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1.
对33个喹啉衍生物的雌激素β受体活性进行了分子对接以及比较分子力场分析(CoMFA)和比较分子相似性指数分析(CoMSIA). 对接结果显示氢键和疏水作用是配体与受体结合的主要因素,同时结果亦显示对接结合能与观测值pIC50具有极显著的线性相关性. 根据对接后各优势构象将33个样本进行叠合并进行CoMFA与CoMSIA研究,均得到了较优的结果,其中以选用立体场、静电场和疏水场建立的CoMSIA模型结果最优,其主成分数,r2,q2(LOO)和r2pred分别为2, 0.894, 0.708和0.802. 构效关系模型分析显示基团的空间位阻、电性及疏水作用是影响活性的主要因素 相似文献
2.
Enhanced Loading of ~(40)K from Natural Abundance Potassium Source with a High Performance 2D~+ MOT
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~(40)K is one of the most important atomic species for ultra-cold atomic physics. Due to the extremely low concentration(0.012%) of ~(40)K in natural abundance of potassium, most experiments use 4–10% enriched potassium source, which have greatly suffered from the extremely low annual production and significant price hikes in recent years. Using naturally abundant potassium source, we capture 5.4 × 10~6 cold ~(40)K atoms with the help of a high performance of two-dimensional magneto-optical trap(2D~+MOT), which is almost three orders of magnitude greater than previous results without the 2D~+ MOT. The number of the ~(40)K atoms is sufficient for most ultra-cold ~(40)K experiments, and our approach provides an ideal alternative for the field. 相似文献
3.
利用荷移反应分光光度法测定针剂中的多巴胺 总被引:6,自引:0,他引:6
研究了多巴胺与四氯苯醌之间的荷移反应,测量络合物组成比为1:1,摩尔吸光系数ε=1.63*10^3。方法的相对标准偏差为1.2%。应用据说 定方法测定物制剂中多巴胺含量与药典方法一致,回收率在94.5%-102%。 相似文献
4.
本文对单位球面S~3中的曲线在Mbius变换下的性质进行了研究.给S~3中的曲线定义了一套由共形弧长参数、共形曲率和共形挠率组成的Mbius不变参数系统,并证明这个系统决定S~3中所有光滑曲线在Mbius变换下的分类. 相似文献
5.
We report the experimental realization of a magneto-optical trap (MOT) of ^174 Yb atoms operating on the ^1 So -^3 P1 intereombination transition at 555.8nm. The green MOT is loaded by a Zeeman-slowed atomic beam. In order to increase the capture velocity of the MOT, we use the trapping laser beams consisting of five discrete frequency components obtained by modulating the laser light through an electro-optic modulator. The trapped atomic number of the ^174Yb isotope is about 6.2 × 105, and the temperature of the cold atomic cloud is estimated to be about 100μK. The success of the green MOT is an clock. important step towards the goal of an ytterbium optical 相似文献
6.
本文研究了双氢氯噻嗪与四氯苯醌之间的荷移反应.结果表明:在碱性水醇介质中双氢氯噻嗪与四氯苯醌形成1:1络合物,其λ_(max)=335nm,摩尔吸光系数ε=3.65×10~4L·mol~(-1)·cm~(-1),相对标准偏差为1.2%(n=10)。应用拟定的方法测定药物制剂含量与药典方法一致。回收率在95%以上。 相似文献
7.
A frequency-stabilized 556-nm laser is an essential tool for experimental studies associated with 1 S 0-3 P 1 intercombination transition of ytterbium (Yb) atoms.A 556-nm laser light using a single-pass second harmonic generation (SHG) is obtained in a periodically poled MgO:LiNbO 3 (PPLN) crystal pumped by a fiber laser at 1111.6 nm.A robust frequency stabilization method which facilitates the control of laser frequency with an accuracy better than the natural linewidth (187 kHz) of the intercombination line is developed.The short-term frequency jitter is reduced to less than 100 kHz by locking the laser to a home-made reference cavity.A slow frequency drift is sensed by the 556-nm fluorescence signal of an Yb atomic beam excited by one probe beam and is reduced to less than 50-kHz by a computer-controlled servo system.The laser can be stably locked for more than 5 h.This frequency stabilization method can be extended to other alkaline-earth-like atoms with similar weak intercombination lines. 相似文献
8.
合成了2-苯并咪唑吡啶镍配合物[Ni(C12H9N3)3](ClO4)28226;H2O, 通过IR, UV-Vis和元素分析对其进行了表征, 并通过X射线单晶衍射确定了其晶体结构. 单晶结构分析表明, 该晶体属于三斜晶系, 空间群为 , a=1.20076(5) nm, b=1.22545(5) nm, c=1.49077(5) nm, α=88.2430(10)°, β=71.7970(10)°, γ=72.544(2)°, Z=2, 最终偏离因子R1=0.0608, wR2=0.1859. 配合物的金属中心与6个配位氮原子形成八面体的几何构型. 用共振瑞利散射(RRS)研究了配合物与DNA的作用, 配合物与DNA相互作用形成复合产物并出现了相应的新的RRS光谱, 且随着配合物浓度的增大引起共振瑞利散射增强, 在低离子强度的环境下与DNA的作用比较明显. 这些实验结果表明了配合物与DNA之间存在较强的相互作用. 相似文献
9.
共价键的极性和极化性是表征共价键性质的两个物理量,是两个不同的概念。在有机化学教学中,特别是在解释化合物的结构与化学性质的关系方面,都十分重要。然而,笔者发现,一些有机化学教科书在羰基结构这部分内容中,常将两个概念相互混淆,让人读起来似是而非。例如有的教材写道:“由于氧原子的电负性较碳原子大,羰基的π电子云就偏向于氧原子方面,使羰基发生了极化,羰基的碳原子带有部分正电荷,而氧原子带有部分负电荷。”这种认为由 相似文献
10.
We build a Zeeman slower with consecutive coils and use it to load an Yb magneto-optical trap(MOTs).Cooling efficiency is measured by the fluorescence intensity of the atomic cloud trapped by the MOT.An optimized magnetic field profile can acquire the maximum cooling efficiency,corresponding to a good compromise between the smaller magnetic field mismatch and the high capture velocity.Our studies provide useful information on how the performance of the Zeeman slower can be improved. 相似文献