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961.
HE Gang~ HUANG Kang~ GUO SongTao~* JI WeiHong~ QI XiaoGuang~ REN Yi~ JIN XueLin~ & LI BaoGuo~ * Key Laboratory of Resource Biology Biotechnology in Western China of Ministry of Education College of Life Sciences Northwest Univer- sity Xi’an China Ecology & Conservation Group Institute for Natural Sciences Massey University Auckl New Zeal Institute of Zoology Shaanxi Academy of Sciences Xi’an Shaanxi Wild Animal Rescue Research Center... 《科学通报(英文版)》2011,56(24):2523-2530
Molecular studies using trace DNA, such as from museum specimens, ancient or forensic samples and samples obtained noninvasively, often have a common problem of low quality of DNA templates. Amplification errors, such as allelic dropout and false allele, may arise during polymerase chain reaction (PCR) using such samples. A mathematical model which treats homozygotes and heterozygotes discriminately has been developed to measure sample quality and compute the confidence level of using multipletube approaches. We use plucked hair samples collected from 26 individual Sichuan snub-nosed monkeys (Rhinopithecus roxel- lana) to test the model. In this case, a confidence level of 99% can be achieved by three positive PCRs. If the sample quality is very poor and requires many PCR replicates, an alternative multiplestep genotyping method is recommended. This model enables researchers to optimize experimental protocols through pilot studies and obtain reliable genetic information using noninvasive sampling method. 相似文献
962.
In this paper,by taking the water-water balanced counterflow heat exchanger as an example,the entransy dissipation theory is applied to optimizing the design of heat exchangers.Under certain conditions,the optimal duct aspect ratio is determined analytically.When the heat transfer area or the duct volume is fixed,analytical expressions of the optimal mass velocity and the minimal entransy dissipation rate are obtained.These results show that to reduce the irreversible dissipation in heat exchangers,the heat exchange area should be enlarged as much as possible,while the mass velocity should be reduced as low as possible. 相似文献
963.
Denoted by M(A), QM(A) and SQM(A) the sets of all measures, quantum measures and subadditive quantum measures on a σ-algebra A, respectively. We observe that these sets are all positive cones in the real vector space F(A) of all real-valued functions on A and prove that M(A) is a face of SQM(A). It is proved that the product of m grade-1 measures is a grade-m measure. By combining a matrix M
μ to a quantum measure μ on the power set A
n
of an n-element set X, it is proved that μ ≪ ν (resp. μ ⊥ ν) if and only if M
μ ≪ M
ν
(resp. M
μ
M
ν
=0). Also, it is shown that two nontrivial measures μ and ν are mutually absolutely continuous if and only if μ·ν∈QM(A
n
). Moreover, the matrices corresponding to quantum measures are characterized. Finally, convergence of a sequence of quantum
measures on A
n
is introduced and discussed; especially, the Vitali-Hahn-Saks theorem for quantum measures is proved. 相似文献
964.
The PHC criterion and the realignment criterion for pure states in infinite-dimensional bipartite quantum systems are given. Furthermore, several equivalent conditions for pure states to be separable are generalized to infinite-dimensional systems. 相似文献
965.
Based on the fact that the transfer function vector between a source receiver array and the dominant scatterer of boundary reverberation at a range can be obtained from the corresponding reverberations scattered from this range cell, a reverberation nulling concept using time reversal processing has been proposed. However, current reverberation nulling methods have certain limitations when applied into practice, which would null boundary reverberation and target echo simultaneously. As a solution, a passive reverberation nulling and echo enhancement method at low frequency using waveguide invariance is proposed in this paper. In this method, the reverberation subspace for the target range cell is not obtained directly from the return signals scattered by the target range cell but from the return signals scattered by a range cell located before the target using waveguide invariance, so as to suppress the reverberation embodied in the target echo by passive reverberation nulling. Besides, a range-dependent optimal weighting vector rather than conventional projector matrix is deduced to null the reverberation component meanwhile maximizing the target echo, thereby enhancing the echo-to-reverberation ratio furthest. Numerical simulations in typical range-independent shallow water environment demonstrate the efficacy and the improved performance of the proposed method for echo-to-reverberation enhancement. 相似文献
966.
平茬萌蘖是中国沙棘种群更新的有效方式,但其中的生态学机制并不清楚,为此,以样地每木检尺资料为基础,以 "空间差异代替时间变化法"及"样地编年序列法"原理为依据、以生物量投资与分配为指标,探讨了中国沙棘平茬更新的生态学机制.结果表明:① 中国沙棘平茬萌蘖种群及其构件生物量积累过程均符合Logistic方程,可分为慢、快、慢3个阶段,但构件之间的生物量投资与分配具有明显差异;② 通过构件之间的生物量投资与分配调节,中国沙棘实现了平茬后的萌蘖更新,尤其是萌蘖根的生物量投资具有"前置效应"和"主导效应";③ 地上与地下构件的生物量分配具有互补效应,即地下分配比例大时则地上分配比例小.因此,种群实施萌蘖更新过程中,必须在繁殖与生长之间做出权衡. 相似文献
967.
形式化概念分析已被证明是一种支持模块重组的有效工具.然而,在使用概念分析进行模块重组时,仍存在一些问题有待进一步解决.本文提出一种自动化的遗留软件重组方法,用于从识别的模块化方案中获取一种最佳解决方案.通过在概念分析过程中引入概念抽象、哑概念和概念相似性度量等新的特性,有助于解决现有方法的不足.概念抽象用于表示候选模块... 相似文献
968.
多普勒天气雷达提供的径向风场资料,是气象预报的重要判据之一.由于所探测到的风场信息存在着噪声、缺测和速度模糊等方面的问题,因此,多普勒天气雷达的速度退模糊技术也相应的受到越来越多的关注.文章根据多普勒天气雷达风场资料的特点,结合实际业务,提出了一种简易的速度退模糊方法.该方法在等距离圈切向和径线方向上进行速度退模糊.在等距离圈切向退模糊中,首先进行圈上的数据分段,然后检测段内和段间的速度模糊,再进行速度扩展退模糊.在径线方向退模糊中,从径线中点向外和向内检测速度模糊,然后进行速度扩展退模糊.进行了实例退模糊实验,证明了该方法的正确性和实用性. 相似文献
969.
针对基于迭代反投影(IBP)算法的视频超分辨率重建,提出了一种改善初始估计来提高重建效果的方法.本文采用小波局部适应插值得到初始估计,结合滑动窗的视频重建模型,由一段低分辨率的视频重建一段高分辨率的视频, 达到提高视频空间分辨率的目的.实验表明改进算法得到的高分辨率视频有更好的视觉效果. 相似文献
970.
设计了基于ASD光谱仪的玻璃水槽实验,测量人工光源穿透不同水深、不同质量浓度含沙水体的辐亮度,以纯水为参照,得出了某一粒径组成下不同质量浓度悬浮泥沙在350~920 nm波段范围内的光学衰减系数。实验泥沙样本的光学衰减系数光谱特征单一,随着波长的增大逐渐减小,表现为一条略倾的曲线,且正比于泥沙质量浓度。在0~0.15 m深度范围内的,相同质量浓度的泥沙光学衰减系数随水深的变化可以忽略不计。从350~920 nm,实验泥沙样本的单位质量浓度光学衰减系数从0.084缓慢减小至0.069 m2/g。 相似文献