全文获取类型
收费全文 | 1166篇 |
免费 | 50篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 236篇 |
金属工艺 | 39篇 |
机械仪表 | 31篇 |
建筑科学 | 57篇 |
矿业工程 | 1篇 |
能源动力 | 40篇 |
轻工业 | 213篇 |
水利工程 | 35篇 |
石油天然气 | 5篇 |
无线电 | 84篇 |
一般工业技术 | 146篇 |
冶金工业 | 202篇 |
原子能技术 | 15篇 |
自动化技术 | 98篇 |
出版年
2023年 | 5篇 |
2022年 | 10篇 |
2021年 | 37篇 |
2020年 | 18篇 |
2019年 | 22篇 |
2018年 | 22篇 |
2017年 | 26篇 |
2016年 | 33篇 |
2015年 | 23篇 |
2014年 | 45篇 |
2013年 | 82篇 |
2012年 | 63篇 |
2011年 | 81篇 |
2010年 | 67篇 |
2009年 | 67篇 |
2008年 | 59篇 |
2007年 | 53篇 |
2006年 | 51篇 |
2005年 | 29篇 |
2004年 | 27篇 |
2003年 | 40篇 |
2002年 | 39篇 |
2001年 | 25篇 |
2000年 | 21篇 |
1999年 | 21篇 |
1998年 | 55篇 |
1997年 | 40篇 |
1996年 | 24篇 |
1995年 | 18篇 |
1994年 | 12篇 |
1993年 | 20篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有1216条查询结果,搜索用时 15 毫秒
61.
Growing concerns about climate change and energy security have led to a strong focus on energy demand reduction and energy
efficiency within United Kingdom (UK) energy policy. At the same time, information and communication technologies (ICTs) have
become pervasive in society and this has brought with it new policy options which use them as enabling technologies. One such
policy option planned for implementation in the UK is the use of smart meters and real-time displays to encourage people to
become more aware of their energy consumption and possibly change their energy-related behaviours. Smart meters and display
units by definition link individuals, technologies and society, and their effectiveness is influenced by a range of factors.
Ten semi-structured stakeholder interviews with industry, government and academia and a review of literature were conducted
in order to identify which factors are most likely to contribute to the effectiveness of implementing smart meters and real-time
displays in the UK. Further analysis showed a number of key themes and perspectives on behavioural change, particularly as
they relate to household electricity use and the role of smart meters in the UK energy policy, including the role of ICTs
in energy demand reduction more generally. 相似文献
62.
Y. Isobe 《Welding International》2013,27(2):105-109
In this work, the pitting corrosion resistance of welding duplex stainless steel 2205 was studied. Joints were made using the GMAW process with different fillers: duplex ER 2209 and two austenitic fillers (ER 316LSi and ER 308LSi). The microstructure obtained with the duplex ER 2209 filler is similar to the duplex 2205 base material, but the joints produced with the austenitic fillers cause a decrease of the α/γ phase ratio. In order to evaluate the influence of the filler on the weld, the pitting corrosion resistance was determined by means of an electrochemical critical pitting temperature test, and the mechanical properties by the hardness test. The phase imbalance produced for the different fillers causes variation of the pitting corrosion resistance and the mechanical properties. The variation in the mechanical properties of the material was also studied by means of hardness tests. 相似文献
63.
Masatoshi Hasegawa Mari Fujii Junichi Ishii Shinya Yamaguchi Eiichiro Takezawa Takashi Kagayama Atsushi Ishikawa 《Polymer》2014
A novel cycloaliphatic monomer for polyimides (PI), 1S,2S,4R,5R-cyclohexanetetracarboxylic dianhydride (H′-PMDA) is proposed in this work. H′-PMDA shows high polymerizability with various diamines in contrast to its isomer, i.e., conventional hydrogenated pyromellitic dianhydride (H-PMDA) and leads to highly flexible and colorless PI films with very high Tg's. In particular, the combinations with rigid structures of diamines give rise to PIs with significantly decreased coefficients of thermal expansion (CTE) owing to high extents of in-plane chain orientation induced by thermal imidization, whereas the H-PMDA-based counterparts do not. The decreased CTE reflects structural rigidity/linearity of the H′-PMDA-based diimide units as supported by liquid crystallinity observed in the corresponding model compound. Solution casting of a chemically imidized PI derived from H′-PMDA and 2,2′-bis(trifluoromethyl)benzidine (TFMB) results in a lower CTE than that of the thermally imidized counterpart, suggesting the presence of a self-orientation phenomenon during solvent evaporation. The mechanism is proposed in this work. H′-PMDA/TFMB and its copolymer systems can be useful as plastic substrates in image display devices and/or novel coating-type optical compensation films. 相似文献
64.
Alessandro Abbotto Erika Herrera Calderon Norberto Manfredi Claudio Maria Mari Chiara Marinzi Riccardo Ruffo 《Synthetic Metals》2011,161(9-10):763-769
Vinylene-linked donor–acceptor–donor semiconducting polymers have been prepared by electropolymerization of the new monomers 2,6-bis[(E)-2-(1-methylpyrrol-2-yl)vinyl]pyridine and 2,5-bis[(E)-2-(1-methylpyrrol-2-yl)vinyl]pyridine. The monomers, consisting of two pyrrole donor units and a central pyridine acceptor ring spaced by vinylene links, differ by the substitution pattern around the central pyridine core (2,6 vs. 2,5-substitution). The electropolymerization process is more efficient on the 2,5-derivative. The new polymers show reversible electrochemistry dominated by a strong charge trapping effect. Poly(2,5-bis[(E)-2-(1-methylpyrrol-2-yl)vinyl]pyridine) energy levels closely match those of design rules for optimized polymers in combination with fullerene derivatives in bulk heterojunction solar cells. 相似文献
65.
Marisa Di Sabatino Mari Juel Lars Arnberg Martin Syvertsen Gabriella Tranell 《Transactions of the Indian Institute of Metals》2009,62(4-5):511-513
Two different cooling rates have been imposed during the early solidification of two multi-crystalline silicon ingots with 250mm diameter and 100mm height in a pilot scale directional solidification furnace. This has been done by opening a variable heat leak system below the crucible in order to achieve a high initial cooling rate in one of the ingots. The grain-structure and -orientation of these two ingots have been investigated by light microscopy (LM) and electron backscattered diffraction (EBSD), and their electrical properties by quasi-steady state photo-conductance (QSSPC) and surface photovoltage (SPV) method. The ingot with the high initial cooling rate shows predominantly grains which are significantly larger than what is usually found in mc-Si. The minority carrier diffusion lengths measured on the large grains in the ingot with high cooling rate show higher values than those measured on the ingot with smaller grains. These results indicate that principles of grain size and -orientation control in mc-Si ingots can be applied to a pilot scale furnace, and the potential for up-scaling to industrial ingots with improved electrical properties and, thus, higher solar cell conversion efficiency. 相似文献
66.
Takanori Isobe Taku Takaku Tadayuki Kitahara Hideo Sumitani Ryuichi Shimada 《Electrical Engineering in Japan》2009,169(4):65-74
This paper proposes a power supply suitable for driving linear induction motors. The power supply consists of a voltage source inverter (VSI) and a magnetic energy recovery switch (MERS). Circuit configuration and operation principles of the power supply are described. Power factor correction by MERS can increase the output power. Technical advantages of using MERS compared with increasing the rated voltage of VSI are discussed. Some experiments with a linear induction motor were conducted. The results confirm that MERS can reduce the capacity of the VSI or increase the output with the same VSI capacity. The number of devices and magnitude of losses are evaluated on a large‐scale drive system. A half‐bridge type of MERS is provided and discussed. The half‐bridge MERS mitigates disadvantages of using MERS. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(4): 65–74, 2009; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20832 相似文献
67.
Potentilla erecta (L.) is known for the high concentration of proanthocyanidin oligomers (PAs) in its underground parts. The use of its preparations as food supplements and the lack of chemical–analytical studies concerning with an efficient chromatographic separation procedure for these compounds led us to develop a strategy to profile PAs occurring in this species. 相似文献
68.
Satoru TakeshitaTatsuya Watanabe Tetsuhiko Isobe Tomohiro SawayamaSeiji Niikura 《Optical Materials》2011,33(3):323-326
YVO4:Bi3+,Eu3+ nanophosphor synthesized by the citrate route shows the photobleaching behavior, i.e., the decrease in photoluminescence intensity under the continuous irradiation of excitation light. This photobleaching property is remarkably suppressed by the washing post-treatment combined with centrifugation and the hydrothermal post-treatment. A relation between the fraction of photobleach and the amount of citrate ions coordinating to metallic ions at the surface of nanoparticles verifies that the photobleaching behavior of YVO4:Bi3+,Eu3+ nanophosphor originates from the redox reaction between the citrate ions and V5+ in YVO4 host crystal. The long-term light fastness test reveals that the hydrothermally treated YVO4:Bi3+,Eu3+ nanophosphor has sufficient photostability for practical use over 15 years outside. 相似文献
69.
Role of microbes in controlling the speciation of arsenic and production of arsines in contaminated soils 总被引:7,自引:0,他引:7
Turpeinen R Pantsar-Kallio M Kairesalo T 《The Science of the total environment》2002,285(1-3):133-145
The influence of microbes on the speciation of arsenic and production of arsines in contaminated soils was investigated under laboratory conditions. Microbes were able to carry out reactions that resulted in changes in the speciation of arsenic in soil. The transformation of soil dominating species, arsenate [As(V)], under both aerobic and anaerobic conditions to arsenite [As(III)], monomethylarsonic acid [MMAA], dimethylarsinic acid [DMAA] and to volatile trimethylarsine [TMA] was, however, less than 0.5%, of which the production of TMA represented 0.02-0.3%. The volatilization process was also verified in the field, in the soil of a dumping area. The 'life-time' of arsines in air was, however, short and they were rapidly converted back to water soluble species, As(V) and trimethyl arsine oxide (TMAO). 相似文献
70.
T. Isa T. Fukase M. Sasaki M. Koyano N. Taniguchi T. Kimura Y. Isobe H. Negishi 《Journal of Low Temperature Physics》2002,127(1-2):63-79
We have measured electrical resistivity, Hall coefficient, thermoelectric power, and magnetization for charge-density wave (CDW) material 1T-TaS2 single crystals grown by varying the excess sulfur content x
es. We have revealed that a small mid-gap state is formed inside the Mott gap and that anomalous low temperature transport is not governed by the Mott gap state itself but by the mid-gap state. The electric properties of the mid-gap state are modified by increasing x
es (or hole doping), and we have found the insulator-metal transition occurs by hole doping below 60K. 相似文献