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排序方式: 共有133条查询结果,搜索用时 15 毫秒
81.
A convenient and portable triacetone triperoxide (TATP) sensor was developed utilizing a thiol-to-disulfide oxidation to trigger a solution-to-gel phase transition. Using this method, TATP can be detected visually without any instrumentation. 相似文献
82.
We show that two new intraspecies P-wave superfluid phases appear in two-component asymmetric Fermi systems with short-range S-wave interactions. In the BEC limit, phonons of the molecular BEC induce P-wave superfluidity in the excess fermions. In the BCS limit, density fluctuations induce P-wave superfluidity in both the majority and the minority species. These phases may be realized in experiments with spin-polarized Fermi gases. 相似文献
83.
A Longitudinal Examination of Middle School Students' Understanding of the Equal Sign and Equivalent Equations 总被引:1,自引:0,他引:1
Martha W. Alibali Eric J. Knuth Shanta Hattikudur Nicole M. McNeil Ana C. Stephens 《Mathematical Thinking and Learning》2007,9(3):221-247
This longitudinal study investigated (a) middle school students' understanding of the equal sign, (b) students' performance solving equivalent equations problems, and (c) changes in students' understanding and performance over time. Written assessment data were collected from 81 students at four time points over a 3-year period. At the group level, understanding and performance improved over the middle school years. However, such improvements were gradual, with many students still showing weak understanding and poor performance at the end of grade 8. More sophisticated understanding of the equal sign was associated with better performance on equivalent equations problems. At the individual level, students displayed a variety of trajectories over the middle school years in their understanding of the equal sign and in their performance on equivalent equations problems. Further, students' performance on the equivalent equations problems varied as a function of when they acquired a sophisticated understanding of the equal sign. Those who acquired a relational understanding earlier were more successful at solving the equivalent equations problems at the end of grade 8. 相似文献
84.
Sagawa H Mori T Abe K Chakrabarti S Fujii Y Higashi Y Ishimoto S Kurihara Y Maki A Mani P Nozaki T Omori T Perez P Sakai Y Sugimoto Y Takaiwa Y Terada S Tsuchiya K Bacala A Imlay R Kirk P Marterer W McNeil RR Metcalf W Cheng CP Mao ZP Yan Y Xu YT Zhou HS Zhu YC Abashian A Gotow K Kajino F Naito F Avignone F Childers R Darden C Edwards J Lusin S Rosenfeld C Wilson S Johnson D Frautschi M Kagan H Kass R Trahern CG Lee HY Ko W Lander RL Maeshima K Malchow RL Saroff D Sparks K Williams MC 《Physical review letters》1988,60(2):93-96
85.
We show how the probabilistic concepts of half-space trimming and depth may be used to define convex scenario sets Qα for stress testing the risk factors that affect the solvency of an insurance company over a prescribed time period. By choosing the scenario in Qα which minimizes net asset value at the end of the time period, we propose the idea of the least solvent likely event (LSLE) as a solution to the forward stress testing problem. By considering the support function of the convex scenario set Qα, we establish theoretical properties of the LSLE when financial risk factors can be assumed to have a linear effect on the net assets of an insurer. In particular, we show that the LSLE may be interpreted as a scenario causing a loss equivalent to the Value-at-Risk (VaR) at confidence level α, provided the α-quantile is a subadditive risk measure on linear combinations of the risk factors. In this case, we also show that the LSLE has an interpretation as a per-unit allocation of capital to the underlying risk factors when the overall capital is determined according to the VaR. These insights allow us to define alternative scenario sets that relate in similar ways to coherent measures, such as expected shortfall. We also introduce the most likely ruin event (MLRE) as a solution to the problem of reverse stress testing. 相似文献
86.
Pressure drop measurements in a 15-row steam condenser configured with in-line tubes, p/D < 1.33, are described. Pressures from 50 to 100 mb and Remax in the range 1,000-18,000 were imposed. It is shown that pressure loss coefficients for the bundle and for two-row pairs were lower than predictions for equivalent single-phase tests except near the bottom of the bundle. There was some evidence that increase in suction parameter increased this effect in the top rows. Taken together with previous investigations [3, 4], a falling trend of suction effect is evident the more closely packed the tubes are. The discrepancy between these findings and the results of simulation experiments [7] is noted. 相似文献
87.
Collum DB McNeil AJ Ramirez A 《Angewandte Chemie (International ed. in English)》2007,46(17):3002-3017
Lithium diisopropylamide (LDA) is a prominent reagent used in organic synthesis. In this Review, rate studies of LDA-mediated reactions are placed in the broader context of organic synthesis in three distinct segments. The first section provides a tutorial on solution kinetics, emphasizing the characteristic rate behavior caused by dominant solvation and aggregation effects. The second section summarizes substrate- and solvent-dependent mechanisms that reveal basic principles of solvation and aggregation. The final section suggests how an understanding of mechanism might be combined with empirical methods to optimize yields, rates, and selectivities of organolithium reactions and applied to organic synthesis. 相似文献
88.
89.
Aihara H Alston-Garnjost M Avery RE Barbaro-Galtieri A Barker AR Barnes AV Barnett BA Bauer DA Bengtsson H Bintinger DL Bobbink GJ Bolognese TS Bross AD Buchanan CD Buijs A Caldwell DO Clark AR Cowan GD Crane DA Dahl OI Derby KA Eastman JJ Eberhard PH Edberg TK Eisner AM Enomoto R Erné FC Fujii T Gary JW Gorn W Hauptman JM Hofmann W Huth JE Hylen J Kamae T Kaye HS Kees KH Kenney RW Kerth LT Ko W Koda RI Kofler RR Kwong KK Lander RL Langeveld WG Layter JG Linde FL Lindsey CS Loken SC Lu A Lu X 《Physical review letters》1986,57(26):3245-3248
90.
Aihara H Alston-Garnjost M Avery RE Barbaro-Galtieri A Barker AR Barnes AV Barnett BA Bauer DA Bengtsson H Bintinger DL Bobbink GJ Bolognese TS Bross AD Buchanan CD Buijs A Caldwell DO Clark AR Cowan GD Crane DA Dahl OI Derby KA Eastman JJ Eberhard PH Edberg TK Eisner AM Enomoto R Erné FC Fujii T Gary JW Gorn W Hauptman JM Hofmann W Huth JE Hylen J Kamae T Kaye HS Kees KH Kenney RW Kerth LT Ko W Koda RI Kofler RR Kwong KK Lander RL Langeveld WG Layter JG Linde FL Lindsey CS Loken SC Lu A Lu X 《Physical review letters》1986,57(15):1836-1838