首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The author formulated the main contradition of the epidemic process consisting of contradiction between the interaction of the motive forces of the epidemic process, since this contradiction at the same time served as the imperative condition of the origination and as the cause of the subsequent arrest of the spread of infection. The main contradiction of the epidemic process is expressed in reduction of the number and limited activity of the sources of infection, attenuation or arrest of the mechanism of transmission of the causative agents, formation of immunity in the population, the appearance of hereditary resistance in the hosts to the causative agent of the infection. The action of the principal internal contradiction of the epidemic process in the course of evolution conditions genetic variability of the causative agents of the infectious diseases, intensification of the mechanisms of excretion of the parasites from the host organism, and increase of their resistance in the external environment, formation of latent forms of infection.  相似文献   

2.
A model of neuronal structures of the medial superior olivary nuclei and inferior colliculus performing the determination of the direction on the source of the short (shorter than 10 ms) sound signals is presented. In the model the difference between the moments of the arrival of the two informational messages formed on the stage of monaural information processing is calculated. The result of this calculation is the firing probability of the primary detector (the neuron of the medial superior olivary nucleus). Because of the internal noise the curve of this probability as a function of the direction on the source is smoothly sloped. The estimation of the direction is the result of the statistical processing of the responses of the primary detectors ensemble. The direction on the source of sound is coded by a position of the secondary detector (the neuron of the inferior colliculus) on the direction "scale".  相似文献   

3.
董林 《冶金设备》2004,(2):30-32,15
针对变辊距矫直机具有不同于恒辊距矫直机的结构特点 ,给出变辊距型钢矫直机辊数、辊距的确定方法 ,并计算出各辊的弯曲力矩及矫直力 ,最后求得设备电机功率。通过设备的具体运行证明 ,变辊距结构对改善设备的受力状况及提高型钢矫直质量十分有利  相似文献   

4.
连铸坯中心线区域钢液的凝固行为与中心偏析缺陷的形成及控制密切相关。基于中碳钢连铸方坯纵断面的实际凝固组织,以中心偏析点内部二次枝晶间距计算局部冷却速率,揭示了铸坯中心线局部冷却速率的波动特征。结合连铸三维凝固模型,研究了铸坯中心线固相率波动引起局部冷却速率波动并最终影响铸坯中心组织和性能的均匀性的机理;对不同工况铸坯中心线固相率和局部冷却速率波动的周期性进行了分析对比,提出了连铸坯凝固终点位置的周期性波动机理并得到了不同拉速下凝固终点波动距离的判断方程,对于所选连铸方坯,凝固终点波动距离为25.0~27.5 mm;在此基础之上,研究了拉速对中心线固相率波动程度的影响规律,并分析了凝固终点波动距离变化对末端电磁搅拌(final electromagnetic stirring, F-EMS)和轻压下(mechanical soft reduction, MSR)作用均匀性的影响。结果表明,拉速由1.8 m/min提高至2.4 m/min后,虽然液相穴长度增加可能增加整体偏析程度,但铸坯中心线固相率波动程度降低了20%,这有利于减轻中心线偏析沿拉坯方向的波动性,提高铸坯中心质量的均匀性。并...  相似文献   

5.
Craniocerebral injuries involve changes in the vascular plexuses and ependyma of the ventricles, and the severity of these changes varies, depending on the duration of the posttraumatic period and severity of the injury. Analysis of the time course of pathomorphological changes in the cerebral ventricular structures extend our notions on the role and impact of liquor circulation in the pathogenesis of craniocerebral injury. Structural changes in the vascular plexuses may disorder the function of the blood-liquor barrier and promote the development of hydrocephalus. Changes in the structure of the ependymal membrane may involve dysfunction of the liquor-encephalic barrier of the inner surface of the brain and promote the development of brain edema.  相似文献   

6.
Electromyographic analysis of gait in eight patients who had had a modified Van Nes rotationplasty was performed to compare the activity of the flexors and extensors of the ankle on the side of the operation with that of the flexors and extensors of the knee on the normal, contralateral side. The resemblance in the activity of the extensors was more pronounced than that of the flexors. In three patients, the angle of flexion of the knee throughout the gait cycle was the same on the side of the rotationplasty as on the normal side. There was more symmetry in the swing phase than has been reported for patients who have had an above-the-knee amputation. The strength of the dorsiflexors of the ankle on the side of the rotationplasty was 68 percent and that of the flexors was 71 per cent when compared with that of the muscles of the normal ankle.  相似文献   

7.
张亮  王会  辛治宏 《世界有色金属》2020,(3):209-209,211
机床液压系统通常,下含义判断产生故障的原因。本文通过对机床液压系统常见故障进行分析,从机床液压系统振动和噪音、液压系统的冲击、液压系统中的“爬行”、液压泵出现吸空情况、液压系统温度上升五个方面进行介绍,提出诊断方法,并且介绍机床液压系统的使用和维护注意事项,希望可以帮助相关工作人员排除故障问题,保障机床液压系统的正常运作。  相似文献   

8.
The authors discuss the methodology and the method of formation of the medico-technical requirements to newly-elaborated or modified vaccine preparations. The following are considered among the principal parameters responsible for the formation of the quality of the vaccines: the prophylactic activity, the extent of the injurious effect, the technological and the exploitation properties. A close association of these parameters in the determination of the quality of the vaccine and the dependence of the efficacy of its use on the character of the epidemic situation was shown. A possibility of using the method of calculation of the efficacy of immunization for detection of the main (leading) parameters of the quality of the vaccine elaborated which should be used in composing the medico-technical requirements. It is emphasize that one of the principal directions of the investigations is the elaboration and the assessment of the correctness of the immunological and laboratory methods of standardization and control of the methods of objective measurement of the parameters forming the quality of the vaccine preparations.  相似文献   

9.
为研究采场充填料浆流动规律及充填料浆离析分层对充填体强度的影响规律,开展了充填料浆流动相似模拟试验及采场原位充填体力学强度测试试验,研究结果表明:单点下料时充填料浆流动终态坡面趋向于正态分布。流动过程中充填料浆产生离析分层现象,主要表现为充填体物料的粒径沿料浆流动方向呈先增大后减小的趋势,充填体强度沿料浆流动方向呈先减小后增大再减小的倒转“S”形趋势。采场原位充填体强度在下料口附近与标准试块强度接近,在采场中间位置附近的充填体强度最小,在距离下料点采场长度7/10左右的位置充填体强度达到最大值。研究成果能够为充填采场下料管的数量及位置设计提供依据,从而保证充填体的整体质量。  相似文献   

10.
韦东 《世界有色金属》2020,(2):257-257,260
党的十八大以后,生态文明建设作为中国特色社会主义建设的重要组成部分,对生态环境保护和治理提出了高标准,而矿山地质环境保护与治理是生态文明建设的主要内容之一,保护与治理工作开展前必先查明矿山地质环境现状。调查评价作为前期工作的主要手段之一,调查的范围、精度与评价技术方法的科学性、创新性,对矿山地质环境保护与治理工作成效起着决定性作用。  相似文献   

11.
An anatomical study was performed to define the course of the radial nerve in the posterior aspect of the arm, with particular reference to its relationship to operative exposures of the posterior aspect of the humeral diaphysis. In ten cadaveric specimens, the radial nerve was found to cross the posterior aspect of the humerus from an average of 20.7 +/- 1.2 centimeters proximal to the medial epicondyle to 14.2 +/- 0.6 centimeters proximal to the lateral epicondyle. As it crossed the posterior aspect of the humerus in each specimen, the nerve had several branches to the lateral head of the triceps; however, no branches were found innervating the medial head of the triceps in the posterior aspect of any of the specimens. At the lateral aspect of the humerus, the nerve trifurcated into a branch to the medial head of the triceps, the lower lateral brachial cutaneous nerve, and the continuation of the radial nerve into the distal part of the upper arm and the forearm. Three operative approaches were performed in each specimen. The posterior triceps-splitting approach exposed an average of 15.4 +/- 0.8 centimeters of the humerus from the lateral epicondyle to the point at which the radial nerve crossed the posterior aspect of the humerus. For the second approach, the radial nerve was mobilized proximally to allow an additional six centimeters of the humeral diaphysis to be visualized. The third approach (the modified posterior approach) involved the identification of the radial nerve distally as it crossed the lateral aspect of the humerus, followed by reflection of both the lateral and the medial heads of the triceps medially. This exposure permitted visualization of 26.2 +/- 0.4 centimeters of the humeral diaphysis from the lateral epicondyle proximally. The results after use of the modified posterior approach in seven patients were also reviewed.  相似文献   

12.
The objective of the study is, on one hand, to determine the etiology and the clinical implications as a function of the isolated germ, of central venous catheterization in patients with parenteral nutrition in our hospital, and on the other hand, to determine which factors are associated with the selection of germs of central venous catheterization in parenteral nutrition. For this we included venous catheters, colonized for 5 years, and with a study of the different segments (connection, insertion point, and tip). As a function of the appearance of associated clinical symptoms, of the results of the blood culture, and of the clinical evolution of the patient, the variables which determine the level of pathogenicity of the different groups of germs in the central venous catheterization, are defined; for the study of the factors associated with the selection of the different groups of germs, 8 variables were chosen. The data obtained are statistically treated, and the results are considered to be significant if p < 0.05. The understanding of the different factors associated with the selection of germs, and the level of clinical pathogenesis of the different groups, allows a better level of the clinical action in the prevention of the infection associated with the catheter.  相似文献   

13.
The connection between the level of Staphylococcus Aureus anti-lysozyme activity (ALA) and the character of the experimental infection course has been revealed. The subsiding type of infection was developed by infecting by clones with the low ALA and at the same time there was a shift in the structure of population at the final stage of infectious process to the reduction of its heterogeneity in respect of ALA and the preservation of the colonies only with the zero and low ALA. The protracted form of infection was provoked by the clone with the high ALA and the dynamics of microbial dissemination had rhythmical nature and a high heterogeneity in respect of ALA in the structure of population of staphylococcus was preserved and the selection of colonies with the high ALA was observed. ALA of staphylococcus is an important link of pathogenesis of persistence as it determines the duration and dynamics of the survival of the pathogen in the organism.  相似文献   

14.
在总结耐候钢采用新标准 (即《铁标》)前后的生产和质量情况的基础上 ,介绍了提高耐候钢实物质量的工艺试验情况及研究结果。结果表明 :适当减少稀土加入量是一种提高耐候钢实物质量的有效措施。  相似文献   

15.
Basic principles of predicting the fatigue life of implants of various types made from titanium nick-elide-based alloys are determined. They include an analysis of the results of preliminary clinical tests for determining the change in the implant shape during the functional displacements of a patient, the calculation of the strain from the change in the implant shape, the determination of conditions for rapid fatigue tests of implants, and the prediction of the fatigue life of the implants using the results of rapid fatigue tests of the implant material.  相似文献   

16.
詹光曹 《中国冶金》2019,29(4):64-69
中厚板轧制过程中,由于板坯在长度和宽度方向的端部会产生不均匀变形,使轧后的钢板平面形状一般非矩形,从而造成钢板的切头、切尾和切边量增加,严重影响中厚板成材率。根据不同坯料规格和展宽比条件下的塑性变形特点,在轧机负荷和液压系统硬件配置不变的前提下,采用轧件的“哑铃状”轧制法进行平面形状控制,通过长度精准计算模型及打滑因子修正方法,实现轧件长度的精准跟踪;通过多点设定方法,得到更加精细化的平面形状控制曲线,使最终产品达到切头、切尾量最优化要求。“哑铃状”轧制法投入实际应用后,与传统轧制法相比综合成材率平均提高了0.59%。  相似文献   

17.
针对螺杆压缩机在运行中出现的支撑轴承及推力轴承磨损,阴阳转子气、油封磨损变形,气缸内壁防腐层脱落及磨损;阴阳转子啮合面防腐层脱落及磨损;阴阳转子气、油封轴颈磨损;阴阳转子同步齿轮轴颈磨损;气缸端面内壁磨损;阴阳转子气封密封垫部分损坏等缺陷作了详细的分析,并以现场应用为例,提出了解决问题的措施,并在实际运用中取得了很大的成效。  相似文献   

18.
Investigation of the value of the sucking effect of the diaphragm in 44 patients was carried out. The first group consisted of 28 patients who have not undergone hepatic resection. The second group included patients after hepatic resections of various volume in local pathology. The balloon method in modification of this clinic was used for measurement of the value of the sucking effect. In patients of the first group the value of sucking effect was almost two times more under the right cupula of the diaphragm (130.33 + 4.78 mm of water column) in comparison with the left infradiaphragmatic space. It is responsible for presence of the slot between the right half of the liver and the diaphragm, which aggravates the sucking effect. In the second group of patients the value of the sucking effect under the right diaphragmatic cupula was practically the same as in patients of the first group. After right-sided hemihepatectomy the value of the sucking effect under right cupula of the diaphragm has significantly diminished. After resection of the right lobe of the liver as well as after left-sided hemihepatectomy, or without them, the value of sucking effect under left cupula of the diaphragm did not significantly differ. The investigations showed that vacuum-aspiration with vacuum of not less than 150 mm water column should be used for effective drainage of infradiaphragmatic space.  相似文献   

19.
叶刚桥 《武钢技术》2012,50(1):59-62
碳钢连退机组中,立式活套中的带钢保持稳定的张力行进,这对机组的连续平稳运行非常重要,而带钢横截面积的变化和活套钢丝绳的拉伸变形是影响活套张力稳定的两个重要因素。从原理上分析阐述带钢横截面积变化和活套钢丝绳拉伸变形对活套张力的影响,并在控制系统中添加相应的补偿环节来消除这些张力扰动。  相似文献   

20.
白振华  林威  王伟  张文军  李学通 《钢铁》2022,57(1):159-166
热镀锌机组圆盘剪工作时,由于剪切工艺参数设定不当等原因造成圆盘剪设备的故障以及带钢边部出现有扣边、毛刺和切断比失衡等主要切边质量问题,以某钢厂热镀锌机组圆盘剪设备为研究对象,对其设备本身和工艺参数展开研究.通过对影响带钢边部质量缺陷因素的分析,以及BP神经网络输入变量相关性要求选择前张力、间隙量、重叠量、切边量4个因素...  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号