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排序方式: 共有2436条查询结果,搜索用时 31 毫秒
781.
Milan Drdák Milota Vallová Gabriel Greif Peter Simko Pavol Kusý 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1990,190(2):121-122
Summary The influence of water activity on the stability of betanine isolated using Sephadex G-25 and crystallized with 0.1% HCl was investigated. The influence of water activity was studied in water/glycerol model systems with water activities ranging from 0.37 to 1.00 at 75° C. From the results obtained, the rate constants for betanine degradation and the half-lives of betanine were calculated. The non-linar dependence obtained was verified using mathematical methods.
Einfluß der Wasseraktivität auf die Stabilität von Betanin
Zusammenfassung Es wurde der Einfluß der Wasseraktivität auf die Stabilität von Betanin, das mit Sephadex G-25 isoliert und aus 0.1% HCl kristallisiert wurde, verfolgt. Der Einfluß der Wasseraktivität wurde in Modellsystemen Wasser-Glycerol mit Werten der Wasseraktivität von 0,37 bis 1,00 (bei 75°C) untersucht. Aus den experimental gewonnenen Daten wurden die Geschwindigkeitskonstante und die Halbwertszeit des Zerfalls von Betanin errechnet. Die erhaltene nichtlineare Abhängigkeit wurde mathematisch getestet.相似文献
782.
The G?ttingen audiometric speech test was originally developed for testing three to four-year old children as well as retarded children. A refinement of this test supplements the original test in order to test five and six-year old children. This latter test follows the same advantages by using one-syllable nouns in combination with four different pictures. These pictures present words containing the same vowel but in contrast to the earlier test, the word list is expanded from twenty to 100 words. Standardization of the test was obtained by testing 62 five and six-year old normal children. 相似文献
783.
Gabriel Michael; Orona Edward; Foster Kent; Lambert Richard W. 《Canadian Metallurgical Quarterly》1980,94(6):1087
Recorded unit activity of the cingulate cortex and the anteroventral (AV) nucleus of the thalamus in 48 New Zealand White rabbits during reversal training following differential conditioning of a locomotory avoidance response. The positive and negative conditional stimuli (CS+ and CS–) were pure tones (1 kHz and 8 kHz), and the UCS was footshock (1.5 mA). During the 1st session, activity appropriate to the original task (i.e., a greater neuronal response to the CS– than to the CS+) occurred in the deep cortical laminae, but the superficial laminae manifested the original discrimination in certain records and the reverse discrimination in others. All discriminative effects diminished during subsequent sessions except the short-latency deep laminar original discrimination, which persisted throughout reversal training. Activity of the AV nucleus underwent gradual transition, in parallel with the behavior, from the original to the reverse discrimination. Arousal-producing footshocks given after behavioral reversal reduced the original and reverse discriminations in the deep and superficial laminae, respectively. These data indicate the role of cingulate cortex and anterior thalamus for encoding the associative significance of the CS (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
784.
Presents an analogy between the learning theorist and the test-theorist, suggesting that present models for test prediction do not provide for generalizability of test results fron 1 situation to another or for explaining failures of tests to predict. It is proposed that future models include motivational variables. As a 1st step, it is proposed that Hull's model of learning be adapted for test prediction. The new model would be as follows: P = A * M * L, where P = performance; A = some weighted sum of aptitude, knowledge, and skills; M = some weighted sum of internal and external motivations; and L = situational variables. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
785.
Laser-induced breakdown spectroscopy (LIBS) was used for the characterization of the main components of the surface residual dirt produced in cold-rolled steel plates as a consequence of the manufacturing stages. At laser fluences between 0.05 J/cm(2) < F < 0.30 J/cm(2), dirt ablation takes place without any contribution from the substrate. Results show that the main components of the dirt are fine particles of Fe mostly homogeneously distributed in a thin layer of grease and soaps. In the primary stages of the manufacturing process carbon residuals can also be found. By measuring light emission from the lambda = 495.9 nm line of Fe(I) after laser ablation, we developed a real-time on-line method for the determination of the concentration of iron particles present in the surface dirt. The obtained results open new possibilities in the design of real-time instruments for industrial applications as a quality control of products and processes. 相似文献
786.
Polycyclic aromatic hydrocarbons (PAHs) are often associated with complex matrixes such as exhaust diesel particulate matter (DPM), which complicates their study. In that case, laser desorption/ionization mass spectrometry is one of the techniques which ensures their direct analysis in the solid state. We demonstrate in this paper that the use of charge-transfer pi-complexing agents allows us to selectively detect by Fourier transform ion cyclotron resonance mass spectrometry PAHs adsorbed on diesel particles with high sensitivity. 2,4,7-trinitro-9-fluorenone and 7,7',8,8'-tetracyanoquinodimethane pi-acceptor compounds form charge-transfer complexes with PAHs and prevent their evaporation in the mass spectrometer during analysis. Moreover, the production of PAH molecular ions is dramatically increased by laser irradiation of these complexes at short wavelength (221.7 nm) and low power density (5 x 10(6) W cm(-)(2)). This methodology is applied for the first time to the examination of DPM collected during the new European driving cycle for light-duty vehicles. Differentiation criteria may coherently be assigned to engine operating mode (engine temperature, driving conditions). DPM samples can also be easily distinguished in negative ions according to the high sensitivity of this detection mode to sulfate compounds. 相似文献
787.
Leitner G Merin U Silanikove N Ezra E Chaffer M Gollop N Winkler M Glickman A Saran A 《The Journal of dairy research》2004,71(3):311-315
The study was aimed at identifying the pathogens causing subclinical udder infections in representative Israeli dairy goat herds and determining their effect on milk quality. Five hundred goats in ten flocks of various breeds and crossbreeds were surveyed. Of the 500 goats, 13.4% were in their first lactation, 36.4% were in their second lactation and 50.2% were in their third or higher lactation. Percentages of udder halves with subclinical intramammary infection in the flocks ranged from 35 to 71%. The effect of the bacteriological infection on somatic cells count (SCC) was significant (P<0.001). Various species of coagulase-negative staphylococci (CNS), mainly Staphylococcus caprae and Staphylococcus epidermidis, were the main pathogens in infected udder halves. Lactation number did not significantly influence either infection rate of udder halves or SCC, although the percentage of udder halves with no bacteriological findings was higher at the first lactation than at the third lactation. Milk composition (fat, protein and lactose) varied among flocks, with lower mean total protein in uninfected halves than in infected ones and higher lactose in uninfected than infected halves. 相似文献
788.
Inhibition of H2O2-induced apoptosis of lymphocytes by calorie restriction during aging 总被引:1,自引:0,他引:1
Calorie restriction (CR) is known to delay the aging process in rodents and is postulated to act by decreasing free radical generation and increasing antioxidant enzyme activity. The present study was designed to investigate the effect of CR and age on oxidative stress-induced apoptosis and associated changes in the levels of TNF-alpha, and Bcl-2 in splenic T lymphocytes. Ad libitum (AL)- or CR-fed C57BL/6J mice were sacrificed either at 6 (young) or 18 (old) months and splenic lymphocytes were incubated with or without 25 micro M H2O2 to induce apoptosis. Apoptosis increased with age in cells of AL-fed mice incubated with H2O2. CR prevented this rise in apoptosis in total splenic lymphocytes and in CD4(+) and CD8(+) T lymphocyte subsets either with or without H2O2. Free radicals increased and mitochondrial membrane potential decreased in aged mice. CR prevented these changes and also prevented the age-associated increase in TNF-alpha and loss of Bcl-2 in total splenic lymphocytes and in CD4(+) and CD8(+) lymphocyte subsets. In summary, lymphocytes in aged AL-fed mice were much more susceptible to oxidative stress-induced apoptosis whereas CR normalized apoptosis by preventing the increase in TNF-alpha and the decrease in Bcl-2 associated with aging. 相似文献
789.
Camilo Rueda Gloria Alvarez Luis O. Quesada Gabriel Tamura Frank Valencia Juan Francisco Díaz Gerard Assayag 《Constraints》2001,6(1):21-52
We propose PiCO, a calculus integrating concurrent objects and constraints, as a base for music composition tools. In contrast with calculi such as NiehrenMueller:Free, milner.parrow.ea:calculus-mobile or TyCO vasconcelos:typed-concurrent, both constraints and objects are primitive notions in PiCO. In PiCO a base object model is extended with constraints by orthogonally adding the notion of constraint system found in the -calculus OzCalculus. Concurrent processes make use of a constraint store to synchronize communications either via the ask and tell operations of the constraint model or the standard message-passing mechanism of the object model. A message delegation mechanism built into the calculus allows encoding of general forms of inheritance. This paper includes encodings in PiCO of the concepts of class and sub-class. These allow us to represent complex partially defined objects such as musical structures in a compact way. We illustrate the transparent interaction of constraints and objects by a musical example involving harmonic and temporal relations. The relationship between Cordial, a visual language for music composition applications, and its underlying model PiCO is described. 相似文献
790.
We suggest what we believe is a new three-dimensional (3-D) camera system for integral photography. Our method enables high-resolution 3-D imaging. In contrast to conventional integral photography, a moving microlens array (MLA) and a low-resolution camera are used. The intensity distribution in the MLA image plane is sampled sequentially by use of a pinhole array. The inversion problem from pseudoscopic to orthoscopic images is dealt with by electronic means. The new method is suitable for real-time 3-D imaging. We verified the new method experimentally. Integral photographs with a resolution of 3760 pixels x 2560 pixels (188 x 128 element images) are presented. 相似文献