新手-熟手教师化学课堂教学有效性比较研究——以“离子反应”为案例

利用《课堂教学基元系统有效性评价量表》,对新手教师和熟手教师"离子反应"课堂教学中基元系统有效性进行评价,并进行对比分析。发现2者在"时间利用的合理性""教学行为链实施质量"和"匹配度"3个维度上存在显著性差异,熟手教师比新手教师表现要好;在"资源和手段使用质量"和"基元内容的合理性"2个维度上不存在显著性差异,2者在"资源和手段使用质量"上均表现不理想,在"基元内容的合理性"上均表现良好;在基元系统有效性总分上2者表现出了显著性差异,整体上而言,熟手教师的课堂教学基元系统有效性高于新手教师。     

男女化学教师课堂教学基元系统有效性的比较研究

基于教学行为视角,依据课堂教学系统CPUP模型理论和课堂教学基元系统有效性评价量表,通过对24位男女化学教师的24节常态课堂中基元系统有效性进行对比分析。结果发现,男女教师的主要差别表现为:在"时间利用的合理性"和"匹配度"2个维度上,女教师显著高于男教师;在"教学行为链实施质量" 和"资源和技术的使用质量"2个维度上,男教师显著高于女教师;而在总分和"基元内容的合理性"维度上,2者不存在显著差异。     

新手-熟手化学教师课堂教学基元系统有效性的比较研究

依据课堂教学系统CPUP模型理论和课堂教学基元系统有效评价量表,通过对24位新手教师和熟手教师的24节常态课堂中基元系统有效性进行对比分析。结果发现,新手教师与熟手教师的主要差别表现在“教学行为链实施质量”和“资源和技术的使用质量”2个维度上,熟手教师显著高于新手教师;而在“时间利用的合理性”“匹配度”和“基元内容的合理性”3个维度上,2者不存在显著差异。     

化学基元组学与药物创新

化学基元组学(chemomics)是与化学信息学、生物信息学、合成化学等学科相关的交叉学科.生物系统从内源性小分子(天然砌块)出发,通过酶催化的化学反应序列制造天然产物.生物系统通过化学反应和天然砌块向目标天然产物"砌入"一组原子,这样的一组原子称为化学基元(chemoyl).化学基元组(chemome)是生物组织中所含有的化学基元的全体.化学基元组学研究各种化学基元的结构、组装与演化的基本规律.在生存压力和繁衍需求的驱动下,生物系统已经进化出有效手段来合成天然产物以应付环境的变化,并产生了丰富多彩的生物和化学多样性.近年来,人们意识到药物创新的瓶颈之一是药物筛选资源的日益枯竭.化学基元组学可以解决这个瓶颈问题,它通过揭示生物系统制备化学多样性的规律,发展仿生合成方法制备类天然化合物库(quasi natural product libraries)以供药物筛选.本文综述了化学基元组学的主要研究内容及其在药物创新各领域中的潜在应用.     

铜(II)与四(间甲基)苯基卟啉镉(II)取代反应动力学

用分光光度法研究了二甲亚砜溶液中, 氯化铜与meso-四(间甲基)苯基卟啉镉(Ⅱ)(Cd(Ⅱ)P)亲电取代反应的动力学. 讨论了影响反应的因素, CuCl_2+Cd(Ⅱ)P→Cu(Ⅱ)P+CdCl_2提出了反应机理并进行了验证. 用AST286微机对实验数据进行非线性最小二乘法拟合, 得到拟合曲线及似平衡步的平衡常数K及其它基元步骤的速率常数k_1, k_(-1), k_2. 研究了温度对反应的影响, 求得似平衡步的△_rH_m~-θ-, △_rS_m~-θ-及其它基元步骤的活化参数△~≠H_m, △~≠S_m.     

甲壳型液晶高分子的化学结构及其与性能间关系的研究

设计并合成了7种新型甲壳型液晶高分子,研究了液晶基元的化学结构和立体效应对单体及其聚合物液晶性的影响.发现在液晶基元的末端引入极性或可极化的原子基团提高了单体的熔点和液晶相的热稳定性;液晶基元的长径比越大,单体的熔点和清亮点越高;聚合使单体的液晶稳定性增加、液晶相温度范围变宽;侧链液晶基元的极性、刚性和空阻越大,聚合物的玻璃化温度越高;酰胺基团无论是在分子的末端还是在连接部位,都使单体的熔点和聚合物的玻璃化温度提高,但在分子末端时液晶相较稳定,作为中心桥键时不利于液晶相的稳定形成.     

化学基元组学与药物创新

化学基元组学（chemomics）是与化学信息学、生物信息学、合成化学等学科相关的交叉学科．生物系统从内源性小分子（天然砌块）出发,通过酶催化的化学反应序列制造天然产物．生物系统通过化学反应和天然砌块向目标天然产物“砌入”一组原子,这样的一组原子称为化学基元（chemoyl）．化学基元组（chemome）是生物组织中所含有的化学基元的全体．化学基元组学研究各种化学基元的结构、组装与演化的基本规律．在生存压力和繁衍需求的驱动下,生物系统已经进化出有效手段来合成天然产物以应付环境的变化,并产生了丰富多彩的生物和化学多样性．近年来,人们意识到药物创新的瓶颈之一是药物筛选资源的日益枯竭．化学基元组学可以解决这个瓶颈问题,它通过揭示生物系统制备化学多样性的规律,发展仿生合成方法制备类天然化合物库（quasi natural product libraries）以供药物筛选．本文综述了化学基元组学的主要研究内容及其在药物创新各领域中的潜在应用．     

Belousov-Zhabotinsky化学体系中超混沌及其同步的研究

曾有报道在Belousov-Zhabotinsky (BZ)体系的实验研究中未实现超混沌。但 通过不同类型的变量耦合方式,我们在该体系的Montanatar模型中得到了超混沌发 现无论采用何种耦合方式,只要耦合强度足够小,均能得到超混沌。另外,对两个 所产生的超混沌BZ体系,在全变量耦合、双变量耦合及K-B空间标量耦合法的策略 下,均实现了同步调制,并且从横截Lyapunov指数判据理论给予验证。探索了个别 状态变量在耦合中对同步所起的作用。通过双变量耦合发现[Ce~(4+)]不起作用; 通过K-B空间标量耦合法发现只有[Br~-]和[HBrO_2]的线性组合能起作用,可能由 于它们出现在同一个基元反应中。     

辅酶B_(12)模型化合物的研究(V)RCo(Salen)L配合物Co—C键断裂的动力学

运用光度法研究了RCo(Salen)L配合物在甲醇中热分解反应动力学;测定了Co—C键断裂的速率常数及活化能,得到表观速率常数顺序为i-C3H7>i-C4H9>n-C4H9>n-C3H7>C2H5,活化能顺序为i-C3H7相似文献   

偶氮苯和氧化偶氮苯液晶基元侧链聚硅氧烷液晶的合成和性能研究

利用侧链带酰氯基的聚硅氧烷与取代偶氮苯酚进行大分子反应,合成了6种以偶氮苯氧羰基为侧链的聚硅氧烷Ⅲ_a-f;将其中的Ⅲ_a-c进行氧化,得到3种以氧化偶氮苯氧羰基为侧链的聚硅氧烷Ⅳ_a-c聚合物结构通过核磁共振、红外光谱和元素分析表征,利用偏光显微镜和差热分析仪研究了聚合物的相行为.讨论了苯环上取代基和液晶基元的中心桥键对聚合物液晶性能的影响.     

Molecularly defined (L)‐lactic acid oligomers and polymers: Synthesis and characterization

The synthesis of (L )‐lactide oligomers from dimer to 64mer via an exponential growth strategy is described. By careful selection of orthogonal protective groups, the synthesis were conducted using a t‐butyldimethylsilyl (TBDMS) ether as the protective group of the hydroxyl group and benzyl (Bn) ester as the protective group of the carboxylic acid group. The yields of both the deprotection steps and coupling reactions using 1,3‐dicyclohexylcarbodiimide or 1‐[3‐(dimethylamino)propyl]‐3‐ethylcarbodiimide hydrochloride were high (70–100%) and the absence of a requirement for conducting the majority of reactions under an inert atmosphere permitted a robust and efficient synthetic strategy to be developed. This allowed monodisperse dimer, tetramer, octamer, 16mer, 32mer, and 64mer materials to be prepared in gram quantities and fully characterized using mass spectrometry and size exclusion chromatography. Evaluation of the thermal and physical properties using thermogravimetric analysis, differential scanning calorimetry, and small angle X‐ray scattering demonstrated a close correlation between the molecular structure of the well‐defined Poly(lactide) oligomers and their physical properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5977–5990, 2008     

Kinetically controlled phase transitions in liquid‐crystalline polymers. III. Influence of the molecular weight and annealing temperature on two‐dimensional K phase formation in a side‐chain polyacrylate

Narrow fractions of a side‐chain acrylate oligomer/polymer with phenyl benzoate side chains are separated in a broad range of the degree of polymerization (7 ≤ P_w ≤ 149). An examination of the phase behavior of the obtained fractions has shown that only the longer macromolecules can form the two‐dimensional K (TDK) mesophase, whereas oligomers of a shorter main chain form the conventional nematic phase only. A critical P_w value has been observed to be necessary for the TDK mesophase formation. The temperatures and enthalpies of liquid‐crystalline phase transitions have been studied as a function of the molar mass, and the phase‐growth kinetics for the TDK phase have been studied with an Avrami treatment. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2352–2360, 2005     

Effects of the architecture and environment on polymeric molecular assemblies of novel amphiphilic diblock copolynorbornenes with narrow polydispersity via living ring‐opening metathesis polymerization

Diblock copolymers of 5‐(methylphthalimide)bicyclo[2.2.1]hept‐2‐ene (NBMPI) and 1,5‐cyclooctadiene were synthesized by living ring‐opening metathesis polymerization with a well‐defined catalyst {RuCl₂(CHPh)[P(C₆H₁₁)₃]₂}. Unhydrogenated diblock copolymers showed two glass transitions due to poly(NBMPI) and polybutadiene segments, such as two glass‐transition temperatures at ?86.5 and 115.3 °C for poly 1a and ?87.2 and 115.3 °C for poly 1b . However, only one melting temperature could be observed for hydrogenated copolymers, such as 119.8 °C for poly 2a and 121.7 °C for poly 2b . The unhydrogenated diblock copolymer with the longer poly(NBMPI) chain (poly 1a ; temperature at 10% mass loss = 400 °C) exhibited better thermal stability than the one with the shorter poly(NBMPI) chain (poly 1b ; temperature at 10% mass loss = 385 °C). Two kinds of hydrogenated diblock copolymers, poly 2a and poly 2b , exhibited relatively poor solubility but better thermal stability than unhydrogenated diblock copolymers because of the polyethylene segments. Poly[(hydrochloride quaternized 2‐norbornene‐5‐methyleneamine)‐b‐butadiene]‐1 (poly 3a ) was obtained after the hydrolysis and quaternization of poly 1a . Dynamic light scattering measurements indicated that the hydrodynamic diameters of the cationic copolymer (poly 3a ) in water (hydrodynamic diameter = 1580 nm without salt), methanol/water (4/96 v/v; hydrodynamic diameter = 1500 nm without salt), and tetrahydrofuran/water (4/96 v/v; hydrodynamic diameter = 1200 nm without salt) decreased with increasing salt (NaCl) concentration. The effect of temperature on the hydrodynamic diameter of hydrophobically modified poly 3a was also studied. The inflection point of the hydrodynamic diameter of poly 3a was observed at various polymer concentrations around 30 °C. The critical micelle concentration of hydrophobically modified poly 3a was observed at 0.018 g dL^?1. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2901–2911, 2006     

毛细管电泳法测定肝素和低分子量肝素平均硫酸化程度

肝素和低分子量肝素（LMWHs）作为临床上常用的抗凝血药物,其抗凝血活性与硫酸化程度（SD）密切相关。然而,肝素类药物的生产需经历一系列复杂的工艺过程,在制备和储存过程中,肝素的硫酸基团容易水解丢失,影响抗凝血活性,这将直接影响肝素药物的使用安全性。为保证产品质量,需要发展一种快速检测肝素硫酸化程度的技术,以监测原料质量和工艺条件的稳定性。虽然已有一些测定肝素硫酸化程度的报道,但这些方法均有局限性,不适用于肝素生产的质量控制。为此,开发了一种基于毛细管电泳技术（CE）检测肝素和低分子量肝素的平均硫酸化程度的方法。首先,用肝素酶混合液彻底消化未分级肝素（UHF）和低分子量肝素,然后用毛细管电泳分离酶解得到的所有寡糖和二糖构建模块,并对它们进行定性和定量分析。随后,根据每种寡糖和二糖的峰面积及其硫酸酯基团的数量,便可计算出每个构成肝素二糖单元硫酸化程度的平均值。使用该方法对来自两个生产商各4个批次依诺肝素（低分子量肝素）和5个批次肝素原料进行检测,并计算了各批次样品的相对标准偏差（RSD）,对不同厂家生产的依诺肝素平均硫酸化程度进行了比较,验证了该方法的实用性。该方法灵敏度高,准确可靠,分析速度快,在肝素类药物生产过程的质量控制中具有良好的应用潜力。     

Nonstoichiometric polyelectrolyte complexes: A mathematical model and some experimental results

A mathematical model is presented to describe nonstoichiometric water‐soluble polyelectrolyte complexes, and the predictions are compared with some experimental results. The theory is a mixture of Madelung's theory for ionic crystals and Manning's counterion condensation theory. The central parameters are the degree of complexation, φ, and the degree of counterion binding, θ. All other quantities are known in principle. It is found that there is a competition between complexation and counterion binding. When φ is large, θ is small, or vice versa. The degree of complexation, φ, depends sensibly on the concentration, c_s, of the added low molecular salt, the polyanion chain length, N, and the dielectric constant, ϵ, of the solvent. There exists a critical salt concentration, c_s,c, at which the complexes salt out and where for c_s > c_s,c the complexes dissociate back into their single strands, the polyanions, and polycations. Further, φ is larger the smaller the polyanion length and the smaller the solvent dielectric constant are. To prove these predictions we have formed nonstoichiometric complexes between IONENE and PAA and IONENE and PMAA, respectively. The degree of complexation was determined by ultracentrifugation and checked by viscometry. The accord found between theory and experiment is both qualitatively as well quantitatively quite well. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 335–348, 1999     

Preparation of partially hydrolyzed oligo(vinylacetate) as polyol for polyurethane formation

Polyols based on oligo(vinylacetate) were synthesized using a convenient one‐pot, two‐step process. Polymerization of vinylacetate was performed in 2‐propanol as a chain‐transfer agent using di‐tert‐butylperoxide as a free‐radical initiator. Saponification of the oligomers was performed in both tetrahydrofuran and 2‐propanol using stoichiometric amounts of methanol in the presence of a basic catalyst. Well‐defined oligo(vinylacetate‐co‐vinylalcohol) polyols with a degree of polymerization below 12 and a hydroxyfunctionality smaller than 4 were obtained. Oligo(vinylacetate‐co‐vinylalcohol) was used as a polyol component in the formation of polyurethanes. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2085–2092, 2002     

The degree of crystallinity of monoclinic isotactic poly(propylene)

The degree of crystallinity of a set of monoclinic (alpha) isotactic poly(propylenes), prepared by a metallocene‐type catalyst, were determined at room temperature. Three different methods were used: density, enthalpy of fusion, and wide‐angle X‐ray scattering, and the results compared. The relation between the heat of fusion and the specific volume of these poly(propylenes) was found to be nonlinear, thus precluding any linear extrapolation to obtain the heat of fusion of the pure crystal (ΔH_u). The value of ΔH_u obtained from depression of the melting temperature by diluents is used. Based on the unit cell density of monoclinic crystals formed from a low defected fraction, the density obtained crystallinity levels were found to be between 0.l5–0.25 higher than those calculated from the heat of fusion. This relatively large difference holds for the isothermally crystallized and quenched isotactic poly(propylenes), and reflects the contribution of the interphase to the density determined crystallinity, which does not contribute to the heat of fusion. Paralleling results found in other systems, the crystallinity levels obtained from wide‐angle X‐ray scattering agree with those obtained from density, indicating a significant contribution of the partially ordered phase to the total diffraction. Emphasis is given on the need to account for the large differences in the crystallinities of poly(propylene) measured by different techniques when evaluating the dependence of properties on this quantity. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 323–334, 1999     

Separation of copper(II) and aluminium(III) from fresh waters by solid phase extraction on a complexing resin column

The solid‐phase extraction (SPE) of copper(II) and aluminium(III) from fresh waters on an ion‐exchange complexing resin containing iminodiacetic groups (Chelex 100) has been examined. Quantitative recovery of the metal ions was related to the breakthrough profile that, for some samples, could not be evaluated directly. A method is suggested for evaluation, instead, of the sorption curves, on the basis of passing different volumes of sample through the column. This enables evaluation of important properties, for instance the central point of the breakthrough curve, V_f. The column used was a small one, containing 0.10 g dry Chelex 100. The metal ion was eluted with a small volume of acid solution, 10 mL of 0.5 mol L^–1 HNO₃; this resulted in good preconcentration factors. For copper(II) it was found that fresh waters of similar composition could have different V_f in the same column. This was ascribed to different reaction coefficients (α_M(I)) of copper(II) in the considered samples, which affects V_f. By use of the proposed SPE procedure it is possible to evaluate the reaction coefficient of copper(II). The values of α_M(I) for two different drinking waters at pH 7.7 were found to be 3.70×10¹² and less than 4.40×10¹¹. Similar results were obtained for aluminium(III).     

Effect of degree of saponification on structural and property change of poly(Vinyl alcohol) fibers

To improve the drawability and finally the mechanical properties, poly(vinyl alcohol)s (PVA₈₆, PVA₉₃, and PVA₉₉) with respective degrees of saponification of 86, 93, and 99% were synthesized using solution polymerization. Following the synthesis dimethylsulfoxide (DMSO) solutions of the PVAs were gel-spun into methanol. After extraction of DMSO from the as-spun fibers the dried fibers were first drawn at 120 °C then at 180 °C. An analysis of the structure and properties of the fibers was performed using FT-IR, differential scanning calorimetry (DSC) and a fiber strength tester. The degree of saponification had an effect on the formation and intensity of the intermolecular hydrogen bonds, melting, drawability and strength of the PVA fibers. Low degrees of saponification weakened the intermolecular hydrogen bonds and interfered with the formation of crystallites, causing low melting points and low heat of fusion. Generally, drawing was easier to carry out at lower temperature, and higher draw ratios could be obtained, leading to higher fiber strengths. Copyright © 2003 John Wiley & Sons, Ltd.     

Effect of Molecular Weight on Photoinduced Birefringence in a Chiral Liquid Crystalline Azodye Polymer

Summary: The evolution of the photoinduced birefringence in thin films of narrow polymer fractions is studied and compared with the behavior of the non‐fractionated polymer. The Δn_ind value decreases by increasing the degree of polymerization ( ) within the oligomeric range but becomes independent of molecular weight starting from a of ≈70. Thermal pretreatment of the films results in higher photoinduced birefringence. The films show good stability of the photorecording.

Birefringence induced after 10 min, Δn_ind(600) and its growth rate at the same moment versus molecular weight.