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排序方式: 共有697条查询结果,搜索用时 15 毫秒
61.
62.
J. Badier J. Boucrot J. Bourotte G. Burgun O. Callot Ph. Charpentier M. Crozon D. Decamp P. Delpierre B. Gandois R. Hagelberg M. Hansroul Y. Karyotakis W. Kienzle P. Le D? J. Lefran?ois Th. Leray J. Maillard A. Michelini Ph. Miné G. Rahal O. Runolfsson P. Siegrist A. Tilquin R. Vanderhaghen S. Weisz NA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1985,26(4):489-494
63.
Wang Y Tang Z Correa-Duarte MA Liz-Marzán LM Kotov NA 《Journal of the American Chemical Society》2003,125(10):2830-2831
Indiscriminate adsorption of nanoparticles (NPs) significantly complicates the preparation of mesoscale NP patterns considered as enabling technology for many devices and processes. Instead of selected chemical functionalization of the substrate surface prior to the assembly of nanocolloids, the required optical properties - in our case, high quantum yield luminescence - are imparted to the layer-by-layer assembled films by spatially selected photoactivation. The films are made by sequential adsorption of a positively charged polyelectrolyte and a negatively charged CdSe/CdS aqueous dispersion with an initial quantum yield of 0.5-2%. The photoactivation process takes place in the presence of oxygen and may be accompanied by photoetching. A 50-500-fold increase in the luminescence intensity of CdSe/CdS citrate-stabilized particles (quantum yield 25-45%) after visible light illumination provides excellent pattern contrast. Micron scale luminescence patterns were produced from NPs of various CdSe core diameters with red, yellow, and green emission. It was also demonstrated that different emission colors such as orange and green can be combined in one image by taking advantage of spatially selective photoetching. The presented optical patterning technique significantly simplifies the preparation of luminescence patterns as compared to conventional methods. The high signal-to-noise ratio associated with it is essential for optical devices, information processing, and biophotonics. The most immediate use of this approach is expected in cryptography and cell monitoring. 相似文献
64.
The extinction coefficient of a birefringent optical fiber (the ratio between the radiation power output of the polarization mode and the radiation power transferred from this mode to another one) characterizes the capability of a birefringent fiber to retain the polarization state of the radiation. In relatively short birefringent fibers (1–100 m), the extinction coefficient may reach 104–106. Such high values of the extinction coefficient are difficult to measure by standard techniques (excitation of one polarization mode by an incoherent source with subsequent recording of the light intensity at the output of the analyzer). An interference method of measuring the extinction coefficient of birefringent fibers is suggested. It is based on using a coherent source and measuring interference oscillations caused by an additional phase modulation at the input of the fiber. This method does not require precise polarization matching between the laser source and fiber and considerably loosens requirements for the polarizer-analyzer extinction and resolution of the photodetector. As a result, using simple standard components (semiconductor laser, film polarizer, and photodetector), one can measure extinction coefficient as high as 106. The suggested interference method of measuring the extinction coefficient of birefringent fibers receives a theoretical analysis, and experimental data obtained for 2- to 1000-m-long fibers are presented. 相似文献
65.
A. A. Kotov L. A. Vaishnene V. G. Vovchenko Yu. A. Gavrikov V. V. Polyakov M. G. Tverskoi O. Ya. Fedorov T. Fukahori Yu. A. Chestnov A. V. Shvedchikov A. I. Shchetkovskii 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(6):809-811
The results of measuring total cross sections for proton-induced fission of natPb, 209Bi, 232Th, 233U, 235U, 238U, 237Np, and 239Pu nuclei at proton energies from 200 to 1000 MeV are reported. The measurements were carried out in steps of ≈100 MeV. Complementary fission fragments were detected in coincidence by two parallel-plate avalanche gas counters placed in the beam line on both sides of the thin target close to it. Energy and isotope dependences of the fission cross sections are analyzed. 相似文献
66.
Zhi NA Bei JIANG Hui YANG Zhong Wen LIN Han Dong SUN* Laboratory of Phytochemistry Kunming Institute of Botany Chinese Academy of Sciences Kunming Chemistry Deparment of the College of Life Science Chemistry Yunnan University K 《中国化学快报》2001,(8)
Isodon enanderianus (Hand. -Mazz.) H. W. Li, has been used in folk medicine as anti-inflammatory and detoxified agent1. The Isodon genus is known to be rich in ent-kaurane diterpenoids, a series of new ent-kaurane diterpenoids have been isolated from the dried leaves of I. enanderianus2-4. In order to find more biologically active substances, we have carefully investigated the chemical constituents of I. enanderianus collected in Shiping county of Yunnan province, and as a result, enanderi… 相似文献
67.
V. V. Kotov D. V. Nenakhov K. E. Stekol’nikov 《Russian Journal of Electrochemistry》2010,46(1):107-111
Characteristics of mass transport of the anions of pyrophosphoric acid are investigated during electrodialysis through MA-40
and MA-41 anion-exchange membranes. It is established that the rate of mass transport for counterions is greater through the
MA-41 membrane than the MA-40 membrane, and thus the former can be used for demineralizing solutions with salts of pyrophosphoric
acid. Higher selectivity to pyrophosphate ions is found for the MA-40 membrane compared to the MA-41 membrane in the electrodialysis
of mixtures of pyrophosphate and hydropyrophosphate ions, and thus the MA-40 membrane can be regarded as promising for the
separation of such mixtures. 相似文献
68.
69.
70.
J. Badier M. Bardadin-Otwinowska C. Bemporad U. Berthon H. Bienvenu J. Boucrot J. Bourotte G. Burgun O. Callot Ph. Charpentier A. M. Cnops M. Cohen F. Constantini M. Crozon D. Décamp P. Delpierre J. F. Detoeuf P. Espigat B. Gandois G. R. Giannini V. Hajjar M. Hansroul Y. Karyotakis P. Lariccia P. Le D? J. Mas A. Michelini G. C. Moneti M. Moniez E. Paré G. Rahal-Callot M. Rumpf O. Runolfsson A. Tilquin S. Weisz NA Collaboration 《Zeitschrift fur Physik C Particles and Fields》1986,31(3):341-347
Direct photon production has been studied by an experiment performed with the NA3 spectrometer at CERN, using incident negative and positive beams at 200 GeV/c interacting with an isoscalar Carbon target. Two different triggers have been used; one of them requires the photon conversion. The experiment is sensitive to direct photons produced with 3.0≦P T ≦6 GeV/c and center-of-mass rapidity ?0.4≦y *≦1.2. Inclusive cross sections are given for incident π± and protons, and compared with second order QCD predictions; finally an estimation of the gluon structure function of the nucleon is given. 相似文献