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排序方式: 共有177条查询结果,搜索用时 15 毫秒
1.
In this paper we describe the synthesis, characterisation and use of two distinct molecularly imprinted polymers (MIPs) prepared using esters of p-hydroxybenzoic acid (parabens) as templates: one MIP was synthesised by precipitation polymerisation using a semi-covalent molecularly imprinting strategy with methyl paraben as the template/target (MIP 1); the second MIP was prepared in monolithic form through a conventional non-covalent molecular imprinting strategy, with butyl paraben as the template (MIP 2). MIP 1 recognized methyl paraben, showed cross-selectivity for other parabens analytes used in the study and higher affinity towards these compounds than did a non-imprinted control polymer. Similarly, MIP 2 demonstrated higher affinity towards paraben analytes than a non-imprinted control polymer.For the analysis of environmental water samples, a solid-phase extraction (SPE) protocol was developed using MIP 2 as sorbent, and results were compared to a SPE using a commercial sorbent (Oasis HLB). With MIP 2 as sorbent and butyl paraben as target, when percolating 500 mL of river water spiked at 1 μg L−1 through the SPE cartridge, and using 1 mL of isopropanol as cleaning solvent, a higher recovery of butyl 4-hydroxybenzoate (butyl paraben) and a cleaner chromatogram where achievable when using the MIP compared to the commercial sorbent. 相似文献
2.
Martina LahmannJoachim Thiem 《Tetrahedron》2011,67(9):1654-1664
α-Tocopherol and as a model compound pentamethylchromanol could be transferred into simple and more complex 5a-ether derivatives including galactopyranose as well as ascorbic acid conjugates. Following elaboration of a glucopyranoside spacer element this could be used for tethering the vitamin E and the vitamin C components to give novel conjugates for subsequent biostudies concerning their proposed synergism of antioxidant properties in tissues. 相似文献
3.
Gemini表面活性剂烷烃尾链在吸附和聚集过程中的疏水协同效应(英文) 总被引:1,自引:0,他引:1
以表面张力法测定了系列Gemini表面活性剂m-6-m以及对应单体表面活性剂CmTABr的临界胶束浓度(cmc)和降低水表面张力20mN·m-1需要的浓度(pC20).比较这些参数表明m-6-m胶束化和在界面吸附的能力均强于CmTABr,这被归结为Gemini表面活性剂烷烃尾链间的疏水协同效应.与不对称Gemini表面活性剂12-6-m比较,对称的Gemini结构更有利于表面活性剂的聚集和吸附. 相似文献
4.
连接基团链长度对季铵盐二聚表面活性剂C12-s-C12·2Br在水溶液中胶团化行为的影响 总被引:12,自引:1,他引:12
用电导法、稳态荧光法和粘度法研究了二聚表面活性剂C12-s-C12*2Br分子中的连接基团链长度(s=2, 3, 4, 6)对其在水溶液中聚集行为的影响. 实验发现, C12-s-C12*2Br的胶团生成能力远比其单体C12TABr强得多, 前者cmc值较后者降低一个数量级. 胶团聚集数N随表面活性剂浓度c的增大而增大, 其中当s=2时的N值在c=7.7 mmol/L后开始急剧增大. 计算结果表明, 此时胶团形状发生了明显变化, 形成了椭球形的胶团. 粘度测定结果也证实了这一点. 相似文献
5.
Chunxia Du Luping Zhang Meiqing Shi Zhu Ming Min Hu Robin B. Gasser 《Electrophoresis》2010,31(4):654-658
Larval nematodes were collected from marine fishes from the Yellow Sea, China. Specimens (n=1731) of Anisakis type I from 311 fishes (representing 40 species) were each identified based on morphological characters. From the genomic DNA from individual specimens, a region of nuclear ribosomal DNA was amplified by PCR, followed by digestion with restriction endonuclease HinfI, TaqI or HhaI. Subsequently, the ITS‐1 and ITS‐2 regions of selected samples were sequenced. The results revealed three species of Anisakis, namely Anisakis pegreffii (n=1709), A. typica (n=3) and a genotype (n=19) proposed, also based on comparison with previous studies, to be a “hybrid” between A. pegreffii and A. simplex sensu stricto. Thus, A. pegreffii was the dominant species, accounting for 98.7% of the total number of specimens examined herein. This is the first report of A. typica and the “hybrid” genotype from fishes from the Yellow Sea. This study provides important basic information on Anisakis in this region and suggests that the genus Anisakis has substantial host and geographical distributions. 相似文献
6.
L. M. Likhosherstov O. S. Novikova L. O. Kononov A. V. Orlova I. B. Sivaev V. I. Bregadze 《Russian Chemical Bulletin》2007,56(10):2105-2108
Conjugates of β-lactosylamine derivatives bearing terminal amino groups in aglycon with ortho-carboranylacetic acid were synthesized. Five glycoconjugates with spacers of different length (from 9 to 18 atoms) and hydrophilicity
containing di-, tri-, and pentapeptide fragments constructed of glycine and serine residues and spacers incorporating ethylenediamine
and tartaric acid or tertiary amine residues were prepared
Dedicated to the memory of outstanding chemist and biochemist V. N. Shibaev.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2033–2036, October, 2007. 相似文献
7.
Yao-Yi Cheng Peggy Cebe Malcolm Capel Heidi Schreuder-Gibson Aaron Bluhm Walter Yeomans 《Journal of Polymer Science.Polymer Physics》1995,33(17):2331-2341
Crystallization and melting behavior are studied by small-angle X-ray scattering (SAXS) for a series of recently synthesized monotropic liquid crystalline polycarbonates based on α-methyl stilbene mesogen and methylene flexible spacer. The one-dimensional electron density correlation function is used to obtain long period, crystal thickness, and linear crystallinity from the Lorentz-corrected SAXS intensity. Changes in these parameters during nonisothermal crystallization and melting are explained by a model of dual crystal populations. The primary crystals form first using the liquid crystalline phase as crystal nuclei, while smaller and less perfect crystals form later from the isotropic phase at low temperature. The results of the real-time SAXS study of isothermal crystallization also support the view that the nematic phase serves as crystal nuclei for fast crystallization. An odd-even effect in crystal thickness and linear crystallinity is observed in all the SAXS experiments mentioned above. The results of this study and our complementary wide-angle X-ray scattering (WAXS) investigation show clearly that the difference in the position of the neighboring carbonate dipoles on a chain affects structural organization both at the unit cell level and at the level of the crystal in these monotropic LCPs. © 1995 John Wiley & Sons, Inc. 相似文献
8.
We have synthesized a homologous series of azoesters consisting of a coumaryl moiety as the end group. Eleven derivatives of this series exhibit mesomorphism. The nematic mesophase is exhibited from ethyl homologue onward, while the smectic phase commences at the pentyl derivative and is exhibited along with the nematic phase up to the hexadecyl derivative. The N-I transition temperatures curves show the usual odd-even effect. All the compounds in this series are thermally stable and exhibit a wide mesomorphic range of nearly 120°C. Their thermal stabilities and other characteristics are discussed. 相似文献
9.
ABSTRACTA homologous series of new chiral liquid crystal compounds, MnBEB (n = 4–10), was prepared by covalently linking a chiral (–)-menthyl with biphenyl-benzoate via a dicarboxylic spacer of varying length and parity. A combination of analysis methods, such as FT-IR, 1H NMR spectra, differential scanning calorimetry (DSC), polarised optical microscopy (POM) and X-ray diffraction was carried out to systematically investigate their phase structures and phase transition behaviours. The length and parity of the flexible spacers has a profound influence on the Tm and Tc and a modest odd-even effect is observed for the chiral liquid crystal compounds MnBEB. Only compound M4BEB developed an N* phase with selectively reflection on heating and a blue phase on cooling process. In addition, increasing the length of the flexible spacers tends to narrow the temperature range of the N* phase and widen the smectic phase, moreover, the pitch becomes longer with the spacer increases. 相似文献
10.