Expression of two myogenic regulatory factors myogenin and MyoD1 during mouse embryogenesis

MyoD1 and myogenin are muscle-specific proteins which can convert non-myogenic cells in culture to differentiated muscle fibres, implicating them in myogenic determination. The pattern of expression of MyoD1 and myogenin during the early stages of muscle formation in the mouse embryo in vivo and in limb-bud explants cultured in vitro, indicates that they may have different functions in different types of muscle during development.     

引水电站侧向进水口体型设计的数值模拟研究

引水电站侧向进水口因河流主流方向与引水管水流方向垂直,易出现贯通式吸气漩涡.为研究进水口合理体型,采用RNG?k-方程紊流模型对四种不同体型电站进水口水流运动进行数值模拟.分析进水口内水流运动螺旋流线、漩涡强度、引水管进口流场分布情况,比较四种体型(大喇叭口型,钟型,碗型,不对称型)进水口的差异.得出碗状进水口内水流流态更好,不易出现贯通性漩涡,水力损失较小,体型设计具有相对优势,对于侧向进水口体型设计有参考意义.     

Replacing the complementarity-determining regions in a human antibody with those from a mouse

The variable domains of an antibody consist of a beta-sheet framework with hypervariable regions (or complementarity-determining regions--CDRs) which fashion the antigen-binding site. Here we attempted to determine whether the antigen-binding site could be transplanted from one framework to another by grafting the CDRs. We substituted the CDRs from the heavy-chain variable region of mouse antibody B1-8, which binds the hapten NP-cap (4-hydroxy-3-nitrophenacetyl caproic acid; KNP-cap = 1.2 microM), for the corresponding CDRs of a human myeloma protein. We report that in combination with the B1-8 mouse light chain, the new antibody has acquired the hapten affinity of the B1-8 antibody (KNP-cap = 1.9 microM). Such 'CDR replacement' may offer a means of constructing human monoclonal antibodies from the corresponding mouse monoclonal antibodies.     

Plasma protease inhibitors in mouse and man: divergence within the reactive centre regions

The plasma protease inhibitors control a wide variety of physiological functions including blood coagulation, complement activation and aspects of the inflammatory response. The inhibitors function by forming a 1:1 complex with a specific protease within the reactive centre region of the inhibitor. Little is known about the evolutionary relationships of these inhibitors. We report here the sequences of cDNAs which represent the C-terminal halves of the two major murine plasma protease inhibitors. One of these, murine alpha 1-antitrypsin, more appropriately called alpha 1-proteinase inhibitor (alpha 1-PI), has diverged from its human counterpart at a vital position in the reactive centre but this has not led to a physiologically significant change in function. Also, we have determined the partial sequence of a recently characterized protein termed contrapsin, which inhibits trypsin-like proteases. We show, surprisingly, that contrapsin is highly homologous to human alpha 1-antichymotrypsin, an inhibitor of chymotrypsin-like proteases. The reactive centre regions of these two inhibitors have diverged considerably, which may account for the differences in specificity. We propose that the genes for contrapsin and human alpha 1-antichymotrypsin are the descendents of a single gene that have evolved since rodent and primate divergence to encode proteins with different functions.     

原子力显微镜对BALB/c小鼠胚胎干细胞表面形貌的研究

以BALB／c小鼠胚胎干细胞为对象,在大气下用原子力显微镜对其进行成象。由所获得的原子力显微图象可知,BALB／c小鼠胚胎干细胞呈圆形,表面结构致密,细胞大小不一,并且是中间高四周低的形状。     

基于流-固耦合的压裂裂缝形态影响因素分析

压裂裂缝形态易受储层物性、地应力、施工参数及压裂液黏度的影响.基于多孔介质流-固耦合的基本方程,根据损伤力学基本理论,利用cohesive黏结单元模拟压裂过程中裂缝起裂、扩展造成的损伤,以此建立水力压裂垂直裂缝扩展的三维有限元模型.模型可以对垂直缝扩展进行动态模拟,定量描述压裂过程中裂缝长度、高度、宽度.通过模拟发现:①储隔层弹性模量差值较小、施工排量过大、储隔层最小水平主应力差值较小均可能造成泥岩穿层,裂缝长度急剧下降,严重影响压裂效率;②渗透率对裂缝长度的影响最大,高弹性模量、低渗透的储层容易造长缝,但是高弹性模量、高渗透或高滤失的储层裂缝长度较短;③弹性模量对裂缝宽度的影响最大.     

带钢热连轧非对称因素对板形的影响

为研究某2250 mm热连轧生产中非对称因素对轧件非对称板形(如楔形和单边浪)的影响,利用基于影响函数法的辊系变形模型、张应力模型和简化的轧制压力横向分布模型相结合的方法,建立了集轧机和轧件为一体的非对称板形计算模型。研究结果表明：来料楔形对轧件楔形的影响明显超过其对轧件平坦度的影响;上游机架和下游机架刚度非对称分别主要影响轧件楔形和平坦度;40益以内的轧件温度不对称分布对轧件平坦度影响较小,对出口楔形的影响可以忽略;轧件跑偏对楔形和平坦度均有显著影响。根据板形良好条件确定了各非对称参数的允许范围。     

几种常见形状函数超声变幅杆性能参量的统一表达

在寻求统一解的基础上，对常见形状函数变截面超声变幅杆各性能参量（如谐振频率方程、位移节点、放大系数、输入力阻抗等）都以同一式子表达出来．     

Structure of the calcium regulatory muscle protein troponin-C at 2.8 A resolution

Crystals of turkey skeletal muscle troponin-C reveal a molecule of two domains with an unusual structure. Two Ca2+ ions are bound to the C-terminal domain. The two cation-binding sites of the regulatory (N-terminal) domain are Ca2+ free; this domain adopts a markedly different conformation from the C-terminal domain. The two domains are connected by a long nine-turn alpha-helix; three of these turns are exposed fully to solvent.     

甘肃少数民族地区健身模式主因素研究

为了能够更加清晰地反映甘肃少数民族地区全民健身的整体情况 ,通过对体育生活各个组成因素进行分析研究 ,共筛选出体育生活认知、生活负荷、生活形式、生活空间、生活内容、生活消费、生活生成、生活制约源和生活心态 9个构成模式的主因子 ,它们与各个变量共同组成了甘肃少数民族地区全民健身的模式     

平交路口通行能力影响因素分析

本文针对国内城市交通以机动车和非机动车混行交通为主的现状,提出影响平交路口通行能力的五大因素。     

试论情感因素对高职英语教学的影响

结合高职院校英语教学的现状,分析五种情感因素,即动机、焦虑、自尊心、移情和课堂交流对于英语教学的影响,将情感因素融入英语教学中,发挥情感因素在英语教学中的积极作用.     

论高职高专院校辅导员工作中的人文元素

高职高专院校辅导员应努力挖掘工作中的人文元素。带着感情工作：只有热爱学生,才能无怨无悔地投入;带着责任工作,只有尽职尽责,才能将爱心深化为对学生的引领;带着智慧工作,只有善用智慧,才能使爱心和责任发挥更大作用。     

精神病患者不安心住院的心理因素及护理

目的探讨更好地做好精神病人的护理防范工作,提高护理质量。方法针对住院精神病人的疾病、社会心理、病室环境等因素进行分析,提出适当的护理计划,采取相应的护理措施。结果密切了护患关系,稳定了病人情绪,保证了护理质量。结论护士首先要成为患者的信任对象,做到心与心交流,处处为患者着想,才能使患者配合治疗,早日回归社会。     

压力容器接管区应力强度因子的数值分析

该文针对压力容器接管区高峰应变的特征,在不同孔径异形模拟试板应力应变场的光弹性分析基础上,应用奇异等参元,分析了裂纹尖端处应力强度因子,数值结果表明,与双参数法获得的应力强度因子较为吻合,为压力容器接管部位的设计和裂纹疲劳扩展分析提供了可靠依据。