDs). The equivalent model consists of a flexural cantilever beam and a shear cantilever beam connected in parallel by a finite number of axially rigid members that allow the consideration of intermediate modes of lateral deformation. The proposed model was validated by a building whose lateral resisting system consists of a combination of shear walls and braced frames. The results showed the effectiveness of TMDs to reduce the peak displacements, interstory drift ratio, and accelerations when the building is subjected to a seismic load. The root mean square accelerations due to along‐wind loads also decrease if TMDs are attached to the building. 相似文献
9.
江西九江地震房屋震害分析 总被引:1,自引:1,他引:1
本文根据地震现场考察,介绍了江西九江5.7级地震造成砌体结构和钢筋混凝土框架结构房屋的震害情况,研究了房屋的震害特征,对房屋破坏原因作了初步分析,总结了防御和减轻震害的经验和教训。 相似文献
10.
提出高层建筑桩基取得完善运行效果的思维和技术方面的主要因素,并根据上述因素提出高层建筑桩基科研取得完善运行效果的勘察、设计、施工的主要技术要求,希望有助于桩基取得完善运行效果。 相似文献