连铸小方坯的组织与性能研究

The hot cracking of the continuous casting bullit is connected with its macrostructure and mechanical property burnt. The macrostructure and the mechanical property of 0. 13 wt- %C continuous casting bullit was investigated. The results are as follows: 1) the classical representation of the casting bullit shows three distinct zones, a peripherial region of small equiaxed grains, a columnar zone, and a central equiaxed zone. The rapid increase of the under cooling layer thickness is the criterion of the transformation from the columnar zone to central equiaxed zone; 2) The hardness decreases with the reducing of the solidification speed; 3) The tensile strength decreases gradually from the peripherial equiaxed maximum principal strain zone to central equiaxed zone ,and increases with the drop of the temperature.     

Clustering of voltage-dependent sodium channels on axons depends on Schwann cell contact.

In myelinated nerves, segregation of voltage-dependent sodium channels to nodes of Ranvier is crucial for saltatory conduction along axons. As sodium channels associate and colocalize with ankyrin at nodes of Ranvier, one possibility is that sodium channels are recruited and immobilized at axonal sites which are specified by the subaxolemmal cytoskeleton, independent of glial cell contact. Alternatively, segregation of channels at distinct sites along the axon may depend on glial cell contact. To resolve this question, we have examined the distribution of sodium channels, ankyrin and spectrin in myelination-competent cocultures of sensory neurons and Schwann cells by immunofluorescence, using sodium channel-, ankyrin- and spectrin-specific antibodies. In the absence of Schwann cells, sodium channels, ankyrin and spectrin are homogeneously distributed on sensory axons. When Schwann cells are introduced into these cultures, the distribution of sodium channels dramatically changes so that channel clusters on axons are abundant, but ankyrin and spectrin remain homogeneously distributed. Addition of latex beads or Schwann cell membranes does not induce channel clustering. Our results suggest that segregation of sodium channels on axons is highly dependent on interactions with active Schwann cells and that continuing axon-glial interactions are necessary to organize and maintain channel distribution during differentiation of myelinated axons.     

运动时血浆皮质醇变化的影响因素

本文综合了在运动时血清皮质醇浓度的变化不仅受运动形式，运动强度，运动持续时间，血浆ｐＨ，训练水平，缺氧，心理等多种因素的影响，并且各因素间的相互作用也是影响其变化的重要因素。     

一个关于抽象经济的均衡存在定理

在抽象经济的均衡存在定理中，一般都假设偏好对应具有开图像。用一个较弱的条件代替关于偏好对应的开图像假设，证明了均衡的存在性。所得结果是Ｙａｎｎｅｌｉｓ（１９８７）均衡存在定理的一个推广．     

数学规划模型的建模语言（FQL）

对数学规划模型的结构作了深入分析。从纵向揭示了数学规划模型自然、清晰的层次结构；横向又把复合模型分解成若干基本模型，而基本模型又可由决策用户十分熟悉的二维形式加以描述。在此基础上，给出了建模语言（ＦＱＬ）的语法和语义。它除了具有建模能力外，消除了代数形式的索引；更重要的是具有数据库查询和模型操作能力。     

大理市土地资源人口承载能力之研究

大理市人地矛盾十分尖锐，深入开展本市土地人口承载力的研究有着很重要的意义。本文在讨论土地承载力研究内容（包括三个部分：（１）土地承载力测算；（２）土地承载力分析；（３）对策与措施的制定）的基础上，测算了本市土地在不同投入水平下的人口承载量，进而分析了本市土地的人口承载状况，划分了不同时期（１９９０年、２０００年、２０３０年）不同投入水平下的土地承载力类型。最后，提出了缓解本市人地矛盾的主要对策和措施。     

A ground‐level ozone forecasting model for Santiago,Chile

A physically based model for ground‐level ozone forecasting is evaluated for Santiago, Chile. The model predicts the daily peak ozone concentration, with the daily rise of air temperature as input variable; weekends and rainy days appear as interventions. This model was used to analyse historical data, using the Linear Transfer Function/Finite Impulse Response (LTF/FIR) formalism; the Simultaneous Transfer Function (STF) method was used to analyse several monitoring stations together. Model evaluation showed a good forecasting performance across stations—for low and high ozone impacts—with power of detection (POD) values between 70 and 100%, Heidke's Skill Scores between 40% and 70% and low false alarm rates (FAR). The model consistently outperforms a pure persistence forecast. Model performance was not sensitive to different implementation options. The model performance degrades for two‐ and three‐days ahead forecast, but is still acceptable for the purpose of developing an environmental warning system at Santiago. Copyright © 2002 John Wiley & Sons, Ltd.     

Mechanism for the learning deficits in a mouse model of neurofibromatosis type 1.

Neurofibromatosis type I (NF1) is one of the most common single-gene disorders that causes learning deficits in humans. Mice carrying a heterozygous null mutation of the Nfl gene (Nfl(+/-) show important features of the learning deficits associated with NF1 (ref. 2). Although neurofibromin has several known properties and functions, including Ras GTPase-activating protein activity, adenylyl cyclase modulation and microtubule binding, it is unclear which of these are essential for learning in mice and humans. Here we show that the learning deficits of Nf1(+/-) mice can be rescued by genetic and pharmacological manipulations that decrease Ras function. We also show that the Nf1(+/-) mice have increased GABA (gamma-amino butyric acid)-mediated inhibition and specific deficits in long-term potentiation, both of which can be reversed by decreasing Ras function. Our results indicate that the learning deficits associated with NF1 may be caused by excessive Ras activity, which leads to impairments in long-term potentiation caused by increased GABA-mediated inhibition. Our findings have implications for the development of treatments for learning deficits associated with NF1.     

蒸球球内温度分布及测量的研究

对蒸球球内温度分布进行了详细的分析，提出采用中通管测量球内温度并通过计算机对测量值进行校正的方法，实践说明了该方法效果良好，为采用Ｈ－因子数学模型控制蒸煮过程提供了更合理的手段。     

The General Machining Process Simulator GMPS

Ｔｈｅ　Ｇｅｎｅｒａｌ　Ｍａｃｈｉｎｉｎｇ　Ｐｒｏｃｅｓｓ　Ｓｉｍｕｌａｔｏｒ　ＧＭＰＳＸｉａｏＴｉａｎｙｕａｎ，ＹａｎｇＧａｎｇ＆ＬｉＸｉｎ（ＤｅｐａｒｔｍｅｎｔｏｆＡｕｔｏｍａｔｉｏｎ，ＴｓｉｎｇｈｕａＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎｇ，Ｃｈｉ...