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981.
C.H.陈 《国外科技新书评介》2006,(12):11-12
本书的第一、二、三版分别于1993、1999和2005年出版。书中全面提供了过去20年中在模式识别与计算机视觉领域中的进展和成就,作者都是这个领域的第一流专家,其中的两位Thomas Huang和Jake Aggarwal是权威的K.S.Fu奖金获得者,该项奖金是由国际模式识别协会(IAPR)授予。 相似文献
982.
J C Chabala V B Waits T Ikeler A A Patchett L Payne L H Peterson R A Reamer K Hoogsteen M Wyvratt W L Hanson 《Experientia》1991,47(1):51-53
1-(Substituted)benzyl-5-aminoimidazole-4-carboxamides are potent orally active inhibitors of Trypanosoma cruzi infections in mice. The most active compounds are the 1-(4-chlorobenzyl)- and 1-(3,4-dichlorobenzyl)-analogs (L-153,094 [2] and L-153,153 [4], resp.) which are approximately 7-fold more potent upon oral administration than nifurtimox (Lampit) in suppressing parasite levels in the blood of mice with acute Trypanosoma cruzi infections. 相似文献
983.
1 .INTRODUCTIONTheabilityofpositioningmobileobjects (MOs) ,in cludingvehiclesandtravelersholdingmobiletermi nals,isafundamentalfunctionforsomeITSsubsys tems,suchasemergencyrescue,securitysystem ,au tomaticnavigationsystem ,andtrafficinducementsystem[1 ] .Atpresent,therearethreedominatingtypes[2 ]ofwirelesspositioningtechnologies,i.e.positioningbasedonsatellites,positioningbasedondedicatedcommunicationsystemsandpositioningbasedonpub liclandwirelesstelecommunicationsystems (PLMTS) ,respe… 相似文献
984.
985.
S. Benvenuti A. Gagliardo T. Guilford P. Luschi 《Cellular and molecular life sciences : CMLS》1996,52(6):608-612
In order to investigate the pigeon's compass mechanism, a series of overcast tests with clock-shifted birds were run at two familiar release sites. While controls were able to assume a correct homeward direction, the experimental birds' initial orientation cannot be explained either on the basis of a time-compensated sun compass or of a time-independent magnetic compass. Speculative explanations of our paradoxical results are attempted. 相似文献
986.
G. Odierna L. G. Badalucci S. M. Guarino C. Gambardella M. De Nicola 《Cellular and molecular life sciences : CMLS》1996,52(7):652-656
Two mediterranean populations ofIdotea baltica basteri from Messina and Naples showed a set of chromosomes composed by 58 all-biarmed chromosomes. The heterochromatin was located in the pericentromeric region of the chromosomes, and its composition appeared heterogeneous. In fact, not all the homologs showed heterochromatin resistant to digestion with three restriction enzymes (Alu I, Hae III and Sau 3A). Moreover, the two populations showed polymorphism in a band of G+C-rich telomeric heterochromatin, which was present only in the population from Messina. It is hypothesized that chromosomal polymorphism might reflect the geographical isolation of the two populations. It is also suggested that a process of diversification is taking place. 相似文献
987.
Sequence-directed curvature of DNA 总被引:42,自引:0,他引:42
P J Hagerman 《Nature》1986,321(6068):449-450
DNAs from both prokaryotic and eukaryotic organisms have yielded restriction fragments which manifest markedly anomalous electrophoretic behaviour (reduced mobility) when run on polyacrylamide gels. We have shown previously that the abnormal electrophoretic behaviour of one such fragment is a consequence of stable curvature of the helix axis in solution. The molecules involved tend to contain oligo(dA)-oligo(dT) runs which are approximately in-phase with the helix repeat; however, the precise structural elements responsible for DNA curvature have not been identified. One popular model for curvature invokes a non-coplanar 'wedge-like' conformation of ApA/TpT dinucleotide pairs. Despite a lack of direct evidence in support of this model, it has been used to provide quantitative estimates of curvature. To critically evaluate the ApA wedge model, we have performed an electrophoretic analysis of a series of closely related DNA polymers in which oligo(dA)-oligo(dT) runs of different polarity were compared. We conclude that ApA dinucleotide wedges cannot account for DNA curvature. Therefore, quantitative estimates for ApA wedge deformations, based solely on apparent curvature, cannot be correct. 相似文献
988.
989.
990.
High frequency of unequal recombination in pseudoautosomal region shown by proviral insertion in transgenic mouse 总被引:16,自引:0,他引:16
The mammalian X and Y chromosomes, in contrast to the autosomes, pair during male meiosis only near the telomeres. Alleles localized in this region can undergo reciprocal exchange during meiosis. Because such sequences do not show strict sex-linked inheritance, they have been termed pseudoautosomal. In man, several DNA sequences have been described which show pseudoautosomal transmission and which are localized in the pairing region at the ends of the short arms of both the X and Y chromosomes (refs 6-9, and D. Page, unpublished results). We now show that the transgenic mouse strain, Mov-15, contains a single Moloney murine leukaemia virus (M-MuLV) genome in its germline, and genetic evidence indicates that the provirus is integrated into the pseudoautosomal region of the sex chromosome. Proviral copies are lost or gained in 7% of male meioses in this strain, and mouse sequences flanking the provirus are tandemly repeated and highly variable. We conclude that unequal recombination events occur with high frequency in the pairing region, possibly because of the presence of repeated sequences. 相似文献