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排序方式: 共有257条查询结果,搜索用时 15 毫秒
221.
Jukka Niskanen Mikko Karesoja Vladimir Aseyev Xing‐Ping Qiu Françoise M. Winnik Heikki Tenhu 《Journal of polymer science. Part A, Polymer chemistry》2016,54(3):425-436
The synthesis and self‐assembling of a thermoresponsive conjugate of hyaluronic acid (HA) and poly(N‐vinylcaprolactam) (PVCL) is reported. Both polymers were end functionalized: HA via reductive amination, thereby introducing an azide endgroup to the chain end, and PVCL via thioetherification to introduce a propargyl group. The two were coupled with a copper assisted “click” reaction into a bioconjugate composed of HA blocks with the molar mass 3,600 g mol?1 (1618 saccharide units) and PVCL blocks of 3,500 g mol?1 (~25 repeating units). The cloud point temperature measured by transmittance was 50–51 °C in water. The calorimetrically observed phase transition temperature of PVCL in the conjugate increased by 2 °C to 47.7 °C, whereas the enthalpy of the phase transition was unaffected by the conjugation. HA‐PVCL conjugate self‐assembles in water upon heating into monodisperse, colloidally stable, hollow spherical particles whose size may be tuned with the heating rate of the solution. Slow and fast heating resulted in vesicles with the hydrodynamic radii of 443 or 275 nm, respectively. The heating rate did not, however, affect the cloud point. Salt did not noticeably affect the size of the polymer particles, presumably because of interactions between the HA and PVCL blocks. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 425–436 相似文献
222.
Sirkka-Liisa Eriksson Heikki Orelma Frank Sommen 《Complex Analysis and Operator Theory》2016,10(2):251-265
In this paper we consider the solutions of the equation \({\mathcal {M}}_\kappa f=0\), where \({\mathcal {M}}_\kappa \) is the so called modifier Dirac operator acting on functions \(f\) defined in the upper half-space and taking values in the Clifford algebra. We look for solutions \(f(\underline{x},x_{n})\) where the first variable is invariant under rotations. A special type of solution is generated by the so called spherical monogenic functions. These solutions may be characterize by a Vekua-type system and this system may be solved using Bessel functions. We will see that the solution of the equation \({\mathcal {M}}_\kappa f=0\) in this case will be a product of Bessel functions. 相似文献
223.
This paper deals with the s-reflexive spaces introduced by Yang and Zhao. The
authors prove that every s-reflexive Hausdorff space is zero-dimensional, and indicate a
close relationship between the theory of s-reflexive spaces and that of continuous selections.
Several examples relating to s-reflexivity are given. 相似文献
224.
Heidi M. Leskinen Jukka‐Pekka Suomela Heikki P. Kallio 《Rapid communications in mass spectrometry : RCM》2010,24(1):1-5
The regioisomer composition of triacylglycerols (TAGs) in various vegetable oils was determined with a new liquid chromatography/tandem mass spectrometry (LC/MS/MS method). A direct inlet ammonia negative ion chemical ionization (NICI) MS/MS method was improved by adapting it to LC negative ion (NI) atmospheric pressure chemical ionization (APCI) MS/MS system using ammonia as nebulizer gas. The method is based on the preferential formation of [M–H–RCOOH–100]? ions during collision‐induced dissociation by loss of sn‐1/3 fatty acids from [M–H]? ions. Calibration curves were created from nine reference TAGs: Ala/L/L, Gla/L/L, L/L/O, L/O/O, P/O/O, P/P/O, Po/Po/V, Po/Po/O, and C/O/O. The calibration curves were used to quantify the regioisomer compositions of selected TAGs in rapeseed oil, sunflower seed oil, palm oil, black currant seed oil, and sea buckthorn pulp oil. The method discriminates the different regioisomers and the results obtained by this method were in good agreement with previous results. This proves that this new method can be used for the determination of regiospecific distribution of fatty acids in TAGs. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
225.
Niina Aaltonen Juha R. Savinainen Casandra Riera Ribas Jani Rönkkö Anne Kuusisto Jani Korhonen Dina Navia-Paldanius Jukka Häyrinen Piia Takabe Heikki Käsnänen Tatu Pantsar Tuomo Laitinen Marko Lehtonen Sanna Pasonen-Seppänen Antti Poso Tapio Nevalainen Jarmo T. Laitinen 《Chemistry & biology》2013,20(3):379-390
226.
J Heikkil? S Stridh B Oberg J Chattopadhyaya 《Acta chemica Scandinavica. Series B: Organic chemistry and biochemistry》1985,39(8):657-669
Influenza virus mRNA synthesis is primed by a capped oligonucleotide which is cleaved off from a cellular mRNA by a viral protein. The dinucleotide A3'p5'G can be used as a primer for the viral RNA polymerase mediated RNA synthesis in a cell-free system. Analogues of A3'p5'G have therefore been synthesized using the phosphotriester approach, and their priming ability for the influenza virus mRNA synthesis has been determined. An absence of the 2'-hydroxyl function in the guanosine residue in the dinucleotide, as in A3'p5'dG, drastically decreased its priming ability. Similarly, an alteration of the 3'----5' phosphate linkage to a 2'----5' phosphodiester linkage affected the priming ability quite severely. However a dinucleotide, with the 2'-hydroxyl function omitted in the adenosine moiety, as in dA3'p5'G, could still stimulate the mRNA synthesis. None of the modified dinucleotides inhibited A3'p5'G or globin mRNA primed influenza mRNA synthesis. 相似文献
227.
Katri Laihia Jaakko Paasivirta Heikki Pikkarainen Sirkku Aho-Pulliainen 《Magnetic resonance in chemistry : MRC》1984,22(2):117-120
The 13C NMR spectra of nine dichlorinated bicyclo[2.2.1]heptanes (norbornanes) have been measured and assigned. The pairwise effects of chlorine substituents which cause deviations from the additivity of single-substituent effects were investigated and are discussed. The largest effect found is the high-field shift of carbons bearing vicinal cis substituents. In the case of geminal substitution deviations from additivity were found to be to low field and large in the γ, smaller in the β and negligible in the α chemical shifts. The observed deviations for 1,3-disubstituted cases vary from ?3.2 to +1.1 ppm at different carbons, allowing no simple explanation. Replacement of α-hydrogen in a diaxial 1,3-arrangement by CH3, OH or CI causes the single substituent effect, namely the γa effect, to change considerably. 相似文献
228.
Vovk Irena Simonovska Breda Andrenšek Samo Yrjönen Teijo Vuorela Pia Vuorela Heikki 《平面色谱法杂志一现代薄层色谱法》2003,16(1):66-70
JPC – Journal of Planar Chromatography – Modern TLC - Extraction of onion (Allium cepa L.) with 80:20 (v/v) methanol—water in water by rotation planar extraction (RPE) and medium-... 相似文献
229.
When is a Volterra space Baire? 总被引:1,自引:0,他引:1
In this paper, we study the problem when a Volterra space is Baire. It is shown that every stratifiable Volterra space is Baire. This answers affirmatively a question of Gruenhage and Lutzer in [G. Gruenhage, D. Lutzer, Baire and Volterra spaces, Proc. Amer. Math. Soc. 128 (2000) 3115-3124]. Further, it is established that a locally convex topological vector space is Volterra if and only if it is Baire; and the weak topology of a topological vector space fails to be Baire if the dual of the space contains an infinite linearly independent pointwise bounded subset. 相似文献
230.