三聚氰胺快速生物降解研究

研究三聚氰胺在特定温度条件下的快速生物降解。将受试物三聚氰胺和参比物定量加入一定体积的已接种少量微生物的培养基中,三聚氰胺作为唯一的有机碳源,在黑暗恒温条件下保持受试物溶液完全充满密闭瓶。根据在28d中溶解氧的消耗来计算降解率。受试物三聚氰胺生物降解时微生物菌落消耗的氧量经平行试验的接种空白对照校正后,以ThOD的百分数表示降解率。参比苯甲酸钠28d降解率为71.4%,而三聚氰胺降解率为6.73%。判定三聚氰胺属于不易快速生物降解物质。     

1，3-金刚烷二醇快速生物降解研究

研究1,3-金刚烷二醇在特定温度条4#-TN快速生物降解。向-定体积的已接种的无机培养基加入适量受试物1,3-金刚烷二醇（100mg／L受试物至少预留50-100mg／L的理论需氧量）作为唯-的有机碳源,密闭烧瓶后在恒温（变化小于±1℃）下连续搅拌28d．通过用仪器测定烧瓶内气体压力的变化,可得到耗氧量。释放的二氧化碳用氢氧化钾吸收。在受试物生物降解的过程中（用平行试验中的接种物空白的耗氧来校正）,微生物种群吸收氧的量以ThOD的百分率来表示,参比苯甲酸钠28d降解率为82．73％,而1,3-金刚烷二醇降解率为4．17％。判定1,3-金刚烷二醇属于不易快速生物降解物质。     

顾客对某品牌衬衣3种款式的喜爱有无差异的研究

某品牌衬衣生产商有必要了解顾客对衬衣3种款式的喜爱有无显著差异,从而合理计划不同款式衬衣的生产量,使市场上不会出现过度供过于求或供不应求的情况。随机询问100名顾客,请他们对3种款式衬衣按喜爱程度排序,对所得数据做Friendman检验,定义χ2检验统计量,在5%显著性水平下检验对衬衣3种款式的喜爱是否有显著性差异。分析结果为顾客对3种款式衬衣的喜爱程度有显著差异,并且款式C最受顾客喜爱,其次是款式A,款式B受喜爱程度最差。作为生产商应定期做这样的检验,从而了解顾客对产品的喜爱程度,不但可以提高生产商的利润,还能满足不同顾客的需要,这样,一种产品才能稳固于顾客心中,在市场上长久不衰。     

任务到达时间依赖资源的单机排序问题

讨论了任务到达时间依赖于分配给它的一类资源约束问题,对问题1|rj=fj(uj),∑^ujj=1≤U^A|Cmax,将已有的一个算法做了改进,对问题1|rj=fj(uj),Cmax≤C^A|∑uj给出了在任意给定排列的条件下求最优解的算法。     

地球上,我们正整装待发

在深空探索领域,中国的步伐越来越快,正在以"后起之秀"的态势,聚集起靠自己开启"太空时代"的力量. 中国首个火星探测器"萤火"一号计划于今年10月和俄罗斯的"福布斯-土壤"卫星一起,搭乘"天顶"号运载火箭发射升空."萤火"一号既能适应火星上超过100℃的昼夜温差,又能从休眠状态中按时苏醒.由于与地面测控站的一次往返"对话"就需44分钟,在大多数情况下,"萤火"一号必须有强大的自控能力来"自己管自己".好在所有地面模拟试验证明,它已经在技术上做好充分准备(1月3日新华网).     

基于目标的新船构造标准对海事监管的影响

主要描述IMO关于基于目标的新船构造标准的现状,以及其对海事监管方面的影响.面对挑战,主管机关应该采取相应的行动去适应新标准带来的变化.同时,在新形势下找到合适的方法去监督船舶安全和保护环境.     

“高薪养廉”能否成为反腐利器探究

腐败作为一种政治行为和行政行为的败坏现象，严重威胁着我国政治、经济、文化建设的健康发展。有人认为“高薪养廉”可以有效地根治腐败现象，有利于社会稳定。这一观点，从根本上不符合中国国情，它违背了马克思主义公仆观思想，不利于和谐社会发展的需要。     

Haematopoietic stem cells do not asymmetrically segregate chromosomes or retain BrdU

Stem cells are proposed to segregate chromosomes asymmetrically during self-renewing divisions so that older ('immortal') DNA strands are retained in daughter stem cells whereas newly synthesized strands segregate to differentiating cells. Stem cells are also proposed to retain DNA labels, such as 5-bromo-2-deoxyuridine (BrdU), either because they segregate chromosomes asymmetrically or because they divide slowly. However, the purity of stem cells among BrdU-label-retaining cells has not been documented in any tissue, and the 'immortal strand hypothesis' has not been tested in a system with definitive stem cell markers. Here we tested these hypotheses in haematopoietic stem cells (HSCs), which can be highly purified using well characterized markers. We administered BrdU to newborn mice, mice treated with cyclophosphamide and granulocyte colony-stimulating factor, and normal adult mice for 4 to 10 days, followed by 70 days without BrdU. In each case, less than 6% of HSCs retained BrdU and less than 0.5% of all BrdU-retaining haematopoietic cells were HSCs, revealing that BrdU has poor specificity and poor sensitivity as an HSC marker. Sequential administration of 5-chloro-2-deoxyuridine and 5-iodo-2-deoxyuridine indicated that all HSCs segregate their chromosomes randomly. Division of individual HSCs in culture revealed no asymmetric segregation of the label. Thus, HSCs cannot be identified on the basis of BrdU-label retention and do not retain older DNA strands during division, indicating that these are not general properties of stem cells.     

Supermassive black holes do not correlate with galaxy disks or pseudobulges

The masses of supermassive black holes are known to correlate with the properties of the bulge components of their host galaxies. In contrast, they seem not to correlate with galaxy disks. Disk-grown 'pseudobulges' are intermediate in properties between bulges and disks; it has been unclear whether they do or do not correlate with black holes in the same way that bulges do. At stake in this issue are conclusions about which parts of galaxies coevolve with black holes, possibly by being regulated by energy feedback from black holes. Here we report pseudobulge classifications for galaxies with dynamically detected black holes and combine them with recent measurements of velocity dispersions in the biggest bulgeless galaxies. These data confirm that black holes do not correlate with disks and show that they correlate little or not at all with pseudobulges. We suggest that there are two different modes of black-hole feeding. Black holes in bulges grow rapidly to high masses when mergers drive gas infall that feeds quasar-like events. In contrast, small black holes in bulgeless galaxies and in galaxies with pseudobulges grow as low-level Seyfert galaxies. Growth of the former is driven by global processes, so the biggest black holes coevolve with bulges, but growth of the latter is driven locally and stochastically, and they do not coevolve with disks and pseudobulges.     

商品混凝土使用中若干问题的探讨

大中城市混凝土预拌实现工业化生产已作为保护环境，保证混凝土质量的一项有力措施正施工正被逐步推广实施，文章探讨了商品混凝土在生产，运输，拌合，浇筑，养护等环节存在的问题，提出了相应的预防改进措施.     

旅游外宣资料汉英翻译中的"译与不译"

旅游外宣资料汉英翻译中的"译与不译"问题,应在功能主义翻译理论"目的论"的指导下,突破传统"忠实"翻译原则的束缚,强调以读者为中心,采用合适的翻译策略予以解决,以实现目的语读者的交际目的.具体表现在增译、缩译、编译和创译四个方面.     

310快速生物降解试验中顶空体积的计算方法

经济合作发展组织发布的310试验是适用性最广的快速生物降解试验,但试验导则中未给出试验系统顶空体积的设定方法。根据试验有效性对溶解氧浓度和受试物在气/水两相系统中分配的要求,使用亨利定律和理想气体状态方程,得到以微生物耗氧量、受试物浓度、受试物理论需氧量和受试物的亨利常数计算试验系统顶空体积的公式。以2-甲基萘和柠檬烯为例,说明了公式的应用过程。研究结果可指导试验设计,促进试验方法的标准化。     

Global hotspots of species richness are not congruent with endemism or threat

Biodiversity hotspots have a prominent role in conservation biology, but it remains controversial to what extent different types of hotspot are congruent. Previous studies were unable to provide a general answer because they used a single biodiversity index, were geographically restricted, compared areas of unequal size or did not quantitatively compare hotspot types. Here we use a new global database on the breeding distribution of all known extant bird species to test for congruence across three types of hotspot. We demonstrate that hotspots of species richness, threat and endemism do not show the same geographical distribution. Only 2.5% of hotspot areas are common to all three aspects of diversity, with over 80% of hotspots being idiosyncratic. More generally, there is a surprisingly low overall congruence of biodiversity indices, with any one index explaining less than 24% of variation in the other indices. These results suggest that, even within a single taxonomic class, different mechanisms are responsible for the origin and maintenance of different aspects of diversity. Consequently, the different types of hotspots also vary greatly in their utility as conservation tools.