全文获取类型
收费全文 | 3596篇 |
免费 | 88篇 |
国内免费 | 82篇 |
专业分类
电工技术 | 124篇 |
综合类 | 288篇 |
化学工业 | 51篇 |
金属工艺 | 117篇 |
机械仪表 | 1527篇 |
建筑科学 | 655篇 |
矿业工程 | 119篇 |
能源动力 | 30篇 |
轻工业 | 20篇 |
水利工程 | 142篇 |
石油天然气 | 34篇 |
武器工业 | 6篇 |
无线电 | 51篇 |
一般工业技术 | 122篇 |
冶金工业 | 226篇 |
原子能技术 | 11篇 |
自动化技术 | 243篇 |
出版年
2024年 | 1篇 |
2023年 | 20篇 |
2022年 | 42篇 |
2021年 | 68篇 |
2020年 | 73篇 |
2019年 | 17篇 |
2018年 | 23篇 |
2017年 | 21篇 |
2016年 | 38篇 |
2015年 | 72篇 |
2014年 | 371篇 |
2013年 | 215篇 |
2012年 | 454篇 |
2011年 | 377篇 |
2010年 | 272篇 |
2009年 | 227篇 |
2008年 | 194篇 |
2007年 | 244篇 |
2006年 | 196篇 |
2005年 | 153篇 |
2004年 | 120篇 |
2003年 | 116篇 |
2002年 | 86篇 |
2001年 | 67篇 |
2000年 | 70篇 |
1999年 | 48篇 |
1998年 | 38篇 |
1997年 | 37篇 |
1996年 | 31篇 |
1995年 | 15篇 |
1994年 | 24篇 |
1993年 | 18篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有3766条查询结果,搜索用时 15 毫秒
1.
Shipboard cranes are extensively utilized in numerous fields such as cargo transferring and offshore engineering. The control of shipboard cranes, especially the antiswing control of payloads, has attracted much research attention due to their typical underactuation characteristics and complicated dynamics. Through comparisons of the traditional land-fixed cranes, a brief review on modeling and dynamics analysis is presented to illustrate the tremendous challenges and difficulties in controller design for shipboard cranes. A comprehensive review and brief analysis of shipboard crane control strategies are further presented. Some future research directions are also put forward for reference. It is expected that the paper will be useful for improving existing control schemes and generating novel control approaches for shipboard crane systems. 相似文献
2.
3.
应力测试是起重机安全评估中必须进行的一项检测。目前在安全评估工作中常采用应变电测法来采集起重机工作过程中的应力时程数据,由于该方法只能采集到结构由于载荷变化产生的应力,而无法采集到结构因自重产生的应力,导致应力测试无法获取结构的完整应力。利用起重机金属结构自重应力在总应力中占有的权重,分析其对应力测试实验结果的影响大小,试验结果表明在危险截面自重应力大小占总应力大小可达60%,此时不考虑自重应力进行结构安全性的判定是不全面的。可考虑利用仿真技术获取自重应力[1,2],从而使得安全评估应力测试实验结论更加准确。 相似文献
4.
曲江矿井主井井塔+54m平台上,需安装1台Gm=32/5T型电动双梁吊钩桥式起重机。由于吊装高度较高,空间狭小,井塔封屋顶面期间,在屋顶面预留400mm×400mm小孔,作为+46m平台的提升吊装孔;在屋顶面中间预留600mm×600mm小孔,作为+54m平台吊装孔。吊装时,先吊装左梁,再吊装右梁,小车正好落在组装好的左、右梁轨道上;然后将起重机推到机房中间位置,进行调试,完成安装。 相似文献
5.
6.
Futoshi Nakamura Nobuo Ishiyama Satoshi Yamanaka Motoki Higa Takumi Akasaka Yoshiko Kobayashi Satoru Ono Nao Fuke Munehiro Kitazawa Junko Morimoto Yasushi Shoji 《河流研究与利用》2020,36(6):921-933
In recent years, we have experienced mega‐flood disasters in Japan due to climate change. In the last century, we have been building disaster prevention infrastructure (artificial levees and dams, referred to as “grey infrastructure”) to protect human lives and assets from floods, but these hard protective measures will not function against mega‐floods. Moreover, in a drastically depopulating society such as that in Japan, farmland abandonment prevails, and it will be more difficult to maintain grey infrastructure with a limited tax income. In this study, we propose the introduction of green infrastructure (GI) as an adaptation strategy for climate change. If we can use abandoned farmlands as GI, they may function to reduce disaster risks and provide habitats for various organisms that are adapted to wetland environments. First, we present a conceptual framework for disaster prevention using a hybrid of GI and conventional grey infrastructure. In this combination, the fundamental GI, composed of forests and wetlands in the catchment (GI‐1) and additional multilevel GIs such as flood control basins that function when floodwater exceeds the planning level (GI‐2) are introduced. We evaluated the flood attenuation function (GI‐1) of the Kushiro Wetland using a hydrological model and developed a methodology for selecting suitable locations of GI‐2, considering flood risk, biodiversity and the distribution of abandoned farmlands, which represent social and economic costs. The results indicated that the Kushiro Wetland acts as a large natural reservoir that attenuates the hydrological peak discharge during floods and suitable locations for introducing GI‐2 are concentrated in floodplain areas developing in the downstream reaches of large rivers. Finally, we discussed the network structure of GI‐1 as a hub and GI‐2 as a dispersal site for conservation of the Red‐crowned Crane, one of the symbolic species of Japan. 相似文献
7.
8.
A method for estimating the sway angle using an observer has already been proposed. The state observer estimates the sway angle accurately and must use the detected sway angle value. However, the estimated sway angle has an error owing to rope length error, friction force, and wind. Moreover, the container mass cannot be determined, and therefore the observer parameter is not suitable. We already proposed robust antisway control for overcoming rope length error without adding a new sensor. Further, we designed a friction disturbance observer to cancel out the influence of the friction force. In this paper, we first propose a container mass estimation method when a crane system performs rolling up control. The observer parameter can be selected using the estimated mass value. Second, in crane parallel shift control, we propose a robust antisway control even when there is a wind disturbance. We design a wind disturbance observer and propose a wind disturbance estimator to separate the friction observer output from the wind disturbance observer output. We confirm through experiments that the proposed method can reduce vibration. 相似文献
9.
This study investigates a berth allocation problem considering the periodic balancing utilization of quay cranes in container terminals. The proposed model considers that the quay cranes allocated to a work shift should be fully used and other real-world considerations, such as the continuous quay line, the penalties for early arrivals and departure delays. To solve the model, several heuristics are developed: the model for large problems is decomposed into sub-models that are solved by rolling-horizon heuristics; neighborhood search heuristics are used for optimizing a berthing order of vessels; parallel computing is used to improve the algorithmic performance. The method performs well when applied to real-world large-scale instances with promising computation time that is linearly related to the number of vessels. 相似文献
10.