一个取代气垫导轨验证牛顿第一定律的演示实验

牛顿第一运动定律在教材中没有安排演示实验,而通常的演示大多是在气垫导轨上进行.我们设计该演示实验不仅可以取代气垫导轨,而且取材容易,操作简单,可见度大,还可在任意方向上演示第一定律,克服了在气垫导轨上演示的固有缺点.具体介绍如下.     

高效液相色谱法测定血浆中左亚叶酸钙的含量

建立了测定血浆中左亚叶酸钙含量的RPHPLC方法。采用DiamonsilC18色谱柱(150mm×4.6mm,5μm),乙腈50mmol/L磷酸氢二钾/磷酸二氢钾缓冲溶液(10∶90,V/V,用磷酸调pH至4.0)为流动相,用前经0.45μm的过滤膜,超声脱气,流速为1.0mL/min,紫外检测波长为290nm,柱温为35℃,进样量20μL。该方法最低检出限为0.2ng;线性范围为0.05～10mg/L,方法平均回收率在97.0%以上;日内及日间精密度的相对标准偏差分别小于4%和6%。该方法简单,快速,灵敏度高,重复性好。     

高硅ZSM—5沸石填充硅像胶膜的研究（Ⅲ）：对纯溶剂的吸附…

研究Ｓｉｌｉｃａｌｉｔｅ－Ｉ填充ＰＤＭＳ膜对乙醇和水的吸附、脱附和渗透蒸发性质以及吸附膜中丙酮在ＤＳＣ测试中的行为。结果表明，沸石填充膜对乙醇的吸附量和渗透蒸发通量均明显高于水，且乙醇的沸石填充膜中达到吸附、脱附平衡的速度均快于水；且吸附在填充和不填充沸石的硅橡胶膜中丙酮的熔融温度有明显的提高，说明硅橡胶膜与有机溶剂有较强的相互作用。此外，沸石填充膜的结构在３０ｗｔ％填充量附近有一改变，表明膜中硅     

Novel ions of quaternary ammonium halides in FDMS

Field desorption mass spectrometry exhibited novel ions [ Y-n H+n R ]+and [ Y-nH+nX]+as well as cluster ions [nY+(n-1)X-mH+mR]+and [nY+( n-1)X-mH+mX]+(n,m=0-3; X and Y represent the cation and anion moieties of quaternary ammonium halides),whose formation mechanism was discussed.     

由分子间氢键导致的丝素构象转变的FT-IR研究

用FT－IR研究发现，在丙烯腈与丙烯酸甲酯的共聚物（PANMA）与聚L-丙氨酸（PLAL）的共混体系中，丝素（SF）与PANMA的共混体系及SF与聚丙烯酸钠（NA）的共混体系中，含有羰基或其它极性基团的高分子与SF形成强弱不等的氢键．由于氢键的形成,使SF分子不得不调整自身的构象，从而引起其构象转变．讨论了可能的分子间氢键的结构．     

被动采样基础上的一氧化碳便携式检气管的研制

基于被动采样中气体分子扩散定律和化学吸收原理研究出一种一氧化碳便携式检气管.在检气管内的惰性载体上涂渍对一氧化碳有特效的显色剂.一氧化碳通过检气管端口扩散进入管内,在经过惰性载体时,与惰性载体上的显色剂发生反应,从而产生颜色变化.检气管显色长度的平方与一氧化碳浓度及采样时间的乘积在0.5～5μg/mL范围内(采样1 h)成线性关系,从而求出环境中一氧化碳的时间加权平均浓度.该检气管检测快速方便、准确,在实际样品的应用中,效果较为满意.     

新型中孔氧化硅柱层状锰钛酸的合成

Mixtures of H₂Ti_2.8Mn_0.2O₇, CH₃(CH₂)₉NH₂, and Si(OC₂H₅)₄ at molar ratios of 1∶2∶20 resulted in swollen and viscous gel once at room temperature, allowing the intercalation compound in which CH₃(CH₂)₉NH₂ and Si(OC₂H₅)₄ were simultaneously intercalated into interlayers of H₂Ti_2.8Mn_0.2O₇. The subsequent hydrolysis of the obtained intercalation compound in pure water solution for 30min at room temperature led to the formation of a new layered H₂Ti_2.8Mn_0.2O₇ sample with an interlayer spacing of 3.85nm. Calcination of this sample in air at 500℃ gave rise to a novel mesoporous(d=3.3nm) silica-pillared layered H₂Ti_2.8Mn_0.2O₇ with a large BET specific area of 624m²·g^-1 and a super-gallery height of 3.24nm.     

ENHANCEMENT OF FERROMAGNETIC CLUSTER INDUCED BY MAGNETIC FIELD IN THE PHASE-SEPARATED La0.5Ca0.5MnO3

Magnetic and transport properties of La_0.5Ca_0.5MnO₃ have been investigated by measuring the magnetization and resistance in zero-field-cooled (ZFC) and field-cooled (FC) modes. Conspicuously irreversible behaviors of magnetization/resistance in the two different modes were observed below the charge ordering transition temperature (T_CO). The ZFC and FC magnetizations at 5K, as functions of the magnetic field, coincide for μ₀H≤1T. Afterwards, the ZFC magnetization tends to an approximate constant, but the FC one increases linearly with increasing field. There exists an excellent correspondence between magnetization and resistance below T_CO. All the results suggest that the ferromagnetic clusters embed in the charge-ordered matrix. The phenomenon of ferromagnetic clusters growing up easily in the FC procedure has been interpreted according to the model of thermally activated two-level system.     

TD-DFT Calculation on the UV-Vis Spectra of Complex 8-（（Trimethoxysilyl）methylthio）quinoline-SnCl4

Electronic structures and absorption spectra properties of complex 8-（（trimethoxysilyl）methylthio）quinoline.SnCh in gas phase and MeCN media have been investigated by using DFT/TD-DFT method. The calculated lowest-energy absorption band shows different mechanisms under these two conditions, and it bears LMCT/LLCT/ILCT character in MeCN solution and LLCT/ILCT character in gas phase. The calculated absorption bands of the title complex in MeCN solvent are in good agreement with the experimental results, and calculation results indicate that the very weak experimentally observed lowest-energy absorption band of the title complex in MeCN solvent originates from the spin-forbidden singlet-triplet transitions.     

分散聚合制备聚苯乙烯/聚氧乙烯两亲磁性高分子微球

采用分散聚合法，以乙醇／水为介质，在Fe3O4磁流体存在下，通过苯乙烯与聚氧乙烯大分子单体共聚制备休磁性高分子微球。 研究了聚合条件对微球粒径的影响。通过改变聚合条件，可以得到平均粒径为5μm-100μm的两亲磁性高分子微球。