全文获取类型
收费全文 | 5230篇 |
免费 | 755篇 |
国内免费 | 211篇 |
专业分类
电工技术 | 540篇 |
综合类 | 242篇 |
化学工业 | 329篇 |
金属工艺 | 106篇 |
机械仪表 | 267篇 |
建筑科学 | 122篇 |
矿业工程 | 77篇 |
能源动力 | 158篇 |
轻工业 | 79篇 |
水利工程 | 26篇 |
石油天然气 | 23篇 |
武器工业 | 38篇 |
无线电 | 1956篇 |
一般工业技术 | 1420篇 |
冶金工业 | 68篇 |
原子能技术 | 58篇 |
自动化技术 | 687篇 |
出版年
2024年 | 26篇 |
2023年 | 174篇 |
2022年 | 77篇 |
2021年 | 186篇 |
2020年 | 230篇 |
2019年 | 189篇 |
2018年 | 175篇 |
2017年 | 237篇 |
2016年 | 224篇 |
2015年 | 223篇 |
2014年 | 360篇 |
2013年 | 300篇 |
2012年 | 339篇 |
2011年 | 388篇 |
2010年 | 297篇 |
2009年 | 302篇 |
2008年 | 312篇 |
2007年 | 317篇 |
2006年 | 265篇 |
2005年 | 189篇 |
2004年 | 167篇 |
2003年 | 148篇 |
2002年 | 135篇 |
2001年 | 106篇 |
2000年 | 124篇 |
1999年 | 90篇 |
1998年 | 100篇 |
1997年 | 44篇 |
1996年 | 62篇 |
1995年 | 46篇 |
1994年 | 57篇 |
1993年 | 40篇 |
1992年 | 40篇 |
1991年 | 25篇 |
1990年 | 24篇 |
1989年 | 25篇 |
1988年 | 16篇 |
1987年 | 7篇 |
1986年 | 12篇 |
1985年 | 17篇 |
1984年 | 32篇 |
1983年 | 31篇 |
1982年 | 23篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1975年 | 2篇 |
1962年 | 2篇 |
1959年 | 1篇 |
1956年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有6196条查询结果,搜索用时 15 毫秒
71.
计量窃电智能化遥距侦测和取证的应用研究综合应用现行营销在线监控的各系统对用户,采用计量自动化遥距侦测并分析窃电行为,同时启动现场摄像机取证。降低了供电企业管理成本,并确保了整个社会和谐发展及电力安全和稳定供应。 相似文献
72.
A. Gadisa W. Mammo L. M. Andersson S. Admassie F. Zhang M. R. Andersson O. Inganäs 《Advanced functional materials》2007,17(18):3836-3842
A new alternating polyfluorene copolymer poly[2,7‐(9,9‐dioctylfluoren)‐alt‐5,5‐(5′,8′‐di‐2‐thienyl‐(2′,3′‐bis‐(3′′‐octyloxyphenyl)‐quinoxaline))] (APFO‐15), which has electron donor–acceptor–donor units in between the fluorene units, is synthesized and characterized. This polymer has a strong absorption and emission in the visible range of the solar spectrum. Its electroluminescence and photoluminescence emissions extend from about 560 to 900 nm. Moreover, solar cells with efficiencies in excess of 3.5 % have been realized from blends of APFO‐15 and an electron acceptor molecule, a methanofullerene [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM). It has also been observed that electron and hole transport is balanced both in the pure polymer phase and in polymer/PCBM bulk heterojunction films, which makes this material quite attractive for applications in opto‐electronic devices. 相似文献
73.
74.
This paper describes the design and prototyping of an auto-balanced contactless current sensor in standard Complementary Metal–Oxide–Semiconductor (CMOS) technology, without any additional post-processing cost. The architecture includes two high-sensitivity Hall plates with differential amplification electronics. A high common mode rejection is insured by the integrated auto-balancing system based on the use of integrated coils. When a common current is applied in the embedded coils, the integrated system provides a feedback signal to a digital control unit which in turn adjusts the biasing current of one of the Hall plates in order to balance the amplification of the two Hall plates. Designed in a standard CMOS technology, this sensor can be integrated in power control System-On-Chip requiring extremely electro-magnetically compatible current sensor. 相似文献
75.
Up to date, MOSFETs have been made through well established techniques that use SiO2 as the gate dielectric and the related design issues are well established. The need to scale down device dimensions allowed researchers to seek for alternative materials, in order to replace SiO2 as the gate dielectric. The implementation of such MOS devices in memory or logic circuits needs to take into account the effects that the use of the new gate dielectrics has on parameters such as the threshold voltage and the drain current. Hence, parameters such as the high dielectric constant values, extra oxide charges and process related defects at the physical level must be taken into account during the device design. As far as circuit applications are concerned, these changes may substantially affect the required performance. This paper presents and provides proposals about the issue of replacing commonly used parameters of the MOSFET modelling with new parameters, in which the presence of a gate dielectric with different properties from those of SiO2 is taken into account. A stepwise procedure is described for the new device design. Moreover, a case study is presented which examines a memory circuit built up by such new technology devices. In particular, this paper presents and analyses the design of a DRAM cell made up of MOSFETs with an alternative gate dielectric. The 90 nm technology and the BSIM4 model equations are used to derive the single MOSFET behaviour and subsequently the DRAM circuit performance. The results are analysed and compared to those obtained from conventional SiO2 devices. A cell layout is provided and the DRAM circuit characteristics are also presented. 相似文献
76.
柔性有机电致发光器件(FOLED)封装材料的研究已成为目前国内外FOLED研究的热点。如何测量水蒸汽、氧气和其他活性气体对FOLED封装材料的渗透率, 是FOLED封装材料研究的一个重要课题。提出用质谱分析技术解决柔性有机电致发光器件封装材料气体渗透率的测量问题, 建立了一个封装材料渗透率的质谱法测量系统。介绍了该系统的原理, 利用该系统测量了水蒸汽、氧气和二氧化碳等气体对PET塑料, 以及水蒸汽对ITO薄膜、银薄膜等材料的渗透率。所获得的实验结果与其他文献报道的数据进行了比较, 证明质谱法测量的结果是可信的。 相似文献
77.
An organic molecule, hexaazatriphenylene hexacarbonitrile (HAT-CN), is found that it can be used not only as a hole-injecting material but also a surface modification material to clean contaminated substrate electrodes for the fabrication of organic electronic devices. As an example, HAT-CN can modify or “clean” indium-tin-oxide (ITO) anode surface in organic light-emitting diodes (OLEDs). Negative effect from ITO surface contamination on the electroluminescence performance of OLEDs can be dramatically reduced with this modification layer. As a result, the OLEDs with the same device architecture but with different ITO surface conditions, even with intentional contamination, can all exhibit substantially identical and superior electroluminescence performance. The surface modification function of this material is feasibly useful for the real fabrications of OLEDs as well as for advanced research on other organic electronic devices. 相似文献
78.
为了获得油品在太赫兹波段的衰减全内反射光谱,实现对油品的在线检测,利用光的折射定律,对太赫兹衰减全内反射系统中的核心部件——衰减全内反射棱镜进行了设计和实验。设计了单次反射棱镜,根据不同物质对太赫兹波的吸收程度不同,将单次反射棱镜用于太赫兹衰减全内反射系统,并进行了水和成品油的测试实验,取得了样品的光谱数据;进一步设计了多次反射棱镜,以增加油品对太赫兹的吸收,并对其进行了光学仿真。结果表明,经过单次全内反射,油品对太赫兹的吸收非常有限,无法实现对成品油的检测。该研究对下一步的油品检测是有帮助的。 相似文献
79.
Highly efficient phosphors are critical in solution-processed organic light-emitting devices (OLEDs). Multinuclear Ir(III) complexes containing more than one metal center have showed great potential in fabricating high performance OLEDs, yet the electroluminescent (EL) properties of multinuclear Pt(II) complexes are rarely studied. In this work, two neutral trinuclear Pt(II) complexes are synthesized based on the triphenylamine core bearing three bidentate ligand arms. Both the yellow emitter (PyTPt) and deep-red emitter (IqTPt) exhibit improved photoluminescent quantum yields (PLQYs) compared with their corresponding mononuclear Pt(II) complexes. Furthermore, the PLQYs of PyTPt and IqTPt doped films are increased to 0.63 and 0.47, respectively. The solution-processed pure yellow-emitting device based on PyTPt achieves impressively high external quantum efficiency (EQE), current efficiency (CE), and power efficiency (PE) of 16.92%, 56.74 cd/A and 29.09 lm W−1, respectively, which are among the best performance reported for the OLEDs employing multinuclear Pt(II) complexes. The solution-processed device based on IqTPt shows pure red emission with the peak EQE approaching 9.0%. Both PyTPt and IqTPt display much higher EL efficiencies than their corresponding mononuclear Pt(II) complexes. This work demonstrates that it is an attritive strategy to develop multinuclear Pt(II) complexes for high-performance OLEDs. 相似文献
80.
Self‐powered perovskite photodetectors mainly adopt the vertical heterojunction structure composed of active layer, electron–hole transfer layers, and electrodes, which results in the loss of incident light and interfacial accumulation of defects. To address these issues, a self‐powered lateral photodetector based on CsPbI3–CsPbBr3 heterojunction nanowire arrays is designed on both a rigid glass and a flexible polyethylene naphthalate substrate using an in situ conversion and mask‐assisted electrode fabrication method. Through adding the polyvinyl pyrrolidone and optimizing the concentration of precursors under the pressure‐assisted moulding process, both the crystallinity and stability of perovskite nanowire array are improved. The nanowire array–based lateral device shows a high responsivity of 125 mA W?1 and a fast rise and decay time of 0.7 and 0.8 ms under a self‐powered operation condition. This work provides a new strategy to fabricate perovskite heterojunction nanoarrays towards self‐powered photodetection. 相似文献