羧甲基壳聚糖对胆红素的吸附性能研究

合成了不同取代度的羧甲基壳聚糖(CM-CTS)作为吸附剂，研究了不同条件对CM-CTS吸附胆红素性能的影响．结果表明：在实验条件下，随着羧甲基取代度的增加和体系温度的升高．最大吸附率和吸附速率均相应增加：在接近人体血液pH值的条件下，CM-CTS对胆红素的吸附性能较佳：人血清白蛋白和离子强度的增加对CM—CTS吸附胆红素有明显的抑制作用。     

The Reaction of Triplet State Benzophenone with Acetylacetone

Irradiation of benzophenone in acetic acid containing acetylacetone resulted in regiospecific addition to form cis-2,2-dihpenyl-3-hydroxy-3-methyl-4-acetyloxetane and the rearrangement products therefrom. In the co-presence of copper ions, the regiospecificity is scrambled to give these products and a small amount of 1,1-diphenyl-1-buten-3-one, the secondary decomposition product of the other oxetane arising from the alternative orientation of the addition.     

端视等离子体原子发射光谱仪的性能评价

端视等离子体原子发射光谱仪与侧视等离子体原子发射光谱仪相比在分析性能方面所表现出来的差异一直是光谱分析工作者所关注的一个重要方面。此文较系统的总结了近年来在此方面所做的研究工作，引用47篇文献。     

Total synthesis of kendomycin: a macro-C-glycosidation approach

Kendomycin, also known as (-)-TAN 2162, is a novel polyketide-derived ansamycin isolated from Streptomyces sp., which exhibits potent antagonist and agonist activities at the endothelin and calcitonin receptors, respectively. This bacterial metabolite also possesses a strong antibiotic activity against a range of gram-positive and -negative bacteria and cytostatic effects on the growth of human cancer cell lines. When a novel macroglycosidation reaction is employed as the key step, the first enantioselective total synthesis of kendomycin has been accomplished. A Friedel-Crafts-type ring closure of the acyclic precursor containing tetrahydropyran and benzofuran moieties produces the macrocycle as a single stereoisomer in good yield, thus establishing the aryl C-glycosidic linkage of the ansa core. This reaction requires a phenolic glycosyl acceptor and appears to proceed through a rapid O-glycosidation followed by a slow rearrangement to an aryl C-glycoside. The requisite secomacrocycle is prepared by the Pd(0)-catalyzed B-alkyl Suzuki-Miyaura cross-coupling of two subunits, which in turn can be expeditiously assembled from readily available building blocks in a modular fashion.     

K对Mn—Co—O的结构及氧化活性的影响

利用XRD,TPD,TFD-MS及催化氧化反应等实验技术,研究了K对Mn-Co-O的结构及氧化活性的影响。XRD结果表明,Mn-Co-O系已形成反尖晶石型的MnCo_2O_4结构;K-Mn-Co-O系中除MnCo_2O_4型结构外,还有新相KMnO_2存在。根据O_2的TPD-MS及吡啶的TPD结果,Mn-Co-O中添加适量的K能提高供氧活性和增加供氧数目,但酸中心数目减少,强度降低。K对Mn-Co—O催化剂氧化活性的影响随反应物分子结构的不同而异,对乙酸乙脂、苯甲酰氯等极性有机物的完全氧化反应,K能提高氧化活性,但对苯、正己烷等非极性有机物的完全氧化反应,K使其活性降低。     

Solid Phase Synthesis of 4H-Pyrimido[2,1-b] Benzothiazol-4-ones from Resin-Bound Cyclic Malonic Ester

The solid phase synthesis of 4H-pyrimido[2,1-6] benzothizaol-4-ones has been reported.     

Semiclassical approach to collision-induced emission in the presence of intense laser radiation: An aspect in the study of cooperative chemical and optical pumping

Collion-induced emission in molecular systems in an intense laser field is studied using the semiclassical approach, with a view towards cooperative chemical and optical pumping in laser production. The formalism is developed with the electronic-field representation, which treats collision and radiative interaction on the same footing. Electronic-field surfaces can be regarded as forming spectra for spontaneous emission; and particular emission events can be accounted for by propagating classical trajectories on emission electronic-field surfaces. Pre-emission loss from the excited state is dealt with by propagating classical trajectories on a loss surface along a complex contour of emission branch points. This loss surface is derived on the basis of localized radiative couplings between electronic-field states and provides a framework to treat the general problem of discrete state-continuum interactions. The formalism is applied to a two-state, collinear exponential model to compute S-matrix elements and transition probabilities between asymptotic states.     

Fibrous crystalline hydrogels formed from polymers possessing a linear poly(ethyleneimine) backbone

Novel thermoreversible physical hydrogels formed from polymers with linear and star architectures possessing a linear poly(ethyleneimine) (PEI) backbone have been investigated. The hydrogelation occurred simply upon natural cooling of hot aqueous solutions of PEIs to room temperature. The X-ray diffraction and differential scanning calorimetry measurements for the resultant hydrogels unambiguously indicated that the hydrogelation originated from the formation of dihydrate crystalline structures of PEI. These crystalline hydrogels are structurally unique and hierarchical. Microscopic images revealed that the morphologies of the crystalline hydrogels depend on their molecular architectures. The linear PEI resulted in branched fibrous bundles organized by unit crystalline nanofibers with a width of ca. 5-7 nm. The six-armed star with benzene ring core produced fanlike fibrous bundles while the four-armed star with porphyrin core assembled into asterlike aggregates. The critical concentration of gelation (C(G)) was low (about 0.2 approximately 0.3%) and the thermoreversible gel-sol transition temperatures (T(G)) were controllable from approximately 43 to approximately 79 degrees C. The hydrogels formed in the presence of the various aqueous additives including organic solvents, hydrophilic polymers, physical cross-linker, chemical cross-linker, and base enabling modification and functionalization during synthesis. The mechanical properties of the hydrogels could be improved by chemical cross-linking of preformed hydrogels by glutaraldehyde. Physically and physical/chemical cross-linked hydrogels served as excellent template roles in biomimetic silicification, which produced silica-PEI hybrid powder or monolith constructed by nanofibers.     

Synthesis of 2‐Dihydrooxadiazolinyl Chromones

Reactions of the substituted 2‐formyl chromones with aroylhydrazines gave corresponding 2‐(aroylhydrazonomethylidyne) chromones. Then 2‐(3′‐acetyl‐5′‐aryl‐2′,3′‐dihydro‐1′,3′,4′‐oxadiazol‐2′‐yl) chromones were prepared by these 2‐(aroylhydrazonomethylidyne) chromones under refluxing with Ac₂O. All target compounds were characterized through elemental analysis and IR, ¹H NMR, MS.     

Synthesis of Cucurbit [ n ] uril-based Rotaxanes

Non-covalent attractive forces are commonly employed in biological systems to drive the assembly of highly orga nized supramolecular entities from relatively simple subunits.