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101.
In addition to several anomalous structures, other general forms of definitely rod-shaped microorganisms have been found by scanning and transmission electron microscopy in the lung tissue taken at autopsy from a patient who succumbed to confirmed Legionnaires' disease with extensive necrotizing lobar pneumonia. The microorganisms were greatly varied in size and shape. They were micrographed in the act of fission. These forms have been found to some extent throughout the tissue. No nickel was demonstrated, either in the lung tissue or in the microorganisms. 相似文献
102.
S. A. Tanco N. V. Watson B. B. Gorzalka 《Cellular and molecular life sciences : CMLS》1993,49(3):238-241
Although 5-HT1 and 5-HT2 receptor activity is known to influence copulation, the effects of 5-HT3 receptor-selective drugs on sexual activity have yet to be systematically studied. The following experiments investigated the effects of the 5-HT3-selective antagonists MDL 72222, ondansetron and ICS 205-930 on female sexual behaviour; male rats were studied using ondansetron and granisetron. These compounds influenced neither male nor female copulatory behaviours, suggesting that 5-HT3 receptors contribute little to the modulation of sexual activity. 5-HT3 receptor antagonists block certain opioid-induced behaviours and opioids selectively inhibit sexual behaviours; therefore, the ability of ondansetron and ICS 205-930 to modify morphine-attenuated copulatory activity was also tested. While morphine inhibited copulation, 5-HT3 antagonists failed to reverse the effects. 相似文献
103.
A. Watson R. Moss R. Parr I. B. Trenholm A. Robertson 《Cellular and molecular life sciences : CMLS》1988,44(3):274-275
Summary This experiment tested whether a cyclic-type population decline can be prevented by removing territorial cock red grouse to keep breeding density below peak levels. The manipulated population did not decline, despite big decreases in food and breeding success, and more parasitic threadworms per bird than on the control. 相似文献
104.
105.
D. Watson 《Cellular and molecular life sciences : CMLS》1966,22(2):76-77
Zusammenfassung Es werden neue Beobachtungen über die Zweckmässigkeit derSakaguchi-Farbreaktion für Arginin mitgeteilt: Aminosäuren, die die Farbreaktion gewöhnlich hindern, wirken in niedriger Quantität (0,05 bis 0,2M) verstärkend. Histidin ergibt eine positiveSakaguchi-Reaktion. 相似文献
106.
The trophic fingerprint of marine fisheries 总被引:3,自引:0,他引:3
Branch TA Watson R Fulton EA Jennings S McGilliard CR Pablico GT Ricard D Tracey SR 《Nature》2010,468(7322):431-435
Biodiversity indicators provide a vital window on the state of the planet, guiding policy development and management. The most widely adopted marine indicator is mean trophic level (MTL) from catches, intended to detect shifts from high-trophic-level predators to low-trophic-level invertebrates and plankton-feeders. This indicator underpins reported trends in human impacts, declining when predators collapse ("fishing down marine food webs") and when low-trophic-level fisheries expand ("fishing through marine food webs"). The assumption is that catch MTL measures changes in ecosystem MTL and biodiversity. Here we combine model predictions with global assessments of MTL from catches, trawl surveys and fisheries stock assessments and find that catch MTL does not reliably predict changes in marine ecosystems. Instead, catch MTL trends often diverge from ecosystem MTL trends obtained from surveys and assessments. In contrast to previous findings of rapid declines in catch MTL, we observe recent increases in catch, survey and assessment MTL. However, catches from most trophic levels are rising, which can intensify fishery collapses even when MTL trends are stable or increasing. To detect fishing impacts on marine biodiversity, we recommend greater efforts to measure true abundance trends for marine species, especially those most vulnerable to fishing. 相似文献
107.
Amoretti M Amsler C Bonomi G Bouchta A Bowe P Carraro C Cesar CL Charlton M Collier MJ Doser M Filippini V Fine KS Fontana A Fujiwara MC Funakoshi R Genova P Hangst JS Hayano RS Holzscheiter MH Jørgensen LV Lagomarsino V Landua R Lindelöf D Lodi Rizzini E Macrì M Madsen N Manuzio G Marchesotti M Montagna P Pruys H Regenfus C Riedler P Rochet J Rotondi A Rouleau G Testera G Variola A Watson TL van der Werf DP;ATHENA Collaboration 《Nature》2002,419(6906):456-459
A theoretical underpinning of the standard model of fundamental particles and interactions is CPT invariance, which requires that the laws of physics be invariant under the combined discrete operations of charge conjugation, parity and time reversal. Antimatter, the existence of which was predicted by Dirac, can be used to test the CPT theorem-experimental investigations involving comparisons of particles with antiparticles are numerous. Cold atoms and anti-atoms, such as hydrogen and antihydrogen, could form the basis of a new precise test, as CPT invariance implies that they must have the same spectrum. Observations of antihydrogen in small quantities and at high energies have been reported at the European Organization for Nuclear Research (CERN) and at Fermilab, but these experiments were not suited to precision comparison measurements. Here we demonstrate the production of antihydrogen atoms at very low energy by mixing trapped antiprotons and positrons in a cryogenic environment. The neutral anti-atoms have been detected directly when they escape the trap and annihilate, producing a characteristic signature in an imaging particle detector. 相似文献
108.
109.
DNA-directed DNA polymerase activity in oncogenic RNA viruses 总被引:34,自引:0,他引:34
S Spiegelman A Burny M R Das J Keydar J Schlom M Travnicek K Watson 《Nature》1970,227(5262):1029-1031
110.
Oaks JL Gilbert M Virani MZ Watson RT Meteyer CU Rideout BA Shivaprasad HL Ahmed S Chaudhry MJ Arshad M Mahmood S Ali A Khan AA 《Nature》2004,427(6975):630-633