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排序方式: 共有600条查询结果,搜索用时 31 毫秒
1.
Annika Jahn Anton Hoffmann Luisa Blaesing Fabian Kunde Martin Bertau Martina Bremer Steffen Fischer 《化学,工程师,技术》2020,92(11):1733-1740
The enzymatic conversion of lignins, possibly in combination with electrochemical oxidation, makes aromatics such as syringol, guaiacol, vanillin and catechol available in the qualities required by the fragrance industry. The lignins were obtained by soda digestion from wheat straw and Miscanthus, characterized and then converted with laccases. The overall yield amounted up to 9 wt % with a product spectrum confined to four substances. Catechol was the major product, with a fraction of ≈75 %. It can easily be isolated by extraction with acetone. 相似文献
2.
F Douaud N Le Roch J Renault R Havouis M Vaultier JP Moulinoux N Seiler 《Canadian Metallurgical Quarterly》1997,12(8):621-633
Several dimethylsilane tetramines [homologs of spermine with an Si(CH3)2 group in the central carbon chain], a carbon analog of the dimethylsilane tetramines [containing C(CH3)2 instead of Si(CH3)2] and a dimethylsilane hexamine were studied with regard to their cytotoxic activity and their ability to interact with double-stranded DNA. All polyamine analogs exerted cytostatic effects to several cell lines at micromolar concentrations. Their ability to condense DNA was comparable to and their ability to displace ethidium bromide from binding to DNA was superior to that of spermine. Their cytostatic effect was not correlated with the depletion of cellular spermidine concentrations. It is suggested that the new polyamine analogs act mainly by displacing spermidine from binding sites which are essential for the promotion of cell growth. 相似文献
3.
J. S. Kim D. G. Seiler R. A. Lancaster M. B. Reine 《Journal of Electronic Materials》1996,25(8):1215-1220
Variable-magnetic-field Hall measurements (0 to 1.5 T) are performed on very-narrow-gap bulk-grown Hg1−xCdxTe single crystals (0.165 ≤ x ≤ 0.2) at various temperatures (10 to 300K). The electron densities and mobilities are obtained
within the one-carrier (electrons) approximation of the reduced-con-ductivity-tensor scheme. The present data together with
the selected data set reported by other workers exhibit a pronounced peak when the electron mobility is plotted against the
alloy composition x-value which has been predicted to be due to the effective-mass minimum at the bandgap-crossing (Eg ≈ 0). The observed position (x ≈ 0.165), height (≈4 x 102 m2Vs), and width (≈0.01 in x) of the mobility-peak can be explained by a simple simulation involving only ionized-impurity scattering.
A lower bound of the effective mass is introduced as a fitting parameter to be consistent with the finiteness of the observed
electron mobility and is found to be of the order of 10−4 of the mass of a free electron. 相似文献
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In Gothenburg tram injuries were identified to be an important cause of traffic injuries and fatalities (48%) among pedestrians. During the summer middle-aged men, often under the influence of alcohol, were often severely injured and the injury rate was also high during the autumn. A majority (60%) of those fatally injured were under the influence of alcohol. Most injury events happened at or near a tram stop. The most serious injuries arose when the victim landed under a tram. In 1992, a runaway tram caused a major disaster, killing 10 pedestrians and injuring 30. The injury reducing measures the tram company has now started to introduce include safety railings at tram stops, side barriers on the tramcars to prevent people from falling under the tram and lower speeds near tram stops. 相似文献
6.
Herzog H.-J. Hackbarth T. Seiler U. Konig U. Luysberg M. Hollander B. Mantl S. 《Electron Device Letters, IEEE》2002,23(8):485-487
Si/SiGe n-type modulation-doped field-effect transistors grown on a very thin strain-relieved Si/sub 0.69/Ge/sub 0.31/ buffer on top of a Si(100) substrate were fabricated and characterized. This novel type of virtual substrate has been created by means of a high dose He ion implantation localized beneath a 95-nm-thick pseudomorphic SiGe layer on Si followed by a strain relaxing annealing step at 850/spl deg/C. The layers were grown by molecular beam epitaxy. Electron mobilities of 1415 cm/sup 2//Vs and 5270 cm/sup 2//Vs were measured at room temperature and 77 K, respectively, at a sheet carrier density of about 3/spl times/10/sup 12//cm/sup 2/. The fabricated transistors with Pt-Schottky gates showed good dc characteristics with a drain current of 330 mA/mm and a transconductance of 200 mS/mm. Cutoff frequencies of f/sub t/=49 GHz and f/sub max/=95 GHz at 100 nm gate length were obtained which are quite close to the figures of merit of a control sample grown on a conventional, thick Si/sub 0.7/Ge/sub 0.3/ buffer. 相似文献
7.
Liisa Lhteenmki Klaus Grunert
ydis Ueland Annika strm Anne Arvola Tino Bech-Larsen 《Food quality and preference》2002,13(7-8):523-533
European consumers, in general, have negative attitudes towards the use of gene technology in food production. The objective of this study was to examine whether taste and health benefits influence the acceptability of genetically modified (gm) products when they are presented as real product alternatives. Consumers in Denmark, Finland, Norway and Sweden (n=738) assessed two cheeses: one was labelled as genetically modified (preferred in an earlier product test) and the other as conventional (neutral in an earlier product test). A smaller control group received two cheeses with blind codes. Labelling decreased consumers' intentions to buy the originally preferred gm-labelled cheese, but still the intentions were at the same level with the conventionally labelled option. Participants chose two gm cheeses out of five possible when given the option to take cheese home after tasting. Intentions to buy gm cheese could best be explained by respondents' attitudes towards gene technology and perceived taste benefits. General health interest was also a reinforcer of intentions for gm cheese with reduced fat content. 相似文献
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10.
Ståhlkrantz Adam Hedström Peter Sarius Niklas Borgenstam Annika 《Metallurgical and Materials Transactions A》2022,53(9):3418-3427
Metallurgical and Materials Transactions A - Variant pairing in bainite was evaluated in four different commercial low alloy steels with medium to high carbon content. The steels investigated were... 相似文献