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排序方式: 共有1319条查询结果,搜索用时 15 毫秒
1.
Nina Georgieva Kostova Elka Kraleva Alla A. Spojakina Erika Godocikova Peter Balaz 《Journal of Materials Science》2007,42(10):3321-3325
The Al-MCM-41 has been used as support to prepare Mo-containing catalysts. The 12- molybdophosphoric heteropoly acid (HPMo)
is used as initial compound. The catalysts are synthesized by two different methods: incipient impregnation with aqueous solution
of the acid and mechanochemical synthesis. The samples were tested in the reaction of the thiophene hydrodesulfurization after
activation with mixture H2 + H2S. The effect of the preparation method of the catalysts on their physicochemical and catalytic properties has been studied.
A partial destruction of the loaded compound is observed in mechanochemically treated sample whereas the aggregates are formed
from the particles of different size in the impregnated sample. The specific surface area of the sample prepared by mechanical–chemical
treatment decreases 2–3 times, while the total pore volume is about four times lower. The HDS activity is higher on the impregnated
sample than on the mechanochemically treated one. 相似文献
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The theory of syntactic bootstrapping proposes that children use the syntactic frames in which verbs are presented as a source of information about their meaning. The purpose of this study was to investigate the extent to which maternal type and diversity of verb frames are consistent with the requirements of that theory. The uses of 25 common verbs in the speech of 57 mothers to their 1- to 2-year-old children were tabulated and parsed for syntactic frame. Analyses revealed 2 major findings concerning the use of verbs in child-directed speech: (a) Verbs in different semantic categories appear in different syntactic environments, and (b) individual verbs are distinguished by the set of frames in which they appear. These findings support the plausibility of the syntactic bootstrapping hypothesis by demonstrating that children's input provides the structural cues to verb meaning that the syntactic bootstrapping procedure requires. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
Explores several questions relating to historical inquiry in the field of social psychology. During its Golden Age, 1945–1970, social psychology was busy defining different fields and paradigms, building theories, and verifying hypotheses; there was little time and need for reflection. The 1970s saw an era of doubts, critique and crisis, during which the constituted knowledge bases were undermined on a number of fronts: methodological, ethical, and theoretical. Examples of how critical history may serve a heuristic function for social psychology are given. The question of how to conduct historical inquiry is addressed, even for as problematic an object as social psychology's development in France. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Sandra L. McLellan Erika J. HollisMorgan M. Depas Meredith Van DykeJosh Harris Caitlin O. Scopel 《Journal of Great Lakes research》2007,33(3):566-580
Escherichia coli distribution and persistence in nearshore Lake Michigan were assessed following heavy rains and sanitary sewer overflow (SSO) and combined sewer overflow (CSO) events over a 5-year period, including an 18-day period following 25.4 cm of rainfall in which intensive studies were conducted following multiple CSO and SSO events. E. coli levels in the Milwaukee estuary and harbor following SSO and CSO events ranged from 104 to nearly 105 CFU/100 mL, which were significantly higher (p ≤ 0.05) than levels following rainfall alone. Sites outside of the breakwall but within the contamination plume (e.g., within 2 km of the harbor) were an order of magnitude lower. Locations 2–5 km from the harbor ranged from below detection limits, of < 1 to 5 CFU/100 mL. E. coli levels corrected for dilution based on specific conductivity measurements were lower than what would be expected for loss due to dilution alone, suggesting a combination of die-off and dilution, were responsible for the rapid disappearance of these organisms outside of the harbor. E. coli and fecal coliforms measured concurrently demonstrated that fecal coliforms could be recovered longer than E. coli in the open waters of the lake. E. coli isolated directly from sewage treatment plant influent were found to have a marked increase in antibiotic resistance traits for ten antibiotics commonly used in the human population compared with isolates from two animal sources of fecal pollution. However, E. coli obtained from sewage impacted water (n = 2,513) and from stormwater impacted water (n = 1,465) collected the previous year when there were no sewage overflows, were found to have no significant difference (p < 0.05) in the frequency of resistance when comparing the two conditions. E. coli survival characteristics and population dynamics are most likely influenced by multiple factors in complex systems such as the watershed/estuarine/lake environments of the Great Lakes. 相似文献
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Erik Mannens Davy Van Deursen Rapha?l Troncy Silvia Pfeiffer Conrad Parker Yves Lafon Jack Jansen Michael Hausenblas Rik Van de Walle 《Multimedia Tools and Applications》2012,59(2):691-715
To make media resources a prime citizen on the Web, we have to go beyond simply replicating digital media files. The Web is based on hyperlinks between Web resources, and that includes hyperlinking out of resources (e.g., from a word or an image within a Web page) as well as hyperlinking into resources (e.g., fragment URIs into Web pages). To turn video and audio into hypervideo and hyperaudio, we need to enable hyperlinking into and out of them. The W3C Media Fragments Working Group is taking on the challenge to further embrace W3C??s mission to lead the World Wide Web to its full potential by developing a Media Fragment protocol and guidelines that ensure the long-term growth of the Web. The major contribution of this paper is the introduction of Media Fragments as a media-format independent, standard means of addressing media resources using URIs. Moreover, we explain how the HTTP protocol can be used and extended to serve Media Fragments and what the impact is for current Web-enabled media formats. 相似文献
9.
Erika Nassar Chris Mulligan Lem Taylor Chad Kerksick Melyn Galbreath Mike Greenwood Richard Kreider Darryn S Willoughby 《Journal of the International Society of Sports Nutrition》2007,4(1):14-13
Melatonin and resistance exercise alone have been shown to increase the levels of growth hormone (GH). The purpose of this
study was to determine the effects of ingestion of a single dose of melatonin and heavy resistance exercise on serum GH, somatostatin
(SST), and other hormones of the GH/insulin-like growth factor 1 (IGF-1) axis. Physically active males (n = 30) and females
(n = 30) were randomly assigned to ingest either a melatonin supplement at 0.5 mg or 5.0 mg, or 1.0 mg of dextrose placebo.
After a baseline blood sample, participants ingested the supplement and underwent blood sampling every 15 min for 60 min,
at which point they underwent a single bout of resistance exercise with the leg press for 7 sets of 7 reps at 85% 1-RM. After
exercise, participants provided additional blood samples every 15 min for a total of 120 min. Serum free GH, SST, IGF-1, IGFBP-1,
and IGFBP-3 were determined with ELISA. Data were evaluated as the peak pre- and post-exercise values subtracted from baseline
and the delta values analyzed with separate three-way ANOVA (p < 0.05). In males, when compared to placebo, 5.0 mg melatonin
caused GH to increase (p = 0.017) and SST to decrease prior to exercise (p = 0.031), whereas both 0.5 and 5.0 mg melatonin
were greater than placebo after exercise (p = 0.045) and less than placebo for SST. No significant differences occurred for
IGF-1; however, males were shown to have higher levels of IGFBP-1 independent of supplementation (p = 0.004). The 5.0 mg melatonin
dose resulted in higher IGFBP-3 in males (p = 0.017). In conclusion, for males 5.0 mg melatonin appears to increase serum
GH while concomitantly lowering SST levels; however, when combined with resistance exercise both melatonin doses positively
impacts GH levels in a manner not entirely dependent on SST. 相似文献
10.
Erika Leitel Wolfgang Hübner Karsten P. Thiessen Ju. B. Makari
ev A. G. Akimov 《工业材料与腐蚀》1988,39(1):1-7
Investigation into the passivation mechanism of iron in phosphate electrolytes on surfaces exposed to erosive attack On iron electrodes in neutral phosphate electrolytes by continuous solid particle impingement a reaction layer is formed within the transition potential region under anodic polarization. XPS and AES investigations show that the reaction layer formed under impingement will be replaced by an oxide layer during the transition into the passive state under simultaneous decrease of the layer thickness. The active/passive transition in phosphate electrolytes may be attached to the equilibrium potential of the reaction . According to this thermodynamic interpretation of both the active/passive transition and the passive/active transition, respectively on iron in presence of phosphate ions may be described as the Fe(II)/Fe(III)-redox reaction with two solid phases, the iron(II)-phosphate phase and the iron(III)-oxide phase. The increase of the interfacial dynamic processes at the solid/liquid interface causes in consequence of the solid particle impingement that thermodynamic laws govern the course of reactions. 相似文献