全文获取类型
收费全文 | 12889篇 |
免费 | 1371篇 |
国内免费 | 520篇 |
专业分类
电工技术 | 958篇 |
综合类 | 999篇 |
化学工业 | 1975篇 |
金属工艺 | 689篇 |
机械仪表 | 1289篇 |
建筑科学 | 832篇 |
矿业工程 | 1517篇 |
能源动力 | 1094篇 |
轻工业 | 279篇 |
水利工程 | 1243篇 |
石油天然气 | 751篇 |
武器工业 | 86篇 |
无线电 | 412篇 |
一般工业技术 | 1134篇 |
冶金工业 | 965篇 |
原子能技术 | 214篇 |
自动化技术 | 343篇 |
出版年
2024年 | 40篇 |
2023年 | 156篇 |
2022年 | 308篇 |
2021年 | 385篇 |
2020年 | 409篇 |
2019年 | 295篇 |
2018年 | 297篇 |
2017年 | 390篇 |
2016年 | 466篇 |
2015年 | 534篇 |
2014年 | 848篇 |
2013年 | 824篇 |
2012年 | 1028篇 |
2011年 | 1055篇 |
2010年 | 738篇 |
2009年 | 732篇 |
2008年 | 637篇 |
2007年 | 772篇 |
2006年 | 713篇 |
2005年 | 633篇 |
2004年 | 534篇 |
2003年 | 492篇 |
2002年 | 396篇 |
2001年 | 362篇 |
2000年 | 301篇 |
1999年 | 290篇 |
1998年 | 210篇 |
1997年 | 184篇 |
1996年 | 159篇 |
1995年 | 130篇 |
1994年 | 116篇 |
1993年 | 78篇 |
1992年 | 54篇 |
1991年 | 52篇 |
1990年 | 49篇 |
1989年 | 29篇 |
1988年 | 22篇 |
1987年 | 17篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1959年 | 5篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
1.
2.
《Advanced Powder Technology》2022,33(8):103602
To operate a bag filter continuously, pulse-jet cleaning of dust particles from the filter medium is commonly required, and the pulse-jet pressure significantly affects the filter performance. In this study, the accumulation structure of residual dust particles inside and on the surface of a filter medium at different pulse-jet pressures was investigated by constructing a simple model, and the influence of the dust structure on the filter performance was clarified. Using a simple model, we determined the effective ratio of filtration area β, which represents the ratio of the filterable area to the total filtration area, the true resistance coefficient due to the primary dust layer ζp’ thinly deposited on the filter surface, and the true resistance coefficient inside the filter media itself ζf’. The effective ratio of filtration area β decreased with operation time for all pulse-jet pressures; however, it maintained a high value when the pulse-jet pressure was high. The validity of β analyzed by the model was verified using two different methods, and the results showed good agreement, indicating that the model is effective in identifying real conditions. The true resistance coefficient due to the primary dust layer ζp’ decreased as the pulse-jet pressure increased; however, the true resistance coefficient inside the filter media itself ζf’ was the highest at 0.5 MPa. In addition, the dust collection efficiency was different at each pulse-jet pressure, which was considered to be caused by the difference in the dust particle accumulation structure. 相似文献
3.
4.
5.
Rectangular section control technology(RSCT)was introduced to achieve high-precision profile control during silicon steel rolling.The RSCT principle and method were designed,and the whole RSCT control strategy was developed.Specifically,RSCT included roll contour design,rolling technology optimization,and control strategy development,aiming at both hot strip mills(HSMs)and cold strip mills(CSMs).Firstly,through the high-performance variable crown(HVC)work roll optimization design in the upper-stream stands and the limited shifting technology for schedule-free rolling in the downstream stands of HSMs,a hot strip with a stable crown and limited wedge,local spot,and single wave was obtained,which was suitable for cold rolling.Secondly,an approximately rectangular section was obtained by edge varying contact(EVC)work roll contour design,edge-drop setting control,and closed loop control in the upper-stream stands of CSMs.Moreover,complex-mode flatness control was realized by coordinating multiple shape-control methods in the downstream stands of CSMs.In addition,the RSCT approach was applied in several silicon-steel production plants,where an outstanding performance and remarkable economic benefits were observed. 相似文献
6.
Adaptive robust boundary control of shaft vibrations under perturbations with unknown upper bounds
下载免费PDF全文
![点击此处可从《International Journal of Adaptive Control and Signal Processing》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper presents robust and adaptive boundary control designs to stabilize the two‐dimensional vibration of hybrid shaft model. The hybrid shaft is mathematically represented by a set of partial differential equations, governing the shaft vibrations, coupled to ordinary differential equations, describing rigid body spinning and dynamic boundary conditions. The control objective is to stabilize the transverse vibrations of the perturbed shaft while regulating the spinning rate. To achieve this, the paper first establishes robust boundary control laws that fulfil the control objective in the presence of modeling uncertainties and external disturbances operating over the shaft domain and boundary. Lyapunov‐based analyses show that the proposed robust control exponentially stabilizes the shaft with vanishing distributive perturbations, while assuring ultimately bounded vibrations in the case of nonvanishing perturbations. Then, adaptive control philosophy is utilized to achieve redesigned robust controllers that only use online adaptation of control gains without acquiring the knowledge of bounds on perturbations, as well as dynamic parameters. An advantage of this design is avoiding an overconservative robust control law, which may induce poor stability and chattering in tackling system perturbations with unknown upper bounds. Simulations through finite element method illustrate the results. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
张峰水库溢洪道体型优化设计 总被引:1,自引:0,他引:1
本文对已设计的张峰水库溢洪道进行了模型试验,根据对试验结果分析,认为原方案设计存在一些问题,并针对问题进行了优化设计。通过对修改方案模型试验结果分析,得出修改方案改进了原方案中存在的不足,优化合理,是可以采用的。 相似文献
8.
丝网气液分离器分离性能和压力损失分析 总被引:3,自引:0,他引:3
对丝网气液分离器的分离机理进行了详细分析,在此基础上给出了丝网气液分离器的分离效率和压降计算公式。与HG/T 21618-1998《丝网除沫器》中的公式相比,此公式可以用于任意组合的丝网结构,更具普适性,并且能定量分析各种分离机理对分离的贡献。对丝网式空气过滤器计算的结果表明,此公式具有很好的精度,可以用于工程设计。 相似文献
9.
10.
高速往复式内燃机平衡轴低质量设计分析 总被引:2,自引:0,他引:2
分析了扇形和偏心圆两种平衡轴设计的要求以及平衡重低质量的设计原则。扇形平衡重半径及宽度应尽量大、夹角应尽量小。偏心圆平衡重的偏心圆半径应尽可能大 ,轴承半径应尽可能小。同样质量的扇形平衡重产生的平衡力比偏心圆平衡重要大。 相似文献