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排序方式: 共有1518条查询结果,搜索用时 31 毫秒
101.
Horst Karl Ines Lehmann Hartmut Rehbein & Reinhard Schubring 《International Journal of Food Science & Technology》2010,45(1):56-66
A range of conventionally and organically farmed Pangasius or sutchi catfish fillets available on the German market were analysed to compare both composition and quality. Differentiation of Pangasius hypophthalmus from Pangasius bocourti was achieved by RFLP-SSCP analysis. The protein content of conventionally farmed fillets ranged between 13.3 and 15.7%, whereas organically produced fillets had significantly higher protein contents of between 17.0 and 17.4%. No difference in the fat content between farming methods was observed, which varied between 1.4 and 3.2%. Polyunsaturated fatty acids represented about 24% of the total fatty acids with a high level of linoleic acid. The comparison of the proximate composition indicated that water was added to most of the conventionally farmed products, in different amounts, as well as water-binding capacity enhancing additives. Differential scanning calorimetry was used to demonstrate the presence of polyphosphate on muscle proteins. Differences in texture, water-binding capacity and colour are discussed. 相似文献
102.
Gregor Schinkel Immo Garrn Benjamin Frank Ulrich Gernert Helmut Schubert Reinhard Schomcker 《Materials Chemistry and Physics》2008,111(2-3):570-577
The engineering aspects of the preparation of nanostructured alumina ceramic precursors by alcoholate hydrolysis using microemulsions as reaction media are investigated here. The precipitate was subjected to several treatment steps. Although the properties of the primary precipitated powders are independent of the chemical or reaction engineering parameters of the precipitation procedure, the structure of treated powders and sintered, dense ceramics strongly depends on thermal and mechanical handling like crystallization or grinding of the alumina ceramic precursor. Strong differences are manifested in relative densities and sintering kinetics and can be observed by SEM analysis. 相似文献
103.
D.T. Tran T.A. Grotjohn D.K. Reinhard J. Asmussen 《Diamond and Related Materials》2008,17(4-5):717-721
Experimental results are presented for the microwave plasma-assisted dry etching of ultrananocrystalline (UNCD), polycrystalline and single crystal diamond materials. A high-rate and anisotropic etching process is developed using a 2.45 GHz microwave plasma reactor. The plasma discharge in this system measures 25 cm in diameter and is located inside a 30 cm diameter microwave cavity applicator. The system is an electron cyclotron resonance (ECR) plasma source operating at pressures of 1–100 mTorr. The process chemistries include mixtures of oxygen, sulphur hexafluoride, and argon. Anisotropic etching profiles have been demonstrated and the measured etching rates range from 4–26 μm/h. 相似文献
104.
D. King M.K. Yaran T. Schuelke T.A. Grotjohn D.K. Reinhard J. Asmussen 《Diamond and Related Materials》2008,17(4-5):520-524
The scale up of two microwave plasma assisted chemical vapor deposition processes from 75 mm to 200 mm substrates is investigated. A thermally floating 2.45 GHz reactor is scaled up by increasing its physical size by a factor of 2.7 and exciting the reactor with 915 MHz microwave energy. Two processes are investigated, 1) the deposition of ultananocrystalline diamond films (UNCD) and 2) the deposition of polycrystalline diamond films (PCD). Gas chemistries of argon/methane/hydrogen were used for UNCD deposition and hydrogen/methane was used for PCD deposition. Experimental pressures range from 40–110 Torr while microwave power input ranged from 1.9–7 kW resulting in steady state substrate temperatures from 630–950 °C. Uniform deposition was demonstrated over 150–200 mm substrates, i.e. thickness variations of 4% over 150 mm and 6% over 200 mm were achieved with deposition rates ranging from 30–460 nm/h. Low temperature deposition at 633 °C was achieved and thereby demonstrated the potential of integrating the process with temperature sensitive materials. A comparison of the power densities between the two reactors indicates that the large reactor operates at five to nine times lower discharge power densities than smaller reactors suggesting improved deposition efficiencies. 相似文献
105.
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107.
An atomic representation of a Herbrand model (ARM) is a finite set of (not necessarily ground) atoms over a given Herbrand universe. Each ARM represents a possibly infinite Herbrand interpretation. This concept has emerged independently in different branches of computer science as a natural and useful generalization of the concept of finite Herbrand interpretation. It was shown that several recursively decidable problems on finite Herbrand models (or interpretations) remain decidable on ARMs.The following problems are essential when working with ARMs: Deciding the equivalence of two ARMs, deciding subsumption between ARMs, and evaluating clauses over ARMs. These problems were shown to be decidable, but their computational complexity has remained obscure so far. The previously published decision algorithms require exponential space. In this paper, we prove that all mentioned problems are coNP-complete. 相似文献
108.
The electrochemical behaviour of mild steel was investigated in near neutral air saturated solutions containing benzoate (Bzo) and benzotriazole (BTA), separately or mixed. In the benzoate/BTA mixtures the open circuit passivation was found to be much better than in pure benzoate electrolytes. Electrochemical impedance spectroscopy (EIS) measurements resulted in characteristic Bode plots due to the synergistic effect of both inhibitors in the presence of oxygen. Open circuit potential (OCP) measurements vs. time supported the observed behaviour. The inhibition effect can be attributed to the blocking of surface sites for anodic dissolution by benzoate and a subsequent strong adsorption of benzotriazole on the natural oxide layer. 相似文献
109.
S.S. Zuo M.K. Yaran T.A. Grotjohn D.K. Reinhard J. Asmussen 《Diamond and Related Materials》2008,17(3):300-305
In this paper, we report on microwave CVD deposition of high quality polycrystalline diamond and on related post-processing steps to produce smooth, flat and uniformly thick films or diamond substrates. The deposition reactor is a 2.45 GHz microwave cavity applicator with the plasma confined inside a 12 cm diameter fused silica bell jar. The deposition substrates utilized are up to 75 mm diameter silicon wafers. The substrate holder is actively cooled with a water-cooled substrate holder to achieve a substrate surface temperature of 600–1150 C. The pressure utilized is 60–180 Torr and the microwave incident power is 2–4.5 kW. Important parameters for the deposition of thick films with uniform quality and thickness include substrate temperature uniformity as well as plasma discharge size and shape. As deposited thickness uniformities of ± 5% across 75 mm diameters are achieved with simultaneous growth rates of 1.9 μm/h. The addition of argon to the deposition gases improves film deposition uniformity without decreasing growth rate or film quality, over the range of parameters investigated. Post-processing includes laser cutting of the diamond to a desired shape, etching, lapping and polishing steps. 相似文献
110.
Devender S. Negi Felix Sobotka Tobias Kimmel Günter Wozny Reinhard Schomäcker 《Journal of the American Oil Chemists' Society》2007,84(1):83-90
The present work focused on the glycerolysis of fatty acid methyl esters. The aim was to develop and test a kinetic model
that could be used to reliably simulate different process alternatives for this reaction. A prerequisite was the identification
and characterization of the factors that affect the reaction kinetics. Experiments were carried out in a batch reactor with
and without forced removal of methanol, which is one of the reaction products. Concentrations of all components in the two-phase
system were measured. It was found that the methanol concentration has a strong effect on the reaction rate and equilibrium
conversion. Near-complete conversions were obtained by stripping methanol with an inert gas. The glycerol concentration in
the ester phase was found to increase as the reaction proceeds, which also accelerates the reaction. Effects of mass transfer
on the reaction rate were not found to control the reaction rate under well-agitated conditions. A semi-empirical model was
used to simulate the reaction. The results from the semi-empirical model show good agreement with experimental results. 相似文献