全文获取类型
收费全文 | 535篇 |
免费 | 4篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 131篇 |
金属工艺 | 17篇 |
机械仪表 | 7篇 |
建筑科学 | 28篇 |
能源动力 | 10篇 |
轻工业 | 86篇 |
水利工程 | 6篇 |
石油天然气 | 1篇 |
无线电 | 38篇 |
一般工业技术 | 67篇 |
冶金工业 | 104篇 |
原子能技术 | 4篇 |
自动化技术 | 36篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 17篇 |
2020年 | 7篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 9篇 |
2013年 | 21篇 |
2012年 | 9篇 |
2011年 | 17篇 |
2010年 | 18篇 |
2009年 | 13篇 |
2008年 | 25篇 |
2007年 | 20篇 |
2006年 | 20篇 |
2005年 | 23篇 |
2004年 | 20篇 |
2003年 | 12篇 |
2002年 | 13篇 |
2001年 | 12篇 |
2000年 | 17篇 |
1999年 | 23篇 |
1998年 | 33篇 |
1997年 | 24篇 |
1996年 | 19篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 3篇 |
1990年 | 8篇 |
1988年 | 9篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 7篇 |
1975年 | 7篇 |
1974年 | 3篇 |
1966年 | 3篇 |
1963年 | 5篇 |
1929年 | 2篇 |
排序方式: 共有539条查询结果,搜索用时 15 毫秒
71.
The dielectric behavior of some polar aromatics dissolved in nonpolar unoriented and stretched linear low‐density polyethylene was investigated within the temperature region between 150 and 350 K. The measurements were carried out in the frequency range 1 kHz to 10 MHz. The maximum temperatures and the half widths of the loss tangent peaks depend upon the shape and the polar structure of guest molecules. Stretching the samples induced a shift of the loss tangent to higher temperatures, decreased the height, and increased the width of tan δ peak. The activation energy is also influenced by the type of guest molecules and orientation of polymer matrix. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1278–1282, 2001 相似文献
72.
Suspension polymerization expands the study of controlled radical polymerization to high conversions and is known as a method to synthesize polymers with high molecular weights. The radical block copolymerizations of styrene (S) and acrylonitrile (AN) or butyl methacrylate (BUMA) controlled by 2,2,6,6‐tetramethylpiperidine‐N‐oxyl (TEMPO) was performed in an oil/water pressure reactor system at a temperature of 125°C. TEMPO‐terminated styrene homopolymer was employed as macroinitiator. The systems were examined by varying the composition of the monomer mixture at a constant reaction time, as well as by varying the reaction time for a characteristic monomer composition to get all of the possible conversion range. The solubility effects of acrylonitrile in the suspension medium were considered. Furthermore, the yield of the reaction was improved through initiator addition by taking control of the reaction. The polymerizations could proceed under control up to a conversion of 80–90%. By using the copolymerization equations, the solubility of pure acrylonitrile in the suspension medium could be calculated and was found to be 8 wt.‐%. 相似文献
73.
74.
The living radical polymerization of styrene, some styrene-analogous vinyl monomers as well as methyl methacrylate (MMA) and butyl methacrylate (BuMA) was investigated with a differential scanning calorimeter. The ability to polymerize was estimated by dynamic measurements, showing that p-methylstyrene, p-chlorostyrene, 3,4-dimethoxystyrene and 4-vinylpyridine polymerize in the presence of 2,2,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO) while MMA and BuMA do not. Isothermal measurements revealed an activation energy of EA = 81 kJ mol–1 for thermal bulk polymerization of styrene and values of EA = 78–94 kJ mol–1 were measured with different iniferter systems. These polymerizations have induction times which depend on the reaction temperature and the initial concentration of the iniferter systems. An influence of the kind of nitroxyl radical on the induction times was not observed. 相似文献
75.
Saevarsdottir Gudrun Kvande Halvor Welch Barry J. 《JOM Journal of the Minerals, Metals and Materials Society》2020,72(1):296-308
JOM - This paper addresses the global challenge of greenhouse gas emissions facing the aluminum industry. The demand, production and use of aluminum are increasing and so are the emissions. From... 相似文献
76.
The influence of temperature on nitroxide-controlled living radical polymerization of styrene was examined. It has been established that only in a temperature range of 110°C to 150°C nitroxides are able to control radical polymerization. At temperatures above 160°C the reaction was of rather a free radical character. The results were similar for all the various nitroxides used as capping agents: TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl), 4-hydroxy-TEMPO, 4-oxo-TEMPO and 4-acetamido-TEMPO. Differences were found only in the induction times of polymerization and were probably due to side reactions with the initiator (benzoyl peroxide). Living radical polymerization can be best controlled with these nitroxides at temperatures between 120°C and 140°C. 相似文献
77.
Through comparative studies on the controlled thermally initiated radical polymerization of styrene in the presence of N-oxyls, the effect of the type of the N-oxyls (2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (OH-TEMPO), 4-oxo-2,2,6,6-tetramethylpiperidine-N-oxyl (oxo-TEMPO) and 4-acetamido-2,2,6,6-tetramethylpiperidine-N-oxyl (acetamido-TEMPO)), as well as the concentration of the N-oxyls (3–20 mmol L–1) are discussed. The radical formation proceeds exclusively through the thermal initiation of styrene, i.e. without using any initiator. It is observed, that the thermal self-initiation of styrene increases the radical yield remarkably with the N-oxyls concentration, independent of the type of the N-oxyl. The concentration-dependent side reactions of substituted N-oxyls are remarkably more pronounced than those of unsubstituted N-oxyl. This leads to the reduction of the overall rate of polymerization (vbr) as compared to TEMPO (vbr = vbr (thermal polymerization)) with respect to the concentration, but independent of the type of substituents. 相似文献
78.
Axel Nechwatal Monika Nicolai Klaus-Peter Mieck Brigitte Heublein Gudrun Kühne Dieter Klemm 《大分子材料与工程》1999,271(1):84-92
The high wet fibrillation tendency of Lyocell fibres forms the background to this investigation. The wet abrasion behaviour can be improved by crosslinking reactions. Substances containing sulfato ethyl sulfonyl groups but different bridging groups were synthesised and optimised regarding to their application. The wet fibrillation tendency can be reduced clearly with these selected substances. If the concentration of the crosslinking agent on the fibre is the basis of comparisons the different structures have a similar effect on the fibrillation tendency. So the swollen Lyocell fibre permits a crosslinking reaction with curing agents of different size. 相似文献
79.
D. Raabe H. Springer I. Gutierrez-Urrutia F. Roters M. Bausch J. -B. Seol M. Koyama P. -P. Choi K. Tsuzaki 《JOM Journal of the Minerals, Metals and Materials Society》2014,66(9):1845-1856
We present recent developments in the field of austenitic steels with up to 18% reduced mass density. The alloys are based on the Fe-Mn-Al-C system. Here, two steel types are addressed. The first one is a class of low-density twinning-induced plasticity or single phase austenitic TWIP (SIMPLEX) steels with 25–30 wt.% Mn and <4–5 wt.% Al or even <8 wt.% Al when naturally aged. The second one is a class of κ-carbide strengthened austenitic steels with even higher Al content. Here, κ-carbides form either at 500–600°C or even during quenching for >10 wt.% Al. Three topics are addressed in more detail, namely, the combinatorial bulk high-throughput design of a wide range of corresponding alloy variants, the development of microstructure–property relations for such steels, and their susceptibility to hydrogen embrittlement. 相似文献
80.