浅谈山区建厂的场地雨排水方式选择

本文主要通过具体工程实例对暗管排水和明沟排水两种常用的厂区雨排水方式进行对比,得出在场地地形坡度较大、岩石较多地区,适合采用明沟排水方式的结论,并同时对两种雨排水方式的选用原则进行了有效的归纳总结,为以后工程设计提供了有力依据。     

光耦合集成晶体管

西德慕尼黑大学的研究人员研制了一种与晶体管激励器相结合的发光二极管。他们预见，该器件可用于包括宽带传输在内的短距离光纤通信，因为其外部调制电流可比采用其他方法时小得多。当它的电平比直接调制发光二极管的电平低一个数量级时，这种器件可用50 ns脉冲进行调制。     

食品接触材料及制品的接触面积与容积的计算

目的研究不同形态的食品接触材料及制品接触面积(S)与食品模拟物体积(V)的测量方法。方法食品接触材料及制品的检测一般先要准确地测定出S与V,但实际检测中由于样品结构的多样性以及某些样品S和V的计算公式不为人熟知,常采用估算方法,会造成较大的人为误差。以某些不锈钢制品为例,检索国内外数学手册,找到相关的计算公式并进行推导,同时综合测定非规则几何体S与V的方法。结果得到了圆环胎、螺旋弹簧、球台、椭球体、桶形体、抛物面体等常见规则几何体的表面积、体积计算公式,以及测定非规则几何体S与V的方法。结论由这些公式及方法可准确测定S和V,可避免人为误差,实现科学、准确的检测。     

Synthesis and Characterization of A Polynuclear Yttrium Trifluoroethoxide and Its Activity for Oligomerization of Phenyl Isocyanate

A polynuclear yttrium trifluoroethoxide was synthesized and its activity for the oligomerization of phenyl isocyanate was tested. Reaction of anhydrous YCl3 with CF3CH2ONa in a 1:3 molar ratio in THF at room temperature, after workup, gave complex 1 as colorless crystals. The composition of complex 1 is [Y(OCH2CF3)3]6ONa2(THF)12, which was identified by elemental analysis and 1H NMR. Further X-ray structure determination reveals that complex 1 is a polynuclear ion pair compound, [Y6(μ6-O)(OCH2CF3)18]2-[Na(THF)6] 2 (1). The crystal data of complex 1 are trigonal, P-3 space group, a=1.78440(14) nm, b=1.78440(14) nm, c=1.27395(12) nm, γ=120°, V=3.5129(5) nm3, Z=1, Dc=1.607 mg·m-3, μ=2.591 mm-1 (Mo Kα), F(000)=1710, R=0.067, wR=0.182. Preliminary results demonstrated that complex 1 is a highly effective catalyst for the oligomerization of phenyl isocyanate.     

老式轻钢结构厂房存在的缺陷及改良建议

通过一起雪灾后单层砖排架厂房钢屋架垮塌事故分析,指出目前老式厂房存在以钢屋架为主的缺陷,以及在设计及施工中的存在的一些弊端,并提出改造建议。     

基于新农村视角的我国农田水利建设

从我国农村农田水利工作实际情况出发,分析了农村农田水利工作的主要内容,介绍了我国农村农田水利工作发展存在的问题,在相关理论分析的基础上,提出了新时期加快发展农田水利建设的措施.     

Polymerization of Dimethylaminoethyl Methacrylate Catalyzed by Substituted Indenyl Lanthanide（Ⅱ） Complexes

The polymerization of dimethylaminoethyl methacrylate （DMAEMA） catalyzed by the 1-cyclopentylindenyl lanthanide （Ⅱ） complex （1-C5H9C9H6）2Yb （THF）2 was investigated. The results indicated that the complex （1- C5H9C9H6）2Yb （THF）2 as a single component catalyst showed high activity. The conversion of the polymerization and the molecular weight of the polymer were affected by temperature, time, amount of catalyst and solvent in the polymerization process. The catalytic activity of （1-C5H9C9H6）2Yb （THF）2 enhanced significantly when a small amount of polar solvent THF was added into the polymerization system in which toluene was selected as the solvent. The optimal temperature of polymerization was about 0 ℃. Other modified substituted indenyl lanthanide （Ⅱ） complexes also showed good catalytic activity. The order of catalytic activity of the complexes was as follows： （1-C5H9C9H6）2Sm（THF）≈ （1- C2 H5 C9H6 ）2 Sm（THF）2 〉 （1 -C5 H9 C9 H6 ）2 Yb（THF）2 〉 （1 -PhCH2 C9 H6 ）2 Sm（THF）2. The steric regularity of p oly （dimeth- ylaminoethyl methacrylate） （PDM AEM A） was characterized by 1H NM R spectra. The polymerization provided syndio- tacticity-rich PDM AEM A. The molecular weight and the molecular weight distribution of PDM AEM A were measured by gel permeation chromatography.     

5.8GHz低噪声放大器的设计与优化

设计了一种低压、低功耗、输出阻抗匹配稳定的CMOS差分低噪声放大器.基于源极电感负反馈共源共栅结构,提出了基于MOS管中等反型区最小化Vdd·Id的方法,以优化功耗.在共栅晶体管处并联正反馈电容,以提升电路增益.对电路的噪声系数、输出阻抗稳定性、芯片面积等也进行了优化.仿真结果表明,当电源电压为1V,工作频率为5.8 GHz时,设计的低噪声放大器的噪声系数为1.53 dB,输入回波损耗为-22.4 dB,输出回波损耗为-24.6 dB,功率增益为19.2dB,直流功耗为4.6 mW.     

Study on Oligomerization of Phenyl Isocyanate Catalyzed by Bis(methylcyclopentadienyl)samarium Complex

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