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排序方式: 共有239条查询结果,搜索用时 15 毫秒
231.
Schümann F Hammache F Typel S Uhlig F Sümmerer K Böttcher I Cortina D Förster A Gai M Geissel H Greife U Iwasa N Koczoń P Kohlmeyer B Kulessa R Kumagai H Kurz N Menzel M Motobayashi T Oeschler H Ozawa A Płoskoń M Prokopowicz W Schwab E Senger P Strieder F Sturm C Sun ZY Surówka G Wagner A Waluś W 《Physical review letters》2003,90(23):232501
An exclusive measurement of the Coulomb breakup of 8B into 7Be+p at 254A MeV allowed the study of the angular correlations of the breakup particles. These correlations demonstrate clearly that E1 multipolarity dominates and that E2 multipolarity can be neglected. By using a simple single-particle model for 8B and treating the breakup in first-order perturbation theory, we extract a zero-energy S factor of S17(0)=18.6+/-1.2+/-1.0 eV b, where the first error is experimental and the second one reflects the theoretical uncertainty in the extrapolation. 相似文献
232.
We demonstrate a novel low coherence Michelson interferometer which can provide simultaneous measurement of the refractive index and thickness of transparent plates used as a measured object. Unlike the existing low coherence interferometers reported so far, either an object or a focusing lens aligned on the signal arm is scanned repeatedly by a precise translation stage in synchronization with movement of a reflection mirror on the reference arm. The so-called object or lens scanning method gives us two measured quantities a movement distance of the stage between two light focusing states on the front and rear planes of an object and the corresponding optical path difference. These two measured quantities, result in desirable values of the index and thickness of the object with a short calculation. The measurement accuracy of ≤0.1% is expected for a thickness of more than 1 mm. In the experiment using the object scanning method, the accuracy of 0.3% or less was successfully attained for nearly 1-mm thick plates of fused quartz, sapphire, LiTaO3 and slide glass. 相似文献
233.
Ohne Zusammenfassung 相似文献
234.
Intercalation of neutral ammonia molecules into trivalent face-centered-cubic (fcc) fulleride superconductors induces a dramatic change in electronic states. Monoammoniated alkali fulleride salts (NH3)K3-xRbxC60, forming an isostructural orthorhombic series, undergo an antiferromagnetic transition, which was found by the electron spin resonance experiment. The Neel temperature first increases with the interfullerene spacing and then decreases for (NH3)Rb3C60, forming a maximum at 76 K. This feature is explained by the generalized phase diagram of Mott-Hubbard transition with an antiferromagnetic ground state. 相似文献
235.
Ma YuGang Fang DeQing Sun XiaoYan Zhou Pei Cai XiangZhou Chen JinGen Guo Wei Tian WenDong Wang HongWei Zhang GuoQiang Cao XiGuang Fu Yao Hu ZhengGuo Wang JianSong Wang Meng Togano Y. Aoi N. Baba H. Honda T. Okada K. Hara Y. Ieki K. Ishibashi Y. Itou Y. Iwasa N. Kanno S. Kawabata T. Kimura H. Kondo Y. Kurita K. Kurokawa M. Moriguchi T. Murakami H. Oishi H. Ota S. Ozawa A. Sakurai H. Shimoura S. Shioda R. Takeshita E. Takeuchi S. Yamada K. Yamada Y. Yasuda Y. Yoneda K. Motobayashi T. 《中国科学:物理学 力学 天文学(英文版)》2011,54(1):18-23
Two-proton relative momentum distributions from the break-up channels 23Al→p+p+21Na and 22Mg→p+p+20Ne at an energy of 60–70 A MeV have been measured together with two-proton opening angles at the projectile fragment separator beamline (RIPS) in the RIKEN Ring Cyclotron Facility. The results demonstrate the existence of diproton emission component from single-step 2He for highly excited 23Al and 22Mg. 相似文献
236.
We characterized pH effect on hole transport through DNA duplexes possessing a partial triplex-forming region. Direct electrochemical measurement of the current response of photosensitizer-tethered DNA immobilized on a gold electrode revealed that the partial triplex formation under acidic conditions suppressed photocurrent due to hole transport, while dissociation of the triplex into the duplex as occurred upon increasing pH values recovered the photocurrent efficiency. Reversible conversion between duplex and triplex induced upon cyclic alternation of pH values resulted in a rise and fall of photocurrent responses, indicating that pH change may feature in the switching function of hole transport in DNA. These electrochemical behaviors could be correlated to the results obtained in long-range photo-oxidative DNA cleavage experiments, in which DNA cleavage at the hole trapping site beyond the triplex region was significantly suppressed under triplex-forming acidic conditions. 相似文献
237.
Miyoko Kamigauchi Yuko Miyamoto Kinuko Iwasa Makiko Sugiura Zjujiro Nishijo Narao Takao Toshimasa Ishida Yasuko In Masatoshi Inoue 《Helvetica chimica acta》1990,73(8):2171-2178
The solid-state and solution conformations of (+)-chelidonine ( 1 ), a biologically active alkaloid, were determined by X-ray diffraction and 1H-NMR spectroscopy, X-Ray diffraction analysis revealed a conformer with B/C ‘anti-type’ cis conjunction, a half-chair of ring B , and a twist half-chair of ring C. One H2O molecule per one alkaloid molecule was cocrystallized and stabilized by H-bonding with OH? C(11). Analysis of the thermal behavior of the crystal showed more thermal stability in the monohydrate than the anhydrate. The NMR measurement of concentration and temperature dependences in CDCl3 and in (CD3)2SO suggested that the OH group of 1 was intramolecularly H -bonded to N(5) in (CD3)2SO and intermolecularly H-bonded to the solvent in CDCl3. Conformational-energy calculations by the MNDO method showed that the intramolecular H -bond was little affected by the conformational stabilization of 1 . 相似文献
238.
Magneto-optical absorption spectra due to exciton states and Landau-levels were measured in GaAs/AlAs multi-quantum-wells. By extrapolating the photon energies of the absorption peaks to zero magnetic field, the lowest state (1S) heavy hole exciton binding energy, EB(1S), was obtained as a function of well size Lz in the range . The Lz dependence of EBh showed the change of the exciton character from three-dimensional to two-dimensional with decreasing Lz. The diamagnetic shift observed for the heavy hole exciton peak was larger than that for the light hole exciton peak, showing the anisotropic nature of the Luttinger-Kohn Hamiltonian. The diamagnetic shift of the heavy hole exciton peak became smaller as Lz was decreased, suggesting the enhancement of the two-dimensional exciton character. 相似文献
239.
Yoshiaki Yuguchi Takayuki Fujiwara Haruna Miwa Mayumi Shirakawa Hirofumi Yajima 《Macromolecular rapid communications》2005,26(16):1315-1319
Summary: We developed a novel thermo‐reversible gelation system by mixing xyloglucan with an iodine solution. Xyloglucan dissolves in water to produce a colorless solution. However, the addition of iodine solution induces color and gelation; heating causes the gel to melt and become colorless. According to results from spectroscopic and small‐angle X‐ray scattering experiments, the gelation mechanism was proposed to involve two xyloglucan chains that associate side‐by‐side and incorporate iodine and/or iodide ions.