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1.
The product from the fluorination of pyridine by KCoF4 at ca. 220° contains eleven fluoropyridines, two fluoro-2-azahex-enes, three azahexa- dienes, and two fluoro-N-methylpyrrolidines, besides an azacyclohexa-1,3- diene. Four products were isolated from a fluorination of pyridine by CoF3 at ca. 150°, a 2-azahexene, two N-methylpyrrolidines, and 4H-nona- fluoropiperidine. 相似文献
2.
Let G be a finite k‐edge‐connected simple graph. We consider when a set of independent edges can be extended to a 2‐factor such that this 2‐factor avoids a fixed set of independent edges. A complete characterization is provided in those cases, where this is feasible. © 2005 Wiley Periodicals, Inc. J Graph Theory 49: 48–58, 2005 相似文献
3.
4.
The tumor microenvironment, or stroma, is chemically and morphologically modified during carcinoma progression. The predominant cell type in the stroma, the fibroblast, maintains collagen properties in normal tissue and often transformed during tumor progression. Biochemical changes within fibroblasts upon initial cancer activation, however, are relatively poorly defined. Here, we hypothesized that Fourier transform infrared (FT-IR) spectroscopic imaging could potentially be employed to examine these early transformations. Further, we employ attenuated total reflectance (ATR) microscopy to characterize subcellular spectra and their changes upon transformation. We characterized fibroblast transitions upon stimulation with both a molecular agent and a carcinoma-mimicking cellular co-culture system. Changes were predominantly observed in the 1080 cm(-1) and 1224 cm(-1) peak absorbance, commonly associated with nucleic acids, as well as in the band at 2930 cm(-1) associated with the C-H stretching of proteins in the cytoplasmic compartment. In conclusion, biochemical changes in cancer-associated fibroblasts that express α-SMA are dominated by the cytoplasm, rather than the nucleus. This ensures that spectral changes are not associated with proliferation or cell cycle processes of the cells and the cells are undergoing a true phenotypic change denoted by protein modifications in the cell body. 相似文献
5.
It is proved that a cyclically (k ? 1)(2n ? 1)-edge-connected edge transitive k-regular graph with even order is n-extendable, where k ≥ 3 and k ? 1 ≥ n ≥ ?(k + 1)/2?. The bound of cyclic edge connectivity is sharp when k = 3. © 1993 John Wiley & Sons, Inc. 相似文献
6.
We prove that a 3-connected cubic graph contains a cycle through any nine points. 相似文献
7.
In a previous paper we have announced that a graph is non-planar if and only if it contains a maximal, strict, compact, odd
ring. Little has conjectured that the compactness condition may be removed. Chernyak has now published a proof of this conjecture.
However, it is difficult to test a ring for maximality. In this paper we show that for odd rings of size five or greater,
the condition of maximality may be replaced by a new one called regularity. Regularity is an easier condition to diagnose
than is maximality. 相似文献
8.
I.R. Holton P. Weightman P.T. Andrews 《Journal of Electron Spectroscopy and Related Phenomena》1980,21(3):219-226
Weak features in the electron spectrum of Al excited by bremsstrahlung radiation from a Cu anode have been studied using a recently developed multidetector. A feature at ~1410 eV which has been identified as the Al 2p internal photoelectron line was found to have an intensity 4.2 × 10?3 times that of the Al KL2,3L2,3:1D2 Auger line, in agreement with a simple theoretical treatment. The identification of this feature is confirmed by the observation of an ~67% decrease in its intensity in spectra obtained from clean Al films in the thickness range 3.1–34.0 nm. The intensity of a plasmon gain peak at ~1404 eV is found to be independent of thickness for films of thickness greater than 7.5 nm. 相似文献
9.
It is shown that no graph contains a maximal 3-ring of bonds. 相似文献
10.
In this paper we determine the circumstances under which a set of 11 vertices in a 3-connected cubic graph lies on a cycle. In addition, we consider the number of such cycles that exist and characterize those graphs in which a set of 9 vertices lies in exactly two cycles. 相似文献