全文获取类型
收费全文 | 511篇 |
免费 | 9篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 28篇 |
综合类 | 4篇 |
化学工业 | 204篇 |
金属工艺 | 9篇 |
机械仪表 | 18篇 |
建筑科学 | 11篇 |
矿业工程 | 1篇 |
能源动力 | 39篇 |
轻工业 | 11篇 |
石油天然气 | 1篇 |
无线电 | 54篇 |
一般工业技术 | 94篇 |
冶金工业 | 3篇 |
原子能技术 | 27篇 |
自动化技术 | 26篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 14篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 26篇 |
2015年 | 21篇 |
2014年 | 37篇 |
2013年 | 40篇 |
2012年 | 32篇 |
2011年 | 33篇 |
2010年 | 47篇 |
2009年 | 22篇 |
2008年 | 28篇 |
2007年 | 36篇 |
2006年 | 24篇 |
2005年 | 17篇 |
2004年 | 9篇 |
2003年 | 12篇 |
2002年 | 8篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 10篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 13篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有530条查询结果,搜索用时 281 毫秒
51.
H.J. Mller 《Advanced Engineering Materials》2004,6(7):501-513
More than 80 % of the current solar cell production requires the cutting of large silicon crystals. While in the last years the cost of solar cell processing and module fabrication could be reduced considerably, the sawing costs remain high, about 30 % of the wafer production. At present the large crystals are cut using the multi‐wire slicing technology[2] which has the advantage of a high throughput (several hundred wafers per day and machine), a small kerf loss of about 200 μm and almost no restrictions on the size of the ingots. Basic knowledge about the microscopic details of the sawing process is required in order to slice crystals in a controlled way. In the following the principles of the sawing process will be described in this review article as far as they are understood today. 相似文献
52.
53.
本文对~(60)Co γ射线诱发的中国田鼠肺成纤维细胞(V79)和小鼠离体胸腺细胞 DNA 单链断裂及其重接修复进行了实验研究。实验结束表明,两种细胞 DNA 单链断裂的程度分别在30Gy 和10Gy 剂量范围内与剂量呈线性相关;V79细胞 DNA 单链断裂的重接修复包含有快修复和慢修复过程;在不加血清的 TC199培养液中 V79细胞 DNA 断链仍能重接修复,而离体小鼠胸腺细胞在不加血清的 TC199或 RPM11640培养液中其 DNA 断链均不能重接修复,表明不同细胞 DNA 断链的重接修复所要求的细胞培养条件不同。 相似文献
54.
Ralph F. Schauer 《Computers in Industry》1982,3(3):169-179
The article discusses the rationale used to make the decision to implement a constrained design capability for VLSI in Wang. A CAD/CAM system will be put in place that will permit product designers to achieve design and manufacturing turn-a-round times that are consistent with a product development cycle of 18 to 24 months. The functional requirements of the various subsystems are discussed as well as those for the excutive, the data base, and the audit capability. The latter capabilities are necessary to achieve a controlled constrained design environment. 相似文献
55.
Cathode catalysts for polymer electrolyte fuel cells (PEFCs) are prepared by depositing Pt nanoparticles on carbon nanospheres (CNSs) and graphitised carbon nanospheres (GCNSs), and their corrosion‐tolerance and electrocatalytic activities for the oxygen reduction reaction are evaluated. Transmission electron micrographs show that the deposited Pt nanoparticles are well dispersed on CNSs. In Pt/GCNS, Pt nanoparticles accumulate selectively along the edges of GCNSs' polygonal surfaces. Electrochemical measurements with a rotating‐ring disk electrode in an O2‐saturated H2SO4 solution show that Pt/GCNS and Pt/CNS produce less H2O2 during oxygen reduction, compared to that obtained with a Pt catalyst on carbon black (CB). Thermogravimetric analysis reveals that GCNSs show greater combustion‐tolerance than CNSs and CB. Furthermore, GCNSs show excellent electrochemical corrosion‐tolerance in a H2SO4 solution. These results indicate that GCNSs are superior for use as carbon supports, and can serve as cathode catalysts in PEFCs even under oxidative conditions. 相似文献
56.
In this work, La0.6Sr0.4CoO3 – δ/Ce1 – xGdxO2 – δ (LSC/GDC) composite cathodes are investigated for SOFC application at intermediate temperatures, especially below 700 °C. The symmetrical cells are prepared by spraying LSC/GDC composite cathodes on a GDC tape, and the lowest polarisation resistance (Rp) of 0.11 Ω cm2 at 700 °C is obtained for the cathode containing 30 wt.‐% GDC. For the application on YSZ electrolyte, symmetrical LSC cathodes are fabricated on a YSZ tape coated on a GDC interlayer. The impact of the sintering temperature on the microstructure and electrochemical properties is investigated. The optimum temperature is determined to be 950 °C; the corresponding Rp of 0.24 Ω cm2 at 600 °C and 0.06 Ω cm2 at 700 °C are achieved, respectively. An YSZ‐based anode‐supported solid oxide fuel cell is fabricated by employing LSC/GDC composite cathode sintered at 950 °C. The cell with an active electrode area of 4 × 4 cm2 exhibits the maximum power density of 0.42 W cm–2 at 650 °C and 0.54 W cm–2 at 700 °C. More than 300 h operating at 650 °C is carried out for an estimate of performance and degradation of a single cell. Despite a decline at the beginning, the stable performance during the later term suggests a potential application. 相似文献
57.
Yao‐Te Chang So‐Lin Hsu Guan‐Yu Chen Ming‐Hsin Su Thounaojam Avinash Singh Eric Wei‐Guang Diau Kung‐Hwa Wei 《Advanced functional materials》2008,18(16):2356-2365
Intramolecular donor–acceptor structures prepared by covalently binding conjugated octylphenanthrenyl‐imidazole moieties onto the side chains of regioregular poly(3‐hexylthiophene)s exhibit lowered bandgaps and enhanced electron transfer compared to the parent polymer, e.g., conjugation of 90 mol% octylphenanthrenyl‐imidazole moieties onto poly(3‐hexylthiophene) chains reduces the optical bandgap from 1.91 to 1.80 eV, and the electron transfer probability is at least twice as high as that of pure poly(3‐hexylthiophene) when blended with [6,6]‐phenyl‐C61‐butyric acid methyl ester. The lowered bandgap and the fast charge transfer both contribute to much higher external quantum efficiencies, thus much higher short‐circuit current densities for copolymers presenting octylphenanthrenyl‐imidazole moieties, relative to those of pure poly(3‐hexylthiophene)s. The short‐circuit current density of a device prepared from a copolymer presenting 90 mol% octylphenanthrenyl‐imidazole moieties is 13.7 mA · cm?2 which is an increase of 65% compared to the 8.3 mA · cm?2 observable for a device containing pure poly(3‐hexylthiophene). The maximum power conversion efficiency of this particular copolymer is 3.45% which suggest that such copolymers are promising polymeric photovoltaic materials. 相似文献
58.
Shi‐Rui Guo Jun‐Yan Gong Peng Jiang Mian Wu Yang Lu Shu‐Hong Yu 《Advanced functional materials》2008,18(6):872-879
Biocompatible and green luminescent monodisperse silver/phenol formaldehyde resin core/shell spheres with controllable sizes, in the range of 180 to 1000 nm, and interesting architectures (centric, eccentric, and coenocytic core/shell spheres) have been synthesized by a facile one‐step hydrothermal approach. These spheres can be used as bioimaging labels for human lung cancer H1299 cells. The results demonstrate that the nanoparticles can be internalized into cells and exhibit no cytotoxic effects, showing that such novel biocompatible core/shell structures can potentially be used as in vivo bioimaging labels. This facile one‐pot polymerization and encapsulation technique may provide a useful tool to synthesize other core/shell particles that have potential application in biotechnology. 相似文献
59.
Ramadan SS Heyn C Mackenzie LT Chambers AF Rutt BK Foster PJ 《Magma (New York, N.Y.)》2008,21(4):251-259
INTRODUCTION: The use of MRI with iron-based magnetic nanoparticles for imaging cells is a rapidly growing field of research. We have recently reported that single iron-labeled cells could be detected, as signal voids, in vivo in mouse brains using a balanced steady-state free precession imaging sequence (b-SSFP) and a customized microimaging system at 1.5 T. METHODS: In the current study we assess the benefits, and challenges, of using a higher magnetic field strength for imaging iron-labeled cells with b-SSFP, using ex vivo mouse brain specimens imaged with near identical systems at 1.5 and 3.0 T. RESULTS: The substantial banding artifact that appears in 3 T b-SSFP images was readily minimized with RF phase cycling, allowing for banding-free b-SSFP images to be compared between the two field strengths. This study revealed that with an optimal 3 T b-SSFP imaging protocol, more than twice as many signal voids were detected as with 1.5 T. CONCLUSION: There are several factors that contributed to this important result. First, a greater-than-linear SNR gain was achieved in mouse brain images at 3 T. Second, a reduction in the bandwidth, and the associated increase in repetition time and SNR, produced a dramatic increase in the contrast generated by iron-labeled cells. 相似文献
60.
《International Journal of Hydrogen Energy》2019,44(35):19036-19054
The article contains examples about hydrogen research and development progress in different countries: Czech Republic, Poland, Romania, Russia and Ukraine. Each chapter describes a specific situation for a country and one of them describes some aspects from Germany for comparison with one of international leaders. The examples described into articles are not aleatory. The intention of the authors is to give to the reader the possibility to understand the concrete examples about what means the state of hydrogen and fuel cell research and innovation in the Central and Eastern European countries. The chapters dedicated to Czech Republic, Poland, and Romania, reveal the commitment of these countries in this adventure, often viewed today as a subject of very advanced countries. The specific situation in the Russia Federation describes a strong background, an uncertain present and a questionable future for the hydrogen and fuel cell technology. Development of hydrogen technologies and fuel cells in Ukraine have a long history, also. All of that, in the EU context, by voice of the main stakeholders, considered the hydrogen and fuel cell a decisive issue, with economic and societal ramifications. 相似文献