基于p范式模型的检索

随着电子文本的大量涌现,人们对信息检索工具提出了更高的要求。本文介绍一种扩展的布尔检索模型及其在中文信息检索系统中的应用,并利用相关反馈技术改善检索系统性能。     

Studying the protein-protein interactions in the postsynaptic density by means of immunoabsorption and chemical crosslinking

Postsynaptic densities (PSDs), isolated from porcine cerebral cortices, are large disk-shaped aggregates consisting of hundreds of different proteins. To study the protein-protein interactions in such complex supramolecules, we developed a procedure to break up the PSD's overall structure, while preserving some interactions between individual proteins. Using the resulting PSD sample and an indirect immunoabsorption procedure, PSD-95 was isolated along with the α- and β-subunits of calcium calmodulin-dependent protein kinase II (CaMKIIα and CaMKIIβ), α-tubulin, β-tubulin, and Chapsyn110. Similarly, CaMKIIα was isolated along with CaMKIIβ, α-tubulin, β-tubulin, and small amounts of PSD-95. The proteins isolated from PSDs treated with a cleavable bifunctional crosslinking reagent were further subjected to diagonal gel electrophoresis analysis, and the results indicated that CaMKIIα resides next to α-tubulin in the PSD. Overall, the results obtained here suggest that within the PSD, large aggregates of CaMKIIα, CaMKIIβ, α-tubulin, and β-tubulin may occur that indirectly associate with PSD-95 and Chapsyn110. Such a protein organization would allow interactions with F-actin in the cytoplasm and with proteins, such as N-methyl-D-aspartate receptors, which reside on the postsynaptic membrane. Furthermore, it would facilitate binding to proteins such as the various microtubule-associated proteins that reside in the core region of the PSD.     

On the removal of shadows from images

This paper is concerned with the derivation of a progression of shadow-free image representations. First, we show that adopting certain assumptions about lights and cameras leads to a 1D, gray-scale image representation which is illuminant invariant at each image pixel. We show that as a consequence, images represented in this form are shadow-free. We then extend this 1D representation to an equivalent 2D, chromaticity representation. We show that in this 2D representation, it is possible to relight all the image pixels in the same way, effectively deriving a 2D image representation which is additionally shadow-free. Finally, we show how to recover a 3D, full color shadow-free image representation by first (with the help of the 2D representation) identifying shadow edges. We then remove shadow edges from the edge-map of the original image by edge in-painting and we propose a method to reintegrate this thresholded edge map, thus deriving the sought-after 3D shadow-free image.     

测定外延层电阻率的面接触方法研究

评论了美国科学家C.C. Allen等于1966年发表的“测定外延层电阻率的点接触方法”之论文的局限性,从而提出了本方法。本方法从理论上解一维Poisson方程并与C.C。Allen法的公式相比较,获得某些公式。文中导出了面接触方法雪崩击穿电压V_(Ba)~∞(V)及点接触方法雪崩击穿电压V_(Bp)~∞(V)的比值为V_(Ba)~∞=0.456;同时还导出了点接触方法外延层耗尽层宽度为t_(min p)(μm)和面接触方法外延层耗尽层宽度t_(mina(μm)的比值为t_(minp)/t_(mina)=2.565。在实践上,为证实两种模型的功能,利用两种探针进行了对比测试。一种是通常被采用的点接触锇尖探针:另一种是利用φ0.8±0.1mm的银针,在银针顶上吸上φ0.4±0.1mm的汞球,以实现面接触。理论和实验吻合良好。     

最大方差模反褶积

1977年,Wiggins提出最小熵反褶积(MED)。这个方法依赖于定义一个能衡量信号简单性的模,这个模就是在“数据分析”中已应用多年的规范方差模。最小熵反褶积就是寻找反褶积因子使规范方差模达到最大值。因此,我们直接称这种反褶积为最大方差模反褶积,简记为MVND (Maximum Variance Norm Deconvolution的缩写)。为什么对地震记录能使用最大方差模反褶积呢?Wiggins的文章并没有分析这个问题。这个问题是很复杂的,这篇文章只是试图作一初步讨论。首先,我们给出了规范方差模的两个基本性质;其次,指出了在什么条件下能使用最大方差模反褶积。我们希望这篇文章能起到抛砖引玉的作用,能引起物探工作者的兴趣,以便进行更多的试验和更深入的研究。     

PE,PP专家系统

简述了专家系统的发展及在塑料加工中的应用特点,介绍了成功地开发PE、PP专家系统的方法、技术及实现功能,并提出了采用压缩库大大节约存贮空间的新途径。     

我国塑料热稳定剂生产现状与研究进展

介绍了国内塑料热稳定剂生产、市场和发展趋势。目前我国塑料热稳定剂无论是品种和产品质量等与国外先进水平仍有较大的差距，提出了我国热稳定剂的发展建议。