全文获取类型
收费全文 | 7480篇 |
免费 | 268篇 |
国内免费 | 76篇 |
专业分类
电工技术 | 52篇 |
技术理论 | 1篇 |
综合类 | 157篇 |
化学工业 | 405篇 |
金属工艺 | 1914篇 |
机械仪表 | 409篇 |
建筑科学 | 1759篇 |
矿业工程 | 146篇 |
能源动力 | 102篇 |
轻工业 | 69篇 |
水利工程 | 41篇 |
石油天然气 | 110篇 |
武器工业 | 10篇 |
无线电 | 27篇 |
一般工业技术 | 594篇 |
冶金工业 | 1892篇 |
原子能技术 | 27篇 |
自动化技术 | 109篇 |
出版年
2024年 | 1篇 |
2023年 | 43篇 |
2022年 | 83篇 |
2021年 | 73篇 |
2020年 | 96篇 |
2019年 | 45篇 |
2018年 | 79篇 |
2017年 | 67篇 |
2016年 | 158篇 |
2015年 | 191篇 |
2014年 | 319篇 |
2013年 | 410篇 |
2012年 | 438篇 |
2011年 | 730篇 |
2010年 | 436篇 |
2009年 | 427篇 |
2008年 | 409篇 |
2007年 | 470篇 |
2006年 | 465篇 |
2005年 | 405篇 |
2004年 | 371篇 |
2003年 | 321篇 |
2002年 | 276篇 |
2001年 | 215篇 |
2000年 | 191篇 |
1999年 | 221篇 |
1998年 | 179篇 |
1997年 | 164篇 |
1996年 | 129篇 |
1995年 | 167篇 |
1994年 | 120篇 |
1993年 | 62篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 11篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有7824条查询结果,搜索用时 15 毫秒
961.
962.
Ronny Budi Dharma 《Journal of Constructional Steel Research》2007,63(8):1066-1076
The behaviour of unrestrained steel I-beams has been studied by means of numerical analysis and published experimental results. The numerical model was developed using a commercial finite element program, MSC.MARC Mentat. A series of different UB and UC sections and different spans, subjected to both uniform moment and midspan point loads, are considered. The numerical predictions of the buckling moments are then compared with published experimental results. Consequently, a new approach is proposed to provide more accurate and safe predictions of the fire resistance of unrestrained beams, as well as to overcome certain weaknesses in the EC3:1.2 [European committee for standardization (CEN). Eurocode 3: Design of steel structures, Part 1.2: General rules — structural fire design, EN 1993-1-2. Brussels (Belgium); 2005] design formula. In addition, to provide a quick and simple design approach for engineers, a straightforward and rational method known as the Rankine method is introduced to predict the LTB failure load of steel beams in fire. It is shown that the Rankine approach generally provides a good lower bound value for numerical predictions. 相似文献
963.
Random material variability effects on full-strength end-plate beam-to-column joints 总被引:1,自引:0,他引:1
In the seismic design of steel frames, beam-to-column joints are generally designed as full strength joints in order to avoid their engagement in the plastic range promoting the location of plastic hinges at the ends of the connected beams. In this paper, the reliability of the criteria to design full strength beam-to-column joints is investigated. In particular, in the first part of the work, starting from probabilistic analyses accounting for random material variability of connecting elements, the reliability of the design criteria suggested by codes is analyzed. Successively, on the basis of the obtained results, a new design criterion able to account for both the random material variability and the overstrength exhibited by the beam before the occurrence of local buckling is proposed. 相似文献
964.
Recent test results on reduced beam section (RBS) steel moment connections showed that specimens with a bolted web connection tend to perform poorly due to premature brittle fracture of the beam flange at the weld access hole. The measured strain data appeared to indicate that a higher incidence of base metal fracture in bolted web specimens is related, at least in part, to the increased demand on the beam flanges due to the web bolt slippage and the actual load transfer mechanism which is significantly different from that usually assumed in connection design. In this paper, the practice of providing web bolts uniformly along the beam depth was brought into question. A new seismic design procedure, which is more consistent with the actual load path identified from analytical and experimental studies, is proposed. A pilot test specimen designed by following the proposed procedure exhibited sufficient cyclic connection rotation capacity without fracture. 相似文献
965.
The use of cold-formed steel members for roof and floor truss applications is gaining widespread acceptance in the United States. However, there is little technical information regarding the behavior and design of thin gusset plates in compression. Thus, a study was initiated at the University of Missouri-Rolla aimed at investigating the behavior of thin steel gusset plates in compression. Key parameters that were considered in the experimental study were the thickness of the gusset plate, the width and length of the gusset plates, the fastener location, and the fastener pattern. Both a plate model and a column model were investigated for computing the strength of a thin plate in compression. Based on the findings of this study, design recommendations are proposed. 相似文献
966.
Ehab Ellobody 《Journal of Constructional Steel Research》2007,63(2):145-155
This paper investigates the buckling behaviour of cold-formed high strength stainless steel stiffened and unstiffened slender square and rectangular hollow section columns. The high strength duplex material is austenitic-ferritic stainless steel approximately equivalent to EN 1.4462 and UNS S31803. The columns were compressed between fixed ends at different column lengths. A nonlinear finite element model has been developed to investigate the behaviour of stiffened slender square and rectangular hollow section columns. The column strengths, load-shortening curves as well as failure modes were predicted for the stiffened and unstiffened slender hollow section columns. An extensive parametric study was conducted to study the effects of cross-section geometries on the strength and behaviour of the stiffened and unstiffened columns. The investigation has shown that the high strength stainless steel stiffened slender hollow section columns offer a considerable increase in the column strength over that of the unstiffened slender hollow section columns. The column strengths predicted from the parametric study were compared with the design strengths calculated using the American Specification, Australian/New Zealand Standard and European Code for cold-formed stainless steel structures. It is shown that the design strengths obtained using the three specifications are generally conservative for the cold-formed stainless steel unstiffened slender square and rectangular hollow section columns, but slightly unconservative for the stiffened slender square and rectangular hollow section columns. 相似文献
967.
Tubular steel jointing system that incorporates prestressed grout sleeve connections has superior strength under both static and dynamic loading. This paper reports an investigation into the effect of elevated temperatures on the load carrying capacity of such connections. Eleven specimens were heated in a furnace and the load was applied through an Instron machine. Three different grout lengths were chosen. The load deflection behaviour at different temperatures was compared. It was found that the ultimate load reduces almost linearly as temperature difference (TD) between outer and inner tubes increases. It is encouraging to observe the ductile behaviour of grouted connections at elevated temperature. Thermal analysis was also conducted to predict the temperature field in the connection. 相似文献
968.
混凝土保持体积稳定是防止混凝土早期开裂的关键措施,而磨细钢渣粉作为活性矿物掺合料对混凝土的干缩性能有着重要的影响。本文针对掺入不同种类、不同掺量钢渣粉的水泥胶砂早期干缩性能进行试验研究,探讨了钢渣粉对水泥胶砂干缩性能的影响规律。试验表明,磨细钢渣粉单掺或与矿渣粉复掺时,水泥胶砂的干缩率存在增大的趋势,在实际工程应用时不容忽视。 相似文献
969.
970.
本文通过对输水工程钢管在不同最大变形限值和钢材材质的条件下进行的结构计算和分析,探讨了在其它条件一定的情况下,管道的变形限值对钢管壁厚的影响和钢材材质的选择,供工程设计人员参考。 相似文献