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101.
102.
Herrmann H Fillol JL Wadepohl H Gade LH 《Angewandte Chemie (International ed. in English)》2007,46(44):8426-8430
103.
This paper deals with the use of Cu(II) complexes of L-tartaric acid or L-threonine as selectors for the chiral separation of drugs containing amino alcohol structure by ligand-exchange CE. Using Cu(II) ions as a complexing agent, a series of sympathomimetics and beta-blockers were resolved. It was found that the resolution strongly depends on selector concentration and pH. The optimum pH for complexation was 12. 相似文献
104.
Kolev T Koleva BB Spiteller M Mayer-Figge H Sheldrick WS 《The journal of physical chemistry. A》2007,111(40):10084-10089
2-amino-4-nitroaniline crystallizes in a noncentrosymmetric space group, which gives it significant potential for second-order nonlinear optical properties (NLO) in the bulk. Crystallographic and linear-polarized IR-spectrocopic data in the solid state unambiguously confirm a quinoide-like structure in the ground state in contrast to UV and theoretical data, which indicate an aromatic one for the excited state. UV-vis spectral elucidations in solutions with different polarities indicate a significant charge-transfer band with shifts of up to 100 nm, corresponding to a large value for the molecular first hyperpolarizability. Calculations of the UV- and IR-spectroscopic properties confirm the stabilization of the quinoide-like structure in the ground state, as well as the theoretically predicted NLO properties at the molecular level and provide a value of beta(tot), which is some 3.6 times higher than the analogous parameter for p-nitroaniline, a classical compound with experimentally confirmed NLO properties. 相似文献
105.
Visualizing the structure of triglyceride nanoparticles in different crystal modifications 总被引:6,自引:0,他引:6
Bunjes H Steiniger F Richter W 《Langmuir : the ACS journal of surfaces and colloids》2007,23(7):4005-4011
Colloidal suspensions of triglycerides are under investigation as potential drug carrier systems. The properties of the matrix lipids are altered in the nanoparticles compared to those of the bulk material. For instance, the metastable alpha-modification of the triglycerides usually transforms into the stable beta-polymorph quite rapidly in the colloidal particles. Recently, it was observed that the alpha-modification can be preserved for a considerable period of time in tristearin nanoparticles when the particles are stabilized with a blend of saturated long-chain phospholipids and the bile salt sodium glycocholate [Bunjes, H.; Koch, M. H. J. J. Controlled Release 2005, 107, 229-243]. As triglyceride nanoparticles in the alpha-modification may offer some advantages over those in the beta-form with regard to drug delivery applications, the structure of the corresponding dispersions was investigated in more detail with differential scanning calorimetry, X-ray diffraction, and electron microscopy. The electron microscopic investigations confirmed a platelet-like, layered structure for particles in the beta-modification and revealed a spheroidal shape with concentric layers for larger particles in the alpha-form. For the first time, not only was information on the internal structure of solid triglyceride nanoparticles obtained from freeze-fracture electron micrographs but also details were observed by cryoelectron microscopy. 相似文献
106.
F. Laue I. Böttcher M. Debowski A. Förster E. Grosse P. Koczoń B. Kohlmeyer M. Mang M. Menzel L. Naumann H. Oeschler F. Pühlhofer E. Schwab P. Senger Y. Shin J. Speer H. Ströbele C. Sturm G. Surówka F. Uhlig A. Wagner W. Waluś 《The European Physical Journal A - Hadrons and Nuclei》2000,9(3):397-410
Production cross-sections of charged pions, kaons and antikaons have been measured in C+C and C+Au collisions at beam energies
of 1.0 and 1.8 AGeV for different polar emission angles. The kaon and antikaon energy spectra can be described by Boltzmann
distributions whereas the pion spectra exhibit an additional enhancement at low energies. The pion multiplicity per participating
nucleon M(π+)/<A
part> is a factor of about 3 smaller in C+Au than in C+C collisions at 1.0 AGeV whereas it differs only little for the C and the
Au target at a beam energy of 1.8 AGeV. The K+ multiplicities per participating nucleon M(K+)/ <A
part> are independent of the target size at 1 AGeV and at 1.8 AGeV. The K- multiplicity per participating nucleon M(K-)/ <A
part> is reduced by a factor of about 2 in C+Au as compared to C+C collisions at 1.8 AGeV. This effect might be caused by the
absorption of antikaons in the heavy target nucleus. Transport model calculations underestimate the K-/K+ ratio for C+C collisions at 1.8 AGeV by a factor of about 4 if in-medium modifications of K-mesons are neglected.
Received: 10 December 1999 / Accepted: 14 November 2000 相似文献
107.
We present an exact solution of a probabilistic cellular automaton for traffic with open boundary conditions, e.g., cars can enter and leave a part of a highway with certain probabilities. The model studied is the asymmetric exclusion process (ASEP) with simultaneous updating of all sites. It is equivalent to a special case (v
max=1) of the Nagel–Schreckenberg model for highway traffic, which has found many applications in real-time traffic simulations. The simultaneous updating induces additional strong short-range correlations compared to other updating schemes. The stationary state is written in terms of a matrix product solution. The corresponding algebra, which expresses a system-size recursion relation for the weights of the configurations, is quartic, in contrast to previous cases, in which the algebra is quadratic. We derive the phase diagram and compute various properties such as density profiles, two-point functions, and the fluctuations in the number of particles (cars) in the system. The current and the density profiles can be mapped onto the ASEP with other time-discrete updating procedures. Through use of this mapping, our results also give new results for these models. 相似文献
108.
Heike Mildenberger 《Mathematical Logic Quarterly》2002,48(4):517-521
We prove that there is no Borel connection for non‐trivial pairs of unsplitting relations. This was conjectured in [3]. 相似文献
109.
Norbert Kuhn Riad Fawzi Martin Grathwohl Heike Kotowski Manfred Steimann 《无机化学与普通化学杂志》1998,624(12):1937-1939
Synthesis and Coordination of 2-Acetylimino-1,3-dimethylimidazoline. The Crystal Structure of [Cu4I4(C7H11N3O)2] 2-Acetylimino–1,3-dimethylimidazoline ( 2 , ImNAc) obtained from 1,3-dimethyl-2-iminoimidazoline ( 1 ) and acetyl chloride forms with CuI the stepped cubane type complex [Cu4I4(ImNAc)2] ( 3 ); the X-ray structure of 3 is reported. 相似文献
110.
Heike Baethge Sren Butz Gudrun Schmidt-Naake 《Macromolecular rapid communications》1997,18(10):911-916
Poly[styrene-co-(N-vinylcarbazole)] copolymers with controlled molecular weights and narrow polydispersities were synthesized by nitroxide-mediated “living” free radical copolymerization using an initiator/capping agent system consisting of benzoyl peroxide (BPO) and the stable nitroxyl radical 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO). The copolymerization behaves in a “living” fashion and allows the synthesis of poly[styrene-co-(N-vinylcarbazole)]/polystyrene block copolymers via a controlled chain-extension reaction of the prepared copolymers with styrene. 相似文献