北京市大气污染物与呼吸系统疾病入院人数的时间序列

为评价北京市空气污染对居民呼吸系统疾病急诊就诊人数的影响,采用基于时间序列的半参广义相加模型,在控制了长期趋势、"星期几效应"及气象因子等混杂因素的影响后,分析2009-2011年北京市空气污染物与呼吸系统疾病入院人数的暴露—反应关系,并按上呼吸道感染(上感)和下呼吸道感染(下感)分层建立模型.结果表明,污染物有一定的滞后效应,NO_2在当天或滞后2 d,SO_2在滞后2 d,PM_(10)在滞后2 d或4 d使得呼吸系统疾病急诊就诊人数的相对危险度(RR)值达到最大,其中SO2、NO2和PM_(10)浓度每增加10μg/m~3,对应的呼吸系统疾病全人群的RR值及95%置信区间(CI)分别为:1.0114(95%CI:1.0077~1.0183),1.021 3(95%CI:1.0150~1.021 3)和1.011 3(95%CI:1.0049~1.0173).同时还发现,大气污染物对上感的影响比下感明显.     

L属性文法属性求值器的自动生成技术

提出一种L属性文法LL（1）属性求值器的自动生成技术.该技术充分利用L属性文法和LL（1）分析方法的特点,节省了属性求值器的存储空间,扩展了语义规则的描述能力．且实现了一本基于该技术的属性求值器自动生成系统．     

Mediation of mouse natural cytotoxic activity by tumour necrosis factor

Natural cell-mediated cytotoxic activity in the mouse has been associated with two types of effector cells, the natural killer (NK) cell and the natural cytotoxic (NC) cell, which seem to differ with regard to their patterns of target selectivity, cell surface characteristics and susceptibility to regulatory factors. During studies on the mechanism of action of cytotoxic molecules, it became evident that WEHI-164, the prototype NC target cell, was highly susceptible to direct lysis by both human and mouse recombinant tumour necrosis factor (TNF). Here we show that NC, but not NK activity mediated by normal splenocytes, is abrogated by rabbit antibodies to recombinant and natural TNF, respectively. Thus, the cell-mediated activity defined as NC is due to release of TNF by normal spleen cells and does not represent a unique natural effector mechanism.     

Ca2+ channel modulation by 8-bromocyclic AMP in cultured heart cells

Modulation of ion channels is of increasing interest as it is an important step in the regulation of cellular functions. We have analysed the effect of 8-bromocyclic AMP on Ca2+ channels in cultured cardiac cells by the patch-clamp method and report here that there was a large increase in the probability of opening of the channels. On the basis of a recently proposed kinetic reaction scheme we suggest that cyclic AMP-dependent phosphorylation of Ca2+ channels primarily promotes the forward rate constants which lead to the open state of a Ca2+ channel during depolarization.     

蓝莓果酒发酵过程与品质关系研究

以贵州省麻江县蓝莓为酿酒原料,采用发酵法生产蓝莓果酒,选取加入酵母量、发酵时间、初始pH、发酵温度等影响果酒品质的4个关键因子,分别以感官评分、酒精度等质量指标,采用正交试验设计优化蓝莓果酒发酵工艺条件。得到以下结论:最佳发酵工艺条件为酵母用量为1.0 g/L,发酵时间为7 d,初始pH为7,发酵温度25℃,发酵酒精度为12.7%vol。最终酿造出品质优良,酒液透亮,且具有浓郁香味的蓝莓果酒,为优质蓝莓果酒的研究和开发提供了理论依据。     

等离子体氧化NO耦合湿式氨法同时脱硫脱硝试验研究

为提高燃煤烟气同时脱硫脱硝工艺中的脱硝效率,将等离子体氧化技术应用到湿式氨法脱硫工艺中,建立了等离子体氧化NO耦合湿式氨法的脱硫脱硝试验装置.考察了液气比、氨水浓度、烟气流量、烟气温度、NO初始浓度、SO2初始浓度等工艺参数对同时脱硫脱硝性能的影响.试验结果表明:提高液气比、增加氨水浓度、减少烟气流量、降低烟气温度、减小NO和SO2初始浓度都可以提高脱硝效率,而试验范围内工艺参数对脱硫效率的影响几乎可以忽略;当液气比为10 L/m3、氨水浓度为4 mol/L、烟气流量为10 m3/h、烟气温度为85℃、NO初始浓度为3.5×10-4、SO2初始浓度为1.0×10-3时,该试验装置的脱硫效率和脱硝效率分别为99.6%和69.4%.     

机动车排放模型的应用及其适用性比较

运用模型估算城市机动车排放因子及排放总量,是机动车污染控制研究的一个重要方向。目前,在模型使用方面,国内主要借用MOBILE等国外较为成熟的模型,这在我国排放因子计算方面缺乏数据积累、基础研究薄弱情况下不失为一种选择。然而,这些模型一般根据不同的需要开发,在数据积累等方面具有较强的地域性,难免会与国内实际情况不符。国内现有研究更多集中于对利用模型得到的排放因子进行分析,对模型适用性的研究鲜有涉及。本文从MOBILE、IVE、EMFAC、CMEM、COPERT模型在国内应用的实际情况出发,从模型类型,地域性,数据库的完整性、模型的可移植性和参数可获性这几个方面,比较了这几个有代表性的机动车排放模型在国内的适用程度,指出了在不同地区情况和不同阶段,模型不同的适用范围。     

Fringe is a glycosyltransferase that modifies Notch

Notch receptors function in highly conserved intercellular signalling pathways that direct cell-fate decisions, proliferation and apoptosis in metazoans. Fringe proteins can positively and negatively modulate the ability of Notch ligands to activate the Notch receptor. Here we establish the biochemical mechanism of Fringe action. Drosophila and mammalian Fringe proteins possess a fucose-specific beta1,3 N-acetylglucosaminyltransferase activity that initiates elongation of O-linked fucose residues attached to epidermal growth factor-like sequence repeats of Notch. We obtained biological evidence that Fringe-dependent elongation of O-linked fucose on Notch modulates Notch signalling by using co-culture assays in mammalian cells and by expression of an enzymatically inactive Fringe mutant in Drosophila. The post-translational modification of Notch by Fringe represents a striking example of modulation of a signalling event by differential receptor glycosylation and identifies a mechanism that is likely to be relevant to other signalling pathways.     

已服役20年的预应力混凝土空心板梁单元静力承载力试验研究

通过对一根已服役20年的预应力混凝土空心板梁单元静力承载力试验室试验,研究该梁单元在不同荷载工况作用下各个截面的挠度情况和混凝土应变,获得该梁单元的静力承载力情况;同时利用有限元分析软件ANSYS建立预应力混凝土空心板梁单元的有限元模型,分析在不同荷载工况作用下梁截面的挠度和混凝土应变,试验分析结果和理论计算结果进行对比分析,以此进行已服役20年结构的耐久性能评估并对结构整体性能进行评定。     

同时改善系统稳定和电压特性的变结构励磁控制器

依据非线性变结构控制理论,提出一种新的励磁控制器的设计方法。应用该方法设计的变结构励磁控制器,在有效地改善电力系统功角稳定性的同时,还可以改善发电机端电压的动态特性。该控制器对系统工作点的变化具有鲁棒性。仿真结果表明:该种控制器与已有的PSS控制相比,在改善系统稳定性的同时,改善了发电机端电压的动态特性