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排序方式: 共有68条查询结果,搜索用时 31 毫秒
31.
32.
S. Dijkgraaf 《Cellular and molecular life sciences : CMLS》1955,11(8):330-331
Summary The sounds produced by the Spiny Lobster,Palinurus vulgaris, and their origin are briefly described. One animal reacted clearly to similar artificial sound stimuli, in some cases even vocally. Elimination of both statocysts had no influence on these reactions. 相似文献
33.
S. Dijkgraaf 《Cellular and molecular life sciences : CMLS》1963,19(1):29-30
Zusammenfassung Intakte Exemplare vonSepia officinalis zeigen nach Drehung um alle drei Hauptachsen Augen- und Kopfbewegungen vom Typus des «Nach-Nystagmus». Diese postrotatorischen Reflexe können nicht optisch ausgelöst sein; sie beweisen vielmehr das Vorhandensein eines echten Rotationssinnes. Es wird angenommen, dass dieser auch hier seinen Sitz in den Statocysten mit ihren hochdifferenzierten Cristae hat. 相似文献
34.
When a female is sexually promiscuous, the ejaculates of different males compete for the fertilization of her eggs; the more sperm a male inseminates into a female, the more likely he is to fertilize her eggs. Because sperm production is limited and costly, theory predicts that males will strategically allocate sperm (1) according to female promiscuity, (2) saving some for copulations with new females, and (3) to females producing more and/or better offspring. Whether males allocate sperm in all of these ways is not known, particularly in birds where the collection of natural ejaculates only recently became possible. Here we demonstrate male sperm allocation of unprecedented sophistication in the fowl Gallus gallus. Males show status-dependent sperm investment in females according to the level of female promiscuity; they progressively reduce sperm investment in a particular female but, on encountering a new female, instantaneously increase their sperm investment; and they preferentially allocate sperm to females with large sexual ornaments signalling superior maternal investment. Our results indicate that female promiscuity leads to the evolution of sophisticated male sexual behaviour. 相似文献
35.
Schnadt J Brühwiler PA Patthey L O'Shea JN Södergren S Odelius M Ahuja R Karis O Bässler M Persson P Siegbahn H Lunell S Mårtensson N 《Nature》2002,418(6898):620-623
The ultrafast timescale of electron transfer processes is crucial to their role in many biological systems and technological devices. In dye-sensitized solar cells, the electron transfer from photo-excited dye molecules to nanostructured semiconductor substrates needs to be sufficiently fast to compete effectively against loss processes and thus achieve high solar energy conversion efficiencies. Time-resolved laser techniques indicate an upper limit of 20 to 100 femtoseconds for the time needed to inject an electron from a dye into a semiconductor, which corresponds to the timescale on which competing processes such as charge redistribution and intramolecular thermalization of excited states occur. Here we use resonant photoemission spectroscopy, which has previously been used to monitor electron transfer in simple systems with an order-of-magnitude improvement in time resolution, to show that electron transfer from an aromatic adsorbate to a TiO(2) semiconductor surface can occur in less than 3 fs. These results directly confirm that electronic coupling of the aromatic molecule to its substrate is sufficiently strong to suppress competing processes. 相似文献
36.
Cichon S Buervenich S Kirov G Akula N Dimitrova A Green E Schumacher J Klopp N Becker T Ohlraun S Schulze TG Tullius M Gross MM Jones L Krastev S Nikolov I Hamshere M Jones I Czerski PM Leszczynska-Rodziewicz A Kapelski P Bogaert AV Illig T Hauser J Maier W Berrettini W Byerley W Coryell W Gershon ES Kelsoe JR McInnis MG Murphy DL Nurnberger JI Reich T Scheftner W O'Donovan MC Propping P Owen MJ Rietschel M Nöthen MM McMahon FJ Craddock N 《Nature genetics》2004,36(8):783-4; author reply 784-5
37.
Although the El Ni?o/Southern Oscillation phenomenon is the most prominent mode of climate variability and affects weather and climate in large parts of the world, its effects on Europe and the high-latitude stratosphere are controversial. Using historical observations and reconstruction techniques, we analyse the anomalous state of the troposphere and stratosphere in the Northern Hemisphere from 1940 to 1942 that occurred during a strong and long-lasting El Ni?o event. Exceptionally low surface temperatures in Europe and the north Pacific Ocean coincided with high temperatures in Alaska. In the lower stratosphere, our reconstructions show high temperatures over northern Eurasia and the north Pacific Ocean, and a weak polar vortex. In addition, there is observational evidence for frequent stratospheric warmings and high column ozone at Arctic and mid-latitude sites. We compare our historical data for the period 1940-42 with more recent data and a 650-year climate model simulation. We conclude that the observed anomalies constitute a recurring extreme state of the global troposphere-stratosphere system in northern winter that is related to strong El Ni?o events. 相似文献
38.
KU Ludwig E Mangold S Herms S Nowak H Reutter A Paul J Becker R Herberz T Alchawa E Nasser AC Böhmer M Mattheisen MA Alblas S Barth N Kluck C Lauster B Braumann RH Reich A Hemprich S Pötzsch B Blaumeiser N Daratsianos T Kreusch JC Murray ML Marazita I Ruczinski AF Scott TH Beaty FJ Kramer TF Wienker RP Steegers-Theunissen M Rubini PA Mossey P Hoffmann C Lange S Cichon P Propping M Knapp MM Nöthen 《Nature genetics》2012,44(9):968-971
We have conducted the first meta-analyses for nonsyndromic cleft lip with or without cleft palate (NSCL/P) using data from the two largest genome-wide association studies published to date. We confirmed associations with all previously identified loci and identified six additional susceptibility regions (1p36, 2p21, 3p11.1, 8q21.3, 13q31.1 and 15q22). Analysis of phenotypic variability identified the first specific genetic risk factor for NSCLP (nonsyndromic cleft lip plus palate) (rs8001641; P(NSCLP) = 6.51 × 10(-11); homozygote relative risk = 2.41, 95% confidence interval (CI) 1.84-3.16). 相似文献
39.
Weedon MN Lango H Lindgren CM Wallace C Evans DM Mangino M Freathy RM Perry JR Stevens S Hall AS Samani NJ Shields B Prokopenko I Farrall M Dominiczak A;Diabetes Genetics Initiative;Wellcome Trust Case Control Consortium Johnson T Bergmann S Beckmann JS Vollenweider P Waterworth DM Mooser V Palmer CN Morris AD Ouwehand WH;Cambridge GEM Consortium Zhao JH Li S Loos RJ Barroso I Deloukas P Sandhu MS Wheeler E Soranzo N Inouye M Wareham NJ Caulfield M Munroe PB Hattersley AT McCarthy MI Frayling TM 《Nature genetics》2008,40(5):575-583
Adult height is a model polygenic trait, but there has been limited success in identifying the genes underlying its normal variation. To identify genetic variants influencing adult human height, we used genome-wide association data from 13,665 individuals and genotyped 39 variants in an additional 16,482 samples. We identified 20 variants associated with adult height (P < 5 x 10(-7), with 10 reaching P < 1 x 10(-10)). Combined, the 20 SNPs explain approximately 3% of height variation, with a approximately 5 cm difference between the 6.2% of people with 17 or fewer 'tall' alleles compared to the 5.5% with 27 or more 'tall' alleles. The loci we identified implicate genes in Hedgehog signaling (IHH, HHIP, PTCH1), extracellular matrix (EFEMP1, ADAMTSL3, ACAN) and cancer (CDK6, HMGA2, DLEU7) pathways, and provide new insights into human growth and developmental processes. Finally, our results provide insights into the genetic architecture of a classic quantitative trait. 相似文献
40.
Thilo Bartolm?s Caroline Hirschfeld-Ihlow Sven Jonas Michael Schaefer Reinhard Ge?ner 《Cellular and molecular life sciences : CMLS》2012,69(22):3851-3862
LI-cadherin belongs to the family of 7D-cadherins that is characterized by a low sequence similarity to classical cadherins, seven extracellular cadherin repeats (ECs), and a short cytoplasmic domain. Nevertheless, LI-cadherins mediates Ca2+-dependent cell–cell adhesion and induces an epitheloid cellular phenotype in non-polarized CHO cells. Whereas several studies suggest that classical cadherins cis-dimerize in a Ca2+-dependent manner and interact in trans by strand-swapping tryptophan 2 of EC1, little is known about the molecular interactions of LI-cadherin, which lacks tryptophan 2. We thus expressed fluorescent LI-cadherin fusion proteins in HEK293 and CHO cells, analyzed their cell–cell adhesive properties and studied their cellular distribution, cis-interaction, and lateral diffusion in the presence and absence of Ca2+. LI-cadherin highly concentrates in cell contact areas but rapidly leaves those sites upon Ca2+ depletion and redistributes evenly on the cell surface, indicating that it is only kept in the contact areas by trans-interactions. Fluorescence resonance energy transfer analysis of LI-cadherin-CFP and -YFP revealed that LI-cadherin forms cis-dimers that resist Ca2+ depletion. As determined by fluorescence redistribution after photobleaching, LI-cadherin freely diffuses in the plasma membrane as a cis-dimer (D?=?0.42?±?0.03?μm2/s). When trapped by trans-binding in cell contact areas, its diffusion coefficient decreases only threefold to D?=?0.12?±?0.01?μm2/s, revealing that, in contrast to classical and desmosomal cadherins, trans-contacts formed by LI-cadherin are highly dynamic. 相似文献