PET/PHB(40/60)共聚反应和链结构

本文通过溶解性试验、富里埃红外光谱(FT-IR)、热台偏光显微镜、差示扫描量热仪(DSC)、高分辨核磁共振氢谱(′H—NMR)等方法,对 PET/PHB(40/60)共聚合反应历程,反应过程中嵌段性的形成,以及链结构的变化情况进行了研究。结果表明:共聚合反应初期,同时存在着 PET 的酸性裂介,PHB 的均聚,以及 PET 和 PHB 链段之间的缩聚。随共聚合反应的进行,均聚反应减慢,反应初期所形成的 PHB 刚性链段重新打开参加酯交换反应,共聚酯序列结构由嵌段性逐渐向无规性靠近。     

Room temperature continuous wave operation of 1.33-μm InAs/GaAs quantum dot laser with high output power

Continuous wave operation of a semiconductor laser diode based on five stacks of InAs quantum dots (QDs) embedded within strained InGaAs quantum wells as an active region is demonstrated. At room temperature, 355-Mw output power at ground state of 1.33-1.35μm for a 20-μm ridge-waveguide laser without facet coating is achieved. By optimizing the molecular beam epitaxy (MBE) growth conditions,the QD density per layer is raised to 4 × 1010 cm-2. The laser keeps lasing at ground state until the temperature reaches 65 ℃.     

如何规避人力资本投资风险

人力资本投资与物质资本投资和金融资本投资一样 ,都具有一定的风险。如何对人力资本投资风险进行规避是企业面临的现实问题 ,本文对人力资源投资风险进行了分类 ,针对人为风险的防范与规避提出了若干对策建议     

Two new acyclic diterpene-y-lactones from the leaves of Salix matsudana

Two new acyclic diterpene-(-lactones named hanliuine III (1) and hanliuine IV (2) were isolated from leaves of Salix matsudana (Chinese name "hanliu"). Their structures were deduced from spectral data.     

Fibonacci数的一类和数列的性质

文中用组合分析中的计算方法得到了关于Fibonacci数的一类和数列的性质。     

A New Method of Separation of Four Benzodiazepines by RP-CEC

A new method to separate diazepam, nitrazepam, estazolam, alprazolam was established on both C18 and C8 CEC columns. The influence of separation voltage, Tris concentration, column temperature and the percentage of acetonitrile on the resolution and retention behavior of four benzodiazepines was investigated. The results showed that the percentage of acetonitrile had the largest effect on the resolution and retention behavior of the four benzodiazepines. Other separation conditions had also effects on the resolution and retention behavior, but smaller than the concentration of acetonitrile. Optimum separation conditions were obtained to separate four benzodiazepines on C18 and C8 CEC columns.     

降钙素原在新生儿感染中的临床应用

目的探讨降钙素原(PCT)在新生儿感染中的临床意义.方法对127例新生儿进行PCT测定,并与CRP、白细胞计数在重症感染、一般感染、非感染性疾病和正常新生儿进行统计学分析.结果以PCT＞0.5ng/ml为阳性,CRP＞8mg/L为阳性.在重症感染时PCT阳性率95%,CRP阳性率55%,两者统计学分析P＜0.005,有显著差异;一般感染时PCT阳性率33.3%,CRP阳性率23.8%,两者无显著差异(P＞0.05);在非感染性疾病和和正常新生儿PCT、CRP无差异性.PCT在重症感染组、一般感染组、非感染组三组间有显著差异,(P＜0.005).白细胞计数在重症感染、一般感染、非感染性疾病各组间无显著差异.结论PCT在新生儿早期全身重症感染时升高明显,比CRP、白细胞计数敏感性高,是新生儿早期重症感染很好的诊断指标.     

应用加权无波动无自由参数耗散差分格式求解平板振荡叶栅流场

引入双时间方法,计算了某三维平板振荡叶栅的非定常流场.在虚拟时间步上用LU-SGS隐式方法做时间推进,对流项采用空间三阶的加权无波动无自由参数耗散差分(WNND)格式离散.湍流模型采用低雷诺数q-ω模型.计算得到了叶栅不同叶高处的升力系数频谱、非定常压差系数以及叶尖处不同振动时刻的熵等值线.对3个叶高处的升力系数频谱分析表明,流场存在显著的振动诱发的非线性扰动,其频率高于升力系数基频.叶尖处不同振动时刻的熵等值线图显示了大振幅下流场强烈的非定常属性.     

北京谱仪桶部簇射计数器能量响应特性研究

在北京正负电子对撞机的J/ψ和Ds能区,选择了辐射巴巴事例,并以此来研究北京谱仪的桶部簇射计数器能量响应特性.在消除了由于电子和辐射光子在桶部簇射计数器中沉积能量区域重叠的影响后,正确地得到了桶部簇射计数器在电子和光子动量小于2GeV以下的能量响应,表明在所研究能区,桶部簇射计数器的能量响应线性很好.对桶部簇射计数器微小的非线性进行修正后,重建的π0不变质量谱得到改善.