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951.
羧基丙烯酸酯涂料合成及其防雾性能研究 总被引:3,自引:2,他引:3
采用种子乳液聚合法合成了一种互穿网络型羧基丙烯酸酯类聚物乳液,研究了加料方式对羧基分布的影响,结果表明丙烯酸加入到核单体中有利于羧基分布在乳胶粒表面。在体系中引入离子键交联结构提高了乳液涂料的硬度和耐水性能,离子键交联PILN型涂料具有优良的防雾性能。 相似文献
952.
A new preresonance light scattering (PRLS) assay of nucleic acids is presented. At pH 7.30, the weak PRLS of morin-cetyltrimethylammonium bromide (CTMAB) can be greatly enhanced by the addition of nucleic acids, owing to the interaction between the nucleic acid and morin-CTMAB. After the addition of morin and CTMAB to DNA, the zeta potential of DNA decreases and changes from negative to positive, which is due to the formation of an associate, the aggregation of morin on nucleic acids and the electric neutralization between DNA and the cationic surfactant CTMAB. Mechanism studies showed that the enhanced PRLS comes from the aggregation of morin in the presence of nucleic acids and CTMAB. The enhanced intensity of PRLS is in proportion to the concentration of nucleic acids in the range 7.5 x 10(-9)-1.0 x 10(-5) g ml(-1) for calf thymus DNA, 7.5 x 10(-9)-1.0 x 10(-6) g ml(-1) for salmon sperm DNA and 1.0 x 10(-8)-1.0 x 10(-6) g ml(-1) for yeast RNA. The detection limits are 3.4, 6.2 and 4.1 ng ml(-1) for calf thymus DNA, salmon sperm DNA and yeast RNA, respectively. Synthetic samples were analyzed satisfactorily. 相似文献
953.
Austen K FlattShawn M Dirk Jay C HendersonDwanleen E Shen Jie SuMark A Reed James M Tour 《Tetrahedron》2003,59(43):8555-8570
Several new classes of oligomers have been synthesized with functionalities designed to aid in the understanding of molecular device behavior, specifically when molecules are interfaced between proximal electronic probes. The compounds synthesized are series of azobenzenes, bipyridines and oligo(phenylene vinylene)s that bear acetyl-protected thiols for ultimate attachment to metallic surfaces. Some initial electrochemical and solid-state test results are also reported. 相似文献
954.
955.
The catalytic effect of chiral Lewis acids on the hetero-Diels-Alder reaction between aldehydes and Danishefsky's diene (1) has been investigated. A variety of combinations of different ligands and Lewis acids have been examined as catalysts for the hetero-Diels-Alder reaction between benzaldehyde and 1, and it has been found that the readily accessible Ti(IV)-H(8)-BINOL (TiHBOL) complex is a very effective catalyst for the reaction, leading to products with very high enantioselectivity (up to 99% ee) and yield (92%). The hetero-Diels-Alder reaction of other aldehydes with 1 under the catalysis of TiHBOL is a general reaction which proceeds well with very high enantioselectivity and isolated yield for various aldehydes at 0 degrees C to room temperature. Based on the experimental results, the proposed mechanism of the hetero-Diels-Alder reaction and the dihedral angle effects of ligands are discussed. 相似文献
956.
Abstract— In order to introduce fullerene cages into an aqueous environment, pendant [60]fullerene-poly(propionylethyle-neimine-co-ethyleneimine) was prepared photochemical-ly. The pendant polymer is highly water soluble, with equivalent aqueous solubilities of the polymer-bound [60]fullerene much higher than the solubility of [60]ful-lerene in toluene. The photochemical reaction between [60]fullerene and secondary amine moieties in the ami-nopolymers likely follows a photoinduced electron transfer-proton transfer mechanism. The pendant polymer structures, which are represented by dehydrogenated di-and tetra-aminofullerene linkages, were characterized by use of proton and 13C NMR, Fourier transform-infrared spectroscopy, gel-permeation chromatography and optical spectroscopic methods. 相似文献
957.
Ai‐Hua Zhao Yan Zhang Zhao‐Hui Xu Jian‐Wen Liu Wei Jia 《Helvetica chimica acta》2004,87(12):3160-3166
Three new enmein‐type ent‐kaurenoids, i.e., the two pairs 1 and 2 of 20‐epimers and the (20R)‐isomer 3 , besides the seven known diterpenoids 4 – 10 , were isolated from the aerial parts of Isodon serra. Their structures were elucidated by spectroscopic techniques and X‐ray diffraction. The immunosuppressive effect for T‐lymphocytes proliferation induced by Con A in BALB/c mouse was evaluated for the isolates 1 – 10 . They all displayed a remarkable inhibitory effect, with multi‐glycosides of Tripterygium wilfordii as positive reference substance (Table 3). 相似文献
958.
Zi-Zhong Li Qing-Xiang Guo Tan Ren Xiao-Qing Zhu You-Cheng Liu 《Journal of inclusion phenomena and macrocyclic chemistry》1993,15(1):37-42
Tetramethylsilane (TMS) can be included by -cyclodextrin (-CD), and sodium 2,2-dimethylsilapentane-5-sulphonate (DSS) can form inclusion complexes with - and -CD. The NMR chemical shifts are changed considerably as a result of the strong interaction between CD and the guest compound in the inclusion complexes. A downfield shift of as much as 0.63 ppm shift downfield has been observed for the protons of external TMS in CD aqueous solution. In view of this, the question arises of whether TMS and DSS can be used as internal references. DSS in D2O is suggested as an external reference for aqueous cyclodextrin solution in NMR measurements. 相似文献
959.
Reaction of powdered Zr with ZrCl4, BaCl2 and Be in suitable proportions in a Ta container at 800°C produces the title compound. Suitable monocrystals for X-ray diffraction were obtained from reactions to which a comparable amount of Hg2Cl2 had been added. The structure of Ba3Zr6Cl18Be is a superstructure of the K2ZrCl6 · Zr6Cl18H type (R3 c, Z = 6; a = 9.6852 (9) Å, c = 52.52 (1) Å; R, Rw = 2.7, 3.2% for 826 independent reflections, 2θ ≤ 50°). Trigonally compressed [Zr6(Be)Cl12i]Cl6a clusters are interconnected by six-coordinate barium atoms that lie in Cla antiprisms (a twisted version of the ZrIV site) while (9 + 3)-coordinate barium substitutes for potassium within chlorine layers. Distortions associated with the size and field of barium are responsible for the superstructure and for differences from other analogues. 相似文献
960.
Daschbach JL Dohnalek Z Liu SR Smith RS Kay BD 《The journal of physical chemistry. B》2005,109(20):10362-10370
The adsorption of water on FeO(111) is investigated using temperature programmed desorption (TPD) and infrared reflection absorption spectroscopy (IRAS). Well-ordered 2 ML thick FeO(111) films are grown epitaxially on a Pt(111) substrate. Water adsorbs molecularly on FeO(111) and desorbs with a well resolved monolayer peak. IRAS measurements as a function of coverage are performed for water deposited at 30 and 135 K. For all coverages (0.2 ML and greater), the adsorbed water exhibits significant hydrogen bonding. Differences in IRAS spectra for water adsorbed at 30 and 135 K are subtle but suggest that water adsorbed at 135 K is well ordered. Monolayer nitrogen TPD spectra from water covered FeO(111) surfaces are used to investigate the clustering of the water as a function of deposition or annealing temperature. Temperature dependent water overlayer structures result from differences in water diffusion rates on bare FeO(111) and on water adsorbed on FeO(111). Features in the nitrogen TPD spectra allow the monolayer wetting and 2-dimensional (2D) ordering of water on FeO(111) to be followed. Voids in a partially disordered first water layer exist for water deposited below 120 K and ordered 2D islands are found when depositing water above 120 K. 相似文献