窄带噪声的调频感受阈

窄带噪声也有音调,其高低决定于通带中心频率f,清晰程度则和带宽B有关。正常人对特定f的调频感受阈时Δf与B的函数关系为Δf=AB~n,A为B=1Hz时Δf的理论值,较接近纯音的Δf。当f小于4000Hz时n值在0.22—0.45的范围内变化,当f为4000或8000Hz时n值略小。对固定的B/f比值,窄带噪声Δf与f的关系曲线与纯音的颇相似。声音强度对Δf的影响不大。在172ms以内,窄带噪声的Δf也和纯音的一样与调频时程的平方根成反比。     

油田稠油污水深度处理回用热采锅炉的软化处理技术

针对油田热采直流蒸汽锅炉给水水质要求，采用离子交换法对稠油污水进行软化处理，经过对比实验，确定选用大孔弱酸阳离子交换树脂D113，投入中试运行二个月，来水平均硬度为170mg/L，出水硬度未检出，达到了蒸汽热采锅炉对进水水质硬度的要求，大孔弱酸阳离子交换树脂进行酸再生和碱转型，可以有效地抵抗有机污染负荷，实现高浓度，高水温有机污水的软化处理。     

高碘酸氧化肝素抑制P-选择素介导的A375细胞粘附

摘要通过选择性化学修饰制备出具有低抗凝血活性的高碘酸氧化肝素, 并系统地分析了其抗肿瘤细胞粘附的活性. 研究结果表明, 具有低抗凝血活性的高碘酸氧化肝素仍然可以显著地抑制P-选择素介导的人恶性黑素瘤A375细胞与血小板间的粘附.     

十二烷基硫酸钠自组装过程中分子间相互作用力的垂直偏振拉曼光谱研究

Molecular self-assembly is extremely important in many fields, but the characterization of their corresponding intermolecular interactions is still lacking. The C-H stretching Raman band can reflect the hydrophobic interactions during the self-assembly process of sodium dodecyl sulfate (SDS) in aqueous solutions. However, the Raman spectra in this region are seriously overlapped by the OH stretching band of water. In this work, vertically polarized Raman spectra were used to improve the detection sensitivity of spectra of C-H region for the first time. The spectral results showed that the first critical micelle concentration and the second critical micelle concentration of SDS in water were 8.5 and 69 mmol/L, respectively, which were consistent with the results given by surface tension measurements. Because of the high sensitivity of vertically polarized Raman spectra, the critical micelle concentration of SDS in a relatively high concentration of salt solution could be obtained in our experiment. The two critical concentrations of SDS in 100 mmol/L NaCl solution were recorded to be 1.8 and 16.5 mmol/L, respectively. Through comparing the spectra and surface tension of SDS in water and in NaCl solution, the self-assembly process in bulk phase and at interface were discussed. The interactions among salt ions, SDS and water molecules were also analyzed. These results demonstrated the vertically polarized Raman spectra could be employed to study the self-assembly process of SDS in water.     

Ceramic synthesis of 0.08BiGaO_3–0.90BaTiO_3–0.02LiNbO_3 under high pressure and high temperature

In this paper, the preparation of 0.08BiGaO_3–0.90BaTiO_3–0.02LiNbO_3 is investigated at pressure 3.8 GPa and temperature 1100–1200?C. Experimental results indicate that not only is the sintered rate more effective, but also the sintered temperature is lower under high pressure and high temperature than those of under normal pressure. It is thought that the adscititious pressure plays the key role in this process, which is discussed in detail. The composition and the structure of the as-prepared samples are recorded by XRD patterns. The result shows that the phases of Ba TiO_3, BaBiO_(2.77), and Ba_2Bi_4Ti_5O_(18) with piezoelectric ceramic performance generate in the sintered samples. Furthermore, the surface morphology characteristics of the typical samples are also investigated using a scanning electron microscope. It indicates that the grain size and surface structure of the samples are closely related to the sintering temperature and sintering time. It is hoped that this study can provide a new train of thought for the preparation of lead-free piezoelectric ceramics with excellent performance.     

智能检索引擎中的网络数据挖掘技术优化研究

随着计算机网络技术的不断发展,对于Web Service检索技术的要求也越来越大。并且现在网络环境当中数据信息流量十分庞大,对于信息可以做到深入搜索,实现全方位信息查询是非常有必要的。为此,利用网络数据挖掘技术在智能检索引擎中的应用,以文本描述为信息作为本文的研究对象,为用户提供运用查询要求实现概念检索功能。其中强调在智能搜索引擎当中的网络数据挖掘技术进行优化研究,从结构设计以及算法分析上总结出当前网络数据挖掘应用智能检索的可能性。最终设计出一种利用数据挖掘技术的智能检索模型,实现在众多网络数据中可以准确快速的进行详细的信息检索功能。     

电感耦合氩等离子体中电子密度及电子温度的测量

电子密度n_e和电子温度T_e是描述ICP放电特性的重要参数。本文对ICP中n_e和T_e的测量从理论上进行了探讨,并根据文献提供的数据,经理论计算,分别与电子密度计算有关的两个系数C(n_e,T)和α_(1/2)(n_e,T)进行了扩展并编制成表。作者基于ICP—AES的实际测定条件,对不同操作参数下ICP中轴向电子密度n_e和电子温度T_e进行了测量,其实验结果与文献推荐值一致。     

MOCVD Growth and Characterization of Epitaxial AlxGa1-xN Films

We study the growth of AlxGa1-x N epilayers on （0001） sapphire by low-pressure MOCVD, using a lowtemperature AIN buffer. By varying the input flow rates of trimethylgallium （TMGa）, we obtain crack-free AlGaN films in the whole range of composition. A linear relationship between gas and solid Al content is observed. The structural properties of the layers （x =0- 1） are investigated by x-ray diffraction, atomic force microscopy （AFM） and scanning electron microscopy （SEM）. It is found that a two-direction growth appears along the c-axis and the （1011） directions for x ≥ 0.45. From the results of Raman spectroscopy, we suggest that the compressive stain and the lack of mobility orAl adatoms can induce the formation of （1011） grains.     

带边界条件复标量场的正则量子化

研究了带边界条件有质量复标量场的量子化. 与把边界条件当作Dirac约束方法不同, 我们在经典解空间研究这个问题, 利用Fadeev-Jackiw(FJ)方法获得所有傅里叶模的对易关系, 避免用Dirac方法而产生的问题.     

单调型条件下随机微分方程θ-方法的均方指数稳定性

本文研究高度非线性随机微分方程(SDEs)的数值解稳定性性质.给出θ-方法均方指数稳定性的充分条件.与现有文献不同,本文无需单边线性增长条件和充分小的步长.本文在单调型的条件下,并且至于要步长满足一个很弱的条件即可.因此本文是对现有文献的很大改进.