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排序方式: 共有4287条查询结果,搜索用时 156 毫秒
971.
M Yasuoka Y Nishimura T Nagaoka K Watari 《Journal of Thermal Analysis and Calorimetry》2006,83(2):407-410
The ceramic industry uses enormous amounts of energy
to produce products at high temperatures. Energy-saving measures based on
sintering process improvements are examined.
Oxide ceramics were irradiated by two different methods
during microwave sintering: intermittent use of the same high power levels
(time-control method) and continuous use of lower, increasing levels of power
(power-control method). We found that: 1) the power consumption and efficiency
of the time-control method were lower than those of the power-control method;
2) the power-control method gave more precise control of temperature under
our experimental conditions; 3) sample densification did not differ greatly
between the two methods; and 4) grain growth did not differ greatly between
the two methods. 相似文献
972.
973.
微波合成水杨酸异丙酯 总被引:9,自引:0,他引:9
研究了微波合成水杨酸异丙酯的工艺,与常规方法相对比,发现利用微波合成 水杨酸异丙酯具有反应速度快、转化率高、杂质含量小、后处理简单、无三废排放 等优点。 相似文献
974.
975.
976.
M. Gopalakrishnan P. Sureshkumar V. Kanagarajan J. Thanusu 《Research on Chemical Intermediates》2007,33(6):541-548
Condensation of structurally diverse aldehydes including heterocyclic aldehydes, like furfural, with various amines in the
presence of calcium oxide affording the corresponding imines in solvent-free conditions in good to excellent yields under
microwave irradiation is described. A comparative study has been done under thermal conditions. The synergy between dry media
and microwave irradiation in this reaction is evaluated by condensing less electrophilic aldehydes with poorly nucleophilic
amines. The main advantages of this environmentally friendly protocol are the use of the non-toxic and inexpensive reagent
calcium oxide and the considerable rate enhancement in comparison with a thermal reaction. 相似文献
977.
N. Lingaiah N. Seshu Babu Rajesh Gopinath P. Siva Sankara Reddy P. S. Sai Prasad 《Catalysis Surveys from Asia》2006,10(1):29-39
The use of supported Pd catalysts, with low and high metal content, for the hydrodechlorination of chlorobenzene is presented in this article. Application of microwave irradiation during preparation of catalysts resulted in the synthesis of large Pd particles at moderate temperatures. The nature of the support played a key role in the formation of cationic Pd species. The extent of interaction of the Pd species with the support, the nature of metal precursor, particularly the residual chlorine on the surface were found to significantly affect the activity of the catalysts. In the case of bimetallic catalysts also microwave heating resulted in creation of bigger particles of Pd compared to those observed in conventionally heated catalysts. Besides, it minimized alloy formation as a result of which the activity of the catalysts in hydrodechlorination was found to be higher compared to that observed on conventionally prepared catalysts. Contrary to the general observation that low dispersed Pd catalysts are preferable for high stability, by means of the deposition-precipitation method adopted for catalyst preparation it was demonstrated that even highly dispersed (low Pd containing) catalysts can exhibit comparable activity and stability. An analysis of the nature of Pd species and its role in the stability of the catalysts is presented.IICT communication No. 051224 相似文献
978.
The aim of the present study is to accelerate the acid-digestion step needed for the study of proteinaceous binding media by gas chromatography. The optimisation of the digestion step was carried out using full and half-fractioned factorial designs. The evaluation of the precision of the proposed digestion method and its comparison with the method considered as the reference showed the high irreproducibility of the derivatisation reaction needed for the analysis of the amino acids by gas chromatography. Although the optimal digestion time was found to be 90 min, the differences between different irradiation times were statistically non-significant, so an extremely high reduction on the analysis time is achieved. 相似文献
979.
微波场协同提取红龙果食用红色素的研究 总被引:4,自引:1,他引:4
黄宁红 《广东微量元素科学》2005,12(9):57-60
研究了应用微波从红龙果(Hylocereus Costaricensis or Weber Britt)中提取食用红色素的新工艺,并确定了最佳工艺条件:提取剂为50%的乙醇溶液,原料用量(g)与提取剂用量(mL)比为1:90。微波功率为700W,提取时间为20s,提取次数为4次。最佳工艺条件下的色素提取率为98.94%,产品pH值为6。与溶剂浸提法相比,微波法提取红龙果食用红色素的每次提取时间由2h减少到20s,提取率从90.96%增加到98.94%。 相似文献
980.
A. V. Gaponov V. A. Flyagin A. Sh. Fix A. L. Gol'denberg V. I. Khizhnyak A. G. Luchinin G. S. Nusinovich M. I. Petelin Sh. Ye. Tsimring V. G. Usov S. N. Vlasov V. K. Yulpatov 《International Journal of Infrared and Millimeter Waves》1980,1(3):351-372
Conclusion The main problems for the further development of high efficiency powerful gyrotrons are obviously the elaboration of electron guns with a large current density and the ensuring of a stable single-mode operation in resonators with a large cross-section. For the increase in microwave pulse energy (with a pulse length of the order of the time of plasma confinement in large tokamaks) the investigation of the possibilities to diminish heating loads in the resonator and output window of a gyrotron is necessary. 相似文献