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121.
122.
Michael R. A. Morgan Ruth McNerney Henry W.-S. Chan Peter H. Anderson 《Journal of the science of food and agriculture》1986,37(5):475-480
An indirect, double antibody enzyme-linked immunosorbent assay (ELISA) has been validated for application to pig kidney. The specificity of the anti-ochratoxin A antiserum employed is such that minimal sample preparation is required prior to assay, with consequent beneficial effects on sample throughput. Kidneys (303) obtained in the UK as being unsuitable for human consumption were examined for ochratoxin A content by ELISA. Of these, 191 (63%) contained no detectable toxin (the detection limit was 0.5 ng g?1). Only eight samples (2.6%) contained more than 5 ng g?1 ochratoxin A, and only two were above 10 ng g?1 (at 11.5 and 12.4 ng g?1). The significance of these findings is discussed. 相似文献
123.
Two experiments examined the effect of reinforcer devaluation on the ability of a discriminative stimulus (Sd) to control instrumental behavior in Sprague-Dawley rats. In Experiment 1 reinforcer devaluation reduced, but did not eliminate, the ability of the Sd to control performance of the original response and to transfer its control to a new response trained with the same reinforcer. The effect of devaluation was more complete in Experiment 2, in which the reinforcer was delivered directly into the oral cavity. However, retraining the response with a different reinforcer partially restored the ability of the Sd to control performance of that response. These results suggest that an Sd may not augment its trained responses when the reinforcer has been completely devalued but may promote responses with which it shares a reinforcer, as long as those responses are associated with some reinforcer that retains its value. The implications of these results for the way that discriminative stimuli control instrumental behavior are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
124.
Studied acquisition of the alphabetic principle in preliterate children, 3–5 yrs. The dependent variable throughout was a forced-choice between, e.g., "mow" and "sow" as pronunciations for the written word mow after the child had been taught to read the words mat and sat. Reliable performance on this transfer task was only achieved by children who (a) understood two aspects of phonological organization—phonemic segmentation of the speech items and the identity of their initial segments, and (b) had learned graphic symbols for the sounds "m" and "s." Most children who demonstrated alphabetic insight with symbols in word-initial position were also successful at transfer when the symbols were word-final. Thus, phonemic awareness and grapheme-phoneme knowledge were needed in combination for acquisition of the alphabetic principle, and, once gained, alphabetic insight proved relatively robust. Implications for reading acquisition are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
125.
Eoin Cunningham Nicholas Dunne Gavin Walker Christine Maggs Ruth Wilcox Fraser Buchanan 《Journal of materials science. Materials in medicine》2010,21(8):2255-2261
The application of synthetic cancellous bone has been shown to be highly successful when its architecture mimics that of the
naturally interconnected trabeculae bone it aims to replace. The following investigation demonstrates the potential use of
marine sponges as precursors in the production of ceramic based tissue engineered bone scaffolds. Three species of natural
sponge, Dalmata Fina (Spongia officinalis Linnaeus, Adriatic Sea), Fina Silk (Spongia zimocca, Mediterranean) and Elephant Ear (Spongia agaricina, Caribbean) were selected for replication. A high solid content (80 %wt), low viscosity (126 mPas) hydroxyapatite slurry
was developed, infiltrated into each sponge species and subsequently sintered, producing a scaffold structure that replicated
pore architecture and interconnectivity of the precursor sponge. The most promising of the ceramic tissue engineered bone
scaffolds developed, Spongia agaricina replicas, demonstrated an overall porosity of 56–61% with 83% of the pores ranging between 100 and 500 μm (average pore size
349 μm) and an interconnectivity of 99.92%. 相似文献
126.
Janet Brigham Christina N Lessov-Schlaggar Harold S Javitz Mary McElroy Ruth Krasnow Gary E Swan 《Nicotine & tobacco research》2008,10(2):287-299
Retrospective assessment of tobacco use underlies much of the data collected in epidemiological and genetic epidemiological research. Although individuals are asked to report lifetime tobacco use for periods spanning months to decades, the test-retest reliability intervals of the instruments often span only a few weeks to several months. The present analyses examined the test-retest reliability of retrospective tobacco use measures, including details of first use, circumstances of first use, and initial subjective reactions. The questions were part of the Lifetime Tobacco Use Questionnaire (LTUQ), a Web-based questionnaire designed to assess use of most forms of tobacco or nicotine retrospectively across the lifespan. A convenience sample of 236 men and women with history of tobacco use (Time 1 mean age, 44.9 years; 74.2% females; 75.1% regular monthly tobacco use) responded verifiably to invitations to self-administer the LTUQ two times, 2 years apart. Test-retest reliability analyses reflected high reliability for salient tobacco-use questions. Acceptable levels of reliability were observed for initial subjective reactions to smoking, if the scaled response options were dichotomized. Few differences in the reliability of recall were apparent between sexes and between age groups. These results indicate that recall of important tobacco use information can form a reliable basis for research. 相似文献
127.
A proposed structural model for amyloid fibril elongation: domain swapping forms an interdigitating {beta}-structure polymer 总被引:1,自引:0,他引:1
Sinha Neeti; Tsai Chung-Jung; Nussinov Ruth 《Protein engineering, design & selection : PEDS》2001,14(2):93-103
We propose a model illustrating how proteins, which differ intheir overall sequences and structures, can form the propagating,twisted ß-sheet conformations, characteristic of amyloids.Some cases of amyloid formation can be explained through a `domainswapping' event, where the swapped segment is either a ß-hairpinor an unstable conformation which can partially unfold and assumea ß-hairpin structure. As in domain swapping, herethe swapped ß-hairpin is at the edge of the structure,has few (if any) salt bridges and hydrogen bonds connectingit to the remainder of the structure and variable extents ofburied non-polar surface areas. Additionally, in both casesthe swapped piece constitutes a transient `building block' ofthe structure, with a high population time. Whereas in domainswapping the swapped fragment has been shown to be an 相似文献
128.
Asian-American acculturation, severity of concerns, and willingness to see a counselor. 总被引:1,自引:0,他引:1
Asian Americans at a major West Coast university were surveyed to determine how severe each of 24 problems was for them and to assess their willingness to see a counselor for each problem. Factor analysis reduced the 24 problems to 8 areas of concern. A repeated measures analysis of variance (ANOVA) revealed that severity ratings for the 8 concerns were related to acculturation and ethnicity. With severity ratings as covariates, a repeated measures analysis of covariance (ANCOVA) was computed for willingness to see a counselor ratings. Willingness to see a counselor was found to be related to both acculturation and gender across all 8 concerns. Women expressed greater willingness to see the counselor than did men and low-medium acculturated students expressed greater willingness to see a counselor than did high-acculturated students. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
129.
130.
Duarte CD Greferath R Nicolau C Lehn JM 《Chembiochem : a European journal of chemical biology》2010,11(18):2543-2548
myo‐Inositol trispyrophosphate (ITPP), a novel membrane‐permeant allosteric effector of hemoglobin (Hb), enhances the regulated oxygen release capacity of red blood cells, thus counteracting the effects of hypoxia in diseases such as cancer and cardiovascular ailments. ITPP‐induced shifting of the oxygen–hemoglobin equilibrium curve in red blood cells (RBCs) was inhibited by DIDS and NAP‐taurine, indicating that band 3 protein, an anion transporter mainly localized on the RBC membrane, allows ITPP entry into RBCs. The maximum intracellular concentration of ITPP, determined by ion chromatography, was 5.5×10?3 M , whereas a drop in concentration to the limit of detection was observed in NAP‐taurine‐treated RBCs. The dissociation constant of ITPP binding to RBC ghosts was found to be 1.72×10?5 M . All data obtained indicate that ITPP uptake is mediated by band 3 protein and is thus highly tissue‐selective towards RBCs, a feature of major importance for its potential therapeutic use. 相似文献