(Mg-ATP)-dependent self-assembly of molecular chaperone GroEL

The important Escherichia coli heat-shock protein GroEL of relative molecular mass 57,259 is a typical molecular chaperone. It possesses ATPase activity and interacts in ATP-driven reactions with non-folded proteins to stimulate their correct folding and/or assembly by preventing the formation of improper protein structures or aggregates. As GroEL is isolated and functions as a 20-25S tetradecameric particle (GroELp), the question arises--what is the mechanism of its own assembly? Here we show the (Mg-ATP)-dependent self-stimulation ('self-chaperoning') in vitro of GroELp reassembly from its monomeric state.     

Expression of a candidate sex-determining gene during mouse testis differentiation

The development of a eutherian mammal as a male is a consequence of testis formation in the embryo, which is thought to be initiated by a gene on the Y chromosome. In the absence of this gene, ovaries are formed and female characteristics develop. Sex determination therefore hinges on the action of this testis-determining gene, known as Tdy in mice and TDF in humans. In the past, several genes proposed as candidates for Tdy/TDF have subsequently been dismissed on the grounds of inappropriate location or expression. We have recently described a candidate for Tdy, which maps to the minimum sex-determining region of the mouse Y chromosome. To examine further the involvement of this gene, Sry, in testis development, we have studied its expression in detail. Fetal expression of Sry is limited to the period in which testes begin to form. This expression is confined to gonadal tissue and does not require the presence of germ cells. Our observations strongly support a primary role for Sry in mouse sex determination.     

Molecular cloning of the microtubule-associated mechanochemical enzyme dynamin reveals homology with a new family of GTP-binding proteins

A complementary DNA encoding the D100 polypeptide of rat brain dynamin--a force-producing, microtubule-activated nucleotide triphosphatase--has been cloned and sequenced. The predicted amino acid sequence includes a guanine nucleotide-binding domain that is homologous with those of a family of antiviral factors, inducible by interferon and known as Mx proteins, and with the product of the essential yeast vacuolar protein sorting gene VPS1. These relationships imply the existence of a new family of GTPases with physiological roles that may include microtubule-based motility and protein sorting.     

在线变参数的单片微机励磁控制

本文介绍一种可在线改变调节参数的单片机励磁控制器．此调节器具有双通道，采用ＰＩＤ调节方案．适用于直流机励磁和自并励励磁的中、小型同步发电机．实验证明，此调节器可靠性高．调节性能好．精度高．使用硬件较少．     

新型J707Ni焊条的研制

本文根据焊缝扩散氢含量、氧含量及焊条工艺性能的测定结果,确定了以CaCO_3-CaF_2-TiO_2为基本渣系;又通过金相及断口分析、能谱分析和机械性能测定,研究了Cr,Ni,Mo对焊缝强度及韧性的影响及焊缝的低温断裂过程,其最佳含量范围如下:Ni为1.4％～1.6％,Cr为0.2％,Mo为0.3％～0.4％。在此基础上研制出一种新型J707Ni焊条,其各项性能基本达到国外同类焊条水平。     

用半导体力敏元件测量人体内压力的研究

本文叙述了半导体压力传感器的基本原理及用半导体压力传感器做为力电转换元件试制成的 HBU—A 型多功能人体压力测试仪的原理。报导了用该仪器在临床应用中测得的实用数据。     

s-单式环的交换性定理(英文)

本文将文献[3]的引理1推广到s-单式环上,并用迭代技术给出文献[4]的定理2一个简易的证明,将若干有1环的交换性定理推广到s-单式环上。     

黄土高原地区产业关联分析

以1985年经济统计资料为依据,分别作出黄土高原地区2000年11×11阶投入产出矩阵,直接消耗系数矩阵,以及相应的里昂节夫逆矩阵.在此基础上分析了2000年黄土高原地区的工业结构、生产波及效果和生产诱发潜力,总结出确定黄土高原工业部门权重的若干原则.     

稀土对Ni9铸钢低温机械性能及断口形貌的影响

着重研究了稀土对Ｎｉ９铸钢常温、低温机械性能和宏观、微观断口形貌的影响；考察了添加稀土钢和未添加稀土钢晶界裂纹倾向程度的大小．分析、讨论了低温机械性能、晶界裂纹倾向、断口形貌、夹杂物含量之间的关系．结果表明：添加稀土后．Ｎｉ９铸钢的晶界裂纹倾向明显降低，钢的常温、低温拉伸性能显著提高，并降低了钢的沿晶断裂倾向，但钢的低温冲击韧性并未得到改善．这与钢中晶界裂纹的倾向和夹杂物的含量有关．     

BOXCAR平均器自动测试系统

通过标准接口实现SR250 BOXCAR平均器与APPLE-Ⅱ和IBM PC/XT等微型机的联机通讯,构成自动测试系统。本文介绍该系统的硬件软件设计以及实现自动测试功能的基本原理和方法。