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141.
142.
Subhash C. Jain Stephen Nowicki Thomas Eisner Jerrold Meinwald 《Tetrahedron letters》1982,23(45):4639-4642
On the basis of spectral data and partial syntheses, structure 1 and 2 are established for zizanal and epizizanal, two new insect-repelling aldehydes isolated from Javanese vetiver oil (Vetiveria zizanoides). 相似文献
143.
The previously proposed left-right-symmetric SU(2)L × SU(2)R × U(1) theory permits one of the two neutral gauge particles N1 and N2 to be particularly light (<mW+L) compatible with all neutrin-data and the present atomic parity experiments. Distinguishing features of this theory (with the light mass solution) for e?e+ → μ+μ? and π+π? at PETRA and PEP energies as compared to the SU(2) × U(1) predictions are given. 相似文献
144.
Ohne Zusammenfassung 相似文献
145.
We present a kinetic study of the reaction of ground state silicon atoms with halogenated unsaturated organic compounds (R). Si(33PJ) was generated by the repetitive pulsed irradiation of SiCl4 in the presence of excess helium buffer gas and the reactant R in a slow flow system, kinetically equivalent to a static system. The ground state atom was monitored by time-resolved atomic resonance absorption spectroscopy at λ = 252 nm [Si(43PJ) ← Si(33PJ)] on time scales by which the optically metastable tates,Si(31D2) and Si(31S0) had relaxed to the 3P state, using signal averaging methods. Computerized fitting of the resulting atomic decay traces in the presence of the various reactants, R, yielded the following new body of absolute second-order rate constants (kR, T = 300 K, errors = 2sigma;):
These data are compared, where appropriate, with analogous data for unsaturated hydrocarbon organic compounds. They are also discussed within the general context of nuclear recoil measurements involving 31Si. 相似文献
R | kR/cm3 molecule?1 s?1 |
---|---|
C2F4 | 1.6 ± 0.2 × 10?10 |
C2Cl4 | 9.9 ± 1.7 × 10?10 |
CH2CF2 | 4.0 ± 0.6 × 10?10 |
CHClCCl2 | 7.0 ± 1.1 × 10?10 |
CF3CH? CH2 | 4.6 ± 0.5 × 10?10 |
C6H6 | 4.4 ± 1.0 times; 10?10 |
C6F6 | 4.4 ± 0.6 × 10?10 |
C6HF5 | 4.6 ± 1.3 × 10?10 |
C6H2F4 | 3.9 ± 0.8 × 10?10 |
C6F5—CF3 | 5.1 ± 0.6 × 10?10 |
146.
The molecular electrostatic potential (MESP) and polarization-corrected MESP (PMESP) minima for some small molecules are calculated on the surface generated by rolling cations (Li+ and Na+) on their van der Waals surfaces. The cation binding energies of these molecules are obtained with HF/6-31G** level ab initio calculations. A noteworthy outcome of the present study is that the plot of these binding energies and the corresponding PMESP surface minimum values turns out to be remarkably linear with a slope close to unity. The PMESP is thus found to work as a powerful tool for unearthing the patterns of cation binding sites and energetics for molecular systems. 相似文献
147.
Hongwen Zhang Spandan Maiti Ghatu Subhash 《Journal of the mechanics and physics of solids》2008,56(6):2171-2187
Shear band spacing in Zr-based bulk metallic glasses (BMGs) under dynamic loads is found to vary with position and local strain rate in the indented region. To investigate the dependence of shear band evolution characteristics on local strain rate and normal stress, a micromechanical model based on momentum diffusion is proposed. The thermo-mechanical model takes into account the normal stress dependence of yield stress, the free volume theory and the associated viscosity change within the shear band region. Temperature rise is obtained from the balance between the heat diffusion to the adjacent regions from a shear band and the heat generation due to the accumulated plastic work in a shear band. The parametric study has revealed that thermal effects play a minor role when the critical shear displacement is below 10 nm (as in nanoindentation) but become significant when the shear displacement accumulated in a shear band is of the order of hundreds of nanometers (as in uniaxial compression and in dynamic indentations). Finally, it is found that the normal stress plays a crucial role in the deformation behavior of BMGs by not only decreasing the time for shear band formation but also increasing the temperature rise significantly. 相似文献
148.
Sally A. Goldman Jyoti Parwatikar Subhash Suri 《Journal of Algorithms in Cognition, Informatics and Logic》2000,34(2):370
We study non-preemptive, online admission control in the hard deadline model: each job must either be serviced prior to its deadline or be rejected. Our setting consists of a single resource that services an online sequence of jobs; each job has a length indicating the length of time for which it needs the resource and a delay indicating the maximum time it can wait for the service to be started. The goal is to maximize total resource utilization. The jobs are non-preemptive and exclusive, meaning once a job begins, it runs to completion, and at most one job can use the resource at any time. We obtain a series of results, under varying assumptions of job lengths and delays. 相似文献
149.
Tapan Kumar Pradhan Karla Mahender Reddy Subhash Ghosh 《Tetrahedron: Asymmetry》2013,24(17):1042-1051
A concise total synthesis of emericellamides A and B, two cyclic depsipeptides exhibiting antibacterial and cytotoxic activities, is reported. A Paterson anti-aldol reaction and a hydroxy directed 1,3-anti reduction were applied for construction of the polypropionate unit with the required stereochemistry in emericellamides A and B. An FDPP mediated macrolactamization was used to construct the macrocycle of emericellamides A and B. 相似文献
150.