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1.
The cell cycle regulatory proteins, which include cyclin-dependent kinases (cdks), cdk inhibitors (CKIs), cyclins, and the pRB, and E2F families of proteins, constitute a network of interacting factors which govern exit from or passage through the mammalian cell cycle. While the proteins within these families have similar structural characteristics, each family member exhibits distinct expression patterns during embryogenesis and distinct biological activities. In order to begin to understand the tissue-specific roles of these interacting factors, we determined the expression pattern and activity of the pRB, E2F, cyclin, cdk, and CKI families of cell cycle regulatory proteins during retinoic acid-induced (neuronal pathway) and DMSO-induced (cardiac muscle pathway) differentiation of the pluripotent murine embryonal carcinoma cell line, P19. We demonstrate here that P19 terminal differentiation causes lineage-specific changes in the expression and activity of distinct members of the E2F, pRB, cyclin, and CKI families. Furthermore, dynamic changes in the activities of these cell cycle regulatory proteins occur through several overlapping mechanisms, culminating in repression of DNA-binding activity by all of the E2F family members as cells terminally differentiate.  相似文献   
2.
应用单组中子微扰理论,对辐照后控制棒钴吸收体内活度分布进行理论分析,得到活度分布计算的解析表达式。对高通量工程试验堆(HFETR)首次出堆的2根控制棒钴吸收体进行数值计算。利用钴靶活度水下测量装置进行这2根钴吸收体活度分布的实验测量。计算与实验测量结果相符。通过理论计算所得到的活度分布可作为辐照后~(60)Co同位素分装依据。本文得到的控制棒相对价值曲线理论计算值与实验测量结果符合良好。  相似文献   
3.
The existing equivalent methods usually only deal with static load models and neglect the dynamic characteristics of loads such as induction motors.This paper presents a dynamic equivalent method which considers motor dynamics.At first,the clustering criterion of motor loads is given.The motors with similar dynamic characteristics are classified into one group.Then,reduction of motors in the same group is carried out.Finally,parameters of the equivalent motor are calculated and the equivalent system is thus...  相似文献   
4.
Experimental and numerical researches were conducted to investigate the cooling performance of a single row of consoles (converging slot-hole) on a large-scale flat-plate model. The results show that the coolant flow from a row of consoles shows good lateral uniformity of adiabatic effectiveness, with regions of slightly enhanced cooling occurring between the consoles. For the console cooling geometry, the interaction between coolant jet from inclined console and the mainstream flow results in reasonable vo...  相似文献   
5.
国有企业计算机网络管理   总被引:1,自引:0,他引:1  
本论文在简单了解了计算机网络的相关内容后,对国有企业的计算机网络进行了简单的介绍,并举例说明了某国有企业的网络管理结构及功能。  相似文献   
6.
This paper describes a rapid assessment of the drug-injecting situation in Viet Nam. The study, which was carried out over a five-week period during October and November 1993, focused on the cities of Hanoi and Ho Chi Minh City. A multi-indicator inductive methodology was adopted that mixed qualitative and quantitative measures. As only limited background epidemiologic and official statistics were available, the study involved the generation of original data, through, for example, the construction of "cognitive maps" describing broad patterns of drug use, semi-structured interviews (for the collection of baseline data), focus groups, in-depth interviews and ethnographic observations. The study revealed that the injection of "blackwater" opium proliferated, often in combination with a range of pharmaceutical preparations. High-risk injecting practices were common at both Hanoi and Ho Chi Minh City, drug scenes and congregation sites being more public and visible at Ho Chi Minh City. The implications for policy and practice are discussed, emphasis being placed on the need for outreach and peer intervention.  相似文献   
7.
This paper presents an approach to automatic course generation and student modeling. The method has been developed during the European funded projects Diogene and Intraserv, focused on the construction of an adaptive e-learning platform. The aim of the platform is the automatic generation and personalization of courses, taking into account pedagogical knowledge on the didactic domain as well as statistic information on both the student’s knowledge degree and learning preferences. Pedagogical information is described by means of an innovative methodology suitable for effective and efficient course generation and personalization. Moreover, statistic information can be collected and exploited by the system in order to better describe the student’s preferences and learning performances. Learning material is chosen by the system matching the student’s learning preferences with the learning material type, following a pedagogical approach suggested by Felder and Silverman. The paper discusses how automatic learning material personalization makes it possible to facilitate distance learning access to both able-bodied and disabled people. Results from the Diogene and Intraserv evaluation are reported and discussed.  相似文献   
8.
变压器对抗短路强度的要求是很高的。文中介绍了变压器短路时的电动力的作用情况,结合单位实际情况介绍了提高变压器抗短路能力的措施。  相似文献   
9.
介绍地方电厂接入系统的基本原则和几种常见方式。  相似文献   
10.
阐述了电容式电压互感器的各种阻尼器的优缺点,并对速饱和阻尼器设计进行了详述,提出了CVT设计速饱和阻尼器应注意的事项。  相似文献   
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