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61.
Violina A. Cocalia John D. Holbrey Keith E. Gutowski Nicholas J. Bridges Robin D. Rogers 《清华大学学报》2006,11(2):188-193
Introduction Ionic liquids (ILs) are proving to be increasingly inter-esting fluids for application in soft-matter materialssystems from electrochemistry to energetic materialsand are also studied as potential solvents in separationprocesses[1-19]. Proper… 相似文献
62.
BINOCULAR stereopsis provides information about the relative distance of objects from the differences in the horizontal position of their images on the two retinas. Because the size of the disparity between two points is inversely related to the square of the viewing distance, it is usually assumed that disparities have to be scaled according to distance using the vergence angle of the eyes, or by using the small vertical disparities that also exist between corresponding points of the two images. Here we present evidence that the visual system could extract information about the shapes of surfaces (without the need for scaling) by using the second spatial derivative of disparity--disparity curvature--which remains invariant with viewing distance. Rather than computing the second derivative, we suggest that an approximation to disparity curvature could be derived from the differences in curvature of corresponding line elements in the two eyes. 相似文献
63.
Vaccination with purified microgamete antigens prevents transmission of rodent malaria 总被引:2,自引:0,他引:2
Malaria vaccination with preparations of microgametes has been shown to inhibit transmission of Plasmodium spp. to the mosquito vectors of avian, rodent and simian parasites. This transmission-blocking immunity results from the induction of microgamete-agglutinating antibodies in the vaccinated host which, when ingested in a mosquito blood meal, react with exflagellating microgametes in the midgut to prevent fertilization and oocyst development. Here we have passively transferred the immunity with gamete-specific monoclonal antibodies raised against the rodent malaria parasite Plasmodium yoelii nigeriensis, and an IgG2a isotype monoclonal antibody from a hybridoma cell line, PYG-1, has been used to identify the target antigens on the gametes and to affinity-purify sufficient quantities of specific gamete antigen to facilitate vaccination studies. This transmission-blocking monoclonal antibody immunoprecipitated microgamete antigens of apparent relative molecular mass (Mr), 67K (67,000), 59K, 57K, 42K and 35K. Immunization of mice with these proteins before infection and mosquito feeding led to a 85-99.7% reduction in transmission to the mosquito vector; vaccination via intravenous or intramuscular routes was equally effective and did not require an adjuvant. 相似文献
64.
Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Fifteen genera representing nine families of spiders were collected in the southwestern United States in 1980. Thomisidae, Araneidae, Dictynidae, and Salticidae were the most commonly collected spider families. Ten genera of spiders not previously reported on sunflowers are reported for the first time. 相似文献
65.
We investigated ecology of flannelmouth sucker ( Catostomus latipinnis ) from 1992 to 1997 in the 26-km Lee's Ferry reach of the Colorado River immediately below Glen Canyon Dam, Arizona. We captured by electrofishing a total of 212 fish and recaptured 52 previously tagged by others. Flannelmouth sucker were captured throughout the tailwater but tended to aggregate about 5 km of the dam, possibly reflecting blockage of historic migration routes. Catch per hour of electrofishing did not differ among years but was greater from November to February than other periods, suggesting seasonal movements of flannelmouth sucker into the tailwater: Mean lengths and weights of fish did not differ among years or seasons. Length frequency analyses also indicated there were no significantly yearly trends in proportion of catch within size classes of fish. Mean condition differed only among seasons and was greatest in February, lowest in August, coinciding respectively with pre- and post-spawning periods of flannelmouth sucker in tributary just down from Lee's Ferry. Recaptured fish migrated from initial tagging locations 1.4-23.1 km downstream from Lee's Ferry. Fifty-nine percent of recaptured fish with known initial tagging locations increased in length, and fish tagged initially as subadults or adults, respectively, grew an average of 45.9 mm and 5.5 mm per year. 相似文献
66.
Observations of the 21-centimetre line of atomic hydrogen in the early Universe directly probe the history of the reionization of the gas between galaxies. The observations are challenging, though, because of the low expected signal strength (~10?mK), and contamination by strong (>100?K) foreground synchrotron emission in the Milky Way and extragalactic continuum sources. If reionization happened rapidly, there should be a characteristic signature visible against the smooth foreground in an all-sky spectrum. Here we report an all-sky spectrum between 100 and 200?MHz, corresponding to the redshift range 6?相似文献
67.
Two Earth-sized planets orbiting Kepler-20 总被引:1,自引:0,他引:1
Fressin F Torres G Rowe JF Charbonneau D Rogers LA Ballard S Batalha NM Borucki WJ Bryson ST Buchhave LA Ciardi DR Désert JM Dressing CD Fabrycky DC Ford EB Gautier TN Henze CE Holman MJ Howard A Howell SB Jenkins JM Koch DG Latham DW Lissauer JJ Marcy GW Quinn SN Ragozzine D Sasselov DD Seager S Barclay T Mullally F Seader SE Still M Twicken JD Thompson SE Uddin K 《Nature》2012,482(7384):195-198
Since the discovery of the first extrasolar giant planets around Sun-like stars, evolving observational capabilities have brought us closer to the detection of true Earth analogues. The size of an exoplanet can be determined when it periodically passes in front of (transits) its parent star, causing a decrease in starlight proportional to its radius. The smallest exoplanet hitherto discovered has a radius 1.42 times that of the Earth's radius (R(⊕)), and hence has 2.9 times its volume. Here we report the discovery of two planets, one Earth-sized (1.03R(⊕)) and the other smaller than the Earth (0.87R(⊕)), orbiting the star Kepler-20, which is already known to host three other, larger, transiting planets. The gravitational pull of the new planets on the parent star is too small to measure with current instrumentation. We apply a statistical method to show that the likelihood of the planetary interpretation of the transit signals is more than three orders of magnitude larger than that of the alternative hypothesis that the signals result from an eclipsing binary star. Theoretical considerations imply that these planets are rocky, with a composition of iron and silicate. The outer planet could have developed a thick water vapour atmosphere. 相似文献
68.
69.
H. J. Rogers 《Cellular and molecular life sciences : CMLS》1972,28(4):435-437
Zusammenfassung Es wird gezeigt, dass Chlorpromazin keine Veränderung der Konzentration von Aminosäuren erzeugt, wohl aber die Inkorporation des Isotopen14C-Glukose im säurelöslichen Anteil des Mäusegehirns temperaturabhängig vermehrt.
Governors' Research Scholar, Guy's Hospital Medical School. 相似文献
Governors' Research Scholar, Guy's Hospital Medical School. 相似文献
70.
Summary Several N-1-alkyl-, 3-, and 4-carbamidopyridinium halides were synthesized and determined to be inhibitors of mitochondrial oxidative phosphorylation. L-Glutamate respiration was most depressed by N-1-dodecylpyridinium bromide whereas succinate respiration was most depressed by N-1-dodecylisonicotinamide bromide. Combination of inhibitors with mitochondrial sites may involve lipophilic interactions as modified by steric restrictions. 相似文献