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排序方式: 共有143条查询结果,搜索用时 468 毫秒
41.
Maize HapMap2 identifies extant variation from a genome in flux 总被引:3,自引:0,他引:3
Chia JM Song C Bradbury PJ Costich D de Leon N Doebley J Elshire RJ Gaut B Geller L Glaubitz JC Gore M Guill KE Holland J Hufford MB Lai J Li M Liu X Lu Y McCombie R Nelson R Poland J Prasanna BM Pyhäjärvi T Rong T Sekhon RS Sun Q Tenaillon MI Tian F Wang J Xu X Zhang Z Kaeppler SM Ross-Ibarra J McMullen MD Buckler ES Zhang G Xu Y Ware D 《Nature genetics》2012,44(7):803-807
Whereas breeders have exploited diversity in maize for yield improvements, there has been limited progress in using beneficial alleles in undomesticated varieties. Characterizing standing variation in this complex genome has been challenging, with only a small fraction of it described to date. Using a population genetics scoring model, we identified 55 million SNPs in 103 lines across pre-domestication and domesticated Zea mays varieties, including a representative from the sister genus Tripsacum. We find that structural variations are pervasive in the Z. mays genome and are enriched at loci associated with important traits. By investigating the drivers of genome size variation, we find that the larger Tripsacum genome can be explained by transposable element abundance rather than an allopolyploid origin. In contrast, intraspecies genome size variation seems to be controlled by chromosomal knob content. There is tremendous overlap in key gene content in maize and Tripsacum, suggesting that adaptations from Tripsacum (for example, perennialism and frost and drought tolerance) can likely be integrated into maize. 相似文献
42.
The purpose of this paper is to simplify the computations of the nor-mal bordism groups Ω_i(W_f,M×P~∞;(?))and Ω_i(C_f,(?)w;θ_f)which Salomonsenand Dax introduced respectively to study the existence and isotopy classificationof differential embeddings of manifolds in manifolds in the metastable range.Asimpler space pair(K_f,M×P~∞)is constructed to replace(W_f,M×P~∞).It isshown that(K_f,M×P~∞)is homotopy equivalent to(W_f,M×P~∞)and homotopy(n-1)-equivalent to(C_f,(?)W).To demonstrate the efficacy of this simplification,the isotopy groups [M~n(?)RP~(n+k)],if n(?)2k-4 and M~n is a closed(n-k+2)-connected manifold,and[M~n(?)L(p;q_1…,q_m)],if 3n(?)4m-2,M~n is a closed(2n-2m+1)-connected manifold and L is a (2m+1)-dimensional lens space,arespecifically computed. 相似文献
43.
Prostatecancer (PC)hasthehighestmorbidityrateinmaleurinarysystemdisordersinEuropeandAmerica ,anditisoneoftheprimaryreasonsofmaledeath[1] .InChina ,althoughtheattackofPCisrela tivelylow ,ithasa growingtrendinrecent 10years[2— 4 ] .Inclinicalpractice ,magneticresonanceimaging (MRI)could providehighresolutionmor phologicalstructureandhasthecapabilityofmulti parameterimaging ,butitcannotreliablydifferentiatePCfrombenignprostatehyperplasia (BPH)andnor maltissues ,particularlyforthepatientswi… 相似文献
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45.
美國和西歐十六國(以及中國)簽訂的雙邊協定,是馬歇爾計劃結晶化的文件。馬歇爾計劃經過美國國會辯論成立法案以後,歐洲復興計劃(ERP)成爲各國內政的一部份,以霍夫曼為主持人的經濟合作總署(ECA)成為各國政府的最高監督。各受援國在經濟上成為美國公司的分公司,在政治上成為託管殖民地。這些雙邊協定是以華爾街的利益爲總方針的。美國避免和各受援國簽訂互有義務的多邊協定,正是為了避免造成集體的反對。個別的 相似文献
46.
Mammalian olfactory systems have extraordi- nary ability to sense and identify various trace odorants. Taking advantages of cell culture and micro-fabrication technologies, olfactory cell- or tissue-based biosensor represent a promising platform for in vitro odorant detec- tion. However, in vitro conditions lead to shortened cell/ tissue survivals, and the working life of neuron chips is short. The purpose of this study is to develop an in vivo recording and analyzing method for long-term and repeatable detection of odor stimulation. In this study, we implanted penetrating micro-wire array electrode into the olfactory bulb of conscious rats to obtain odor-evoked electrophysiological activities. Then, we investigated the response of ensembles of mitral/tufted cells to stimulation with carvone at a number of concentrations in time and frequency domains. The stable, repeatable odorant responses from up to 16 neural regions could be obtained for at least 3 weeks. Further, we explored the concentration detection sensitivity limitation of developed method, and found the detection low limit of carvone was below 10-a~ mol/L. The result demonstrates that the concentra- tion range of in vivo odorant detection method is much wider than in vitro method. 相似文献
47.
EXISTENCE OF AUTHENTICATION CODES 总被引:4,自引:0,他引:4
FENG Rong quan 《系统科学与复杂性》2000,(1)
1.IntroductionLetS,e,andMbethreenon--emptysetsandletf:Sxe-- Mbeamap;thefourtuple(S,E,M;f)iscalledanauthenticationcoded],if1)Themapf:Sxe-Missurjectiveand2)ForanymEMandeEE,ifthereisansESsatisfyingf(s,e)=m,thensuchansisuniquelydeterminedbythegivenmande... 相似文献
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49.
Herein, a multi-index analysis of the nickel content of an alloy, output rate of the alloy, nickel recovery rate, and iron recovery rate during the melting of laterite metallized pellets was performed. The thermodynamic reduction behavior of oxides such as NiO, FeO, Fe3O4, and Cr2O3 was studied using the FactSage software, which revealed that SiO2 is not conducive to the reduction of iron oxides, whereas the addition of basic oxides such as CaO and MgO is beneficial for the reduction of iron oxides. On the basis of a comprehensive analysis to achieve greater nickel recovery and lower iron recovery rates, the optimum experimental parameters in the orthogonal experiment were A3B1C3 (t=30 min, C/O=0.4, R=1.2); the indicators wNi, φalloy, ηNi, and ηFe had values of 15.0wt%, 12.1%, 44.9%, and 96.4%, respectively. In single-factor experiments, increasing basicity (R) substantially improved the separation effect in the low-basicity range 0.5 ≤ R ≤ 0.8 but not in the high-basicity range 0.8 ≤ R ≤ 1.2. Similar results were obtained for the effect of the C/O ratio. Moreover, the recovery rate of nickel increased with increasing recovery rate of iron. 相似文献
50.
ZHOU Chong LU Yansheng ZOU Lei HU Rong 《武汉大学学报:自然科学英文版》2006,11(5):1345-1351
Most of the existing text clustering algorithms overlook the fact that one document is a word sequence with semantic information. There is some important semantic information existed in the positions of words in the sequence. In this paper, a novel method named Frequent Itemset-based Clustering with Window (FICW) was proposed, which makes use of the semantic information for text clustering with a window constraint. The experimental results obtained from tests on three (hypertext) text sets show that FICW outperforms the method compared in both clustering accuracy and efficiency. 相似文献