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41.
Targeted disruption of the mouse transforming growth factor-beta 1 gene results in multifocal inflammatory disease. 总被引:149,自引:0,他引:149
M M Shull I Ormsby A B Kier S Pawlowski R J Diebold M Yin R Allen C Sidman G Proetzel D Calvin 《Nature》1992,359(6397):693-699
Transforming growth factor-beta 1 (TGF-beta 1) is a multifunctional growth factor that has profound regulatory effects on many developmental and physiological processes. Disruption of the TGF-beta 1 gene by homologous recombination in murine embryonic stem cells enables mice to be generated that carry the disrupted allele. Animals homozygous for the mutated TGF-beta 1 allele show no gross developmental abnormalities, but about 20 days after birth they succumb to a wasting syndrome accompanied by a multifocal, mixed inflammatory cell response and tissue necrosis, leading to organ failure and death. TGF-beta 1-deficient mice may be valuable models for human immune and inflammatory disorders, including autoimmune diseases, transplant rejection and graft versus host reactions. 相似文献
42.
在煤油渗剂中添加微量稀土元素对A3钢耐火砖模具进行稀土高浓度渗碳 ,可使渗速加快 ,渗层碳浓度增高 ,层深尤其是过共析 共析层深度增加 ;渗层硬度较高且硬度梯度较缓 ;渗层组织中的碳化物数量增多 ,且呈细小颗粒状弥散分布。生产实践表明 ,经该工艺处理的耐火砖模具 ,使用寿命可比常规气体渗碳处理的提高2— 3倍。 相似文献
43.
李黎 《东华大学学报(英文版)》2002,(1)
This paper is a case study about how a new product developed by Western multinational company enters new market ?the Mainland China. In this study, a new fabric ?DuPont's hi-technical Tyvek?PU Coating, is fashionized and developed into a new fashionable and functional casual-rainwear, using the approach of new product development method ( idea generation; screening; business analysis; development; evaluation and testing; commercialization). 相似文献
44.
Abnormal pattern detected in fragile-X patients by pulsed-field gel electrophoresis. 总被引:26,自引:0,他引:26
The fragile-X syndrome is the most frequent inherited form of mental retardation, with an incidence of 1 in 1,500 males. It is characterized by the presence of a fragile site at Xq27.3 induced in vitro by folate deprivation or by inhibitors of deoxynucleotide synthesis. Its mode of inheritance is unusual for an X-linked trait, with incomplete penetrance in both males and females. Some phenotypically normal males transmit the mutation to all their daughters who rarely express any symptoms, but penetrance is high in sons and daughters of these carrier women. Genetic and physical mapping of the Xq27-q28 region has confirmed that the disease locus is located at or very near the fragile site. Hypotheses proposed to account for the abnormalities in the inheritance of the disease include sequence rearrangements by meiotic recombination or a mutation that affects reactivation of an inactive X chromosome during differentiation of female germ cells. To detect such rearrangements, or methylation changes that may reflect a locally inactive X chromosome, we used pulsed-field gel analysis of DNA from fragile-X patients with probes close to the fragile-X locus. The probe Do33 (DXS465) detected abnormal patterns in fragile-X patients, but not in normal controls or in non-expressing male transmitters. 相似文献
45.
基于LDAP协议实现统一的网络管理研究 总被引:2,自引:0,他引:2
基于网络上信息存储方式的不统一及其所面临的困难 ,结合复旦大学校园网的特点 ,在深入研究LDAP协议的基础上 ,给出了一套跨协议认证的解决方案 ,提出了关于同步问题的两个模型和基于CSN方法的实现办法 相似文献
46.
In the determination of the attitude parameters from a multi-antenna GPS array, one of the major assumptions is that the body frame is rigid at all times. If this assumption is not true then the derived attitude parameters will be in error. It is well known that in airborne platforms the wings often experience some displacement during flight, especially during periods of initializing maneouvres, such as taking off, landing,and banking. Often it is at these points in time that it is most critical to have the most precise attitude parameters.There are a number of techniques available for the detection of modeling errors.The CUSUM algorithm has successfully been implemented in the past to detect small persistent changes. In this paper the authors investigate different methods of generating the residuals, to be tested by the CUSUM algorithm, in an effort to determine which technique is best suited for the detection of structural deformation of an airborne platform. The methods investigated include monitoring the mean of the residuals generated from the difference between the known body frame coordinates, and those calculated from the derived attitude parameters. The generated residuals are then passed to a CUSUM algorithm to detect any small persistent changes. An alternative method involves transforming the generated residuals into the frequency domain through the use of the Fast Fourier Transform. The CUSUM algorithm is then used to detect any frequency changes. The final technique investigated involves transforming the generated residuals using the Haar wavelet. The wavelet coefficients are then monitored by the CUSUM algorithm in order to detect any significant change to the rigidity of the body frame.Detecting structural deformation, and quantifying the degree of deformation, during flight will ensure that these effects can be removed from the system, thus ensuring the most precise and reliable attitude parameter solutions. This paper, through a series ofsimulations, will assess the effectiveness of the above mentioned techniques for detecting structural deformation effects on a GPS multi-antenna array. These principles are then tested with experimental data. 相似文献
47.
微连接用无铅钎料及稀土在钎料中的应用现状 总被引:2,自引:0,他引:2
综述了微连接用无铅钎料的应用研究现状,指出SnAgCu系合金因良好的综合性能将成为最有潜力的锡铅钎料替代品。基于对稀土在钎料中应用研究成果的分析,认为添加微量稀土有望成为改善SnAgCu系无铅钎料蠕变性能的重要途径。充分利用我国丰富的稀土资源开发低Ag的SnAgCuRE系钎料,应当成为中国今后无铅钎料研究开发的重点。 相似文献
48.
A. Fernández-Guasti K. Larsson C. Beyer 《Cellular and molecular life sciences : CMLS》1985,41(11):1414-1416
Summary Intracerebral infusion of (+) bicuculline methiodide, but not of its (–) isomer, in the preoptic area, stimulated masculine sexual behavior in rat as evidenced by a decrease in the number of intromissions preceding ejaculation and a shortening of the ejaculation latency and postejaculatory interval. Data suggest a role of the GABAergic system in mediating masculine sexual behavior.Acknowledgments. Authors wish to thank Ms Elisabeth Wallin for excellent technical assistance and Ms Madelene Kröning for preparing the figures. 相似文献
49.
根据塑料挤出的特点,在编程实现对型材截面轮廓凸凹性自动判断的基础上,采用射线法与比例间隔法相结合的方法,确定流道入口圆周上型值点的位置.以三次多项式作为流道模腔型曲线的数学模型,依据流线型要求给出的初始、边界条件,得出型曲线的数学方程.构建了挤出模流道的三维参数化曲面模型.有限元分析结果显示,该方法创建的流线型流道模型,其流动稳定性和平顺性都优于直线型流道. 相似文献
50.
刘华 《广西民族大学学报》2005,(3)
通过对瑞典导演伯格曼的电影《假面》所进行的电影美学方面的文本分析,探讨存在于人类的言语与沉默之间的哲学与美学关系,并进而探讨电影作为一种语言的形式的本体论意义。 相似文献