电阻炉温度微机控制系统的研制

以个人计算机为基础，以Ａ／Ｄ转换器为核心，并配以适当的外围接口电路，实现对电阻炉温度自动控制．设计了一种过零检测电路，将ＰＩＤ控制增量转换成占空比，并由数字电路输出有一定占空比的矩形波，利用硬件方法实现普通双向可控硅的同步过零触发从而实现功率可调     

熔模铸造高强薄壳工艺研究

提高水玻璃型壳强度，减薄型壳厚度，对节能降耗有相当大的意义．针对影响硅酸铝质粉料型壳强度的３个主要因素，进行了实验室和生产验证试验，结果表明，粒度分散分布的阳泉三级矾土粉料，在９００℃下可获得很高的高温强度．与生产现场用的二级矾土粉料相比，减薄型壳２１％以上，节约焙烧时间２５％     

在不同水硬度下铜对草鱼、鲢和大鳞泥鳅的急性毒性

实验以草鱼、鲢和大鳞泥鳅的鱼苗为材料,测定了水硬度对铜的急性毒性的影响,水硬度在255、141、37和14mg/L(以 CaCO_3计)时铜对草鱼的48小时 LC_(50)分别是519、354、91和76μg/L,96小时 LC_(50)则分别为460、307、67和39μg/L.在同样的硬度条件下,对鲢的48小时 LC_(50)是452、393、71和40μg/L,96小时 LC_(50)分别为452、296、41和31μg/L.大鲢泥鳅鱼苗在硬度260、137、36和10μg/L(以 CaCO_3计)条件下,铜的48小时 LC_(50)为369、305、1113和67μg/L,而96小时 LC_(50)则分别是226、135、67和18μg/L.铜的急性毒性和水硬度之间的关系可用下列方程来描述:草鱼 ln96小时■_(50)=1.1345+0.9051ln 硬度 r=0.99ln96小时■_(50)=2.2118+0.7220ln 硬度 r=0.97鲢 ln96小时■_(50)=0.4564+1.0207ln 硬度 r=0.97ln96小时■_(50)=1.1371+0.9232ln 硬度 r=0.98大鳞泥鳅ln96小时■_(50)=1.2823+0.7506ln 硬度 r=0.99ln96小时■_(50)=2.8635+0.5563ln 硬度 r=0.99     

论有机体代謝过程中能量供应的偶联反映和对ATP的再认识

本文着重阐述了有机体能量代谢过程中ATP—CP系统、有氧氧化和无氧酵解三大供能系统的偶联反应。并对ATP恢复的影响因素作了分析,同时介绍了作者对ATP的再认识和理解。     

尼古丁-FET传感器的研制

尼古丁是烟草中最重要的生物碱。本文报导以四苯硼酸尼古丁缔合物为活性材料,研制了尼古丁场效应管传感器,测试了器件的性能参数,获得满意的结果。其线性范围在10~(-1)～10~(-4)mol/l,斜率为56±1mV/pc,适用的 pH 范围在5.5～7.5之间。     

现代组合机床技术及其发展

本文介绍了现代组合机床技术发展的主流。分析了组合机床柔性化的几个主要方面,以及通用部件、加工精度、应用范围方面的现状及发展。最后从柔性制造技术角度介绍了组合机床综合自动化技术的发展新动向。     

An early cretaceous<Emphasis Type="Italic">Ginkgo</Emphasis> ovule-bearing organ fossil from Liaoning,Northeast China and its evolutionary implications

Ginkgo is a very important gymnospermous genus that has only one surviving species, Ginkgo biloba L. As a so-called “living fossil“, wild Ginkgo was found only in China, but it once flourished well and had a world-wide distribution in the Mesozoic. The earliest Ginkgo has been known from the Middle Jurassic, based on ovule-bearin gorgans. In the Jurassic and Early Cretaceous, Ginkgo was one of the dominant gymnosperms in floras and possibly one of the coal-forming plants in North China. During the Early Tertiary, it reduced to a circumpolar distribution in the North Hemisphere; only a few reported from the South Hemisphere. From the Pliocene onwards, the Ginkgoales has been represented by the extant monotypic “living fossil“ Ginkgo biloba.     

Regulation of BMP4 on the proliferation and differentiation in SVZa neural stem cells

The neural stem cells in the anterior subventricular zone (SVZa) mainly generate the progenitors that will differentiate into neurons, and along a highly circumscribed migratory access Rostral migratory stream (RMS), they migrate to the olfactory bulbs (OB). To understand the effects of BMPs on SVZa neural stem cells, in this study BMP4 at various concentrations was used to induce SVZa neural stem cells, and the living cell labeling using BMP4 promotor conjugated with red fluorescence protein showed the expression of BMP4 dynamically. The results demonstrated that low BMP4 doses (1-5 ng/mL) promoted while high doses (10-100 ng/mL) inhibited the proliferation of SVZa neural stem cells, and BMP4 promotedneuron differentiation in the early stage (1-3 d), howeverm, it inhibited the neuron commitment after 4 d. Noggin, the antagonist of BMP4, blocked the physiological effects of BMP4. In OB, BMP4 is mainly to accelerate the progenitors to withdraw from the cell cycle and trigger the differentiation, and in RMS, it promotes the proliferation of committed progenitors and not differentiation, further in SVZa, BMP4 enhances astrocyte commitment.     

HAb18G/CD147-mediated calcium mobilization and hepatoma metastasis require both C-terminal and N-terminal domains

HAb18G/CD147 is a heavily glycosylated protein containing two immunoglobulin superfamily domains. Our previous studies have indicated that overexpression of HAb18G/CD147 enhances metastatic potentials in human hepatoma cells by disrupting the regulation of store-operated Ca²⁺ entry by nitric oxide (NO)/cGMP. In the present study, we investigated the structure-function of HAb18G/CD147 by transfecting truncated HAb18G/CD147 fragments into human 7721 hepatoma cells. The inhibitory effect of HAb18G/CD147 on 8-bromo-cGMP-regulated thapsigargin-induced Ca²⁺ entry was reversed by the expression of either C or N terminus truncated HAb18G/CD147 in T7721C and T7721N cells, respectively. The potential effect of HAb18G/CD147 on metastatic potentials, both adhesion and invasion capacities, of hepatoma cells was abolished in T7721C cells, but not affected in T7721N cells. Release and activation of matrix metalloproteinases (MMPs), MMP-2 and MMP-9, were found to be enhanced by the expression of HAb18G/CD147, and this effect was abolished by both truncations. Thapsigargin significantly enhanced release and activation of MMPs (MMP-2 and MMP-9) in non-transfected 7721 cells, and this effect was negatively regulated by SNAP. However, no effects of thapsigargin or SNAP were observed in T7721 cells, and expression of HAb18G/CD147 enhanced secretion and activation of MMPs at a stable and high level. Taken together, these results suggest that both ectodomain and intracellular domains of HAb18G/CD147 are required to mediate the effect of HAb18G/CD147 on the secretion and activation of MMPs and metastasis-related processes in human hepatoma cells by disrupting the regulation of NO/cGMP-sensitive intracellular Ca²⁺ mobilization although each domain may play different roles.Received 1 April 2004; received after revision 15 June 2004; accepted 22 June 2004