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排序方式: 共有2185条查询结果,搜索用时 15 毫秒
21.
Berger Ralf G. Drawert Friedrich Kollmannsberger Hubert 《European Food Research and Technology》1989,188(2):122-126
European Food Research and Technology - The volatile constituents of cape gooseberry (Physalis peruviana L.) were characterized using liquid/liquid extraction and fractionation of the flavour... 相似文献
22.
The influence of the doping density in the active sections of InP-based injectorless quantum cascade lasers, emitting at 6.8 mum, is investigated. The doping sheet density is varied in the range 2.5-8.6times1010 cm-2. Lasing is observed in the whole range, with a threshold current density as low as 1.2 kA/cm2 at 300 K for the smallest doping sheet density of 2.5times10 10 cm-2. Further improvement has been made by additionally increasing the number of periods in the active region from 40 to 60. With the same doping level of 2.5times1010 cm-2 record low threshold current densities of 0.73 kA/cm2 at 300 K were achieved 相似文献
23.
This paper presents a spatially distributed and dynamic billing, pricing and allocation mechanism for which a user terminal
requires Cognitive Radio abilities. That is, the Cognitive Radio abilities will be applied to the economical environment.
The radio resource goods are allocated to the users by a multi-unit sealed-bid auction. Intelligent entities like the bidding
strategy have to represent operator’s and users’ behavior and to make decisions for them in order to fulfill the preferences
and QoS. The main functionalities, used to execute the dynamic auction sequence and located in the MAC are described, assuming
the entities possess Cognitive Radio abilities.
相似文献
Friedrich JondralEmail: |
24.
A comparison of noninvasive reconstruction of epicardial versus transmembrane potentials in consideration of the null space 总被引:1,自引:0,他引:1
Messnarz B Seger M Modre R Fischer G Hanser F Tilg B 《IEEE transactions on bio-medical engineering》2004,51(9):1609-1618
We compare two source formulations for the electrocardiographic forward problem in consideration of their implications for regularizing the ill-posed inverse problem. The established epicardial potential source model is compared with a bidomain-theory-based transmembrane potential source formulation. The epicardial source approach is extended to the whole heart surface including the endocardial surfaces. We introduce the concept of the numerical null and signal space to draw attention to the problems associated with the nonuniqueness of the inverse solution and show that reconstruction of null-space components is an important issue for physiologically meaningful inverse solutions. Both formulations were tested with simulated data generated with an anisotropic heart model and with clinically measured data of two patients. A linear and a recently proposed quasi-linear inverse algorithm were applied for reconstructions of the epicardial and transmembrane potential, respectively. A direct comparison of both formulations was performed in terms of computed activation times. We found the transmembrane potential-based formulation is a more promising source formulation as stronger regularization by incorporation of biophysical a priori information is permitted. 相似文献
25.
Friedrich Recknagel Takehiko Fukushima Takayuki Hanazato Noriko Takamura Hugh Wilson 《Lakes & Reservoirs: Research and Management》1998,3(2):123-133
An artificial neural network model was developed for Lake Kasumigaura to predict timing and magnitudes for chlorophyll a, five species of blue-green algae and three zooplankton groups. The model was trained by 8 years of limnological time series and validated by two independent years. The validation showed the potential of neural networks as predictive tools for highly non-linear phenomena such as blue-green algal blooms in freshwater lakes. 相似文献
26.
Mingchao Wang Huanhuan Shi Panpan Zhang Zhongquan Liao Mao Wang Haixia Zhong Friedrich Schwotzer Ali Shaygan Nia Ehrenfried Zschech Shengqiang Zhou Stefan Kaskel Renhao Dong Xinliang Feng 《Advanced functional materials》2020,30(30)
2D conjugated metal‐organic frameworks (2D c‐MOFs) are emerging as a novel class of conductive redox‐active materials for electrochemical energy storage. However, developing 2D c‐MOFs as flexible thin‐film electrodes have been largely limited, due to the lack of capability of solution‐processing and integration into nanodevices arising from the rigid powder samples by solvothermal synthesis. Here, the synthesis of phthalocyanine‐based 2D c‐MOF (Ni2[CuPc(NH)8]) nanosheets through ball milling mechanical exfoliation method are reported. The nanosheets feature with average lateral size of ≈160 nm and mean thickness of ≈7 nm (≈10 layers), and exhibit high crystallinity and chemical stability as well as a p‐type semiconducting behavior with mobility of ≈1.5 cm2 V?1 s?1 at room temperature. Benefiting from the ultrathin feature, the nanosheets allow high utilization of active sites and facile solution‐processability. Thus, micro‐supercapacitor (MSC) devices are fabricated mixing Ni2[CuPc(NH)8] nanosheets with exfoliated graphene, which display outstanding cycling stability and a high areal capacitance up to 18.9 mF cm?2; the performance surpasses most of the reported conducting polymers‐based and 2D materials‐based MSCs. 相似文献
27.
Gaidis M.C. Friedrich S. Segall K. Prober D.E. Szymkowiak A.E. Moseley S.H. 《Applied Superconductivity, IEEE Transactions on》1996,6(1):1-4
We report the development of Nb-Ta-Al-Al2O3-Al superconducting tunnel junction structures for high energy resolution and high efficiency X-ray detection. These devices utilize a Ta X-ray absorber with superconductor “bandgap engineered” quasiparticle trapping to improve charge collection. Experimental results at 0.3 K are presented, showing energy resolution of 102 eV full-width-half-maximum for 6 keV X-rays. Collected charge is in excess of 5×106 electrons. The absorption efficiency is better than 35%. Devices thermally cycle with no change in characteristics 相似文献
28.
Sorantin E Halmai C Erdöhelyi B Palágyi K Nyúl LG Ollé K Geiger B Lindbichler F Friedrich G Kiesler K 《IEEE transactions on medical imaging》2002,21(3):263-273
PURPOSE: Demonstration of a technique for three-dimensional (3-D) assessment of tracheal-stenoses, regarding site, length and degree, based on spiral computed tomography (S-CT). PATIENTS AND METHODS: S-CT scanning and automated segmentation of the laryngo-tracheal tract (LTT) was followed by the extraction of the LTT medial axis using a skeletonization algorithm. Orthogonal to the medial axis the LTT 3-D cross-sectional profile was computed and presented as line charts, where degree and length was obtained. Values for both parameters were compared between 36 patients and 18 normal controls separately. Accuracy and precision was derived from 17 phantom studies. RESULTS: Average degree and length of tracheal stenoses was found to be 60.5% and 4.32 cm in patients compared with minor caliber changes of 8.8% and 2.31 cm in normal controls (p < 0.0001). For the phantoms an excellent correlation between the true and computed 3-D cross-sectional profile was found (p < 0.005) and an accuracy for length and degree measurements of 2.14 mm and 2.53% respectively could be determined. The corresponding figures for the precision were found to be 0.92 mm and 2.56%. CONCLUSION: LTT 3-D cross-sectional profiles permit objective, accurate and precise assessment of LTT caliber changes. Minor LTT caliber changes can be observed even in normals and, in case of an otherwise normal S-CT study, can be regarded as artifacts. 相似文献
29.
30.
Friedrich Bauer und Klaus Hofmann 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1990,190(3):223-227
Zusammenfassung Die Hitzestabilität der Sarkoplasmaproteine bei Rind- und Schweinefleisch wurde anhand der Löslichkeit und der Proteinmuster nach elektrophoretischer Auftrennung untersucht. Als Untersuchungsmethoden kamen die Proteinbestimmung nach Bradford und die isoelektrische Focussierung in rehydratierbaren Polyacrylamidgelen zur Anwendung. Die focussierten Proteine wurden mit Hilfe der Silberfärbung sichtbar gemacht. Die Gesamtproteinkonzentrationen der Extrakte verringerten sich bis zu einer Temperatur von 80°C mit zunehmender Höhe und Dauer der Hitzebelastung. Bei den auf 100°C erhitzten Proben nahmen die Proteinkonzentrationen wieder geringfügig zu. Die Intensität der Proteinbanden nahm allgemein mit steigender Temperatur und Erhitzungszeit ab. Die deutlichsten Änderungen der Bandenmuster zeigten sich im untersuchten Temperaturbereich bei dem auf 100°C erhitzten Fleisch. Durch eine Nacherhitzung der Fleischproben konnten erhitzungsbedingte Unterschiede in den Bandenmuster ausgeglichen werden. Auf diese Weise ist eine elektrophoretische Tierartenidentifizierung bei erhitztem Fleisch unabhängig von der Kenntnis der Erhitzungsbedingungen möglich.
Influence of heat on solubility and electrophoretic behaviour of sarcoplasmic proteins of beef and pork
Summary The heat stability of sarcoplasmic proteins of beef and pork was investigated by means of their solubility and their protein patterns after electrophoretic separation. The method of determination of proteins described by Bradford and isoelectric focusing in rehydratable polyacrylamide gels were used for these investigations. The electrofocused proteins were visualized by silver staining. The concentration of total protein of the extracts decreased with increase in temperature and heating time (up to a temperature of 80° C). However the protein concentration increased in samples heated to 100° C. The intensity of the protein bands decreased with increasing temperature and heating time. In the investigated range of temperature, variations in protein patterns were most significant in meat heated to 100° C. Differences of protein pattern caused by different heating conditions could be equalized by a second heating of the samples. In this way it is possible to identify meat species without knowing the heating conditions.相似文献