一种混合的中文分词算法

给出了一种将基于统计与基于词典方法融合而成的混合中文分词方法,利用统计方法进行词典的动态扩展,克服了基于词典算法对"完全词典"的依赖;利用词典对统计的一些参数进行估计,避免了以往靠实验得到这些参数的不确定性,同时将RMM算法与统计算法结合起来.最后通过仿真说明该混合算法比传统的基于词典和基于统计的方法更有效.     

Effect of D-allethrin on proteinase activity in the midgut of the spider Pardosa pseudoannulata detected by bulk acoustic wave impedance technique

The piezoelectric bulk acoustic wave (BAW) impedance analysis method was employed to monitor in situ the proteinase-catalyzed hydrolyzation of casein and the effect of pesticide D-allethrin on the proteinase activity in the midgut of the spider Pardosa pseudoannulata, and the results obtained were verified by ultraviolet spectroscopy. The hydrolyzation was significantly increased in the presence of low-dose D-allethrin, whereas significantly inhibited in the presence of high-dose D-allethrin, and a correlation was found precisely between the enzyme activity reflected by the final frequency shift after the hydrolyzation and the concentration of D-allethrin, with a significant frequency response observed even at a 1.5×10^-5 volume ratio of D-allethrin to distilled water. The present work may have presented a novel method feasible for study on the mechanism of excitability of spiders under low-dose D-allethrin pesticide and quick detection of proteinase activity.     

ZrO2掺杂TiO2纳米粉的共沉淀法制备及相变

为探讨离子掺杂对晶体相变的促进或抑制作用，采用共沉淀法制备了Zr^4＋掺杂量分别为0，2％，5％，7％，10％和13％（摩尔分数，余同）的纳米TiO2，研究Zr^4＋掺杂对TiO2从纳米锐钛矿型向金红石型转变的影响，透射电子显微镜研究显示所制备的锐钛矿型TiO2的颗粒直径在10～20nm之间，经X射线衍射研究发现，少量的Zr^4＋掺杂抑制了锐钛矿晶粒的长大，将锐钛矿开始向金红石转变的相变温度从750℃提高到850℃．锆可与TiO2反应生成化合物ZrTiO2，为避免该化合物的生成，Zr^4＋掺杂量不宜超过10％．     

具有量子修正功能的三维蒙特卡罗MOS器件模拟

为了处理纳米MOS场效应管的量子效应，在蒙特卡罗模拟中引入有效势量子修正，并提出了基于PC机群的三维并行模拟算法．每个节点应用多层网格法求解一个子区域内各网格点的Poisson方程，采用有效势法对各网格点进行量子修正，并跟踪模拟一组带电粒子的加速飞行和随机散射运动，使所有节点的负载始终保持平衡．模拟实例表明，引入有效势修正的蒙特卡罗模拟结果与薛定鄂方程计算结果吻合得较好，所提并行算法也具有较高的加速比．     

热加工降低板蓝根对狗肾上皮细胞的毒性

调查不同热加工阶段板蓝根样品对狗肾上皮细胞的毒性.选用常用于流感病毒检测和抗流感药物的狗肾上皮细胞作实验模型,采用MTT比色法研究菘蓝新鲜根、板蓝根、板蓝根煎剂三种样品对MDCK细胞的细胞毒性情况.结果显示:菘蓝新鲜根、板蓝根和板蓝根煎剂三种样品的细胞半数致死浓度分别为3.74、39.55和61.95 mg·mL-1.该结果表明,热加工可降低板蓝根对狗肾上皮细胞的细胞毒性,这可能与热加工过程中发生的美拉德反应相关.     

槽式热发电聚光跟踪控制研究

对槽式单轴跟踪控制系统进行研究,结合示范工程的应用效果,分析跟踪控制系统的实用调试方法.推导了太阳相对于聚光跟踪装置的位置计算公式.结合研制的跟踪示范装置对影响跟踪精度的安装位置因素进行了仿真,总结了槽式聚光跟踪精度的校正方法,为大规模的槽式热发电系统的建立和工程化应用提供了参考.     

金属卟啉类化合物特性及光催化机理与应用研究

概述了卟啉及金属卟啉类化合物的合成、性质及相关应用,重点综述了卟啉及金属卟啉类化合物的光电特性和光电化学性质,包括光致电子转移、光激发能量转移和高价金属卟啉氧化物种形成等,归纳了其光催化作用机理,包括光致电子转移产生的对分子氧的活化机理（超氧阴离子自由基机理）、光激发能量转移导致基态三线态氧活化产生的单线态氧机理和高价氧化物种对分子氧和H2O2的活化产生具有高氧化活性自由基机理,并对异相光催化体系及光催化应用作了概括.     

Functional genomic screen reveals genes involved in lipid-droplet formation and utilization

Eukaryotic cells store neutral lipids in cytoplasmic lipid droplets enclosed in a monolayer of phospholipids and associated proteins. These dynamic organelles serve as the principal reservoirs for storing cellular energy and for the building blocks for membrane lipids. Excessive lipid accumulation in cells is a central feature of obesity, diabetes and atherosclerosis, yet remarkably little is known about lipid-droplet cell biology. Here we show, by means of a genome-wide RNA interference (RNAi) screen in Drosophila S2 cells that about 1.5% of all genes function in lipid-droplet formation and regulation. The phenotypes of the gene knockdowns sorted into five distinct phenotypic classes. Genes encoding enzymes of phospholipid biosynthesis proved to be determinants of lipid-droplet size and number, suggesting that the phospholipid composition of the monolayer profoundly affects droplet morphology and lipid utilization. A subset of the Arf1-COPI vesicular transport proteins also regulated droplet morphology and lipid utilization, thereby identifying a previously unrecognized function for this machinery. These phenotypes are conserved in mammalian cells, suggesting that insights from these studies are likely to be central to our understanding of human diseases involving excessive lipid storage.     

Comparison of the carbon isotope composition of total organic carbon and long-chain <Emphasis Type="Italic">n</Emphasis>-alkanes from surface soils in eastern China and their significance

Surface soil samples collected over a high spatial resolution in eastern China were analyzed for carbon isotope composition （δ^13C） of total organic carbon （TOC） and higher plant-derived long-chain n-alkanes, with the latter reported as weighted mean values. The two sets of δ^13C values are significantly correlated and show similar trends in spatial variation. The spatial distribution of δ^13C shows less negative values in the mid-latitudes between 31°N and 40°N and more negative ones at higher and lower latitudes. This is consistent with previously reported carbon isotope data from surface soil phytoliths in the same region and suggests that the mid-latitude area provides relatively favorable growing condi- tions for C4 plants. Furthermore, δ^13C values of both TOC and long-chain n-alkanes from 12 surface soil samples collected from a small grassland in north China displayed similar carbon isotope values and the difference between paired δ^13C of a soil samples remains relatively constant. Our data demonstrate that in eastern China, soil δ^13C composition of both TOC and long-chain n-alkanes is effective indicators of C3/C4 ratios of the prevailing vegetation. This work suggests that -22‰ and -32‰ are good es- timated end members for the weighted mean δ^13C values of long-chain n-alkanes （C27, C29 and C31 n-alkanes） from soils under dominant C4 or C3 vegetation, allowing us to reconstruct paleovegetation trends.