全文获取类型
收费全文 | 205篇 |
免费 | 15篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 40篇 |
金属工艺 | 8篇 |
机械仪表 | 5篇 |
建筑科学 | 11篇 |
矿业工程 | 1篇 |
能源动力 | 9篇 |
轻工业 | 16篇 |
水利工程 | 2篇 |
无线电 | 28篇 |
一般工业技术 | 70篇 |
冶金工业 | 13篇 |
原子能技术 | 3篇 |
自动化技术 | 13篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 9篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 11篇 |
2011年 | 11篇 |
2010年 | 13篇 |
2009年 | 12篇 |
2008年 | 12篇 |
2007年 | 17篇 |
2006年 | 16篇 |
2005年 | 6篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 8篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1957年 | 3篇 |
排序方式: 共有221条查询结果,搜索用时 15 毫秒
31.
Christian Müller Morteza Esmaeili Christian Riekel Dag W. Breiby Olle Inganäs 《Polymer》2013,54(2):805-811
Using raster-scanning wide-angle X-ray scattering, we investigate oriented fibres of the low bandgap conjugated polymer, poly[2,7-(9,9-dioctylfluorene)-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (F8TBT), that was developed in particular for polymer solar cells. For the first time, structural data are provided for F8TBT. Our results demonstrate that the nano-scale structure of this polymer is closely related to the externally observable features of the fibre, and thus emphasise the importance of having full control over the local molecular conformation. Liquid-crystalline phases are observed at elevated temperatures, and the molecular alignment in the drawn fibres yields scattering patterns that are dominated by broad peaks of equatorial diffuse scattering. The significant degree of preferred orientation facilitates the analysis, leading to estimates of (average) nearest-neighbour packing distances and coherence length of this macromolecule. In particular, we observe a pronounced broad signal assigned to packing of the conjugated backbone with an approximate spacing of 4.00–4.39 Å that is coherent over 5-6 polymer segments. 相似文献
32.
33.
Olle Ginstrup 《仪器科学与技术》2013,41(3):141-155
ABSTRACT A potentiometric titrator designed mainly for complex formation investigations is described. The titrator is constructed from electronic building blocks, without a computer. The functioning of the titrator may be described by a rigid cyclic program with the possibility of adapting the titrator to the actual chemical system by varying a few key parameters on thumbwheel switches. Before the titration, the experimenter makes the decisions necessary. The titrator has no inherent facilities to decide whether equilibrium has been attained. Experiences gained with this titrator and the advantages over a computer-based system are discussed. 相似文献
34.
We compared three different bibliometric evaluation approaches: two citation-based approaches and one based on manual classification of publishing channels into quality levels. Publication data for two universities was used, and we worked with two levels of analysis: article and department. For the article level, we investigated the predictive power of field normalized citation rates and field normalized journal impact with respect to journal level. The results for the article level show that evaluation of journals based on citation impact correlate rather well with manual classification of journals into quality levels. However, the prediction from field normalized citation rates to journal level was only marginally better than random guessing. At the department level, we studied three different indicators in the context of research fund allocation within universities and the extent to which the three indicators produce different distributions of research funds. It turned out that the three distributions of relative indicator values were very similar, which in turn yields that the corresponding distributions of hypothetical research funds would be very similar. 相似文献
35.
Desta A. Gedefaw Zaifei Ma Zewdneh Genene Stefan Hellström Fengling Zhang Wendimagegn Mammo Olle Inganäs Mats R. Andersson 《Polymer International》2014,63(1):22-30
Two polymers with polar side chains, namely poly[2,7‐(9,9‐dioctylfluorene)‐alt‐5,5‐(5',8'‐di‐2‐thienyl‐(2',3'‐bis(3''‐(2‐(2‐methoxyethoxy)ethoxy)phenyl)quinoxaline))] ( P1 ) and poly[2,7‐(9,9‐bis(2‐(2‐methoxyethoxy)ethyl)fluorene)‐alt‐5,5‐(5',8'‐di‐2‐thienyl‐(2',3'‐bis(3''‐(2‐(2‐methoxyethoxy)‐ethoxy)phenyl)quinoxaline))] ( P2 ), were synthesized for solar cell application. A series of bulk heterojunction solar cells were systematically fabricated and characterized by varying the electron‐acceptor materials, processing solvents and thickness of the active layer. The results show that P1 , with a higher molecular weight and good film‐forming properties, performed better. The best device showed an open circuit voltage of 0.87 V, a short circuit current of 6.81 mA cm?2 and a power conversion efficiency of 2.74% with 1:4 polymer:[6,6]‐phenyl‐C71‐butyric acid methyl ester (PCBM[70]) mixture using o‐dichlorobenzene (o‐DCB) as processing solvent. P2 on the other hand showed a poorer performance with chlorobenzene as processing solvent, but a much improved performance was obtained using o‐DCB instead. Thus, an open circuit voltage of 0.80 V, short circuit current of 6.21 mA cm?2 and an overall power conversion efficiency of 2.22% were recorded for a polymer:PCBM[70] mixing ratio of 1:4. This is presumably due to the improvement of the morphology of the active layer using o‐DCB as processing solvent. © 2013 Society of Chemical Industry 相似文献
36.
Glenn P. Svensson Eylem Akman Gündüz Natalia Sjöberg Erik Hedenström Jean-Marc Lassance Hong-Lei Wang Christer Löfstedt Olle Anderbrant 《Journal of chemical ecology》2014,40(4):387-395
The greater wax moth, Galleria mellonella (L.), is a serious and widespread pest of the honeybee, Apis mellifera L. In contrast to most moths, for which long-range mate finding is mediated by female-produced sex pheromones, G. mellonella males attract conspecific females over long distances by emitting large amounts of a characteristic scent in combination with bursts of ultrasonic calls. The male scent for this species was previously identified as a blend of nonanal and undecanal. When these compounds were bioassayed, characteristic short-range sexual behavior, including wing fanning, was triggered in conspecific females, but the aldehyde blend failed to elicit attraction over longer distances. We identified, via analysis and synthesis, a third male-specific compound, 5,11-dimethylpentacosane. We show that it acts as a behavioral synergist to the aldehydes. In wind tunnel experiments, very few female moths responded to the aldehyde blend or to 5,11-dimethylpentacosane tested separately, but consistently showed orientation and source contact when a combination of all three compounds was applied. The level of attraction to the three-component mixture was still lower than that to male extract, indicating that the composition of compounds in the synthetic blend is suboptimal, or that additional pheromone components of G. mellonella are yet to be identified. The identification of 5,11-dimethylpentacosane is an important step for the development of an efficient long-range attractant that will be integrated with other environmentally safe strategies to reduce damage to beehives caused by wax moths. 相似文献
37.
Ricardo Morales Ragnhild E. Aune Seshadri Seetharaman Olle Grinder 《JOM Journal of the Minerals, Metals and Materials Society》2003,55(10):20-23
Molybdenum and tungsten are refractory metals in the elemental form with the largest production volume in the world. The fabrication
of these refractory metals, as well as their alloys and intermetallics, using high-temperature powder metallurgy (PM) is reviewed
in this article. The primary focus is on the role of traditional high-temperature PM in producing alloys with tailor-made
properties. An insight into the bulk production of molybdenum and tungsten alloys with nano-grains is highlighted.
For more information, contact R.E. Aune, Royal Institute of Technology, Department of Materials Science and Engineering, SE-100
44 Stockholm, Sweden;+46-8-790-8363;fax+46-8-790-0939;e-mail aune@mse.kth.se. 相似文献
38.
Fengling Zhang Sasa Lacic Mattias Svensson Mats R. Andersson Olle Ingans 《Solar Energy Materials & Solar Cells》2006,90(11):1607-1614
The temperature dependence of device parameters of polymer solar cells based on alternating copolyfluorene incorporating dioctyl-fluorene and di-thienyl-benzothiadiazole (APFO-3) mixed with [6,6]-phenyl-C61-butyric acid methylester (PCBM) was modeled theoretically by simulation and investigated experimentally under illumination of AM1.5 (100 mW/cm2). Both simulation and experimental results show photocurrent, fill factor and power conversion efficiency all increase, and the open-circuit voltages monotonically decrease with temperature increase from room temperature (RT) to 120 °C. These results can be explained by taking into account the temperature dependence of the mobility, and the thermal activation of the injection current from the electrodes. The increase of PCE with temperature is a distinguishing feature of polymer solar cells. 相似文献
39.
Growth of highly resistive semi-insulating InP : Fe has been achieved by the Hydride VPE technique in an ambient consisting
mostly of nitrogen. After dealing with some thermodynamic considerations pertinent to InP:Fe growth, the experimental growth
parameters are described. It is shown that various amounts of iron can be introduced into the InP crystal just by varying
the temperature of the iron source. The crystal quality of the grown material is estimated to be good by etch pit density
and x-ray diffraction analyses. Current-voltage behaviour and capacitance studies on ann
+-SI-n
+ structure are explained by invoking the theory of current injection in solids by Lampert and Mark: the experimental current
densities at the threshold of each observed regime are compared with the theoretically derived current densities; in the absence
of current injection, the measured capacitance is found to be the same as the geometrical capacitance. 相似文献
40.
Xabier Rodríguez-Martínez Paula Hartnagel Sergi Riera-Galindo Gulzada Beket Thomas Österberg Feng Gao Thomas Kirchartz Olle Inganäs 《Advanced functional materials》2023,33(27):2301192
Non-fullerene acceptors have recently revolutionized indoor organic photovoltaics (OPVs) with power conversion efficiencies exceeding 30% in laboratory scale. Nevertheless, transferring their superior performance to larger-scale prototyping, i.e., air-processing via roll-to-roll compatible techniques, still shows severe challenges. Herein, the industrial potential of the PM6:IO4Cl blend, which is one of the most successful indoor OPV photoactive layers (PALs), is thoroughly investigated. The corresponding thick and semitransparent laminated devices are fabricated entirely in air, by blade and slot-die coating. Their current–voltage (J–V) characteristics show anomalous features depending on the illumination side, with the cathode side generally outperforming the anode counterpart. Electrical and optical modeling reveal that a plausible cause of such a phenomenon is a dead layer that forms at the PAL/anode contact interface that does not contribute to the photocurrent. Said layer becomes undetectable when the PALs are made thin enough (<35 nm each) leading to symmetric J–V curves and improved light utilization efficiency. By screening the photovoltaic performance of multiple donor:acceptor blends, certain all-polymer and polymer:fullerene PALs are identified as adequately symmetric candidates for thick device up-scaling. Finally, ternary blends based on PM6:IO4Cl:fullerene may constitute a viable route to mitigate the electrical asymmetry detected on conventional binary blends. 相似文献