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991.
Bhaggy Duggal Robin Harte In Ho Jeon 《Proceedings of the American Mathematical Society》2004,132(5):1345-1349
``Polaroid elements" represent an attempt to abstract part of the condition, ``Weyl's theorem holds" for operators.
992.
The objective of ISLES (Inverse-Square Law Experiment in Space) is to perform a null test of Newton's law in space with a resolution of one part in 105 or better at 100 m. ISLES will be sensitive enough to detect axions with the strongest allowed coupling and probe large extra dimensions of string theory down to a few m. The experiment will be cooled to 2 K, which permits superconducting magnetic levitation of the test masses. This soft, low-loss suspension, combined with a low-noise SQUID, leads to extremely low intrinsic noise in the detector. To minimize Newtonian errors, ISLES employs a near null source, a circular disk of large diameter-to-thickness ratio. Two test masses, also disk-shaped, are suspended on the two sides of the source mass at a nominal distance of 100 m. The signal is detected by a superconducting differential accelerometer. 相似文献
993.
Drutskoy A Abe K Abe K Abe T Aihara H Akatsu M Asano Y Aulchenko V Aushev T Bakich AM Ban Y Bay A Bedny I Behera PK Bizjak I Bondar A Bozek A Bracko M Browder TE Casey BC Chao Y Cheon BG Chistov R Choi Y Chuvikov A Danilov M Dash M Dong LY Eidelman S Eiges V Gabyshev N Garmash A Gershon T Golob B Haba J Hagner C Handa F Hastings NC Hayashii H Hazumi M Hinz L Hokuue T Hoshi Y Hou WS Huang HC Igarashi Y Iijima T Inami K Ishikawa A Itoh R Iwasaki H Iwasaki M Iwasaki Y Jang HK Kang JH Kang JS 《Physical review letters》2004,92(5):051801
The radiative decay B-->phi K gamma is observed for the first time. The branching fraction for the charged B--->phi K- gamma decay mode is measured to be B(B--->phi K- gamma)=(3.4+/-0.9+/-0.4)x10(-6). The photon energy distribution for the B--->phi K- gamma decay is presented. The signal for the neutral B(0)-->phi K(0)gamma decay mode is not statistically significant and an upper limit, B(B(0)-->phi K(0)gamma)<8.3x10(-6) at 90% C.L., is set. The analysis is based on a data set of 90 fb(-1) collected by the Belle experiment at the e(+)e(-) asymmetric collider KEKB. 相似文献
994.
Szyczewski A Hołderna-Natkaniec K Natkaniec I 《Solid state nuclear magnetic resonance》2004,25(1-3):21-27
Internal dynamics of 17- and 21-substituted progesterone derivatives was studied by the methods NMR, inelastic incoherent neutron scattering (IINS) and quantum chemical calculations. Comparison of the computer simulation of the phonon density of states (PDS) spectrum performed by the density functional theory (DFT) method with the spectrum obtained after a transformation of the experimental results permits an interpretation of subsequent modes. Only for 17OH prg the second moment of NMR line decreases to 10 G2 near room temperature, most probably because of the oscillations about direction of inter-molecular hydrogen bond. Significant mobility of protons in this compound is also confirmed by a low intensity of the elastic peak in INS and broadening of this spectrum. 相似文献
995.
Highly sulfated cyclosophoraoses (HS-Cys) were synthesized by the chemical modification of a family of neutral cyclosophoraoses isolated from Rhizobium leguminosarum bv. trifolii. The HS-Cys were then analytically characterized using Fourier transform-infrared spectroscopy and elemental analysis. These HS-Cys were successfully used as a novel chiral additive, in low-pH aqueous background electrolytes, for capillary electrophoretic separation of five basic chiral drugs such as arterenol, atenolol, isoproterenol, propranolol, and metoprolol. 相似文献
996.
Brogan KL Shin JH Schoenfisch MH 《Langmuir : the ACS journal of surfaces and colloids》2004,20(22):9729-9735
Specific and nonspecific interactions between antibody-modified probes and substrate-immobilized proteins were monitored by atomic force microscopy (AFM). Probes were modified with anti-ovalbumin IgG antibodies immobilized in either an oriented or a random manner. The oriented immobilization of whole IgG was accomplished through the use of Protein A, and random immobilization was carried out with glutaraldehyde. Nonspecific interactions may lead to false detection of antibody-antigen binding events even when the antigen binding sites are properly positioned by an oriented immobilization strategy. Thus, nonionic and zwitterionic surfactants, including Tween 20, Tween 80, Triton X-100, and CHAPS, were evaluated to determine if nonspecific binding events could be reduced without compromising the desired specific antibody-antigen binding. Enzyme-linked immunosorbent assay and surface plasmon resonance assays were also employed to study antibody-antigen binding as a function of immobilization strategy and surfactant concentration. The data from these studies indicate that Protein A can be used to immobilize whole IgG onto AFM probes for force measurement experiments and that a surfactant is useful for improving the selectivity for such measurements. 相似文献
997.
Hao B Zhao G Kang PT Soares JA Ferguson TK Gallucci J Krzycki JA Chan MK 《Chemistry & biology》2004,11(9):1317-1324
L-pyrrolysine, the 22(nd) genetically encoded amino acid, was previously deduced to be (4R, 5R)-4-substituted-pyrroline-5-carboxylate attached to the epsilon-nitrogen of lysine based on the crystal structure of the M. barkeri monomethylamine methyltransferase (MtmB). To confirm L-pyrrolysine's identity, structures of MtmB have been determined following treatment with hydroxylamine, N-methylhydroxylamine, or dithionite. Analysis of these structures has provided additional support for the presence of the pyrroline ring and, together with previous mass spectroscopy data, has led us to assign the C(4)-substituent to a methyl group. Based on this assignment, synthetic L-pyrrolysine was prepared by chemical methods. Detailed study of this chemically synthesized L-pyrrolysine has allowed us to characterize its physical properties, to study its chemical stability, and to elucidate the role of its C(4) substituent. Future applications of this synthetic L-pyrrolysine include its in vivo incorporation into recombinant proteins. 相似文献
998.
Growth of poly(pseudorotaxane) on gold using host-stabilized charge-transfer interaction 总被引:1,自引:0,他引:1
A novel supramolecular polymer (poly(pseudorotaxane)) in which the repeating units are linked by host-stabilized charge-transfer interaction between the guest molecules is grown on gold and characterized. 相似文献
999.
Kang YS Lee HI Zhang Y Han YJ Yie JE Stucky GD Kim JM 《Chemical communications (Cambridge, England)》2004,(13):1524-1525
Highly ordered mesoporous materials constructed with integrated polymer-silica hybrid frameworks can be obtained via a one-step synthetic strategy using a mixture of polymer and silicate as the framework sources in the presence of a structure-directing agent. 相似文献
1000.
Dramatic solvent effect of nitroethane was observed in the catalytic asymmetric reductions of allenyl ketones and alpha,beta-ynones using the oxazaborolidine cayalyst to yield the corresponding alcohols in high levels of enantioselectivity. 相似文献