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排序方式: 共有81条查询结果,搜索用时 15 毫秒
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THE RATIO OF CALCAREOUS AND ORGANIC SHELL COMPONENTS OF FRESHWATER SPHAERIID CLAMS IN RELATION TO WATER HARDNESS AND TROPHIC CONDITIONS 总被引:1,自引:0,他引:1
BURKY ALBERT J.; BENJAMIN MICHELE A.; CATALANO DENNIS M.; HORNBACH DANIEL J. 《Journal of Molluscan Studies》1979,45(3):312-321
Shells from 14 populations of sphaeriid clams including Sphaeriumstriatinum, S. simile, Pisidium walkeri, Musculim partumeiumand M. iransversum were analyzed for organic carbon (µgCmg1 shell), nitrogen (µg,N mg1 shell) andCaCOs (%CaCO3 of total clam dry weight). Habitat waters wereassessed for total hardness (expressed as ppm CaCo3), ppm Ca,ppm Mg, conductivity (µmho) and suspended organic Carbon(µgCl1). For all populations, shell organic C andN are positively correlated and there is an inverse relationshipbetween the amounts of shell CaCO3 and shell organic carbon.Trophic considerations give the best correlation with shelltype at the generic level of consideration since species ofMusculium are found at the opposite end of the trophic scale(eutrophic) from all other populations studied. For S. striatinum,the most extensively studied species, the amount of shell CaCO3is inversely related to water hardness. The selection of shellsin the Sphaeriidae is discussed in relation to structural-functionalneeds and habitat conditions
1 Present Address: Department of Biology, Syracuse University,Syracuse, New York 13210, U.S.A.
2 Present Address: Department of Zoology, Miami University,Oxford, Ohio 45056, U.S.A. (Received 5 December 1978; 相似文献
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JAMES K. WHEELER BRETT A. HUGGETT ALENA N. TOFTE FULTON E. ROCKWELL N. MICHELE HOLBROOK 《Plant, cell & environment》2013,36(11):1938-1949
We investigated the common assumption that severing stems and petioles under water preserves the hydraulic continuity in the xylem conduits opened by the cut when the xylem is under tension. In red maple and white ash, higher percent loss of conductivity (PLC) in the afternoon occurred when the measurement segment was excised under water at native xylem tensions, but not when xylem tensions were relaxed prior to sample excision. Bench drying vulnerability curves in which measurement samples were excised at native versus relaxed tensions showed a dramatic effect of cutting under tension in red maple, a moderate effect in sugar maple, and no effect in paper birch. We also found that air injection of cut branches (red and sugar maple) at pressures of 0.1 and 1.0 MPa resulted in PLC greater than predicted from vulnerability curves for samples cut 2 min after depressurization, with PLC returning to expected levels for samples cut after 75 min. These results suggest that sampling methods can generate PLC patterns indicative of repair under tension by inducing a degree of embolism that is itself a function of xylem tensions or supersaturation of dissolved gases (air injection) at the moment of sample excision. Implications for assessing vulnerability to cavitation and levels of embolism under field conditions are discussed. 相似文献
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MARIA RENÉE ORELLANA JORDI LÓPEZ-PUJOL CÈSAR BLANCHÉ MARIA BOSCH 《Biological journal of the Linnean Society. Linnean Society of London》2007,92(4):773-784
Allozyme diversity was evaluated in four closely-related taxa of the Delphinium series Fissa distributed throughout the Western Mediterranean area. All are considered threatened plants. Delphinium bolosii and Delphinium mansanetianum are narrowly endemic to the Eastern Iberian Peninsula, whereas Delphinium fissum ssp. sordidum is found in a few populations across the Peninsula. Delphinium fissum ssp. fissum is more widely distributed but often in small and isolated populations. In this group, Delphinium bolosii is dysploid (2 n = 18) whereas the other taxa are diploid (2 n = 16). A total of 12 populations were surveyed, including all known locations for D. bolosii , D. mansanetianum , and D. fissum ssp. sordidum . Eleven enzyme systems were assayed and 15 loci were resolved. Markedly depauperate values for genetic diversity were obtained for D. mansanetianum ( H e = 0.013) and D. fissum ssp. sordidum ( H e = 0.044). The estimates for D. fissum ssp. fissum ( H e = 0.071) were below the values expected for widespread species. Small population size and marginal distribution have probably contributed to the low variability observed in this group. By contrast, D. bolosii exhibited comparatively larger populations and greater genetic diversity ( H e = 0.138). We suggest that, apart from population size and local adaptation, genetic diversity during speciation may have been promoted by dysploidy through genomic recombination. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 773–784. 相似文献
5.
The constructs of atypical depression, bipolar II disorder and borderline
personality disorder (BPD) overlap. We explored the relationships between
these constructs and their temperamental underpinnings. We examined 107 consecutive
patients who met DSM-IV criteria for major depressive episode with atypical
features. Those who also met the DSM-IV criteria for BPD (BPD+), compared
with those who did not (BPD-), had a significantly higher lifetime comorbidity
for body dysmorphic disorder, bulimia nervosa, narcissistic, dependent and
avoidant personality disorders, and cyclothymia. BPD+ also scored higher on
the Atypical Depression Diagnostic Scale items of mood reactivity, interpersonal
sensitivity, functional impairment, avoidance of relationships, other rejection
avoidance, and on the Hopkins Symptoms Check List obsessive-compulsive, interpersonal
sensitivity, anxiety, anger-hostility, paranoid ideation and psychoticism
factors. Logistic regression revealed that cyclothymic temperament accounted
for much of the relationship between atypical depression and BPD, predicting
6 of 9 of the defining DSM-IV attributes of the latter. Trait mood lability
(among BPD patients) and interpersonal sensitivity (among atypical depressive
patients) appear to be related as part of an underlying cyclothymic temperamental
matrix. 相似文献
6.
SANTIAGO ANDRÉS CATALANO JUAN CÉSAR VILARDI DANIELA TOSTO BEATRIZ OFELIA SAIDMAN 《Biological journal of the Linnean Society. Linnean Society of London》2008,93(3):621-640
The genus Prosopis is an important member of arid and semiarid environments around the world. To study Prosopis diversification and evolution, a combined approach including molecular phylogeny, molecular dating, and character optimization analysis was applied. Phylogenetic relationships were inferred from five different molecular markers ( mat K- trn K, trn L- trn F, trn S- psb C, G3pdh, NIA). Taxon sampling involved a total of 30 Prosopis species that represented all Sections and Series and the complete geographical range of the genus. The results suggest that Prosopis is not a natural group. Molecular dating analysis indicates that the divergence between Section Strombocarpa and Section Algarobia plus Section Monilicarpa occurred in the Oligocene, contrasting with a much recent diversification (Late Miocene) within each of these groups. The diversification of the group formed by species of Series Chilenses, Pallidae, and Ruscifoliae is inferred to have started in the Pliocene, showing a high diversification rate. The moment of diversification within the major lineages of American species of Prosopis is coincident with the spreading of arid areas in the Americas, suggesting a climatic control for diversification of the group. Optimization of habitat parameters suggests an ancient occupation of arid environments by Prosopis species. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 621–640. 相似文献
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PETER L. BORDI JR. DANIELLE M. HACK SUSAN J. COCCI MICHELE D. RAGER S. WILLIAM HESSERT JR. 《Journal of sensory studies》2009,24(1):41-57
This is an initiative study on the use of trans -fat-free products in the bakery industry. A standardized doughnut product was cooked in three doughnut shortenings, one containing trans fat and two that were trans fat-free. Six hundred forty-one panelists, students, faculty and staff of a large northeastern university rated each of the three doughnuts on a variety of categories, including texture, moisture content and overall liking. Results showed that there were no significant differences between doughnuts cooked in the three shortenings – this was true for all attributes tested.
The results from this study have many significant implications for the foodservice industry, as they work to cut down or eliminate the use of trans fats in their establishments because of the significant health risks they have been proven to cause.
This study demonstrates the variances on texture, taste, appearance and overall liking characteristics of doughnuts fried in different doughnut shortenings. The nutritional breakdown of the doughnuts and the shortenings are also addressed. In the case of shortenings, the ideal type of fat is a mixture of canola, soybean and hydrogenated cottonseed. This shortening mixture, which is trans fat-free, produced the most preferred doughnut. 相似文献
The results from this study have many significant implications for the foodservice industry, as they work to cut down or eliminate the use of trans fats in their establishments because of the significant health risks they have been proven to cause.
PRACTICAL APPLICATIONS
This study demonstrates the variances on texture, taste, appearance and overall liking characteristics of doughnuts fried in different doughnut shortenings. The nutritional breakdown of the doughnuts and the shortenings are also addressed. In the case of shortenings, the ideal type of fat is a mixture of canola, soybean and hydrogenated cottonseed. This shortening mixture, which is trans fat-free, produced the most preferred doughnut. 相似文献