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排序方式: 共有106条查询结果,搜索用时 31 毫秒
31.
Anat Fischer Itzhak Gilboa Moshe Shpitalni 《Journal of Algorithms in Cognition, Informatics and Logic》1992,13(4)
The following problem arises in the context of object representation: given two endpoints of an interval in a Gray code table, find a Boolean function in DNF that represents this interval, with as few prime implicants as possible. This paper shows that there is a unique minimal representation and presents a polynomial algorithm that finds it. 相似文献
32.
扫描电镜对胆色素结石溶解前后的微观结构观察及元素检测 总被引:1,自引:1,他引:0
本实验用JEM-1200EX/S扫描电镜观察了溶解前后20例胆色素结石的微观结构,并对所含元素作了检测和比较。结果表明:胆色素结石及其难溶组分中主要有12种元素,钙含量最高,这说明元素钙在胆色素结石的成石过程中起了重要作用。 相似文献
33.
808 nm近红外激光辐照三种不同的离体人组织的光传输特性 总被引:3,自引:1,他引:2
采用双积分球系统和光辐射测量技术的基本原理以及运用生物组织的光学模型 ,研究了 80 8nm激光及其线偏振激光辐照人正常小肠、人正常膀胱和人膀胱癌组织的光学特性。结果表明 ,Kubelka Munk二流模型下 ,人正常膀胱组织与人膀胱癌组织对 80 8nm激光及其线偏振激光的各个光学特性参量均有非常显著的差异 (P <0 0 1)。人正常膀胱组织对 80 8nm激光及其线偏振激光的光学特性参量均有差异 ,其中吸收系数和有效衰减系数有明显差异。人膀胱癌组织对 80 8nm激光及其线偏振激光的光学特性参量均没有显著性差异 (P >0 0 5 ) ,表明人膀胱癌组织对 80 8nm线偏振激光的退偏振较大。人正常小肠组织对 80 8nm激光及其线偏振激光的光学特性参量均有显著性差异 (P <0 0 1) ,表明人正常小肠组织对 80 8nm线偏振激光的退偏振较小。在Kubelka Munk二流模型下 ,80 8nm激光及其线偏振激光辐照三种人组织的光强分布均有明显的不同 相似文献
34.
Anat Reiner-Benaim 《Methodology and Computing in Applied Probability》2016,18(3):717-745
A scan statistic is examined for the purpose of testing the existence of a global peak in a random process with dependent variables of any distribution. The scan statistic tail probability is obtained based on the covariance of the moving sums process, thereby accounting for the spatial nature of the data as well as the size of the searching window. Exact formulas linking this covariance to the window size and the correlation coefficient are developed under general, common and auto covariance structures of the variables in the original process. The implementation and applicability of the formulas are demonstrated on multiple processes of t-statistics, treating also the case of unknown covariance. A sensitivity analysis provides further insight into the variant interaction of the tail probability with the influence parameters. An R code for the tail probability computation and the data analysis is offered within the supplementary material. 相似文献
35.
Dr. Yaron Bram Ayala Lampel Dr. Ronit Shaltiel‐Karyo Anat Ezer Dr. Roni Scherzer‐Attali Prof. Dr. Daniel Segal Prof. Dr. Ehud Gazit 《Angewandte Chemie (International ed. in English)》2015,54(7):2062-2067
Amyloid deposits are pathological hallmark of a large group of human degenerative disorders of unrelated etiologies. While accumulating evidence suggests that early oligomers may account for tissue degeneration, most detection tools do not allow the monitoring of early association events. Here we exploit bimolecular fluorescence complementation analysis to detect and quantify the dimerization of three major amyloidogenic polypeptides; islet amyloid polypeptide, β‐amyloid and α‐synuclein. The constructed systems provided direct visualization of protein‐protein interactions in which only assembled dimers display strong fluorescent signal. Potential inhibitors that interfere with the initial intermolecular interactions of islet amyloid polypeptide were further identified using this system. Moreover, the identified compounds were able to inhibit the aggregation and cytotoxicity of islet amyloid polypeptide, demonstrating the importance of targeting amyloid dimer formation for future drug development. 相似文献
36.
Anat Levi-Zada Daniela FeferLeonid Anshelevitch Anna LitovskyMarie Bengtsson Galina GindinVictoria Soroker 《Tetrahedron letters》2011,52(35):4550-4553
The identification of the sex pheromone of the lesser date moth, Batrachedra amydraula (Meyrick) was based on GC-MS analysis of volatiles released by virgin females using sequential SPME auto-sampling of headspace and by synthesis of the key component, (4Z,7Z)-4,7-decadien-1-yl acetate. Substantial capture of males in a date palm plantation using a bait consisting of the key component and 5Z-decen-1-yl acetate in a ratio of 1:2 indicated that these are the essential components of the sex pheromone. Addition of 4Z-decen-1-yl acetate and decan-1-yl acetate, which were also identified, did not affect trap-capture. The lesser date moth is the first member of the Batrachedridae whose sex pheromone has been identified. (4Z,7Z)-4,7-Decadien-1-yl acetate is a novel compound among moth sex pheromones. 相似文献
37.
Uriya A. First 《代数通讯》2013,41(6):2567-2582
We introduce and study categorical realizations of quivers. This construction generalizes comma categories and includes representations of quivers on categories, twisted representations of quivers (in the sense of [9]), and bilinear pairings as special cases. In this general context, we prove the cancelation from direct sums, and show the existence and uniqueness of decomposition into a sum of indecomposable objects, provided certain assumptions hold. This yields similar results for the special cases just mentioned. Using similar ideas, we also prove a version of Fitting's Lemma for natural transformations between functors. 相似文献
38.
In this paper, we present the concept of a soluble tubular conjugated polymer (TCP). We report on a fluorescent 5,5'-Bicalixarene-based polymer where the calixarene units are seamlessly incorporated in the conjugated polymeric chain that can respond to a small molecule complexation inside the hydrophobic cavity. In particular, our system demonstrated a reversible rapid fluorescence quenching upon interaction of gaseous nitric oxide with the calixarene moiety. 相似文献
39.
Current challenges in compound-specific stable isotope analysis of environmental organic contaminants 总被引:3,自引:0,他引:3
Elsner M Jochmann MA Hofstetter TB Hunkeler D Bernstein A Schmidt TC Schimmelmann A 《Analytical and bioanalytical chemistry》2012,403(9):2471-2491
Compound-specific stable-isotope analysis (CSIA) has greatly facilitated assessment of sources and transformation processes of organic pollutants. Multielement isotope analysis is one of the most promising applications of CSIA because it even enables distinction of different transformation pathways. This review introduces the essential features of continuous-flow isotope-ratio mass spectrometry (IRMS) and highlights current challenges in environmental analysis as exemplified for the isotopes of nitrogen, hydrogen, chlorine, and oxygen. Strategies and recent advances to enable isotopic measurements of polar contaminants, for example pesticides or pharmaceuticals, are discussed with special emphasis on possible solutions for analysis of low concentrations of contaminants in environmental matrices. Finally, we discuss different levels of calibration and referencing and point out the urgent need for compound-specific isotope standards for gas chromatography-isotope-ratio mass spectrometry (GC-IRMS) of organic pollutants. 相似文献
40.
Private Information Retrieval (PIR) protocols, which allow the client to obtain data from servers without revealing its request, have many applications such as anonymous communication, media streaming, blockchain security, advertisement, etc. Multi-server PIR protocols, where the database is replicated among the non-colluding servers, provide high efficiency in the information-theoretic setting. Beimel et al. in CCC 12’ (further referred to as BIKO) put forward a paradigm for constructing multi-server PIR, capturing several previous constructions for servers, as well as improving the best-known share complexity for 3-server PIR. A key component there is a share conversion scheme from corresponding linear three-party secret sharing schemes with respect to a certain type of “modified universal” relation. In a useful particular instantiation of the paradigm, they used a share conversion from -CNF over to three-additive sharing over for primes where and , and the relation is modified universal relation . They reduced the question of the existence of the share conversion for a triple to the (in)solvability of a certain linear system over , and provided an efficient (in ) construction of such a sharing scheme. Unfortunately, the size of the system is which entails the infeasibility of a direct solution for big m’s in practice. Paskin-Cherniavsky and Schmerler in 2019 proved the existence of the conversion for the case of odd , when , obtaining in this way infinitely many parameters for which the conversion exists, but also for infinitely many of them it remained open. In this work, using some algebraic techniques from the work of Paskin-Cherniavsky and Schmerler, we prove the existence of the conversion for even m’s in case (we computed in this case) and the absence of the conversion for even m’s in case . This does not improve the concrete efficiency of 3-server PIR; however, our result is promising in a broader context of constructing PIR through composition techniques with servers, using the relation where m has more than two prime divisors. Another our suggestion about 3-server PIR is that it’s possible to achieve a shorter server’s response using the relation for extended . By computer search, in BIKO framework we found several such sets for small m’s which result in share conversion from -CNF over to 3-additive secret sharing over , where is several times less than , which implies several times shorter server’s response. We also suggest that such extended sets can result in better PIR due to the potential existence of matching vector families with the higher Vapnik-Chervonenkis dimension. 相似文献