全文获取类型
收费全文 | 2675篇 |
免费 | 417篇 |
国内免费 | 128篇 |
专业分类
电工技术 | 323篇 |
综合类 | 257篇 |
化学工业 | 155篇 |
金属工艺 | 138篇 |
机械仪表 | 222篇 |
建筑科学 | 302篇 |
矿业工程 | 144篇 |
能源动力 | 95篇 |
轻工业 | 43篇 |
水利工程 | 140篇 |
石油天然气 | 47篇 |
武器工业 | 36篇 |
无线电 | 643篇 |
一般工业技术 | 166篇 |
冶金工业 | 96篇 |
原子能技术 | 15篇 |
自动化技术 | 398篇 |
出版年
2024年 | 20篇 |
2023年 | 44篇 |
2022年 | 73篇 |
2021年 | 84篇 |
2020年 | 116篇 |
2019年 | 97篇 |
2018年 | 90篇 |
2017年 | 104篇 |
2016年 | 101篇 |
2015年 | 132篇 |
2014年 | 206篇 |
2013年 | 171篇 |
2012年 | 234篇 |
2011年 | 196篇 |
2010年 | 176篇 |
2009年 | 171篇 |
2008年 | 133篇 |
2007年 | 164篇 |
2006年 | 152篇 |
2005年 | 129篇 |
2004年 | 98篇 |
2003年 | 91篇 |
2002年 | 93篇 |
2001年 | 62篇 |
2000年 | 60篇 |
1999年 | 66篇 |
1998年 | 45篇 |
1997年 | 26篇 |
1996年 | 22篇 |
1995年 | 19篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1984年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有3220条查询结果,搜索用时 803 毫秒
101.
《International Journal of Hydrogen Energy》2019,44(14):7053-7058
This work shows how to manufacture completely coated membrane electrode assemblies (CC-MEAs) for PEM water electrolysis by only using a slot die. Platinum, Nafion®, and IrO2 dispersions are successively coated to the respective dried layer. For comparison reasons, MEAs with the same Iridium loading of 2.1 mg cm−2 and Platinum loading of 0.4 mg cm−2, assembled with a commercial membrane of the same 20 μm thickness, were produced via decal method. Differences in polarization curves are attributed to the lower high frequency resistance of CC-MEAs determined by impedance spectroscopy. The easy-to-scale CC-MEA method presented here offers the advantages of direct membrane deposition (DMD) without the challenge of homogenously coating a porous transport layer (PTL). Therefore, it allows a free choice of different PTLs – regardless if in sintered form or as expanded metal. The comparability between the produced CC-MEAs and published DMD results is shown by means of cross-sectional and electrochemical measurements. 相似文献
102.
Development of Motor Model of Rotor Slot Harmonics for Speed Sensorless Control of Induction Motor
下载免费PDF全文
![点击此处可从《Electrical Engineering in Japan》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper proposes a novel mathematical dynamic model to represent the steady‐state and transient‐state characteristics of rotor slot harmonics of an induction motor for sensorless control. Although it is well known that the rotor slot harmonics originate from the mechanical structure of the induction motor, a mathematical model that describes the relationship between the stator/rotor currents of the induction motor and the slot harmonics has not yet been proposed. Therefore, in this paper, a three‐phase model of the induction motor that depicts the rotor slot harmonics is developed by taking into consideration the magnetomotive force harmonics and the change in the magnetic air gap caused by the rotor slots. The validity of the proposed model is verified by comparing the experimental results and the calculated values. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(3): 63–74, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22478 相似文献
103.
104.
槽式预埋件安装方便,机动灵活,是解决悬挂系统受力点难题的一种有效方法。随着愈来愈多的工程应用,其承载力设计方法逐渐引起重视。文中从承载特点、破坏模式、现有试验研究几个方面,对其研究现状进行综述,并介绍了在工程中的实例应用。 相似文献
105.
A novel low‐profile slot‐loaded epsilon‐negative (ENG) transmission line (TL) is proposed for efficiency‐improved zeroth‐order resonant antennas. It is demonstrated that the quality factor of the ENG TL‐based zeroth‐order resonator can be remarkably reduced by enlarging the slot size, therefore, a highly efficient radiating resonator can be designed with higher gain at the zeroth‐order frequency. Two one‐dimensional zeroth‐order resonant antennas with identical unit cell size but different unit cell number are fabricated and measured, each of which can realize a monopole‐like radiation pattern at nearly the same frequency. A maximum gain of 1.96 dBi is generated for the electrically small two‐unit‐cell configuration together with an improved efficiency from 57.0% to 69.1%, while the compact four‐unit‐cell antenna can realize a maximum gain of 3.86 dBi with an improved efficiency from 71.0% to 82.4%. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013. 相似文献
106.
口语理解是对话系统重要的功能模块,语义槽填充和意图识别是面向任务口语理解的两个关键子任务。近年来,联合识别方法已经成为解决口语理解中语义槽填充和意图识别任务的主流方法,介绍两个任务由独立建模到联合建模的方法,重点介绍基于深度神经网络的语义槽填充和意图识别联合建模方法,并总结了目前存在的问题以及未来的发展趋势。 相似文献
107.
DAISUKE HIRAMATSU KAZUMA TSUJIKAWA TAKASHI UEDA MASAFUMI FUJITA HIROAKI ISHIZUKA MASASHI OKUBO HIDEYUKI HACHIYA JUNJI MORI DAI NOZAKI DAISUKE IWASHITA TADASHI TOKUMASU 《Electrical Engineering in Japan》2017,198(2):39-49
Fractional‐slot windings are widely used in rotating machines in order to improve the output voltage waveform, increase the design flexibility, and gain many other advantages. However, fractional‐slot windings are known to produce different harmonic components such as an even order and/or fractional number of space flux harmonics compared to integral‐slot windings. These harmonics may increase stray losses and cause stator core vibration. This paper describes an analysis of space flux harmonics and proposes new winding methods such as “novel interspersed windings” to reduce these harmonic components. The proposed winding methods were verified by numerical analysis and model tests. 相似文献
108.
A new hybrid assembly line design, called parallel U-shaped assembly line system, is introduced and characterised along with numerical examples for the first time. Different from existing studies on U-shaped lines, we combine the advantages of two individual line configurations (namely parallel lines and U-shaped lines) and create an opportunity for assigning tasks to multi-line workstations located in between two adjacent U-shaped lines with the aim of maximising resource utilisation. Utilisation of crossover workstations, in which tasks from opposite areas of a same U-shaped line can be performed, is also one of the main advantages of the U-shaped lines. As in traditional U-shaped line configurations, the newly proposed line configuration also supports the utilisation of crossover workstations. An efficient heuristic algorithm is developed to find well-balanced solutions for the proposed line configurations. Test cases derived from existing studies and modified in accordance with the proposed system in this study are solved using the proposed heuristic algorithm. The comparison of results obtained when the lines are balanced independently and when the lines are balanced together (in parallel to each other) clearly indicates that the parallelisation of U-shaped lines helps decrease the need for workforce significantly. 相似文献
109.
Kuo‐Lung Lo Chia‐Jen Kao Kai‐Wei Lan Wei‐Yuan Cheng Ta‐Jo Liu 《Journal of the Society for Information Display》2014,22(7):337-345
Ink drops have to be filled into the square cells for an electrowetting display panel. Several ink solutions such as dodecane, tetradecane, and hexadecane were used as test liquids. These fluids have viscosities less than 4 mPas and surface tensions between 23.3 and 26 mN/m and contact angles less than 50°. A slot coating die was employed to deliver these liquids to fill up the square cells. The effects of several parameters such as coating thickness and coating speed were examined. Operating windows inside which the stable filling is possible could be found for these liquids. Several defects were observed outside the operating windows. A flow visualization technique was applied to observe the fluid motion in the coating bead region, particularly the movements of upstream and downstream menisci, the mechanism of liquid filling was discussed. 相似文献
110.
Yun‐Mei Hsiung 《中国工程学刊》2013,36(1):145-154
Abstract In this paper, the procedure of normalizing load‐deflection curves of lateral piles in a homogeneous elasto‐plastic soil is presented. An analytical method using subgrade reactions reveals that the normalized relation of load‐deflection exists for force, moment or combined load. The normalized curves for force and moment load fit very well with the predictions using the equations. For the combined load, the normalized curves are distributed between the force and moment load curves, so it is easy to use interpolation from a family of curves. These normalized curves provide a very convenient way for calculating the pile load or deflection in the design stage. 相似文献