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排序方式: 共有569条查询结果,搜索用时 453 毫秒
91.
研究对成年口吃者在流畅朗读过程中的塞音进行了声学分析,测量了嗓音起始时间并且计算了塞音爆破时刻的频谱矩,并将口吃者在言语矫治前后与非口吃者进行了对比。多因素方差分析结果显示,口吃者嗓音起始时间虽稍长于非口吃者但未达到统计意义上的显著性差异水平,而且受发音部位和韵母的影响程度较大。同时还观察到矫治前口吃者和非口吃者在塞音爆破段的频谱均值呈现出显著性差异,口吃者频谱均值低于非口吃者可能是由于口吃者舌与齿龈或软硬腭形成阻塞的部位在声道中偏后所导致,还发现口吃者韵母对塞音爆破段频谱的影响较小,此结果表明口吃者表现出相对较弱的协同发音现象。口吃者经过言语矫治后塞音的嗓音起始时间和爆破段频谱有向非口吃者逼近的趋势。 相似文献
92.
Yongqiang Zhang Guangjun Xie Mengbo Sun Hongjun Lv 《International Journal of Theoretical Physics》2018,57(10):3005-3025
Quantum-dot cellular automata (QCA), a new computing paradigm at nanoscale, may be a prospective alternative to conventional CMOS-based integrated circuits. Modular design methodology in QCA domain has not been widely investigated. In this paper, an efficient module with fault tolerance is proposed, which can be employed to fabricate three-input and five-input majority gates that are the fundamental primitives for designing circuits in QCA. With cells omission in the versatile module, various logic gates will be achieved, such as Nand-Nor-Inverter (NNI) gate and And-Or-Inverter (AOI) gate. Moreover, in order to seek out an efficient full adder, five various QCA full adders are designed and exhaustively compared in terms of area, complexity, latency, reliability and power dissipation and also compared with existing fault-tolerant full adders. Two simulation tools, QCADesigner and QCAPro, are utilized in the waveform simulations for verifying the correctness of proposed circuits and power consumption, respectively. The analysis results reveal that full adder V has significant improvements in contrast to its counterparts with above criteria. To test the practicability of full adder V, multi-bit adders will be designed in single-layer and compared with previous adders in terms of area, complexity and QCA cost, which proves the merits of our work. 相似文献
93.
制备了苯基甲苯基二苯并富烯(phenyltolyldibenzofulvene,1)并研究了其发光性能.化合物1具有聚集诱导发光(aggregation induced emission,AIE)及结晶诱导荧光增强(crystallization enhanced emission,CEE)的性质,且化合物1可形成蓝色、蓝绿色荧光的晶体以及黄绿色荧光的无定形态.因化合物1分子为扭曲的螺旋桨构象,分子在聚集态中以较疏松的形式堆积,故化合物1可在热、溶剂气氛以及外力刺激下发生多种聚集态间的可逆转变,从而实现在三种不同发光状态间的可逆转变.我们尝试将化合物1用于光学记录,以单一化合物1为发光材料,其可在蓝绿及蓝色荧光颜色背景上以暗黄绿色字迹记录,可通过研磨、加热及溶剂气氛处理擦除字迹,并将记录纸分别转变为蓝色、蓝绿色及黄绿色,因此化合物1有望用于光存储材料. 相似文献
94.
应用密度泛函理论的B3LYP方法和6-311++g(d,p)基组,研究Li2、LiS和Li2S分子的基态构型.结果表明它们的基电子态分别为X1Σg+、X2Π和X1Σg+.通过非线性曲线拟合,得到基态LiS和Li2分子的4参数Murrell-Sorbie分析势能函数,计算它们的光谱参数和力常数.基于多体项展式理论得到了基态Li2S分子的单重态势能面的分析函数.利用得到的分析势能函数重构基态单重Li2S分子的旋转图、伸缩图和旋转伸缩图,准确地再现了Li2S分子的静态特征,如平衡结构,最低能量,合理反应通道.从等值势能面图看出,反应Li+S+Li→Li2S是一个无阈值反应.S原子攻击Li2分子的反应通道上,有一个过渡态.Li原子攻击LiS分子通道上也有一个过渡态. 相似文献
95.
Zhu C Shao R Reddy RA Chen D Shen Y Gong T Glaser MA Korblova E Rudquist P Maclennan JE Walba DM Clark NA 《Journal of the American Chemical Society》2012,134(23):9681-9687
We report a bent-core liquid crystal (LC) compound exhibiting two fluid smectic phases in which two-dimensional, polar, orthorhombic layers order into three-dimensional ferroelectric states. The lower-temperature phase has a uniform polarization field which responds in an analog fashion to applied electric field. The higher-temperature phase is a new smectic state with periodic undulation of the polarization, structurally modulated layers, and a bistable response to applied electric field which originates in the periodically splay-modulated bulk of the LC rather than by surface stabilization at the cell boundaries. 相似文献
96.
Y Wen L Xu C Li H Du L Chen B Su Z Zhang X Zhang Y Song 《Chemical communications (Cambridge, England)》2012,48(67):8410-8412
DNA assembles that can perform "OR" and "AND" logic gate operations were fabricated. The feasibility of intelligent logic controlled release was demonstrated through the controlled organization of gold nanoparticles on the surface of mesoporous silica by stimuli-induced structural transformation of DNA ensembles. 相似文献
97.
The ubiquitous and essential V-ATPase is a worthy chemotherapeutic target in the escalating battle against invasive fungal infections. Pathogenic fungi require optimum V-ATPase function for secretion of virulence factors, induction of stress response pathways, hyphal morphology and homeostasis of pH and other cations in order to successfully survive within and colonize the host. This review discusses why impairment of V-ATPase activity confers multidrug sensitivity and loss of virulence. Recent evidence points to the V-ATPase as a novel downstream target of the azole class of antifungals that inhibit the biogenesis of ergosterol. Depletion of ergosterol from vacuolar membranes led to progressive alkalization of yeast vacuoles, loss of V-ATPase activity and growth inhibition that could be rescued by exogenous ergosterol feeding. Other studies point to a critical role for sphingolipids, phospholipids and cardiolipin in V-ATPase function. Thus, drugs that inhibit the V-ATPase directly, or indirectly by modulating the membrane milieu, can profoundly affect fungal viability and virulence. These findings justify a systematic screen for fungal specific V-ATPase inhibitors or membrane active compounds that can be used in antifungal chemotherapy. 相似文献
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