高速客运通道上多种运输方式的分担率分析

为预测高速铁路建成后高速客运通道上各种运输方式的分担率,优化高速客运的资源配置,面向具有高速出行需求的乘客实施SP(Stated Preference)问卷调查,利用调查数据构建Logit模型,分析高速客运通道上各种运输方式的分担率.针对高速铁路和民航的出行耗时、票价和发班频率等参数进行敏感性分析,得出高速客运需求对两种运输方式各种属性的敏感程度.基于竞合博弈模式提出哈-大高速客运通道上高速客运服务商应该采取的运营策略,以实现该通道上高速客运资源配置的整体优化.     

基因替换及多基因共表达强化大肠杆菌辅酶Q10的合成能力

为了强化大肠杆菌合成辅酶Q10（CoQ10）的能力,对大肠杆菌进行了相关的基因操作。通过敲除大肠杆菌染色体上的聚八异戊二烯焦磷酸合成酶基因ispB,并导入来自Gluconobactersuboxydans的聚十异戊二烯焦磷酸合成酶基因ddsA,使大肠杆菌具有CoQ10合成能力的同时降低了内源性辅酶Q8（CoQ8）的合成。采用双质粒共表达系统,对CoQ生物合成途径中多个功能基因进行了强化表达,构建得到的重组大肠杆菌CoQ的合成能力、CoQ10合成的专一性都有明显改善,其中ubiCA和ddsA基因的协同表达效果最为明显,CoQ的合成能力比对照提高了65%,而CoQ10的合成量也提高了1.1倍。     

A simple and effective method for total RNA isolation of appressoria in Magnaporthe oryzae

Appressorium formation is an important event in establishing a successful interaction between the rice blast fungus, Magnaporthe oryzae, and its host plant, rice. An understanding of molecular events occurring in appressorium differentiation will give new strategies to control rice blast. A quick and reliable method to extract total RNA from appressorium is essential for studying gene expression during appressorium formation and its mechanism. We found that duplicate film is an efficient substratum for appressorium formation, even when inoculated with high density conidia. When inoculated with conidia at 1 × 106 ml^-1, the percentages of conidium germination and appressorium formation were （97.98±0.67）% and （97.88±0.45）%, respectively. We applied Trizol before appressorium collection for total RNA isolation, and as much as 113.6 lag total RNA was isolated from the mature appressoria at 24 h after inoculation. Functional analysis of two genes, MNH6 and MgATG1, isolated from the cDNA subtractive library, revealed that the quantity of RNA was good enough to construct a cDNA （complementary DNA） library or a cDNA subtractive library. This method may be also applicable for the appressorium RNA isolation of other pathogenic fungi in which conidia differentiate into appressoria in the early stages of host infection.     

基于收益率与风险比率的期货套期保值策略研究

引入目标收益率作为衡量套期保值行为盈亏的界线,建立基于改进的收益率与风险比率相对数最大化的期货套期保值优化决策模型。使得单位风险下组合期望收益率大于目标收益率的收益程度最大,从理论上推导出空头和多头套期保值的最优套期比率,并与传统套期比作比较,求出了空头和多头在传统最优套期比基础上的调整量。给出了当目标收益率满足一定条件时,空头和多头套期保值的最优套期比公式。     

Regulatory networks define phenotypic classes of human stem cell lines

Stem cells are defined as self-renewing cell populations that can differentiate into multiple distinct cell types. However, hundreds of different human cell lines from embryonic, fetal and adult sources have been called stem cells, even though they range from pluripotent cells-typified by embryonic stem cells, which are capable of virtually unlimited proliferation and differentiation-to adult stem cell lines, which can generate a far more limited repertoire of differentiated cell types. The rapid increase in reports of new sources of stem cells and their anticipated value to regenerative medicine has highlighted the need for a general, reproducible method for classification of these cells. We report here the creation and analysis of a database of global gene expression profiles (which we call the 'stem cell matrix') that enables the classification of cultured human stem cells in the context of a wide variety of pluripotent, multipotent and differentiated cell types. Using an unsupervised clustering method to categorize a collection of approximately 150 cell samples, we discovered that pluripotent stem cell lines group together, whereas other cell types, including brain-derived neural stem cell lines, are very diverse. Using further bioinformatic analysis we uncovered a protein-protein network (PluriNet) that is shared by the pluripotent cells (embryonic stem cells, embryonal carcinomas and induced pluripotent cells). Analysis of published data showed that the PluriNet seems to be a common characteristic of pluripotent cells, including mouse embryonic stem and induced pluripotent cells and human oocytes. Our results offer a new strategy for classifying stem cells and support the idea that pluripotency and self-renewal are under tight control by specific molecular networks.     

炼镁还原罐材质的成份设计

本文针对炼镁还原罐在使用条件下的破坏形式及对该材质的成份设计进行了分析 ,还原罐材质在具有单一奥氏体的基础上 ,进行良好的合金化处理是提高其抗蠕变性和热强性的有效方法 ,对提高材质的使用寿命起到良好的作用。     

One-step disposal of Cr (Ⅵ)-bearing wastewater by natural pyrrhotite

Cr(VI)-bearing wastewater can be treated by natural pyrrhotite which is used for reductant to reduce Cr(VI) and precipitant to precipitate Cr(III) simultaneously. The disposal products can be divided into three parts in the beakers, namely supernatant in the upper part, the yellowish colloidal precipitates in the middle part and the pyrrhotite in the lower part. The content of total Cr=Cr(VI)+Cr(III) in the supernatant liquid is 0.06 mg/L, which is lower than 1.5 mg/L of the discharge standard of China and near to 0.05 mg/L of the standard of potable water. This one-step disposal composing of both reduction and precipitation which is traditionally divided into two independent steps called reducing technology and precipitating technology respectively. The new method is of obvious economic advantage and favourable to decreasing surplus mud derived from adding Ca(OH)₂ to precipitate Cr(III) traditionally so as to avoid recontamination. In fact, sodium sulfite (Na₂SO₃) used in disposal of Cr(VI) was traditionally produced from natural mineral of pyrrhotite (FeS). One molecule of FeS is 4 times more than that of Na₂SO₃ from a view point of rational use of mineral resources. Therefore the prospective of application of the one-step disposal of Cr(VI) method is full of promise.     

Ionization and dissociation of acetonitrile by intense femtosecond laser pulse

Photoionization and photodissociation of CH3CN were studied by a linear time of flight mass spectrometer coupled with 800 nm, 50 fs laser pulses at intensities of 6.3×1013-1.2×1014 W/cm2. The laser power dependences for principal ions CH3CN+, CH2CN+, CHCN+ and CCN+ were measured, which are consistent with the numbers of photons required to produce the ions via multiphoton ionization and dissociation. The results show that eight-photon non-resonant multiphoton ionization is the main photoionization mechanism of the parent ion CH3CN+, while the fragment ions were produced through the dissociation of the molecules in the super-excited states.     

环台湾岛海域M2分潮特征的数值模拟

利用９７版ＰＯＭ模式对环台湾岛海域Ｍ２分潮作了分辨率较高的三维数值模拟。在较准确地模拟了潮汐分布的基础上,研究了Ｍ２分潮流椭圆分布、最大流同时线分布以及潮流场结构。结果表明,环台泫岛海域的Ｍ２潮波主要为大洋传来的胁振潮,台湾海峡为强潮区;Ｍ２分潮最大流同时线在海峡中部形成密集区;构成海峡潮波系统的两支潮波中嵫支潮波的强度远大于南支潮波,其影响范围可以到达台湾浅滩南缘,但两支潮波影响范围并没有达到“     

缓冲液条件对水霉细胞壁结合Ca2+的影响

用原子吸收光谱研究了pH值、Tris 马来酸缓冲液浓度对水霉 (Saprolegniaferax)顶端生长菌丝细胞壁与Ca2 结合的影响 .发现在 pH 3.5～ 6 .0范围内 ,细胞壁结合的Ca2 随 pH值升高而增加 ,pH >6 .0时 ,细胞壁结合的Ca2 呈下降趋势 .细胞壁结合的Ca2 随Tris 马来酸缓冲液浓度升高而增加 ,Tris浓度高于 9mmol/L时 ,细胞壁结合的Ca2 则减少 .细胞壁最多可结合Ca2 量>6 0 μmol/L .证明细胞壁Ca2 确实是水霉顶端生长赖以维持的胞外Ca2 库 .