不同成分系列微合金钢抗奥氏体晶粒长大能力研究

研究了ＮｂＶ－Ｖ，Ｎｂ－Ｔｉ，Ｎｂ－Ｖ－Ｔｉ三种成分系列微合金钢的抗奥氏体晶粒长大能力，以及含氮量对Ｎｂ－Ｖ－Ｔｉ微合金钢抗奥氏体晶粒长大能力的影响。试验结果表明，微合金钢中加入微量钛可大大提高钢抗奥氏体晶粒长大能力，Ｎｂ－Ｖ－Ｔｉ微合金钢中含氮量增多抗奥氏体晶粒长大能力增强，但含氮量过高会影响焊接热影响区韧性。     

Guanine tetraplex formation by short DNA fragments containing runs of guanine and cytosine

Using CD spectroscopy, guanine tetraplex formation was studied with short DNA fragments in which cytosine residues were systematically added to runs of guanine either at the 5' or 3' ends. Potassium cations induced the G-tetraplex more easily with fragments having the guanine run at the 5' end, which is just an opposite tendency to what was reported for (G+T) oligonucleotides. However, the present (G+C) fragments simultaneously adopted other conformers that complicated the analysis. We demonstrate that repeated freezing/thawing, performed at low ionic strength, is a suitable method to exclusively stabilize the tetraplex in the (G+C) DNA fragments. In contrast to KCl, the repeated freeze/thaw cycles better stabilized the tetraplex with fragments having the guanine run on the 3' end. The tendency of guanine blocks to generate the tetraplex destabilized the d(G5).d(C5) duplex whose strands dissociated, giving rise to a stable tetraplex of (dG5) and single-stranded (dC5). In contrast to d(G3C3) and d(G5C5), repeated freezing/thawing induced the tetraplex even with the self-complementary d(C3G3) or d(C5G5); hence the latter oligonucleotides preferred the tetraplex to the apparently very stable duplex. The tetraplexes only included guanine blocks while the 5' end cytosines interfered neither with the tetraplex formation nor the tetraplex structure.     

计算机在市场营销管理中的应用

文章采用系统工程的观点和方法来讨论计算机这一现代化信息处理工具如何在市场营销管理中的应用问题。首先分析了市场营销管理系统的现状和存在的问题、系统的输入输出信息关系以及系统的数据流程图（即业务流程图）等，然后根据现代化市场营销管理的要求，构造出市场营销管理系统的功能结构图和系统的计算机处理模型图（即系统模型图）。     

Byssotoxin A, a secondary metabolite of Byssochlamys fulva

Byssochlamys fulva, isolated from corn, was grown on nutrient-amended shredded wheat medium for 14 days at 25 C. Crude solvent extract from these cultures was toxic to brine shrimp, chicken embryos, and rats. The extract was slightly inhibitory to the germination of of pea seeds, but was nontoxic to ten species of bacteria and one of yeast. One metabolite was isolated, given the trivial name byssotoxin A, and partially characterized chemically and physically.     

凝结芽孢杆菌产生的木聚糖酶作为预漂剂在非木材制浆中的应用

随着人们对环境的日益关注,制浆造纸工业漂白废水的排放也受到了更加严格的限制.因此,降低纸浆漂白对环境的影响就显得尤为重要.使用生物制剂(如半纤维素酶)是降低耗氯量的方法之一,Viikari等人早在1986年就首次验证了这个观点.据报道,半纤维素酶对阔叶木浆和针叶木浆的作用效果不同.     

脱墨浆高白度漂白初步研究

通过对脱墨浆(主要是旧新闻纸脱墨浆)漂白的研究,探求获取高白度漂白脱墨浆的途径.结果表明,采用螯合剂预处理的H2O2-FAS两段漂白效果优良,白度增值达到11.9%ISO,浆料最终白度可达66.6%ISO.     

Bacterial Community of Koumiss from Mongolia Investigated by Culture and Culture-Independent Methods

The bacterial community of fermented horse milk (koumiss) from Mongolia was studied using three methods: cultivation, direct identification by 16S rRNA clone library and denaturing gradient gel electrophoresis (DGGE). Ninety-eight strains were isolated by traditional cultivation and 61 of those were randomly selected for further identification by 16S rRNA gene sequencing. The strains were dominated by lactic acid bacteria (LAB; six different lactobacilli), Acinetobacter, Bacillus and Psychrobacter. Construction of the clone library analysis revealed that 16S sequences of 220 clones, genus Lactobacillus was dominant, but Streptococcus thermophilus, Acetobacter pasteurianus and uncultured clones were also detected. Ten unique bands were sequenced from the DGGE and revealed: Lactococcus lactis, Lactococcus lactis subsp. lactis, Clostridium acidurici, Acinetobacter johnsonii, Dickeya sp., Enterobacter sp., Pseudomonas sp., Raoultella sp., and Ruminococcus sp.. In vitro growth inhibition of three human pathogens, Escherichia coli, Enterobacter sakazakii and Staphylococcus aureus by 14 culturable bacteria displayed that only three of the isolates tested inhibit growth of E. sakazakii while most of the other bacteria delayed growth of the target bacteria.     

复印纸机的新压榨技术

单压区靴式压榨的发展进一步改善了纸机的生产能力和效率。这种新技术已成功地应用于斯洛伐克的1台高速复印纸机上。压榨后的纸幅干度很高，松厚度好，并且两面差小。     

封闭水循环的发展前景

近年来，新纸机的设计车速成倍增加。随着对纸产品质量要求的提高和对二次纤维利用的增加，对过程中水的质量要求也就更高。     

连铸工艺参数对圆管坯内部质量的影响初探

通过对圆管坯连铸钢水过热度、拉坯速度及二次冷却配水的系列试验,分析了其浇注工艺参数对铸坯内部裂纹及结晶组织结构的影响。通过进一步优化工艺参数,减少了圆管坯内部裂纹,扩大中心等轴晶区。缩短柱状晶区,使圆管坯质量得以改善,从而提高了圆管坯的穿孔性能,减少钢管内折。