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排序方式: 共有1614条查询结果,搜索用时 31 毫秒
91.
Summary Polymerizable enamines were synthesized by the reaction of 2-acetoacetoxyethyl methacrylate (AAEMA) with various aliphatic mono- and diamines. The enamines were characterized by elemental analyses, IR,1H NMR and13C NMR spectroscopy. Radical polymerization of synthesized enamines yielded polymers with pendant enamine groups which were also prepared by the reaction of poly(AAEMA) with the corresponding amines. 相似文献
92.
The previously developed high temperature set-up has been used to monitor the redox state of molten slags at 1500°C directly by UV/VIS spectroscopy. Slags of the CaO-MgO-SiO2-system were doped with Fe2O3 mass contents of 0.80 and 5%. Spectroscopical results at different oxygen partial pressures of the investigated Fe3+ charge-transfer (CT) transitions in the wavelength range between 200 and 800 nm were found to be representative for the redox state of the slag. The peak positions and shifts give further information about the optical basicity and the structure of molten slags. The time dependence of the oxidation/reduction equilibrium process was measured and evaluated concerning diffusion mechanisms. In Cr2O3-doped silicate-slags in the liquid state CrO3 - and Cr3+- species occur. The different CrO3-species (CrO42- and Cr2O72-) in silicate slags have been indicated spectroscopically and registed quantitatively. Further investigations on Cr2O3-doped slags uncovered the well known evaporation of chromium out of molten slags as a decrease in the CrO3 concentration in time. In the molten slag the CrO3 slowly evaporates, which can be seen spectroscopically as a decrease in the CT-band intensity. The results obtained on numerous optical parameters of molten slags will establish the application of reflection spectroscopy at high temperatures. 相似文献
93.
94.
Robust DNA microarray image analysis 总被引:6,自引:0,他引:6
Norbert?Br?ndleEmail author Horst?Bischof Hilmar?Lapp 《Machine Vision and Applications》2003,15(1):11-28
DNA microarrays are an increasingly important tool that allow biologists to gain insight into the function of thousands of genes in a single experiment. Common to all array-based approaches is the necessity to analyze digital images of the scanned DNA array. The ultimate image analysis goal is to automatically quantify every individual array element (spot), providing information about the amount of DNA bound to a spot. Irrespective of the quantification strategy, the preliminary information to extract about a spot includes the mapping between its location in the digital image and its possibly distorted position in the spot array (gridding). We present a gridding approach divided into a spot-amplification step (matched filter), a rotation estimation step (Radon transform), and a grid spanning step. Quantification of the spots is performed by robustly fitting of a parametric model to pixel intensities with the help of M-estimators. The main advantage of parametric spot fitting is its ability to cope with overlapping spots. If the goodness-of-fit is too bad, a semiparametric spot fitting is employed. We show that our approach is superior to simple quantification strategies such as averaging of the pixel intensities. The system was extensively tested on 1740 images resulting from two DNA libraries.Received: 15 June 2001, Accepted: 21 July 2002, Published online: 3 June 2003
Correspondence to: Norbert Brändle 相似文献
95.
Kuczewski B Marquardt CM Seibert A Geckeis H Kratz JV Trautmann N 《Analytical chemistry》2003,75(24):6769-6774
Capillary electrophoresis (CE) was coupled to ICPMS in order to combine the good performance of this separation technique with the high sensitivity of the ICPMS for the analysis of plutonium and neptunium oxidation states. The combination of a fused-silica capillary with a MicroMist AR 30-I-FM02 nebulizer and a Cinnabar small-volume cyclonic spray chamber yielded the best separation results. With this setup, it was possible to separate a model element mixture containing neptunium (NpO2(+)), uranium (UO2(2+)), lanthanum (La3+), and thorium (Th4+) in 1 M acetic acid. The same conditions were also suitable for the separation of various oxidation states of plutonium and neptunium in different aqueous samples. All separations were obtained within less than 15 min. A detection limit of 50 ppb identical with 2 x 10(-7) M (3-fold standard deviation of a blank) was achieved. To prove the negligible disturbance of the plutonium and neptunium redox equilibria during the CE separations, plutonium and neptunium speciation by CE-ICPMS in acidic solutions was compared with the results of UV/visible absorption spectroscopy and was found to be in good agreement. The CE-ICPMS system was also applied to study the reduction of Pu(VI) in a humic acid-containing groundwater at different pH values. 相似文献
96.
Lohbauer U Frankenberger R Krämer N Petschelt A 《Journal of materials science. Materials in medicine》2003,14(12):1047-1053
Elastic modulus (EM), initial fracture strength (FS) and flexural fatigue limit (FFL) of dental restorative materials were measured in a simulated oral environment to correlate mechanical response under the influence of water with the chemical nature of the test materials under investigation. One resin composite (RC; Tetric Ceram, Ivoclar-Vivadent Corp., Liechtenstein), an ion-leaching resin composite (ILRC; Ariston pHc, Ivoclar-Vivadent Corp., Liechtenstein) a compomer (CO; Dyract AP, Dentsply Corp., USA) and a glass-ionomer cement (GIC; Ketac Molar, 3MEspe Corp., Germany) were tested. Static EM, FS and dynamic FFL experiments were performed. The FFL was determined under cyclic loading for 10(5) cycles in terms of a staircase approach. The materials were stored for 1, 8, 30, 90 and 180 days in 37 degrees C distilled water, respectively. The RC degraded over time due to water adsorption followed by failure within the resin matrix. The ILRC suffered from a pronounced decrease in FS as well as in FFL due to a constant ion-leaching and macroscopic crack growth. CO failed over time due to resin-filler interface cracking. The GIC exhibited improved mechanical performance over time due to a post-hardening mechanism. The results reveal the necessity for substantial preclinical evaluation of direct restorative materials. The material parameters under investigation are capable of predicting clinical performance over time. 相似文献
97.
Zusammenfassung Nachdem wir im letzten Artikel die Funktionen einer digitalen Signatur kennen gelernt und den Bedarf an kryptographischen
Prüfsummen und Zertifikaten erl?utert haben, wollen wir diesmal auf die Infrastrukturen zur Verwaltung von Schlüsseln bzw.
Zertifikaten eingehen: die so genannten Public-Key-Infrastrukturen (PKI).
Prof. Dr. Norbert Pohlmann ist Gesch?ftsführender Direktor des Instituts für Internet-Sicherheit der Fachhochschule Gelsenkirchen.
Malte Hesse ist Mitarbeiter am Institut für Internet-Sicherheit der Fachhochschule Gelsenkirchen. 相似文献
98.
This paper explores the growing phenomenon of international co-productions in the film industry. We argue that the rise of co-productions is part of a wider narrative of financial and institutional innovation shaping industrial organization in the film industry. This narrative centres on film finance as a central risk distribution mechanism, and discusses how changes in film support policy, increased tax competition, the search for finance and an abundance of inflowing capital are increasingly driving industrial dynamics in the film industry. 相似文献
99.
Armando Almendarez Camarillo Stephan Volkher Roth Peter Bösecke Stefan Buchner Klaus Krenn Rainer Gehrke Norbert Stribeck 《Journal of Materials Science》2007,42(15):6212-6221
Commercial skived film from ultra-high molecular-weight polyethylene (UHMWPE) with considerable uniaxial orientation of lamellae
is studied by ultra-small-angle X-ray scattering (USAXS) and wide-angle X-ray scattering (WAXS) during melting and crystallization
in order to identify its mechanisms of crystallization. For the analysis of the nanostructure two-dimensional USAXS patterns
are analyzed by means of the multidimensional chord distribution function (CDF) method. WAXS shows that crystallization is
always isotropic and fast. WAXS reflections are observed before—under certain processing conditions—the SAXS pattern becomes
anisotropic. Thus crystallization is decoupled from a slower process of oriented nanostructure formation (nanoforming). If
nanoforming is performed isothermally at 105 °C, the evolving nanodomain layers obtain some preferential orientation, as long
as the orientation of the melt has not previously been erased by melt-annealing at temperatures of 140 °C or above. Crystallization
at temperatures ≥110 °C followed by quenching leads to isotropic nanostructure. Although crystallization is always observed
early in the WAXS patterns, the USAXS patterns exhibit only weak discrete scattering during isothermal treatment at temperatures
of 110 °C and higher. At 105 °C anisotropic isothermal nanoforming starts after 1.5 min. The melting of the original material
resembles an inverted random car-parking mechanism. Only next-neighbor correlations are observed among the crystalline layers.
The average nanodomain layer thickness is only slightly increasing (26–30 nm), whereas the long period increase is strong
(from 60 nm to 140 nm). 相似文献
100.
Lauraine Tiogning Kueti Norbert Tsopze Cezar Mbiethieu Engelbert Mephu-Nguifo Laure Pauline Fotso 《国际通用系统杂志》2013,42(8):849-868
ABSTRACTWe propose a novel approach to define Artificial Neural Network(ANN) architecture from Boolean factors. ANNs are a subfield of machine learning applicable to several areas of life. However, defining its architecture for solving a given problem is not formalized and remains an open research problem. Since it is difficult to look into the network and figure out exactly what it has learnt, the complexity of such a technique makes its interpretation more tedious. We propose in this paper to build feedforward ANNs using the optimal factors obtained from the Boolean context representing a data. Since optimal factors completely cover the data and therefore give an explanation to these data, We could give an interpretation to the neurons activation and justify the presence of a neuron in our proposed neural network. We show through experiments and comparisons on the use data sets that this approach provides relatively better results for some key performance measures. 相似文献