关于函数(S)k(n)的均值

研究了函数S^-k（n）的均值性质,并用初等方法得到了关于它的一个渐近公式.     

Role of general stress-response alternative sigma factors σ(S) (RpoS) and σ(B) (SigB) in bacterial heat resistance as a function of treatment medium pH

This investigation aimed to determine the role of general stress-response alternative sigma factors σ^S (RpoS) and σ^B (SigB) in heat resistance and the occurrence of sublethal injuries in cell envelopes of stationary-phase Escherichia coli BJ4 and Listeria monocytogenes EGD-e cells, respectively, as a function of treatment medium pH. Given that microbial death followed first-order inactivation kinetics (R² > 0.95) the traditional D_T and z values were used to describe the heat inactivation kinetics.Influence of rpoS deletion was constant at every treatment temperature and pH, making a ΔrpoS deletion mutant strain approximately 5.5 times more heat sensitive than its parental strain for every studied condition. Furthermore, the influence of the pH of the treatment medium on the reduction of the heat resistance of E. coli was also constant and independent of the treatment temperature (average z value = 4.9 °C) in both parental and mutant strains.L. monocytogenes EGD-e z values obtained at pH 7.0 and 5.5 were not significantly different (p > 0.05) in either parental or the ?sigB deletion mutant strains (average z value = 4.8 °C). Nevertheless, at pH 4.0 the z value was higher (z = 8.4 °C), indicating that heat resistance of both L. monocytogenes strains was less dependent on temperature at pH 4.0. At both pH 5.5 and 7.0 the influence of sigB deletion was constant and independent of the treatment temperature, decreasing L. monocytogenes heat resistance approximately 2.5 times. In contrast, the absence of sigB did not decrease the heat resistance of L. monocytogenes at pH 4.0.The role of RpoS in protecting cell envelopes was more important in E. coli (4 times) than SigB in L. monocytogenes (1.5 times). Moreover, the role of σ^S in increasing heat resistance seems more relevant in enhancing the intrinsic resilience of the cytoplasmic membrane, and to a lesser extent, outer membrane resilience.Knowledge of environmental conditions related to the activation of alternative sigma factors σ^S and σ^B and their effects on heat resistance would help us to avoid and/or identify situations that increase bacterial stress resistance. Therefore, more efficient food preservation processes might be designed.     

St(a)ubli: 新型提花机

由瑞士Staubli　Sargans公司所产LX3201新型高速提花机,能配置14336针。该机适合应用于平面织物,尤其是丝绸和室内装饰品的高速生产。     

Steri粘胶纤维和莫代尔(Modal)粘胶纤维

前言纺织纤维分为天然纤维和人造纤维。在这两大类纤维中,最重要的纤维是棉花、羊毛和亚麻。人造纤维又可进一步分为再生纤维、合成纤维和无机纤维。作为纺织原料的最重要的再生纤维是用粘胶法生产的粘胶和莫代尔再生纤维素纤维,而最重要的合成纤维是聚酯纤维、聚丙烯腈纤维和聚酰胺纤维。这一分类法示于表1。     

St(a)ubli: 最新的科技成果

遵循"让技术革新服务于客户"的理念,史陶比尔一直以来不懈地努力,为纺织工业提供保持竞争力的产品.这些先进技术使客户扩大了生产能力,并为客户提供了更有效的生产方法.     

St(a)ubli: 新型高端提花机

在土耳其伊斯坦布尔举行的ITM 2006上,瑞士Stubli公司展示了两款新型电子提花机--LX 1602和LX 3202(图1).两种机型都是设计用于高速高产织造普通织物和毛圈织物,是在LX 1600/3201机型的基础上开发的.两款新机型保留了原有的概念并接纳了许多改进,具有更好的性价比.     

求解方程f(a+b)=f(a)+f(b)的一种方法

给出了求函数方程f(α b)=f(α) f(b)的所有连续解的一种方法，并分析了这种方法形成的直观背景．     

Chirale Phthalid-Aromastoffe: (3a–7a)-cis-3-Butylhexahydrophthalid-Stereoisomere in Knollensellerie (Apium graveolens L var.rapaceum)

In diethyl ether extracts from celeriac (Apium graveolens L. var.rapaceum) all four stereoisomers of (3a–7a)-cis-3-butylhexahydrophthalide were found to be present. The analyses were carried out by means of GC, enantioselective GC and GC-MS. The assignment of the relative configuration of the diastereomers3 and4 was accomplished by NOE difference spectroscopy.     

中国原创设计推荐(29) S12书桌

设计说明:S12书桌使用美国白橡木制作,圆润别致的外形加上木材的天然纹理是它最主要的特点,此外,为了方便运输、实现平板包装、桌腿是可以拆卸的,在构造上结合了榫卯与五金各自的优点。产品尺寸为长120cm×宽60cm×高75cm.SPACE推荐:这款简洁优雅的书桌,以最简单的表现手法展现出术质自身最天然的魅力。可拆卸的设计便于运输、也体现了环保的概念。价格:1600元/件售卖地点:http://smartwood.taobao.com/     

NOVACRON(R)S:达到极限,超越领域

对印染厂而言,实现真正的深色色彩-直是一个巨大的挑战.只有采用大量染料才能实现真正的深色色彩,但能源和水的消耗量巨大,染料成本高,且色牢度较差,废水中存在大量染料,对环境造成极大的危害.     

稻谷中苯并(a)芘的测定

将粉碎后的稻谷样品置于脂肪提取器中，采用石油醚回流提取８ｈ，提取液用中性氧化铝净化，ＫＤ浓缩器浓缩。采用液相色谱对稻谷中苯并芘的含量进行测定，分离柱ＯＤＣＳ－Ｃ１８；流动相为８５％，甲醇和１５％水，流速为１ｍｌ／ｍｉｎ；荧光检测器检测。     

蜚声世界的铁狮东尼(a.testoni)

意大利皮件品牌铁狮东尼历史悠久,声誉世界,自前年进入中国市场以来,为我国消费者所逐步了解,其产品的优良品质和设计的高雅品位也赢得越来越多中国消费者的青睐。     

食用油中苯并(a)芘分析方法研究进展

苯并(a)芘由于其强致癌性,引起各国科学家对其进行深入广泛的研究。介绍了食用油中苯并(a)芘的分析方法及样品前处理方法的研究进展,提出食用油中苯并(a)芘分析方法的新需求。     

Guitang (Group) Announced to Build a 15,000 t/a Paper Production Line

On January 6th, 2013, the 60,000 t/a household paper project of Zijinghua Paper Co., Ltd. was approved by Development and Reform Commission of Ningxia Hui Autonomous Region.     

J2101S(2)型胶印机电气线路的改进

我厂新购进一台江苏如皋印刷机械厂生产的J2101S(2)型胶印机。在使用过程中,该机经常出现点动变连动;清洗胶辊时,不得不用手搬动飞轮进行擦洗,给操作人员带来许多麻烦。究其原因,是因电气线路存在一定的缺陷:     

日本栗田化学研究所的KR-TEX(S)重氮感光胶

1982年4月下旬,日本栗田化学研究所在上海第一丝绸印染厂进行技术交流,交流的题目是KR—TEX(S)重氮感光胶。 日方首先介绍了栗田化学研究所的简况。该所是专门研究生产重氮感光胶的商社研究所,重氮感光胶KR-TEX是该所近两年中最新研究生产的商品,用它制作印花网版和印刷网版,具有无味、无毒、制版精细,使用方便的优点,尤其与重铬酸铵相比没有三废之患;但在显影时有显影困难之弊。     

烤肉中苯并(a)芘的检测分析

苯并(a)芘是一种常见致癌、致畸、致突变作用的有机化合物。烧烤肉制品容易产生苯并(a)芘,且烧烤过程中周围空气中也产生大量苯并(a)芘颗粒,对人体带来安全性问题,而烤肉的加工方式对烤肉制品中苯并(a)芘的残留有很大的关系,是控制苯并(a)芘的源头,间接接触明火是苯并(a)芘的残留降到最低的烤制方式。