介值定理的推广

本文给出了介值定理的一个推广,并给出了弱条件下的介值定理的另一种表示     

浅谈函数的介值性

讨论了函数的介值性与连续性之间的相互关系以及导函数的介值性 .     

浅谈函数的介值性

讨论了函数的介值性与连续性之间的相互关系以及导函数的介值性。     

介值定理的一种推广

利用区间套定理将闭区间上连续函数的介值定理推广到了更加一般的情况,给出了闭区间上仅有第一类间断点的函数的介值定理.推广后的介值定理包含了原定理的情况,在原定理的条件下仍是原定理的结论.     

函数的加权平均介值点及其渐近性质

讨论了连续函数的加权平均介值点的一个渐近性质.     

函数的加权平均介值点及其渐近性质

讨论了连续函数的加权平均介值点的一个渐近性质。     

关于介值定理的进一步探讨

在闭区间连续函数的介值定理的基础上,适当改变或附加一些条件,证明了开区间上连续函数也具有介值性以及闭区间上具有介值性的函数能成为连续函数     

关于函数介值性连续性的研究

本文对函数介值性与连续性之间的关系进行了和讨论，指出函数连续性只是函数介值性的充分条件而必要条件，从而说明连续函数介值定理的逆命题并不成立。同时并给出并证明了函数介值性或连续性的几个充分条件。     

关于函数介值性与连续性的研究

本文对函数介值性与连续性之间的关系进行了研究和讨论,指出函数连续性只是函数介值性的充分条件而非必要条件,从而说明连续函数介值定理的逆命题并不成立。同时并给出并证明了函数介值性或连续性的几个充分条件。     

测度的介值定理及其应用

利用连续函数的介值性和Lebesgue测度的单调性得到了Lebesgue测度具有介值性质，并利用所得结果证明了Lebesgue积分的绝对连续性的逆命题也是成立的。     

400Hz中频电源设计

以实际工程项目中要求的中频电源为研究对象，设计了一种基于SPWM技术的中频电源系统方案．系统以单片机和SPWM信号发生芯片为核心，利用频率和电压反馈实现了中频电源设计．分别给出了实现本设计方案的单片机89C51与信号发生器SA8282的接口电路、IGBT的驱动隔离电路、外围扩展芯片、SA8282内部结构和工作原理和软件设计流程图．     

Calculation of depth-dose distribution of intermediate energy heavy-ion beams

Based on the characteristics of the interactions between intermediate energy heavy-ion beam and target matter, a method to calculate the depth-dose distribution of heavy-ion beams with intermediate energy (10 -100 MeV/u) is presented. By comparing high energy beams where projectile fragmentation is overwhelm ing with lowenergies where energy straggling is the sole factor instead, a crescent energy spread with increasing depth and a simple fragmentation assumption were included for the depth-dose calculation of the intermediate energy beam. Rel ative depth-dose curves of carbon and oxygen ion beams with intermediate energie s were computed according to the method here. Comparisons between the calculated relative doses and measurements are shown. The calculated Bragg curves, especially the upstream and downstream Bragg peaks, agree with the measured data. Differences between the two results appear only around the peak regions because of th e limitations of the calculation and experimental conditions, but the calculated curves generally reproduce the measured data within the experimental errors. Th e reasons for the divergences were analyzed carefully and the magnitudes of the deviations are given.     

Diversity and productivity peak at intermediate dispersal rate in evolving metacommunities

Positive relationships between species diversity and productivity have been reported for a number of ecosystems. Theoretical and experimental studies have attempted to determine the mechanisms that generate this pattern over short timescales, but little attention has been given to the problem of understanding how diversity and productivity are linked over evolutionary timescales. Here, we investigate the role of dispersal in determining both diversity and productivity over evolutionary timescales, using experimental metacommunities of the bacterium Pseudomonas fluorescens assembled by divergent natural selection. We show that both regional diversity and productivity peak at an intermediate dispersal rate. Moreover, we demonstrate that these two patterns are linked: selection at intermediate rates of dispersal leads to high niche differentiation between genotypes, allowing greater coverage of the heterogeneous environment and a higher regional productivity. We argue that processes that operate over both ecological and evolutionary timescales should be jointly considered when attempting to understand the emergence of ecosystem-level properties such as diversity-function relationships.     

Electrolyte membranes for intermediate temperature proton exchange membrane fuel cell

An overview of intermediate temperature (100–300 °C) proton conducting membrane electrolyte materials for fuel cells is presented in this review. The fuel cells operated in intermediate temperature range could enhance the electrochemical kinetics, simplify water management, and improve impurities resistance. Polyfluorosulfonic acid polymer membrane represented by Nafion, and non-fluorinated arylene polymer membranes represented by polybenzimidazole are the two most widely polymer electrolyte membranes for intermediate temperature membrane. The structure regulation and fillers addition are two effective ways to maintain the conductivity and mechanical properties of membranes at intermediate temperature. Moreover, heteropolyacids, metal pyrophosphates and inorganic membranes also have attracted widespread attention when they operate at intermediate temperature.     

海相沉积粉质中间土的物理状态

长江河口地区通启高速公路工程地质研究发现,该区域广泛分布海相粉质中间土,其液性指数与一般海相软粘土相似,具有较高的原位强度、较低的塑性和显著的结构性,而其粒度分布、强度特性、压缩性和塑性图与海相软粘土明显不同.采用主成分与主分量分析,对海相粉质中间土的多指标反映其土性信息的能力进行了分析.分析结果表明,采用液性指数划分其稠度的传统方法不尽合理,而采用F孔隙函数确定其物理状态更加合理.根据物理状态指标与工程力学特性的相关性,建立孔隙函数划分中间土物理状态新方法.通启高速公路工程实践表明,海相粉质 中间土具有良好的力学特性,不应隶属于软粘土地基.     

阿哌沙班中间体的合成

阿哌沙班是一种新型口服抗凝血药物。以对硝基苯胺和5-氯戊酰氯为原料,依次经过酰化-环合、二氯化、缩合-消除、[3+2]环合-消除反应合成阿哌沙班的关键中间体。该方法4步反应总收率为58.1%,反应所需原料易得,反应条件温和,反应步骤短,产品纯度高达99.5%(HPLC法),为阿哌沙班的合成提供了原料。     

并联谐振中频电源的节能降耗与谐波抑制

针对三相整流并联谐振中频电炉能耗较高、谐波电流含量多的问题,采用双电源供电方式,提高逆变器输出电压,降低感应圈电流损耗,进而有效减少了中频炉对电网的谐波污染.在此基础上,为提高触发信号的对称度、齐整度,对电源控制电路做了改进设计.最终通过对某铸造企业中频炉的节能改造试验,证明节能效果非常明显.     

多级供应链中间产品动态定价模型的稳定性

在多级供应链中上下游企业分别具有中间产品价格决定权的情况下,研究了中间产品动态定价机理.当上(或下)游企业给定中间产品价格后,下(或上)游企业会给出使自己利润最大的需求量(或供应量),上(或下)游企业把满足下(或上)游企业需求量(或供应量)的匹配价格作为下一周期中间产品的价格,从而得到了各级中间产品的动态定价模型.通过对模型稳定性的分析表明:两级供应链中,上下游企业中至少有一方决定的中间产品价格是稳定的,而三级以上供应链中会出现上下游企业无论哪方决定的中间产品价格都不稳定的情况.     

UHF RFID高中频接收机的研究

通过对UHF RFID系统的研究,提出了一种基于高中频结构的超高频RFID（射频识别）阅读器的接收机结构,并进行了详细的链路预算,同时论证了高中频接收机具有较强的抗阻塞能力,相对零中频结构避免了同频干扰,同时与欠采样技术相结合,具有更高的灵敏度和更优越的性能．     

20Cr板坯中间裂纹原因及解决措施

针对某钢厂生产20Cr板坯时铸坯出现中间裂纹的问题,对铸坯进行了枝晶检验,对中间裂纹部位进行了扫描电镜的分析。结果表明,在保证设备完善的情况之下,降低S含量、适当调高二冷段的比水量以及提高拉速,可使中间裂纹的发生率和级别大幅下降。从控制MnS夹杂、二冷配水、铸坯拉速以及设备保障方面提出解决措施。