Control of Cracking of Fruit by Rain     

Powers WL  Bollen WB 《Science (New York, N.Y.)》1947,105(2726):334-335

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EVIDENCES OF AQUATIC LIFE FROM THE GLENWOOD STAGE OF LAKE CHICAGO     

Ball JR  Powers WE 《Science (New York, N.Y.)》1929,70(1812):284

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THE FUNDAMENTALS OF SALMON CONSERVATION     

Powers EB 《Science (New York, N.Y.)》1943,97(2515):242-243

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泸州荔枝果园AM真菌菌根及孢子数量调查与分析   总被引：1，自引：0，他引：1  

姜国金  许兰珍  杨晓红  王容春  朱邦松 《安徽农业科学》2007,35(22):6701-6702

[目的]对泸州荔枝园AM真菌进行调查,确认荔枝菌根类型,了解果园土壤中AM真菌孢子种群数量的大致情况。[方法]利用"湿筛法"和Phllips&Hayman的方法对3个泸州荔枝果园春季的土壤AM真菌进行了调查分析。[结果]荔枝菌根是内生菌根,共生真菌为囊泡——丛枝菌根真菌,即AM真菌。春季的菌根感染率在9%~32%之间,普遍低于25%。VA菌根感染率的平均值在15%~21%之间,低于25%。三个荔枝园每25 g土样中AM真菌孢子数平均值为869±76个。[结论]果园生草或对果园进行有机覆盖,是促进荔枝生长,增加荔枝果实产量,改善荔枝果实品质的一种绿色环保途径。  相似文献   

Hemoglobin adaptation for fast and slow water habitats in sympatric catostomid fishes   总被引：1，自引：0，他引：1  

D A Powers 《Science (New York, N.Y.)》1972,177(46):360-362

The oxygen equilibria of Catostomus insignis hemoglobins are pH dependent. Catostomus clarkii hemoglobins have some components (20 percent) whose oxygen equilibria are independent of pH because the alpha chains have NH(2)-termini that are blocked and the beta chains lack the "usual" COOH-terminal histidine. Since the Bohr effect is normally a beneficial phenomenon, the maintenance of some hemoglobins without a Bohr effect must provide a physiological advantage that is habitat specific. The intrastream ecological preferences of these sympatric catostomids suggest that the hemoglobins without the Bohr effect confer an ecological advantage in a swift water habitat.  相似文献   

Rain-Making     

Powers E 《Science (New York, N.Y.)》1891,18(453):205-206

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Regulation of yeast replicative life span by TOR and Sch9 in response to nutrients   总被引：1，自引：0，他引：1  

Kaeberlein M  Powers RW  Steffen KK  Westman EA  Hu D  Dang N  Kerr EO  Kirkland KT  Fields S  Kennedy BK 《Science (New York, N.Y.)》2005,310(5751):1193-1196

Calorie restriction increases life span in many organisms, including the budding yeast Saccharomyces cerevisiae. From a large-scale analysis of 564 single-gene-deletion strains of yeast, we identified 10 gene deletions that increase replicative life span. Six of these correspond to genes encoding components of the nutrient-responsive TOR and Sch9 pathways. Calorie restriction of tor1D or sch9D cells failed to further increase life span and, like calorie restriction, deletion of either SCH9 or TOR1 increased life span independent of the Sir2 histone deacetylase. We propose that the TOR and Sch9 kinases define a primary conduit through which excess nutrient intake limits longevity in yeast.  相似文献   

Local Control of Microdomain Orientation in Diblock Copolymer Thin Films with Electric Fields     

TL Morkved  M Lu  AM Urbas  EE Ehrichs  HM Jaeger  P Mansky  TP Russell 《Science (New York, N.Y.)》1996,273(5277):931-933

Local control of the domain orientation in diblock copolymer thin films can be obtained by the application of electric fields on micrometer-length scales. Thin films of an asymmetric polystyrene-polymethylmethacrylate diblock copolymer, with cylindrical polymethylmethacrylate microdomains, were spin-coated onto substrates previously patterned with planar electrodes. The substrates, 100-nanometer-thick silicon nitride membranes, allow direct observation of the electrodes and the copolymer domain structure by transmission electron microscopy. The cylinders aligned parallel to the electric field lines for fields exceeding 30 kilovolts per centimeter, after annealing at 250°C in an inert atmosphere for 24 hours. This technique could find application in nanostructure fabrication.  相似文献   

Interference and forgetting in bird and fish     

E R Behrend  A S Powers  M E Bitterman 《Science (New York, N.Y.)》1970,167(917):389-390

Retention in the pigeon and in the goldfish was measured 1 day or 2 weeks after the mastery of each of a series of color discrimination. The amount of forgetting in the pigeon increased with the number of prior problems and increased more rapidly at the longer than at the shorter interval. the amount of forgetting in the goldfish was independent, at both intervals, of the number of prior problems. These results point to the operation of different memory mechanisms in the two animals.  相似文献   

THE SPAWNING MIGRATION OF THE SALMON     

Powers EB 《Science (New York, N.Y.)》1940,92(2390):353-354

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