微合金元素对高碳钢盘条组织性能的影响

在高碳钢盘条生产中,通过添加微量合金元素Cr、V并配以合适的控冷工艺,可使盘条获得较完伞的索氏体组织和较高的机械性能,满足预应力钢丝、钢绞线生产要求.     

多准则框架下的蛋白质三维结构相似性检索

蛋白质三维结构与功能的关系问题是当前生命科学领域的一个重大科学问题，蛋白质三维结构相似性比较则是探索蛋白质结构与功能关系的一种重要手段．文中就蛋白质结构在空间分布的特殊性提出了一种多准则框架下的蛋白质三维结构相似性检索模型．在该模型下，通过三种蛋白质空间旋转与平移不变特征的获取，实现了蛋白质骨架空间走向函数的一致性、蛋白质骨架距离直方图的一致性以及蛋白质距离矩阵数据分布一致性的多准则相似性检索策略．作者对实际的27804个蛋白质样本数据库进行实验，结果表明该文所提出的检索模式以及相似性准则的设计是实现大规模蛋白质三维结构相似性检索的一种有效方法．     

Antimicrobial resistance of Escherichia coli O157 from cattle in Korea

Of 45 Escherichia coli O157 isolates from cattle feces, which were collected between May 2000 and September 2003 in Korea, 32 were resistant to at least 1 antibiotic and 28 were resistant to 4 or more antibiotics, with 32, 30 and 30 of the isolates being resistant to streptomycin, tetracycline and sulfisoxazole, respectively. Two isolates were resistant to fluoroquinolones and to 10 or more of the 22 other antimicrobial agents that were tested. Thirteen antimicrobial resistant patterns were observed. The most frequent resistance type, which was found for 11 isolates, was streptomycin-tetracycline-kanamycin-ampicillin-piperacillin-cephalothin-sulfisoxazole-ticarcillin. Polymerase chain reaction (PCR) analysis of the isolates for E. coli O157 virulence markers revealed that 25 of the resistant E. coli O157 isolates tested positive for stx2 or both stx1 and stx2 genes. These findings suggest that many of the resistant E. coli O157 isolates might cause disease in humans.     

顶空气相色谱法快速测定酱油中丙酸盐的含量

目的建立顶空技术串联气相色谱法快速检测酱油中丙酸盐的含量。方法准确称取一定量酱油至顶空品瓶内,加入磷酸使丙酸盐酸化为丙酸,采用ZB-WAXplus毛细管柱(30 m×0.25 mm, 0.25μm)分离,火焰离子检测器检测器检测,外标法定量。结果丙酸盐在10～200μg/mL浓度范围内线性关系良好,相关系数为0.9992,检出限为0.02 g/kg,三水平加标回收率为97%～107.5%,相对标准偏差为1.95%～2.63%。结论该方法前处理简单,检测结果可靠准确,适用于酱油中丙酸盐的含量的测定。     

基于三维数据场拓扑抽取的蛋白质结构分析

介绍了抽取蛋白质分子三维数据场的局部特征，并组织数据场的整体拓扑的初步工作．基于拓扑分析的方法，计算出数据场的局部特征点，这些特征点潜在地揭示了蛋白质的活性位点．在此基础上，利用这些局部特征点构造出表示数据场的几何拓扑结构．将实验结果与实际的蛋白质数据比较，验证了方法的可行性．     

基于运动控制卡的PCB钻、铣、雕一体机数控系统

针对现代PCB加工的要求,采用基于DMC3400运动控制卡结合PC机的开放式数控系统结构,以WINXP下采用Visual B6.0作为软件开发工具,开发出PCB钻、铣、雕一体机数控系统.经过实际应用,证明该开放式数控系统的功能齐全,性能优良,操作简单.     

兰州百合采后贮藏保鲜研究进展

目的兰州百合营养丰富,采后易褐变,造成经济损失严重。通过对兰州百合采后贮藏保鲜研究进行综述,以期为兰州百合品质提升和减损增效提供一定的参考。方法在查阅国内外相关文献的基础上,紧密结合产业发展,综合分析兰州百合的传统保鲜、物理保鲜和化学保鲜方法。结果窖藏、沙藏、预冷、低温、气调、臭氧、紫外照射、二氧化氯、1-甲基环丙烯(1-MCP)和涂膜保鲜均可有效地保持兰州百合的贮藏品质,生物保鲜研究仍有待进一步加强。结论兰州百合贮藏过程中的褐变机制亟需明确,贮藏保鲜技术仍需挖掘,不同保鲜技术的复合应用前景广阔。     

Fast single sample face recognition based on sparse representation classification

Multimedia Tools and Applications - The extended sparse representation classification (ESRC) is one of the benchmark classification algorithms in the field of single sample face recognition (SSFR)....     

Polybrominated diphenyl ethers in airborne particulates collected during a research expedition from the Bohai Sea to the Arctic

In July to September 2003, particulates in the oceanic atmosphere from the Bohai Sea to the high Arctic (37 degrees N to 80 degrees N) were collected aboard a research expedition icebreaker, Xuelong (Snow Dragon), under the 2003 Chinese Arctic Research Expedition Program (CHINARE 2003). These samples were analyzed to elucidate the atmospheric distributions of polybrominated diphenyl ethers (PBDEs) in the North Pacific Ocean and adjacent Arctic region. The levels of 11 PBDE congeners (BDE-28, -47, -66, -100, -99, -85, -154, -153, -138, -183, and -209; the sum was defined as sigma11PBDE) in the oceanic atmosphere of Far East Asia (34-48 degrees N/122-148 degrees E) ranged from 2.25 to 198.9 pg/m3 with a mean of 58.3 pg/m3. BDE-47, -99, -100, and -209 were the dominant congeners in all the samples, suggesting that the widely used commercial penta- and deca-BDE products were the original sources. The PBDE levels exhibited a decreasing trend from the mid- to high-latitudinal regions of the North Pacific Ocean, probably resulting from dilution, deposition, and decomposition of PBDEs during long-range transport of air masses. On the other hand, no apparent geographical pattern of PBDE distribution was observed within the Arctic, attributable to unstable air circulation and strong air mixing. Correlations among the PBDE congeners suggested that air masses collected from the North Pacific Ocean were relatively fresh, whereas those from the Arctic were aged as a result of photodecompoisiton. The higher average level (17.3 pg/m3) of PBDE congeners in the Arctic than those in the adjacent North Pacific Ocean (12.8 pg/m3) or other remote areas reported in the literature was attributed to the impact of the North American continent and temperature effects, which was consistent with the hypotheses of global fractionation.