全文获取类型
收费全文 | 30394篇 |
免费 | 5811篇 |
国内免费 | 1586篇 |
专业分类
电工技术 | 3376篇 |
技术理论 | 2篇 |
综合类 | 2170篇 |
化学工业 | 2319篇 |
金属工艺 | 10549篇 |
机械仪表 | 3066篇 |
建筑科学 | 1442篇 |
矿业工程 | 453篇 |
能源动力 | 1093篇 |
轻工业 | 459篇 |
水利工程 | 273篇 |
石油天然气 | 1428篇 |
武器工业 | 281篇 |
无线电 | 2415篇 |
一般工业技术 | 4170篇 |
冶金工业 | 980篇 |
原子能技术 | 211篇 |
自动化技术 | 3104篇 |
出版年
2024年 | 126篇 |
2023年 | 574篇 |
2022年 | 862篇 |
2021年 | 1027篇 |
2020年 | 1227篇 |
2019年 | 1160篇 |
2018年 | 1092篇 |
2017年 | 1488篇 |
2016年 | 1498篇 |
2015年 | 1399篇 |
2014年 | 2062篇 |
2013年 | 2400篇 |
2012年 | 2206篇 |
2011年 | 2358篇 |
2010年 | 1772篇 |
2009年 | 1656篇 |
2008年 | 1564篇 |
2007年 | 2065篇 |
2006年 | 1974篇 |
2005年 | 1580篇 |
2004年 | 1420篇 |
2003年 | 1147篇 |
2002年 | 975篇 |
2001年 | 828篇 |
2000年 | 690篇 |
1999年 | 536篇 |
1998年 | 407篇 |
1997年 | 390篇 |
1996年 | 330篇 |
1995年 | 245篇 |
1994年 | 196篇 |
1993年 | 125篇 |
1992年 | 100篇 |
1991年 | 91篇 |
1990年 | 64篇 |
1989年 | 71篇 |
1988年 | 28篇 |
1987年 | 18篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1959年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Kotaro Matsuuchi Tadashi Fukami Nobuyuki Naoe Ryoichi Hanaoka Shinzo Takata Toshio Miyamoto 《Electrical Engineering in Japan》2005,150(2):43-49
This paper presents a method of predicting the steady‐state performance of a new hybrid‐excitation synchronous machine (HESM) theoretically. The field pole of this HESM is axially divided into two parts; one is an excitation part and the other a permanent‐magnet (PM) part. A nonlinear equivalent circuit, which can include the saliency of the rotor and the magnetic saturation due to the iron core, is derived. Based on this equivalent circuit, the steady‐state performance of the HESM is calculated, and the results are confirmed through experiments. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 43–49, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20033 相似文献
62.
This paper proposed a novel hybrid probabilistic network, which is a good tradeoff between the model complexity and learnability
in practice. It relaxes the conditional independence assumptions of Naive Bayes while still permitting efficient inference
and learning. Experimental studies on a set of natural domains prove its clear advantages with respect to the generalization
ability. 相似文献
63.
G. Biallas Dr.‐Ing. C. Sick J. Schneider K.‐H. Trautmann 《Materialwissenschaft und Werkstofftechnik》2007,38(9):705-711
Biaxial fatigue of friction stir welded stiffened panels Within the framework of the European WelAir project, cruciform specimens made from stiffening FSW overlap joints were fatigued in the DLR biaxial test rig. To resemble the loading situation of pressurized fuselage structures, proportional loading without any phase shift, but with different load ratios λ between the loading components in both directions was applied.Natural crack initiation and subsequent crack growth were governed by the stiffness gradient caused by introducing the stringer. Cracks initiated and propagated at run‐in and run‐out locations in a direction perpendicular to the weld seam. The shortest fatigue life was observed for uniaxial loading in welding direction (λ = 0). An additional stress component perpendicular to the joint line (λ > 0) resulted in a higher number of cycles to failure. Similar to single stringer panels, increasing the load ratio also increased the number of cycles to failure for FSW clip‐stringer structural members, but additionally gives a different location of the fatal crack. 相似文献
64.
65.
66.
Influence of Ni Interlayers on the Mechanical Properties of Ti6Al4V/(WC-Co) Friction Welds 总被引:2,自引:0,他引:2
M. Shamanian M. Salehi A. Saatchi T. H. North 《Materials and Manufacturing Processes》2003,18(4):581-598
Ni interlayers were introduced prior to dissimilar friction welding of Ti6Al4V base material to three cemented carbide substrates. The fracture strength of Ti6Al4V/(WC-6 wt% Co) welds were poor and were markedly improved when 20-µm thick Ni interlayers were introduced prior to dissimilar friction welding. These results were only produced when the (WC-6 wt% Co) cermet was electroplated prior to friction welding. When the Ti6Al4V alloy was electroplated prior to friction welding, fractured WC particles and cracking were observed in the (WC-Co) carbide substrate. The fracture strengths of Ti6Al4V/(WC-11 wt% Co) and Ti6Al4V/(WC-24 wt% Co) welds were not improved when 20-µm thick Ni interlayers were introduced prior to friction welding. During mechanical testing, the Ni layer retained at the dissimilar joint interface created a region of weakness. 相似文献
67.
68.
本文研究当机械臂的终端受有约束时的控制问题,其中心内容是给出“任务规范投影算子”的概念,利用它首先将机械臂的动态方程解耦为两组方程,它们分别描述了运动与约束力,在此基础上给出了机械臂的控制律,使闭环系统跟踪期望的速度与约束力。 相似文献
69.
70.
ZHENG Yuanmou 《有色金属材料与工程》2003,(1)
在爆炸焊接工艺中,存在一种称为边界效应的物理现象。即在一般情况下,在爆炸焊接后的复合材料中,会出现雷管区不复、其余周边被打伤、打裂和变形严重等问题。这些问题严重地影响着这类材料的质量。该文从传统的和经典的力学及能量原理出发,探讨了边界效应产生的力学 能量原理,并且提出了预防的措施。 相似文献