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101.
A series of poly [2-(dimethylamino)ethyl methacrylate (DMA)-sodium acrylate (SA)] diblock copolymers were synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymerization exhibits controlled characters: well-controlled molecular weight, narrow molecular weight distribution, molecular weight increasing with polymerization time. The zwitterionic diblock copolymers show rich solution behaviors. Dynamic light scattering (DLS) indicated the formation of micelles and reverse micelles of copolymers is affected by net charge density of copolymers. Microcalorimetry studies showed that the lower critical solution temperature (LCST) increases with incorporation of hydrophilic segments in buffer. 相似文献
102.
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104.
This article examines the current status of Markov processes in single molecule fluorescence. For molecular dynamics to be described by a Markov process, the Markov process must include all states involved in the dynamics and the first-passage time (FPT) distributions out of those states must be describable by a simple exponential law. The observation of non-exponential FPT distributions or other evidence of non-Markovian dynamics is common in single molecule studies and offers an opportunity to expand the Markov model to include new dynamics or states that improve understanding of the system. 相似文献
105.
侧链液晶聚合物的合成方法,可归纳为3类:一是烯基的单体,如甲基丙烯酸酯,或丙烯酸酯,氯代丙烯酸酯等,经自由基聚合反应,阴离子聚合反应及甲基丙烯酸酯的基团转移聚合反应,得到侧链液晶聚合物;二是变性反应,如聚硅氧烷与丙烯酸酯介 相似文献
106.
Synthesis and characterization of segmented liquid crystal poly(azoxy polyester-co-polyoxypropylene)
Jaine-Ming Huang Jen-Feng Kuo Chuh-Yung Chen 《Journal of polymer science. Part A, Polymer chemistry》1995,33(1):165-173
In this study a series of a segmented copolyester, poly(4,4′-dioxy-2,2′-dimethyl-azoxybenzene dodecanedioyl) (PMABD)-co-polyoxypropylene 400 (POP), was prepared. The chain length of PMABD studied (n) was varied from 7.8-18.2, and that of POP was unchanged. The intrinsic viscosity of the segmented copolyesters was 1.04-1.30, and the number average molecular weight obtained was 2.53 × 104?3.49 × 104 g/mol. The mesophase texture and thermal properties of the segmented copolyesters were measured as functions of n. It was found that the insert of flexible POP between those liquid crystalline domains of PMABD did affect thermotropic properties of PMABD. As the n value was 9.0 and 7.8 (or 7.4 and 8.6% by weight POP) the texture appeared as cholesteric-like oily streaks. The effect could not be attained by simply copolymerizing a mesogenic moiety with a pair of spacers of different lengths. The fluidity and domain structure of the flexible dodecanedioyl-POP-dodcanedioyl segments are taken into account for the obtained results. © 1995 John Wiley & Sons, Inc. 相似文献
107.
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109.
Denote by *
n
the set of all k
*-cycle resonant hexagonal chains with n hexagons. For any B
n
*
n
, let m(B
n
) and i(B
n
) be the numbers of matchings (=the Hosoya index) and the number of independent sets (=the Merrifield–Simmons index) of B
n
, respectively. In this paper, we give a characterization of the k
*-cycle resonant hexagonal chains, and show that for any B
n
*
n
, m(H
n
)m(B
n
) and i(H
n
)i(B
n
), where H
n
is the helicene chain. Moreover, equalities hold only if B
n
=H
n
. 相似文献
110.
There are many methods available for the detection of nucleotide variations in genetic material. Most of these methods are applied after amplification of the target genome sequence by the polymerase chain reaction (PCR). Many efforts are currently underway to develop techniques that can detect single nucleotide variations in genes either by means of, or without the need for, PCR. Allele-specific PCR (asPCR), which reports nucleotide variations based on either the presence or absence of a PCR-amplified DNA product, has the potential to combine target amplification and analysis in one single step. The principle of asPCR is based on the formation of matched or mismatched primer-target complexes by using allele-specific primer probes. PCR amplification by a DNA polymerase from matched 3'-primer termini proceeds, whereas a mismatch should obviate amplification. Given the recent advancements in real-time PCR, this technique should, in principle, allow single nucleotide variations to be detected online. However, this method is hampered by low selectivity, which necessitates tedious and costly manipulations. Recently, we reported that the selectivity of asPCR can be significantly increased through the employment of chemically modified primer probes. Here we report further significant advances in this area. We describe the synthesis of various primer probes that bear polar 4'-C-modified nucleotide residues at their 3' termini, and their evaluation in real-time asPCR. We found that primer probes bearing a 4'-C-methoxymethylene modification have superior properties in the discrimination of single nucleotide variations by PCR. 相似文献