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101.
102.
Sigurd Höger Klaus Bonrad Silvia Rosselli Anne-Désirée Ramminger Thomas Wagner Beate Silier Simone Wiegand Wolfgang Häußler Günter Lieser Volker Scheumann 《Macromolecular Symposia》2002,177(1):185-191
Alkyl- and Oligostyrene substituents were attached to shape-persistent macrocycles based on a phenyl-ethynyl backbone. In good solvents for both the rigid core and the flexible corona no aggregation occurred. Whereas, addition of a solvent that selectively solubilizes the corona induced a solvophobic aggregation. For alkyl substituted rings the experimental data were described by a monomer-dimer equilibrium. In contrast, the oligostyrene substituted rings formed more expanded aggregates which were investigated by scattering and by imaging methods. The superstructures are consequently described as hollow supramolecular cylindrical brushes. 相似文献
103.
104.
We study critical points of the indefinite functional by applying Floer's homology construction to the ordinary gradient flow of the functional f on a suitable Sobolev space. One of our main observations is that even though this flow is well posed in both time directions
and lacks any kind of smoothing property one can still obtain compactness of connecting orbit spaces and thus define the Floer
homology for .
Received November 11, 1997; in final form March 12, 1998 相似文献
105.
Sigurd Schraders Xuan Li Fanxiu Guo Yong Liu Jijiang Luo Duanfu Xu 《Macromolecular Symposia》1989,30(1):161-167
In the current paper the morphology of a slightly crosslinked polyester-polyurethane (hard-segment content ca. 33 wt.-%) is studied by means of transmission electron microscopy (TEM). A new staining technique based on ruthenium tetroxide was applied. This new technique allows the unambiguous visualization of the typical microdomain structure of the polyurethane and also of a wide size spectrum of globular hard-segment-rich domains which result from phase separation in the early stage of preparation. The hard-segment-rich microdomains have a size between 1.5 and 10 nm while the globular domains span a size spectrum from 10 to 2000 nm. 相似文献
106.
Sigurd Schrader Xuan Li Fanxiu Guo Yong Liu Jijiang Luo Duanfu Xu 《Macromolecular rapid communications》1988,9(9):597-601
Microphase separation of as-reacted polyester-polyurethane samples based on α-hydro-ω-hydroxypoly(oxyethyleneoxyadipoyl)/4,4′-methylenedi(phenyl isocyanate)/1,4-butanediol/2-ethyl-2-hydroxymethyl-1,3-propanediol (mole ratio 1:3,2:1,9:0,1) was studied using transmission electron microscopy. A new staining technique was applied which uses ruthenium tetroxide vapour for the treatment of the polymer. Ruthenium tetroxide reacts preferably with the hard-segment-rich microdomains of the polyester-polyurethane. Therefore, a well-contrasted pattern is formed by staining which reflects the microdomain structure of the polymer. The hard-segment-rich microdomains have irregular, mostly globular shape, and their sizes range from about 2 to 8 nm. 相似文献
107.
Dr. Steffen Pockes Dr. David Wifling Prof. Dr. Armin Buschauer Prof. Dr. Sigurd Elz 《ChemistryOpen》2019,8(3):285-297
New classes of alkylated hetarylpropylguanidines with different functionality and variation in spacer length were synthesized to determine their behavior at the four histamine receptor (H1R, H2R, H3R, H4R) subtypes. Alkylated guanidines with different terminal functional groups and varied basicity, like amine, guanidine and urea were developed, based on the lead structure SK&F 91486 ( 2 ). Furthermore, heteroatomic exchange at the guanidine structure of 2 led to simple analogues of the lead compound. Radioassays at all histamine receptor subtypes were accomplished, as well as organ bath studies at the guinea pig (gp) ileum (gpH1R) and right atrium (gpH2R). Ligands with terminal functionalization led to, partially, highly affine and potent structures (two digit nanomolar), which showed up a bad selectivity profile within the histamine receptor family. While the benzoylurea derivative 144 demonstrated a preference towards the human (h) H3R, S-methylisothiourea analogue 143 obtained high affinity at the hH4R (pKi=8.14) with moderate selectivity. The molecular basis of the latter finding was supported by computational studies. 相似文献
108.
Vollmeyer J Jester SS Eberhagen F Prangenberg T Mader W Höger S 《Chemical communications (Cambridge, England)》2012,48(52):6547-6549
The aggregation of shape-persistent macrocycles with an empty cavity, an undecyldiether strand and a tetraethylene glycol strand leads in all cases to a macroscopic gelation of the solvent. However, the gelation temperatures are fine-tuned by the intraannular substituents. 相似文献
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110.