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661.
从立体图像对中获取精确的三维信息需要进行相机建模、标定和图像点的匹配[1,2].提出了特征点的选取;利用金字塔图像结构进行立体匹配,以及对匹配点进行整体性检验的准则。实验表明,该算法匹配速度快,错误概率小,匹配点在整个景物中分布均匀。 相似文献
662.
针对多个相似信号分量的到达时间检测问题提出了一种基于小波包理论的新算法(WaveletPacketsDetectionAlgorithm,WPDA).即使在各信号分量严重重叠的情况下,该算法都能非常精确地确定各分量的到达时间。为了进行比较,引用了B.Friedlander提出的改进Gabor表征方法(IGRM)及其信号模型。实验证明,小波包检测算法可以得到更为优越的性能。还讨论了小波包检测算法中的正交镜像滤波器选择问题。 相似文献
663.
在对语音信号进行LPC分析的基础上,提出了一种有效的语音基音周期检测算法。该算法利用小波变换中著名的Mallat算法逐层分解LPC预测误差信号,在最低分辨率的逼近信号中寻找峰值,然后逐层回溯各个分辨率的逼近信号,最后在LPC预测误差中确定出峰值,从而求出相应的基音周期。 相似文献
664.
H. Miyamoto N. Manabe Y. Akiyama T. Watanabe M. Sugimoto E. Sato 《Cellular and molecular life sciences : CMLS》1994,50(9):808-811
The morphometric parameters of spermatogenic cells in a mouse strain prone to accelerated senescence (SAM-P), a novel murine model of spontaneously promoted aging, were compared with those of a SAM resistant strain (SAM-R) after birth until 40 weeks (mean life span of SAM-P). A mixture of gonocytes and spermatogonia were present in the testis in 1-week-old mice, and no gonocytes were observed in 2-week-old mice. At 6 weeks of age, the absolute number of spermatogonia in SAM-P was 27% greater than that in SAM-R, whereas the cell number in 40-week-old SAM-P was 17% less than in SAM-R. Primary spermatocytes were first observed in 3-week-old animals, and the cell numbers in SAM-P at 3, 5 and 6 weeks were 78%, 31% and 25%, respectively, greater than in SAM-R, whereas the cell number in SAM-P at 40 weeks was 30% less than SAM-R. Round spermatids were first observed in all SAM-P at 4 weeks old, but 20% of SAM-r had no spermatids and the rest had only a few. At 5 and 6 weeks old, the absolute numbers of round spermatids in SAM-P was about 34% and 41%, respectively, greater than in SAM-R, whereas the cell number in 40-week-old SAM-P was about 34% less than SAM-R. These results indicate that testicular maturation begins at an earlier age in SAM-P than SAM-R. Furthermore, at the age of 40 weeks signs of testicular deterioration are evident in SAM-P mice only 相似文献
665.
E. Ottaviani A. Franchini P. Fontanili 《Cellular and molecular life sciences : CMLS》1994,50(9):857-859
The effect of corticotropin-releasing factor (CRF) and pro-opiomelanocortin (POMC)-derived peptides on hemocyte phagocytosis in two molluscs,Planorbarius corneus andViviparus ater was studied. The peptides and related fragments examined are those which have been shown to influence hemocyte motility in the two species. The results obtained revealed that the effects on phagocytosis are not directly correlated with previous findings on cell motility. Furthermore, the mode of action of an individual peptide could be species-specific and dose-dependent. The relationships between peptides, locomotion and phagocytosis in these molluscs are discussed. 相似文献
666.
五峰垃圾填埋场渗滤液污染特征及处理系统 总被引:1,自引:0,他引:1
系统分析了五峰垃圾填埋场渗滤液中COD,BOD_5的季节变化特征,并对该填埋场的污水处理系统进行了研究和评价。 相似文献
667.
Li/MgO甲烷氧化偶联催化剂引入铌的氧化物可降低活性温度,750℃以下便达到最高C2烃产率。铌与锂、镁有多种结合方式,引入方法对活性测试结果有重要影响。铌不与镁紧密结合且分布于锂、镁之间时作用最好。 相似文献
668.
Calcium/calmodulin-dependent protein kinase II increases glutamate and noradrenaline release from synaptosomes 总被引:28,自引:0,他引:28
A variety of evidence indicates that calcium-dependent protein phosphorylation modulates the release of neurotransmitter from nerve terminals. For instance, the injection of rat calcium/calmodulin-dependent protein kinase II (Ca2+/CaM-dependent PK II) into the preterminal digit of the squid giant synapse leads to an increase in the release of a so-far unidentified neurotransmitter induced by presynaptic depolarization. But until now, it has not been demonstrated that Ca2+/CaM-dependent PK II can also regulate neurotransmitter release in the vertebrate nervous system. Here we report that the introduction of Ca2+/CaM-dependent PK II, autoactivated by thiophosphorylation, into rat brain synaptosomes (isolated nerve terminals) increases the initial rate of induced release of two neurotransmitters, glutamate and noradrenaline. We also show that introduction of a selective peptidergic inhibitor of Ca2+/CaM-dependent PK II inhibits the initial rate of induced glutamate release. These results support the hypothesis that activation of Ca2+/CaM-dependent PK II in the nerve terminal removes a constraint on neurotransmitter release. 相似文献
669.
R D Salter R J Benjamin P K Wesley S E Buxton T P Garrett C Clayberger A M Krensky A M Norment D R Littman P Parham 《Nature》1990,345(6270):41-46
Adhesion measurements between CD8 and 48 point mutants of HLA-A2.1 show that the CD8 alpha-chain binds to the alpha 3 domain of HLA-A2.1. Three clusters of alpha 3 residues contribute to the binding, with an exposed, negatively charged loop (residues 223-229) playing a dominant role. CD8 binding correlates with cytotoxic T-cell recognition and sensitivity to inhibition by anti-CD8 antibodies. Impaired alloreactive T-cell recognition of an HLA-A2.1 mutant with reduced affinity for CD8 is not restored by functional CD8 binding sites on an antigenically irrelevant class I molecule. Therefore, complexes of CD8 and the T-cell receptor bound to the same class I major histocompatibility complex molecule seem to be necessary for T-cell activation. 相似文献
670.
Genetic mapping of chronic childhood-onset spinal muscular atrophy to chromosome 5q11.2-13.3 总被引:16,自引:0,他引:16
L M Brzustowicz T Lehner L H Castilla G K Penchaszadeh K C Wilhelmsen R Daniels K E Davies M Leppert F Ziter D Wood 《Nature》1990,344(6266):540-541
SPINAL muscular atrophy (SMA) describes a group of heritable degenerative diseases that selectively affect the alpha-motor neuron. Childhood-onset SMAs rank second in frequency to cystic fibrosis among autosomal recessive disorders, and are the leading cause of heritable infant mortality. Predictions that genetic heterogeneity underlies the differences between types of SMA, together with the aggressive nature of the most-severe infantile form, make linkage analysis of SMA potentially complex. We have now analysed 13 clinically heterogeneous SMA families. We find that 'chronic' childhood-onset SMA (including intermediate SMA or SMA type II, and Kugelberg-Welander or SMA type III) is genetically homogeneous, mapping to chromosomal region 5q11.2-13.3. 相似文献