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121.
The boron isotope effect in ZrB(12) has been determined to be T(c) infinity M(alpha), where alpha is equal to - 0.09 +/- 0.05, M is the boron mass, and T(c) is the supercondiucting transition temperature. 相似文献
122.
Sex pheromone of the winter moth, a geometrid with unusually low temperature precopulatory responses
Roelofs WL Hill AS Linn CE Meinwald J Jain SC Herbert HJ Smith RF 《Science (New York, N.Y.)》1982,217(4560):657-659
The sex pheromone for the winter moth, Operophtera brumata (L.), has been identified as the novel compound (Z,Z,Z)-1,3,6,9-nonadecatetraene. The male moths respond to the pheromone at low temperatures (4 degrees to 15 degrees C) and exhibit an upper response limit that coincides with the lower response limit for other reported moth sex pheromone systems. The pheromone attracted two other geometrid species, O. bruceata (Bruce spanworm) and O. occidentalis. 相似文献
123.
Ellsworth WL Campbell RH Hill DP Page RA Alewine RW Hanks TC Heaton TH Hileman JA Kanamori H Minster B Whitcomb JH 《Science (New York, N.Y.)》1973,182(4117):1127-1129
Seismological investigations show that the Point Mugu earthquake involved north-south crustal shortening deep within the complex fault zone that marks the southern front of the Transverse Ranges province. This earthquake sequence results from the same stress system responsible for the deformation in this province in the Pliocene through Holocene and draws attention to the significant earthquake hazard that the southern frontal fault system poses to the Los Angeles metropolitan area. 相似文献
124.
Pyridoxol, one of the forms of vitamin B(6), is derived from three glycerol units. One of these is incorporated by way of pyruvate as a two-carbon fragment at the oxidation level of acetaldehyde. The other two glycerol units are incorporated intact, possibly by way of triose phosphate. 相似文献
125.
126.
Chien M Morozova I Shi S Sheng H Chen J Gomez SM Asamani G Hill K Nuara J Feder M Rineer J Greenberg JJ Steshenko V Park SH Zhao B Teplitskaya E Edwards JR Pampou S Georghiou A Chou IC Iannuccilli W Ulz ME Kim DH Geringer-Sameth A Goldsberry C Morozov P Fischer SG Segal G Qu X Rzhetsky A Zhang P Cayanis E De Jong PJ Ju J Kalachikov S Shuman HA Russo JJ 《Science (New York, N.Y.)》2004,305(5692):1966-1968
We present the genomic sequence of Legionella pneumophila, the bacterial agent of Legionnaires' disease, a potentially fatal pneumonia acquired from aerosolized contaminated fresh water. The genome includes a 45-kilobase pair element that can exist in chromosomal and episomal forms, selective expansions of important gene families, genes for unexpected metabolic pathways, and previously unknown candidate virulence determinants. We highlight the genes that may account for Legionella's ability to survive in protozoa, mammalian macrophages, and inhospitable environmental niches and that may define new therapeutic targets. 相似文献
127.
van Rooij E Sutherland LB Qi X Richardson JA Hill J Olson EN 《Science (New York, N.Y.)》2007,316(5824):575-579
The heart responds to diverse forms of stress by hypertrophic growth accompanied by fibrosis and eventual diminution of contractility, which results from down-regulation of alpha-myosin heavy chain (alphaMHC) and up-regulation of betaMHC, the primary contractile proteins of the heart. We found that a cardiac-specific microRNA (miR-208) encoded by an intron of the alphaMHC gene is required for cardiomyocyte hypertrophy, fibrosis, and expression of betaMHC in response to stress and hypothyroidism. Thus, the alphaMHC gene, in addition to encoding a major cardiac contractile protein, regulates cardiac growth and gene expression in response to stress and hormonal signaling through miR-208. 相似文献
128.
Understanding the fate and turnover of the pools that comprise dissolved organic nitrogen (DON) in soil is key to determining its role in ecosystem functioning. We investigated seasonal changes of dissolved organic carbon (DOC) and nitrogen (DON) concentrations within four molecular weight (MW) size fractions across an altitudinal gradient (from lowland to montane systems), and quantified individual amino acids and amino acid constituents of oligopeptidic-N, as well as nitrate and ammonium. We tested two ideas: first, that DON is more abundant than DIN in low-productivity relative to high-productivity grassland ecosystems; and second, that the abundance of peptides and amino acids is likewise greater in low- than high-productivity grassland. The most productive site had a history of inorganic fertiliser application, and hence in this site alone DIN was more abundant than DON. Plant productivity varied 3-fold between the other sites, and DON was generally at higher concentrations in the sites of lower productivity both in absolute terms as well as relative to DIN, with a large increase observed in spring. The fraction containing the highest concentration of the DON had a MW of >100 kDa, and in summer and autumn this fraction was more abundant at the lowest productivity site. We conclude that relationships between the abundance of DON relative to DIN and ecosystem productivity is dependent on season, and hence more complex than previously suggested, and that peptides are a dynamic and potentially nutritionally significant component of DON. 相似文献
129.
Paul A MorrisNicholas M Hill Edward G ReekieHeather L Hewlin 《Biological conservation》2002,106(1):79-90
Diversity patterns of riparian plant communities have been associated with disturbance. Populations of a diversity of Atlantic Coastal Plain plants occur as disjuncts on shores of large catchment area lakes in Nova Scotia. These lakeshore communities contain rare plants with local, national and global rankings. The populations of rare plants are dynamic and their management requires an understanding of the relationship between disturbance and the survival of rare plants. This present study measured (overwinter wooden dowel removal) and observed disturbance along gradients of catchment area (CA), exposure and depth. In three separate experiments ranging from the landscape to the lake, to the single shoreline level, disturbance was linked to lake CA, exposure and depth, respectively. At all scales, disturbance was positively associated with the presence of rare species. The pattern of rare species richness over the river system was complex; at the within-lake level, the frequency of rare species per site was greatest in the intermediate CA lake while the pool of rare species was greatest in the largest CA lake. The findings focus field efforts on wide, exposed shorelines of large CA lakes where new rare plants continue to be discovered. In addition, the discrepancy between highest frequency of rare plants on intermediate CA lakes and highest species pools of rarities on large CA lakes, reinforces the need for larger protected area systems for the most naturally disturbed ecosystems which often support populations having a high turnover rate but a low site to site frequency. 相似文献
130.