动力学中的临界问题

在动力学问题中,常常会出现临界状态,此类问题的解法一般有以下三种方法. 一、极限法 在题目中如果出现"最大"、"最小"、"刚好"等关键词时,一般隐藏着临界问题.处理这类问题时,常常把物理问题或过程推向极端,从而将临界状态及临界条件显露出来,达到尽快求解的目的.     

装载机工作装置偏载工况动力学分析

在工程上运用的重要机器装载机,工作装置是装载机进行工作的重要构件。用PRO/E4.0创工作装置的三维模型,然后倒入ADAMS2010中,且以偏载工况为例,对动臂及摇臂进行动力学分析,其结果表明,在铲掘和卸载工况时,动臂、摇臂各自的受力较大,铰接点不同。     

酶催法研究超氧自由基（O^·—2）的动力学

实验选择黄嘌呤－黄嘌呤氧化酶作为系统，反应在O2存在下，底物黄嘌呤发生催化氧化，产生超氧自由基（O^&;#183;-2)，由2，6－－二氯靛酚钠试剂检测，通过运用Michaelis反应机理处理，最终得到氏常数（KM),Cu^2+能抑制黄嘌呤氧化酶的作用效果，其抑制作用可通过v0-[Cu^2+]曲线看出。     

中国科学院1992年度自然科学奖一等奖项目简介

经中国科学院自然科学奖评审委员会评选、院长办公室审定，1992年度自然科学奖一等奖17项，简介如下：     

溃疡性结肠炎的食疗方法

溃疡性结肠炎在临床表现为慢性腹泻、粘液便或粘液血便及腹痛,病程缓慢,轻重不一,有缓解和反复发作的趋势。其发病机制仍未明确,大多数学者认为,它是基因的易感性、肠道细菌、自身免疫反应及环境因素协同作用的结果。当前治疗仍以糖皮质激素类、柳氮磺胺类和免疫抑制剂等药物为主,这些治疗有副作用大,停药后易复发等缺点。现介绍几种结合中医药的食疗方法。柴胡桂枝饮配方:柴胡25克、人参10克、半夏20克、桂枝15克、黄芩10克、白芍10克、生姜10克、大枣10克、甘草6克、白糖20克制作:1·将以上药物洗干净,放入铝锅内,加水适量。2·将铝锅置武…     

人工智能产业创新能力与融资生态耦合演进——基于系统动力学视角

基于系统动力学视角构建中国人工智能产业创新能力与融资环境仿真系统,采用耦合协调度模型分析产业创新能力与融资生态的耦合演进阶段,并探索不同创新情景对融资环境耦合协调阶段的影响效果。研究结果表明:(1)中国人工智能产业创新能力与融资环境长期处于基本协调和中度协调状态,系统仿真结果预测将于2019年跨入高度协调。(2)创新能力的增量改变对系统耦合协调程度有不同程度的正向改善作用,创新资源的拉动作用最为显著,人工智能产业的生态情境依赖性决定了政府在对资金量总体供给进行适度引导的同时应避免陷入"政府干预陷阱"。     

用电流的定义式I=Δq／Δt破解含容电路问题

含容电路问题是一类非常典型的直流电路问题,它不仅涉及直流电路的一般计算,同时还涉猎到电路中的运动学、动力学、乃至动量与能量问题,综合性强,难度大．现用以下三例说明含容电路问题的解决方法．     

Novel distribution pattern of fibrinolytic components in rabbit tissues extract： a preliminary study

Objective: The purpose of this work was to investigate the distribution pattern of fibrinolytic factors and their inhibitors in rabbit tissues. Methods: The components of the fibrinolytic system in extracts from a variety of rabbit tissues, including tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), plasminogen (Plg), plasmin (Pl) and α2 plasmin inhibitor (α2PI), were determined by colorimetric assay. Results: The tissue extracts in renal, small intestine, lung, brain and spleen demonstrated strong fibrinolytic function, in which high activity of tPA, Plg and Pl was manifested; whereas in skeletal muscle, tongue and stomach, higher activity of PAI-1 and α2PI showed obviously. Also excellent linear correlations were found between levels of tPA and PAI-1, Pl and α2PI, Plg and Pl. In related tissues, renal cortex and renal marrow showed distinctly higher activity of tPA and lower activity of PAI-1, with the levels of Plg and Pl in renal cortex being higher than those in renal marrow, where the α2PI level was higher than that in renal cortex. Similarly, the levels of tPA, Plg and Pl in small intestine were higher than those in large intestine, but with respect to PAI-1 and α2PI, the matter was reverse. In addition, the fibrinolytic activity in muscle tissue was lower, however, the levels of tPA, Plg, and Pl in cardiac muscle were obviously higher than those in skeletal muscles, and the levels of PAI-1 and α2PI were significantly lower than those in skeletal muscle. Conclusion: Our data demonstrate that a remarkable difference of the fibrinolytic patterns exists in rabbit tissues, which has probable profound significance in understanding the relationship between the function of haemostasis or thrombosis and the physiologic function in tissues.     

一道经典题的多种扩展

例1如图1所示,质量为m_1的物体A经一轻质弹簧与下方地面上的质量为m_2的物体B相连,弹簧的劲度系数为k,A,B都处于静止状态。一条不可伸长的轻绳绕过轻滑轮,一端连物体A,另一端连一轻挂钩,开始时各     

氧化单壁碳纳米角对环丙沙星的吸附动力学及热力学研究

本文研究讨论氧化单壁碳纳米角(ox SWNHs)对环丙沙星的吸附行为,考察其吸附动力学和热力学.结果表明,ox SWNHs对环丙沙星的吸附量为347 mg/g,且其吸附动力学行为符合伪二级模型. ox SWNHs对环丙沙星的吸附量随着温度的升高而增加,使用Langmuir方程及Freundlich方程能较好的拟合吸附过程,但Freundlich拟合效果更加.所得热力学参数表明,ox SWNHs对环丙沙星的吸附是一个吸热熵增的自发过程.