One of the products formed upon incubation of linolenic acid (cis9,12,15-octadecatrienoic acid) with an extract of flaxseed acetone powder has been characterized as 8-[2-(cis-pent-2′-enyl)-3-oxo-cis-cyclopent-4-enyl]octanoic acid. The cyclopentenone ring structure of this acid is analogous to that of the A-type prostaglandins
produced in mammalian systems. 相似文献
Styrene-acrylonitrile copolymers, SAN, are known to be miscible with poly(methyl methacrylate). Based on the presence of a single composition dependent glass transition and lower critical solution temperature behaviour, it is shown that SAN is also miscible with poly(ethyl methacrylate). However, the SAN does not appear to be miscible with other polymethacrylates or polyacrylates. 相似文献
The feasibility of using a dynamic, i.e. multivariable, test procedure instead of the more usual single point tests has been investigated by determining the limiting conditions for burning. The rate of burning and the limiting conditions for flaming and smoldering combustion have been determined over a range of temperatures and oxygen concentrations. Results show that the relative burning rates of materials and also their relative combustion thresholds can alter significantly with changes in the tests environment. 相似文献
Reviews the book, Aesthetics and Psychobiology by D. E. Berlyne (see record 1973-00821-000). Progress in the aesthetic disciplines has been at a snail's pace. Berlyne charges six factors with having impeded advance: the belief in art as a supernatural phenomenon, the failure to separate factual from normative questions, the conception of art as a unitary phenomenon, the habit of treating art in isolation from nonartistic forms of behavior, the preoccupation with uniqueness in aesthetic taste, and the concentration on verbal judgments in aesthetic work. But the future looks brighter, due primarily to the following developments: (1) the rise of information theory, which provides procedures for rigorously analyzing some of the features of stimulus patterns that most concern aesthetics, (2) recent empirical and theoretical contributions in both psychology and neurophysiology to the understanding of pleasure and arousal, and (3) findings bearing on the nature of exploratory behavior, both in animals and humans, particularly as these teach the motivational importance of such elements as complexity, novelty and uncertainty, so-called "collative" variables, that "seem to be identifiable with the irreducibly essential ingredients of art and of whatever else is aesthetically appealing" (viii). The principal aim of Berlyne's book is to establish the ground gained in these three areas, compare it to the contributions made by earlier workers, and effectuate "a provisional synthesis that will at least bring key problems to the fore" (viii). It is a formidable task. Inevitably, the effort fares better in some assignments than others. Ironically, what discrepancies in quality do exist would probably project less were Berlyne not so knowledgeable about his subject matter. He is, quite obviously, in the tradition of those "cultured gentlemen" with whom he is wont to populate the early history of psychological science. Parenthetically, one suspects that he could supplement the present work with a very creditable companion volume in the philosophy of aesthetics. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
In early 1973, the phosphorus supply to Shagawa Lake, Minnesota, was reduced by about 80% when a tertiary wastewater treatment plant began operating. Significant reductions in total and soluble reactive phosphorus concentrations have occurred in the lake since that time. By 1976 the average (volume weighted over the entire lake) total and soluble reactive phosphorus concentrations had declined from about 51 and 21 μg l−1 to about 30 and 4.5 μg l−1, respectively, corresponding to 40 and 80% reductions. During 1975 and 1976, chlorophyll a (averaged over the top 5 m) had decreased to less than 50% of the pretreatment level during May-June but during July-August little change had occurred.
A phosphorus residence time model projected equilibrium total phosphorus concentrations of about 12 μg l−1 within 1.5 years. The fact that this level was not reached is attributed to a feedback of phosphorus from the sediments, primarily during summer. This phenomenon has been incorporated into a modified total phosphorus mass balance model which projects the phosphorus pattern through 1976 quite accurately. The close fit of the modified mass balance model implies that the phosphorus supply from the sediments has not diminished since treatment since treatment began, and that further recovery of the lake will depend upon how long this feedback of phosphorus from the sediments continues. 相似文献
Presented to 247 Black male and female high school students racial and attitudinal information about a hypothetical male or female counselor and asked them to express their perceptions of the counselor. Attitudinal information about a counselor had a stronger effect than racial information on Ss' perception of the counselor: Counselors portrayed as attitudinally similar were rated significantly higher in attractiveness, trustworthiness, expertness, and social attraction than those portrayed as attitudinally dissimilar. Racial information also influenced perceived attractiveness: White counselors were rated higher than Black ones in attractiveness, although there was no difference in ratings of trustworthiness or expertise. White female counselors were perceived as more expert than their Black female counterparts, whereas the ratings of male counselors were not influenced by the racial variable. Implications for counselor–client relationships and the development of mental health services for minority populations are discussed. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献