Continuous Method for Describing Dendrite Evolution During Solidification

A continuous method is presented to deal with the discontinuous physical properties on both sides of solid/liquld interface during the solidification process. Then single dendrite evolution in two and three dimensions is simulated by using this method. Multi-grain evolution is also simulated during solidification by the method. The method is easy to be understood and does not need all details of dendrite. The simulated results can reflect the random characteristic of dendrite evolution and the micro-segregation of solute.     

An efficient Jacobian scaling method for time-domain optical mammography

<正>Time-domain diffuse optical tomography can efficiently reconstruct optical parameters which can be further applied in diagnosing early breast cancer.Nevertheless,the performances of reconstructed imaging are badly influenced by different Jacobian magnitudes of absorption coefficient and reduced scattering coefficient.With the introudction of a relative data type based on generalized pulse spectrum technique, an efficient Jacobian scaling method is proposed.The interrelated simulated validation is also revealed for the enhancing performances.     

新荧光试剂4-氨基安替比林芳香席夫碱的合成

新荧光试剂4-氨基安替比林芳香席夫碱的合成     

石墨炉原子吸收法测定黑花生中的硒

该文以转基因食品黑花生为研究对象,针对硒易挥发的特点,建立了高压密闭消解-石墨炉原子吸收光谱法测定黑花生中总硒含量的测定方法.研究表明,HNO3-H2O2可使样品达到最佳消解,以Pd(NO3)2+Mg(NO3)2为基体改进剂,最佳灰化温度和原子化温度分别为500 ℃和2 000 ℃.在优化实验条件下,该方法测定硒的线性...     

提高微细图形光刻分辨力的相移滤波技术研究

详细研究了提高投影成像光刻分辨力的相移滤波技术的基本理论,给出了理论模型,进行了模拟计算.对不同掩模图形设计制作的不同优化滤波器进行光刻对比实验并取得实验结果.研究表明,相移滤波能显著提高部分相干成像系统光刻分辨力和增大焦深,同时能提高光能利用率,有利于提高光刻生产率,是一种有效提高光刻分辨力和焦深的波前工程技术.     

2012年浙江省高考化学试题评析:基于课程标准的视角

以浙江省2012年高考理综化学试题为研究对象,采用Webb一致性定量分析的方法,从知识与技能、过程与方法、情感态度与价值观3方面研究高考化学试题与课程标准的一致性。研究结果表明:2012年浙江省高考化学试题与课程标准之间一致性水平较高,发挥了课程标准标准化、规范化的作用;但是,"常见无机物及其应用"这一内容领域在知识与技能维度上与课程标准有较大偏差。     

A wideband sensitive holographic photopolymer

A novel wideband sensitive dry holographic photopolymer sensitized by rose bengal (RB) and methylene blue (MB) is fabricated, the holographic storage characteristics of which are investigated under different exposure wavelengths. The result shows that the sensitive spectral band exceeds 200 nm in visible light range, the maximum diffraction efficiency under different exposure wavelengths is more than 40% and decreases with the decrease of exposure wavelength, the exposure sensitivity is not change with the exposure wavelength. This photopolymer is appropriate for wavelength multiplexing or multi-wavelength recording in digital holographic storage.     

一种宽频带超材料吸波体的设计及其特性

为了获得吸收率高、吸波带宽宽的超材料,设计了一种谐振超材料吸波体.该吸波体由多个开口圆环组成,采用商业软件CST Studio Suite 2009频域求解器计算了其在25～35 GHz波段内的S参量,并计算了其吸波率A(ω),在28.4 GHz处吸收率达到86％,带宽达到3.5 GHz.利用不同吸波频段的叠加效应,设计了一种谐振超材料吸波组合体,计算了在25～35 GHz波段的S参量,在29.7 GHz处吸波率达99.9％,吸波带宽达到3.1 GHz,吸收率明显增加.将GHz波段的结构缩小1 000倍,在THz波段同样可以达到高吸收,说明超材料吸波体可以通过对结构尺寸调节改变吸收波段.同时,对其阵列进行仿真计算,发现不同的排列方式仿真结果不同.由于各个谐振环之间的相互作用对吸收效果影响较大,吸收率减小.该吸波材料由金属组成,能灵活地对介电常量和磁导率进行调节,从而实现高吸收.     

氨基酸混合物分离效果提高的实验研究

纸层析法分离氨基酸混合物是以滤纸为载体,正丁醇、甲酸、水以体积比15：3：2的混合溶剂为展开剂,喷洒茚三酮显色剂,烘烤后显色。学生做的结果分离效果不佳,如氨基酸显色斑点不清晰,拖尾现象严重。针对以上弊端,对影响氨基酸分离的因素进行探索,得出了分离氨基酸的最佳条件:即用正丁醇：冰醋酸：水的体积比为4：1：1的混合溶剂为展开剂,将0.14g的茚三酮显色剂加到展开剂中,在弱酸性条件下进行展层,层析完成后烘烤即显斑点。实现了展层和显色合并为一步完成,既可节约时间,且实验结果佳,氨基酸分离效果理想。     

新的手性β-亚磺酰亲双烯体用于不对称Diels-Alder反应

手征性cis-β-亚磺酰丙烯酸酯可从(1R, 2S, 3R)-3-巯基-1,7,7-三甲基二环[2.2.1]庚-2-醇制备, 它与环戊二烯的反应得Diels-Alder加成物, 并具有相当高的端基差向异构选择性。