全文获取类型
收费全文 | 4476篇 |
免费 | 886篇 |
国内免费 | 91篇 |
专业分类
电工技术 | 646篇 |
综合类 | 144篇 |
化学工业 | 521篇 |
金属工艺 | 54篇 |
机械仪表 | 100篇 |
建筑科学 | 45篇 |
矿业工程 | 14篇 |
能源动力 | 141篇 |
轻工业 | 31篇 |
水利工程 | 5篇 |
石油天然气 | 9篇 |
武器工业 | 26篇 |
无线电 | 1624篇 |
一般工业技术 | 1781篇 |
冶金工业 | 14篇 |
原子能技术 | 65篇 |
自动化技术 | 233篇 |
出版年
2024年 | 19篇 |
2023年 | 178篇 |
2022年 | 94篇 |
2021年 | 189篇 |
2020年 | 239篇 |
2019年 | 211篇 |
2018年 | 215篇 |
2017年 | 261篇 |
2016年 | 252篇 |
2015年 | 257篇 |
2014年 | 335篇 |
2013年 | 282篇 |
2012年 | 327篇 |
2011年 | 400篇 |
2010年 | 288篇 |
2009年 | 277篇 |
2008年 | 273篇 |
2007年 | 228篇 |
2006年 | 277篇 |
2005年 | 211篇 |
2004年 | 146篇 |
2003年 | 104篇 |
2002年 | 79篇 |
2001年 | 59篇 |
2000年 | 41篇 |
1999年 | 39篇 |
1998年 | 27篇 |
1997年 | 25篇 |
1996年 | 26篇 |
1995年 | 19篇 |
1994年 | 17篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 18篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有5453条查询结果,搜索用时 15 毫秒
991.
992.
To raise the utilization ratio of lithium-ion battery in portable devices, a novel green-switch controller IC is proposed to constitute a 4-switch cascade buck–boost prototype, which is capable of outputting non-inverting step down and step up voltages. According to the relations between the input and output voltages through duty ratio, a finite state machine automatically determines the work method of converter namely buck method, boost method or transition method by combining peak and valley current programmed mode so as to improve the line regulation over the entire input voltage range. A three-phase seamless transition method is introduced into the controller. Its additional advantage is to lower output ripples. Furthermore, a special burst mode is added to reduce the power consumption during light-load operation. An elaborately designed circuitry and rigorous stability analysis further improves the seamless performance. The controller IC is designed and fabricated in 1.5 μm BCD (Bipolar-CMOS-DMOS) technology with an area of 8.75 mm2 and applied to a 2.7 V–4.2 V/3.3 V, maximum output power 1.65 W buck–boost converter. It features over 90% conversion efficiency during normal application and still remains over 80% under standby mode. The experimental results show that all functional and performance targets are successfully achieved as expected. 相似文献
993.
利用直流磁控溅射法,在室温水冷玻璃衬底上成功制备出了可见光透过率高、电阻率低的钛镓共掺杂氧化锌(TG-ZO)透明导电薄膜。X射线衍射和扫描电子显微镜研究结果表明,TGZO薄膜为六角纤锌矿结构的多晶薄膜,且具有c轴择优取向。研究了厚度对TGZO透明导电薄膜电学和光学性能的影响,结果表明厚度对薄膜的光电性能有重要影响。当薄膜厚度为628 nm时,薄膜具有最小电阻率2.01×10-4Ω.cm。所制备薄膜在波长为400~760 nm的可见光中平均透过率都超过了91%,TGZO薄膜可以用作薄膜太阳能电池和液晶显示器的透明电极。 相似文献
994.
本文分析了目前《电力电子技术》教学中普遍存在的一些问题,提出了基于工学结合的项目式课程开发思路。通过采用“项目引导、任务驱动”的教学方法能很好的激发学生的学习兴趣及学习主动性,从而进一步提高了人才的培养质量。 相似文献
995.
本文介绍了透明数据加密方法的理论知识和实现方法,分析了该加密方法的缺点和限制,并为方法的使用给出了一些建议. 相似文献
996.
Vijay Sivan Shi‐Yang Tang Anthony P. O'Mullane Phred Petersen Nicky Eshtiaghi Kourosh Kalantar‐zadeh Arnan Mitchell 《Advanced functional materials》2013,23(2):144-152
Liquid metal marbles that are droplets of liquid metal encapsulated by micro‐ or nanoparticles are introduced. Droplets of galinstan liquid metal are coated with insulators (including Teflon and silica) and semiconductors (including WO3, TiO2, MoO3, In2O3 and carbon nanotubes) by rolling over a powder bed and also by submerging in colloidal suspensions. It is shown that these marbles can be split and merged, can be suspended on water, and are even stable when moving under the force of gravity and impacting a flat solid surface. Furthermore, the marble coating can operate as an active electronic junction and the nanomaterial coated liquid metal marble can act as a highly sensitive electrochemical based heavy metal ion sensor. This new element thus represents a significant platform for the advancement of research into soft electronics. 相似文献
997.
Yun Hao Lu Hongmei Jin Hongjun Zhu Shuo‐Wang Yang Chun Zhang Jian Zhong Jiang Yuan Ping Feng 《Advanced functional materials》2013,23(18):2233-2238
Based on first‐principles electronic structure calculations and molecular dynamics simulations, a possible reaction pathway for fabricating half‐metallic Mo‐borine sandwich molecular wires on a hydrogen‐passivated Si(001) surface is presented. The molecular wire is chemically bonded to the silicon surface and is stable up to room temperature. Interestingly, the essential properties of the molecular wire are not significantly affected by the Si substrate. Furthermore, their electronic and magnetic properties are tunable by an external electric field, which allows the molecular wire to function as a molecular switch or a basic component for information storage devices, leading to applications in future molecular electronic and spintronic devices. 相似文献
998.
Johannes Krantz Tobias Stubhan Moses Richter Stefanie Spallek Ivan Litzov Gebhard J. Matt Erdmann Spiecker Christoph J. Brabec 《Advanced functional materials》2013,23(13):1711-1717
Silver nanowire (Ag NW) thin films are investigated as top electrodes in semitransparent inverted organic solar cells. The performance of semitransparent poly(3‐hexylthiophene‐2,5‐diyl):[6,6]‐phenyl‐C61‐butyric acid methyl ester (P3HT:PCBM) organic solar cells with Ag NW top electrode layers is found to match very closely the performance of reference devices based on thermally evaporated, highly reflective metal silver top electrodes. The optical losses of the semitransparent electrodes are investigated in detail and analyzed in terms of transmission, scattering, and reflection losses. The impact on an external back reflector is shown to increase the light harvesting efficiency of optically thin devices. Further analysis of transparent devices under illumination from the indium tin oxide (ITO) backside and through the Ag NW front electrode open the possibility to gain deep insight into the vertical microstructure related devices performance. Overall, Ag NW top electrodes are established as a serious alternative to TCO based electrodes. Semitransparent devices with efficiencies of over η = 2.0% are realized. 相似文献
999.
Suk Ho Kim Jongwon Yoon Su Ok Yun Youngkyu Hwang Hun Soo Jang Heung Cho Ko 《Advanced functional materials》2013,23(11):1375-1382
To create ultrathin sticker‐type electronic devices that can be attached to unconventional substrates, it is highly desirable to develop printable membrane‐type electronics on a handling substrate and then transfer the printing to a target surface. A facile method is presented for high‐efficiency transfer printing by controlling the interfacial adhesion between a handling substrate and an ultrathin substrate in a systematic manner under mild conditions. A water‐soluble sacrificial polymer layer is employed on a dimpled handling substrate, which enables the topological confinement of the polymer residue inside and near the dimples during the etching and drying processes to reduce the interfacial adhesion gently, creating a high yield of transfer printing in a deterministic manner. As an example of an electronic device that was created using this method, a highly flexible sticker‐type ZnO thin film transistor was successfully developed with a thickness of 13 μm including a printable ultrathin substrate, which can be attached to various substrates, such as paper, plastic, and stickers. 相似文献
1000.
Emmanuel Kymakis Kyriaki Savva Minas M. Stylianakis Costas Fotakis Emmanuel Stratakis 《Advanced functional materials》2013,23(21):2742-2749
The first reduction methodology, compatible with flexible, temperature‐sensitive substrates, for the production of reduced spin‐coated graphene oxide (GO) electrodes is reported. It is based on the use of a laser beam for the in situ, non‐thermal, reduction of spin‐coated GO films on flexible substrates over a large area. The photoreduction process is one‐step, facile, and is rapidly carried out at room temperature in air without affecting the integrity of the graphene lattice or the flexibility of the underlying substrate. Conductive graphene films with a sheet resistance of as low as 700 Ω sq?1 and transmittance of 44% can be obtained, much higher than can be achieved for flexible layers reduced by chemical means. As a proof of concept of our technique, laser‐reduced GO (LrGO) films are utilized as transparent electrodes in flexible, bulk heterojunction, organic photovoltaic (OPV) devices, replacing the traditional ITO. The devices displayed a power‐conversion efficiency of 1.1%, which is the highest reported so far for OPV device incorporating reduced GO as the transparent electrode. The in situ non‐thermal photoreduction of spin‐coated GO films creates a new way to produce flexible functional graphene electrodes for a variety of electronic applications in a process that carries substantial promise for industrial implementation. 相似文献