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951.
Dibutyroyl derivatives of monoacylglycerols (DBMAG) from conifer seed oil triacylglycerols (TAG) were prepared by partial
deacylation of TAG with ethylmagnesium bromide followed by diesterification with n-butyryl chloride. The resulting mixtures were analyzed by gas-liquid chromatography (GCL) with 65% phenylmethyl silicon open
tubular fused-silica capillary column operated under optimal conditions and separated according to both their fatty acid structures
and their regiospecific distribution. Seed oils of 18 species from 5 conifer families (Pinaceae, Taxaceae, Cupressaceae, Cephalotaxaceae,
and Podocarpaceae) were analyzed. The chromatograms showed a satisfactory resolution of DBMAG containing palmitic (16∶0) stearic
(18∶0), taxoleic (cis-5, cis-9 18∶2), oleic (cis-9 18∶1), cis-vaccenic (cis-11 18∶1), pinolenic (cis-5, cis-9, cis-12 18∶3), linoleic (cis-9, cis-12 18∶2), α-linolenic (cis-9 cis-12, cis-15 18∶3), and an almost baseline resolution of DBMAG containing gondoic (cis-11 20∶1), cis-5, cis-11 20∶2, sciadonic (cis-5, cis-11, cis-14 20∶3), dihomolinoleic (cis-11 cis-14 20∶2), juniperonic (cis-5, cis-11, cis-14, cis-17 20∶4), and dihomo-α-linolenic (cis-11, cis-14, cis-17 20∶3) acids. We have observed that results for Pinus pinaster and P. koraiensis seed oils obtained with this new simple method compared favorably with literature data established with other usual regiospecific
analytical techniques. Δ5-Olefinic acids are esterified mainly at the external positions of the glycerol backbone in all cases,
in agreement with data obtained by other methodologies allowing validation of the GLC regiospecific method. To date, 45 gymnosperm
species (mostly Coniferophytes) from 21 genera belonging to 9 families have been analyzed, all of them showing a definite
enrichment of Δ5-olefinic acids in the external positions of TAG. These fatty acids (FA), with one exception only, represent
between-2 and 8% of FA esterified to the internal positions. For some species, i.e., P. koraiensis and P. pinaster, this asymmetrical distribution was established by at least three analytical procedures and confirmed by stereospecific analysis
of their seed TAG. 相似文献
952.
953.
Robert Upton 《Planning Theory & Practice》2013,14(2):111-114
954.
Vinnars Bo; Thorm?hlen Barbro; Gallop Robert; Norén Kristina; Barber Jacques P. 《Canadian Metallurgical Quarterly》2009,46(3):362
Studies involving patients with personality disorders (PDs) have not focused on improvement of core aspects of the PD. The authors examined changes in quality of object relations, interpersonal problems, psychological mindedness, and personality traits in a sample of 156 patients with Diagnostic and Statistical Manual of Mental Disorders (4th ed.) PD diagnoses being randomized to either manualized or nonmanualized dynamic psychotherapy. Effect sizes adjusted for symptomatic change and reliable change indices were calculated. The authors found that both treatments were equally effective at reducing personality pathology. Only in neuroticism did the nonmanualized group do better during the follow-up period. The largest improvement was found in quality of object relations. For the remaining variables, only small and clinically insignificant magnitudes of change were found. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
955.
Taking tests enhances learning. But what happens when one cannot answer a test question—does an unsuccessful retrieval attempt impede future learning or enhance it? The authors examined this question using materials that ensured that retrieval attempts would be unsuccessful. In Experiments 1 and 2, participants were asked fictional general-knowledge questions (e.g., “What peace treaty ended the Calumet War?”). In Experiments 3–6, participants were shown a cue word (e.g., whale) and were asked to guess a weak associate (e.g., mammal); the rare trials on which participants guessed the correct response were excluded from the analyses. In the test condition, participants attempted to answer the question before being shown the answer; in the read-only condition, the question and answer were presented together. Unsuccessful retrieval attempts enhanced learning with both types of materials. These results demonstrate that retrieval attempts enhance future learning; they also suggest that taking challenging tests—instead of avoiding errors—may be one key to effective learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
956.
Robert Gracie Ted Belytschko 《International journal for numerical methods in engineering》2009,78(3):354-378
A method for the modeling of dislocations and cracks by atomistic/continuum models is described. The methodology combines the extended finite element method with the bridging domain method (BDM). The former is used to model crack surfaces and slip planes in the continuum, whereas the BDM is used to link the atomistic models with the continuum. The BDM is an overlapping domain decomposition method in which the atomistic and continuum energies are blended so that their contributions decay to their boundaries on the overlapping subdomain. Compatibility between the continua and atomistic domains is enforced by a continuous Lagrange multiplier field. The methodology allows for simulations with atomistic resolution near crack fronts and dislocation cores while retaining a continuum model in the remaining part of the domain and so a large reduction in the number of atoms is possible. It is applied to the modeling of cracks and dislocations in graphene sheets. Energies and energy distributions compare very well with direct numerical simulations by strictly atomistic models. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
957.
958.
Robert Günther Thomas Klassen Birte Dickau Frank Gärtner Arno Bartels Rüdiger Bormann 《Journal of the American Ceramic Society》2001,84(7):1509-1513
New (inter)metallic-ceramic composites for high-temperature structural and functional applications are prepared via high-energy ball milling. During compaction by pressureless sintering, dense Al2 O3 /Ti-based alloy composites are formed that consist of inter-connected networks of the ceramic and the (inter)metallic phases. Ti-Al-V/Al2 O3 and Ti-Al-Nb/Al2 O3 composites show enhanced damage tolerance over monolithic Al2 O3 , i.e ., fracture toughnesses up to 5.6 MPa·m0.5 and bending strengths up to 527 MPa. The resistance against abrasive wear is almost doubled with respect to monolithic Al2 O3 ceramic. Electrical resistivity scales with the ceramic volume fraction and ranges between 0.3 mΩ·cm and 55.1 mΩ·cm, with only a weak temperature dependence ≤700°C. 相似文献
959.
960.
South Susan C.; Krueger Robert F.; Iacono William G. 《Canadian Metallurgical Quarterly》2009,21(4):622
The Dyadic Adjustment Scale (DAS; G. B. Spanier, 1976) is the most widely used inventory of relationship satisfaction in the social sciences, yet the question of whether it is measuring the same concept in men and women has never been addressed. In the current study, the authors examined the factor structure of the DAS in a sample of 900 currently married couples who participated in the Minnesota Twin Family Study. Confirmatory factor analysis was applied to a second-order factor solution with Spanier’s four factors (Dyadic Consensus, Dyadic Satisfaction, Dyadic Cohesion, Affectional Expression) loading on one higher order factor (Relationship Adjustment), to test for measurement invariance across gender. The second-order solution was relatively invariant across gender, even when taking into account the nonindependent nature of the data. This suggests that the best conceptualization of the DAS is one of a gender-invariant measure of marital adjustment with four distinct subfactors and that differences between men and women on any of these constructs can be interpreted by both clinicians and researchers as true mean differences rather than measurement bias. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献