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101.
Riassunto L'iniezione ad animali normali di ARN estratto dalla milza di animali immunizzati con antigene H diS. typhi, provoca la comparsa, nel siero degli animali riceventi, di anticorpi diretti contro tale antigene. 相似文献
102.
Cassan A Kubas D Beaulieu JP Dominik M Horne K Greenhill J Wambsganss J Menzies J Williams A Jørgensen UG Udalski A Bennett DP Albrow MD Batista V Brillant S Caldwell JA Cole A Coutures Ch Cook KH Dieters S Prester DD Donatowicz J Fouqué P Hill K Kains N Kane S Marquette JB Martin R Pollard KR Sahu KC Vinter C Warren D Watson B Zub M Sumi T Szymański MK Kubiak M Poleski R Soszynski I Ulaczyk K Pietrzyński G Wyrzykowski L 《Nature》2012,481(7380):167-169
Most known extrasolar planets (exoplanets) have been discovered using the radial velocity or transit methods. Both are biased towards planets that are relatively close to their parent stars, and studies find that around 17-30% (refs 4, 5) of solar-like stars host a planet. Gravitational microlensing, on the other hand, probes planets that are further away from their stars. Recently, a population of planets that are unbound or very far from their stars was discovered by microlensing. These planets are at least as numerous as the stars in the Milky Way. Here we report a statistical analysis of microlensing data (gathered in 2002-07) that reveals the fraction of bound planets 0.5-10?AU (Sun-Earth distance) from their stars. We find that 17(+6)(-9)% of stars host Jupiter-mass planets (0.3-10?M(J), where M(J) = 318?M(⊕) and M(⊕) is Earth's mass). Cool Neptunes (10-30?M(⊕)) and super-Earths (5-10?M(⊕)) are even more common: their respective abundances per star are 52(+22)(-29)% and 62(+35)(-37)%. We conclude that stars are orbited by planets as a rule, rather than the exception. 相似文献
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104.
Vivek S. Peche Tad A. Holak Bhagyashri D. Burgute Kosmas Kosmas Sushant P. Kale F. Thomas Wunderlich Fatiha Elhamine Robert Stehle Gabriele Pfitzer Klaus Nohroudi Klaus Addicks Florian Stöckigt Jan W. Schrickel Julia Gallinger Michael Schleicher Angelika A. Noegel 《Cellular and molecular life sciences : CMLS》2017,74(21):4045-4045
105.
W. H. Gerwick Ch. Mrozek M. F. Moghaddam S. K. Agarwal 《Cellular and molecular life sciences : CMLS》1989,45(2):115-121
A Caribbean cyanobacterium,Hormothamnion enteromorphoides, was found to produce a complex mixture of ichthyotoxic peptides, perhaps explaining the apparent absence of predation upon these potentially palatable life forms. Bioassay-guided fractionation was used to isolate these toxic and antimicrobial natural products, and a variety of techniques including HR FAB mass spectrometry, 2D-NMR, traditional hydrolysis-amino acid analysis, and several chemical reactions were used to define the basic structural features of the major peptide, hormothamnin A. Hormothamnin A is a cyclic undecapeptide containing six common and five uncommon or new amino acid residues. HPLC analyses indicate that the relative proportions of these peptide natural products remain relatively constant between different collection locations and years, however, they do vary seasonally. Clonal isolates of this cyanobacterium in culture produce the full spectrum of toxic peptides. 相似文献
106.
Summary Furasterin, 4-chloro-7-hydroxy-5-methoxy-2-methyl-benzofuran, a new naturally occurring mono-chlorinated fungal metabolite was isolated fromPhialophora Asteris (Downson) Burge et Isaac. Its possible relationship with the biosynthetical pathway of the fungitoxic dichlorinated fungal metabolite cryptosporiopsin is discussed.This work was supported by a combined grant from the French C. N. R. S. and the Dutch foundation Z. W. O. 相似文献
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108.
Summary The octapeptide Val5-Angiotensin II-Asp1--amide is split into characteristic fragments by hydrogen peroxide, when complexed with Ni2+; this degradation does not occur with the Cu2+ complex, presumably because an active ternary peroxo complex cannot be formed. 相似文献
109.
Ch. Pilgrim 《Cellular and molecular life sciences : CMLS》1967,23(11):943-943
Summary In hypothalamic neurosecretory nuclei of rats subject to water withdrawl for 1–14 days, a marked increase in the activities of histochemically detected acid phosphatase, thiamine pyrophosphatase and glucose-6-phosphate dehydrogenase is observed. LDH and SDH activities do not change. Two different cell types can be distinguished by means of the acid phosphatase and TPPase reactions. 相似文献
110.