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111.
The magnetic field effect (<800 G) on the hydrogen abstraction of xanthone from xanthene in SDS aqueous micellar solutions was studied using laser flash photolysis. The rate of triplet-singlet intersystem crossing of the radical pair of xanthone ketyl and 9-xanthenyl formed upon photolysis decreases from 1.4 × 106 s?1 at O G to 0.4 × 106 s?1 at 640 G. 相似文献
112.
The flow curves of fractionated polydimethylsiloxanes of different molecular weights were obtained over a wide range of shear rates, from 3 × 10?1 to 4.3 × 106 sec?1, by use of a gas-driven capillary viscometer designed to decrease the experimental error in high shear rate region. Non-Newtonian flow can occur at molecular weights below the critical molecular weight Mc for the entanglement of polymer chain. The critical molecular weight M′c for the onset of the non-Newtonian flow is identical with that of the segment of viscous flow. For the polymer of molecular weights from M′c to Mc, the upper Newtonian viscosity increases with an increase in molecular weight. Above Mc, the upper Newtonian viscosity is almost independent of the molecular weight. 相似文献
113.
114.
Kim SW Zimmer JP Ohnishi S Tracy JB Frangioni JV Bawendi MG 《Journal of the American Chemical Society》2005,127(30):10526-10532
Quantum dots with a core/shell/shell structure consisting of an alloyed core of InAs(x)P(1-x), an intermediate shell of InP, and an outer shell of ZnSe were developed. The InAs(x)P(1-x) alloyed core has a graded internal composition with increasing arsenic content from the center to the edge of the dots. This compositional gradient results from two apparent effects: (1) the faster reaction kinetics of the phosphorus precursor compared to the arsenic precursor, and (2) a post-growth arsenic-phosphorus exchange reaction that increases the arsenic content. The cores have a zinc blend structure for all compositions and show tunable emission in the near-infrared (NIR) region. A first shell of InP leads to a red-shift and an increase in quantum yield. The final shell of ZnSe serves to stabilize the dots for applications in aqueous environments, including NIR biomedical fluorescence imaging. These NIR-emitting core/shell/shell InAs(x)P(1-x)/InP/ZnSe were successfully used in a sentinel lymph node mapping experiment. 相似文献
115.
Y. Takashima 《Journal of Radioanalytical and Nuclear Chemistry》1993,171(1):83-93
Although there are 430 govemment and private universities in Japan, only a limited number of them have departments associated with nuclear science education. Moreover, mainly because of financial pressures, this association is often limited to government universities. Nuclear engineering departments are incorporated with only seven of the larger universities, and there are three institutes with nuclear reactors. In these facilities, education in reactor physics, radiation measurements, electromagnetic and material sciences, are conducted. In terms of radiation safety and radiological health physics, tem radioisotope centers and seven radiochemistry laboratories in universities play an important role. Virtually all of the financial support for nuclear education comes from the Japanese Govemment via the Ministry of Education, Science, and Culture. These are supplemented via private and corporate grants to various university faculty members. In addition to these universities, and private/corporate research institutes, The Japan Atomic Energy Research Institute teaches a short lecture course in nuclear science on a regular basis. 相似文献
116.
117.
118.
Manuel Blickle Karl Schwede Shunsuke Takagi Wenliang Zhang 《Mathematische Annalen》2010,347(4):917-949
We prove that the F-jumping numbers of the test ideal
t(X; D, \mathfrakat){\tau(X; \Delta, \mathfrak{a}^t)} are discrete and rational under the assumptions that X is a normal and F-finite scheme over a field of positive characteristic p, K
X
+ Δ is
\mathbb Q{\mathbb {Q}}-Cartier of index not divisible p, and either X is essentially of finite type over a field or the sheaf of ideals
\mathfraka{\mathfrak{a}} is locally principal. This is the largest generality for which discreteness and rationality are known for the jumping numbers
of multiplier ideals in characteristic zero. 相似文献
119.
Keiichi Kinashi Shunsuke Takenaka Shigekazu Kusabayashi 《Molecular Crystals and Liquid Crystals》2013,570(1):49-58
Some mesogenic materials involving a piperazine skeleton were prepared and the thermal properties were examined by DSC and microscopic analyses. Although the piperazines have a thermal flexibility similar to cyclohexyl ring, a lateral interaction due to lone pair electrons of nitrogens largely enhances the thermal stability of the mesophase. The piperazine compounds tend to preserve a smectic arrangement. 相似文献
120.
C. Wade Downey Grant J. Dixon Jared A. Ingersoll Claire N. Fuller Kenneth W. MacCormac Anna Takashima Rohina Sediqui 《Tetrahedron letters》2019,60(44):151192
Trimethylsilyl trifluoromethanesulfonate (TMSOTf) and a trialkylamine base promote both in situ enol silane/silyl ketene acetal formation and Mukaiyama aldol addition reactions between a variety of reaction partners in a single reaction flask. Isolation of the required enol silane or silyl ketene acetal is not necessary. For example, crossed aldol reactions between α-disubstituted aldehydes and non-enolizable aldehydes yield β-hydroxy aldehydes in good yield. In a related reaction, the common laboratory solvent ethyl acetate functions as both an enolate precursor and a green reaction solvent. When thioesters are employed as enolate precursors, high yields for additions to non-enolizable aldehydes are routinely observed. 相似文献