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1.
P Nürnberg I Barth E Fuhrmann C Lenzner T Losanova C Peters H P?che G Thiel 《Electrophoresis》1991,12(2-3):186-192
Germline and somatic instability of the human genome was studied, using synthetic oligonucleotides specific for simple repeat motifs. The following probes were used: (GTG)5, (GACA)4, (GATA)4, (CT)8, (TTAGGG)3, (GT)8, (GAA)6 and (GGAT)4. Each of them is unique with respect to the target regions recognized in the genome. Thus compilation of the various fingerprint data provides a complex map of the genome (and its deviations). While the fingerprints of differentiated somatic tissues never showed any alterations, in tumor tissues (namely gliomas) many changes could be detected. Most of the latter reflect secondary karyological aberrations. In nearly one third of the gliomas, drastically amplified and apparently monomorphic DNA fragments were identified. This marker should make it possible to deal with causal pathogenetic mechanisms as well as novel diagnostic strategies. 相似文献
2.
3.
Ronald I. Becker Isabella Lari Andrea Scozzari Giovanni Storchi 《Annals of Operations Research》2007,150(1):65-78
In this paper we consider the location of a path shaped facility on a grid graph. In the literature this problem was extensively
studied on particular classes of graphs as trees or series-parallel graphs. We consider here the problem of finding a path
which minimizes the sum of the (shortest) distances from it to the other vertices of the grid, where the path is also subject
to an additional constraint that takes the form either of the length of the path or of the cardinality. We study the complexity
of these problems and we find two polynomial time algorithms for two special cases, with time complexity of O(n) and O(nℓ) respectively, where n is the number of vertices of the grid and ℓ is the cardinality of the path to be located.
The literature about locating dimensional facilities distinguishes between the location of extensive facilities in continuous
spaces and network facility location. We will show that the problems presented here have a close connection with continuous
dimensional facility problems, so that the procedures provided can also be useful for solving some open problems of dimensional
facilities location in the continuous case. 相似文献
4.
S. Barth H. R. Ott F. N. Gygax B. Hitti E. Lippelt A. Schenck Z. Fisk 《Hyperfine Interactions》1989,50(1-4):709-716
μ+ SR-measurements in transversally applied magnetic fields of 2000 G and 4000 G on heavy-electron single crystal U2Zn17 are presented. They reveal that at least two types of interstitial sites are occupied by the positive muons. One of these
sites (1/3, 2/3, 5/6) could be identified via induced local dipolar fields which aboveT
N=9.7 K can exactly be derived from the magnetic susceptibility. The corresponding component of the μ+-signal exhibits a steplike decrease by about 40% atT
N which is caused by the onset of a very broad distribution of static internal magnetic fields (ΔB≈1000 G) with zero average. Such a field distribution is in distinct contrast to dipolar-field calculations performed for
the simple antiferromagnetic structure deduced from neutron diffraction. The remaining 60% of the muons contributing to this
component belowT
N are subject to a narrow static field distribution (ΔB≈1 G). The induced dipolar fields at the site (1/3, 2/3, 5/6) are temperature-independent belowT
N. A weak dipolar coupling to the U-moments renders similar observations for muons occupying the second type of interstitial
impossible. 相似文献
5.
F. N. Gygax B. Hitti E. Lippelt A. Schenck S. Barth 《Zeitschrift für Physik B Condensed Matter》1988,71(4):473-490
Using a high purity Bi single crystal the temperature and orientation dependence of the zero and transverse field muon spin relaxation rate has been studied in detail. The results imply that the + occupies one of the two possible interstitial sites in the distorted rhombohedral crystal structure of Bi below 10 K and the other site above 80 K. At both sites the nearest neighbor Bi atoms are found to be shifted towards the + by 10% of their nominal distance, implying a large local lattice contraction. In concomitance extremely strong electric field gradients are manifest at the nn Bi nuclei. An almost temperature independent reduced relaxation rate in the temperature range from 20 K to 60 K is interpreted in terms of short range diffusion along a limited chain of alternating types of sites. Above 100 K both long range and short range diffusion are indicated. 相似文献
6.
7.
At pH 5 (AcOHAcONa) protonation of the enamine of 3,6,6-trimethylnorpinane 2-one (3-methylnopinone) yields the cis immonium ion 6 (X OAc), which isomerizes to the thermodynamically more stable trans immonium ion 6′ (X OAc). Under more strongly acid conditions (aqueous hydrochloric or perchloric acids), the enamonium salts 7 (X Cl or ClO4) are formed; these isomerize, with a rate increasing with decreasing acidity to the cis immonium salts 6, stable under these conditions. Epimerization of the cis salt 6 (X Cl), occurs in ethereal hydrogen chloride, the rate increasing also with decreasing acidity. At pH 5, hydrolysis of the enamine yields 3-methylnopinone, the proportion of the less thermodynamically stable trans isomer increasing with a rise in reaction temperature. 相似文献
8.
Aravinda S Shamala N Das C Sriranjini A Karle IL Balaram P 《Journal of the American Chemical Society》2003,125(18):5308-5315
Aromatic-aromatic interactions between phenylalanine side chains in peptides have been probed by the structure determination in crystals of three peptides: Boc-Val-Ala-Phe-Aib-Val-Ala-Phe-Aib-OMe, I; Boc-Val-Ala-Phe-Aib-Val-Ala-Phe-Aib-Val-Ala-Phe-Aib-OMe, II; Boc-Aib-Ala-Phe-Aib-Phe-Ala-Val-Aib-OMe, III. X-ray diffraction studies reveal that all three peptides adopt helical conformations in the solid state with the Phe side chains projecting outward. Interhelix association in the crystals is promoted by Phe-Phe interactions. A total of 15 unique aromatic pairs have been characterized in the three independent crystal structures. In peptides I and II, the aromatic side chains lie on the same face of the helix at i/i + 4 positions resulting in both intrahelix and interhelix aromatic interactions. In peptide III, the Phe side chains are placed on the opposite faces of the helix, resulting in exclusive intermolecular aromatic interactions. The distances between the centroids of aromatic pair ranges from 5.11 to 6.86 A, while the distance of closest approach of ring carbon atoms ranges from 3.27 to 4.59 A. Examples of T-shaped and parallel-displaced arrangements of aromatic pairs are observed, in addition to several examples of inclined arrangements. The results support the view that the interaction potential for a pair of aromatic rings is relatively broad and rugged with several minima of similar energies, separated by small activation barriers. 相似文献
9.
S. Steffen M. Otto L. Niewoehner M. Barth Z. Bro¿żek-Mucha J. Biegstraaten R. Horváth 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007
A gunshot residue sample that was collected from an object or a suspected person is automatically searched for gunshot residue relevant particles. Particle data (such as size, morphology, position on the sample for manual relocation, etc.) as well as the corresponding X-ray spectra and images are stored. According to these data, particles are classified by the analysis-software into different groups: ‘gunshot residue characteristic’, ‘consistent with gunshot residue’ and environmental particles, respectively. Potential gunshot residue particles are manually checked and – if necessary – confirmed by the operating forensic scientist. 相似文献
10.
Kent Morrill Robert E. Linder Edith M. Bruckmann Günter Barth Edward Bunnenberg Carl Djerassi Lloyd Seamans Albert Moscowitz 《Tetrahedron》1977,33(8):907-911
The magnetic CD spectra of a number of Me substituted trans-2-decalones and bicyelo[2.2.2]octan-2-ones were measured. The results showed a large, and sometimes dominant, contribution to the MCD intensity which could be correlated with the presence of α-substituents lying outside of the plane of the carbonyl chromophore. 相似文献