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排序方式: 共有103条查询结果,搜索用时 15 毫秒
1.
Summary The essential oils of Estonian spruce and pine needles have been analysed by a combination of steam distillation/extraction, GC and GC-MS. According to their monoterpene composition Estonian pines belong to a high carene chemotype with monoterpenes representing up to 85% of total oil. Estonian spruce needle oil contains up to 70% of oxygenated terpenes and more limonene and 1,8-cineole than the same spruce species [Picea abies (L.) Karst.] from other localities.A total of 60 components were identified. Coefficients of variation describe the range of component contents in individual trees within the population. 相似文献
2.
A. Karnik S. Kailas A. Chatterjee P. Singh A. Navin D. C. Biswas D. M. Nadkarni A. Shrivastava S. S. Kapoor 《Zeitschrift für Physik A Hadrons and Nuclei》1995,351(2):195-198
The fission fragment angular distributions for the system12C +232Th have been measured in the energy range 0.97<>c.m./VB<1.22. the=" measured=" anisotropies=" have=" been=" compared=" with=" the=" predictions=" of=" the=" standard=" saddle=" point=" statistical=" model,=" using=" the=" second=" moment=" of=" the=" compound=" nucleus=" spin=" distribution=">1.22.>l2 deduced from a Wong model fit to the fission excitation function. While the measured anisotropies agree with the standard saddle point statistical model for Ec.m./VB>1.05, they are abnormally large at lower energies. This is also true for the existing measurements of16O and19F +232Th systems. Since for this system pre-equilibrium fission contributions are not expected, this anomaly indicates strong channel coupling effects leading to an increase in l2 at sub-barrier energies.The authors thank Drs. R.K. Choudhury and A. Saxena for useful discussions, Dr. R.J. Singh for making the thorium target and the Pellectron operation staff for excellent operation of the machine. 相似文献
3.
4.
Kristin Lippur Cindy Elmers Tiiu Kailas Aleksander-Mati Müürisepp Tõnis Pehk 《合成通讯》2013,43(2):266-281
A general method for the synthesis of 5,5′-disubstituted bimorpholines is proposed. According to the method, methyl-substituted and benzyl-substituted compounds were synthesized, starting from tartaric ester acetal. Target compounds were obtained in good yield and high enantiomeric purity. 相似文献
5.
Kailas K. Sanap Rama S. Kulkarni Shriniwas D. Samant 《Journal of heterocyclic chemistry》2013,50(3):713-719
The thermal [4 + 2] cycloaddition reaction of 7‐substituted 4‐styrylcoumarins with N‐phenylmaleimide and tetracyanoethylene in nitrobenzene under reflux conditions rapidly gives 3,4‐annulated coumarins as the Diels–Alder adducts. The position of the surviving double bond was determined on the basis of NMR and supported by energies of the possible structures. The effects of the 7‐substituent and the solvent on the reaction were studied. 相似文献
6.
Tripathi V Navin A Mahata K Ramachandran K Chatterjee A Kailas S 《Physical review letters》2002,88(17):172701
Results for the cross section and average angular momentum for complete fusion at energies around the Coulomb barrier are presented for 7Li with 165Ho. Comparison of the cross sections with a one-dimensional barrier penetration model, using a potential consistent with the measured elastic scattering, showed a reduction above the barrier and an enhancement below it. An increase in the measured average angular momentum, , above the barrier and its consistency with that obtained from the fusion excitation function for weakly bound nuclei, is reported. These results together with a reanalysis of existing data conclusively demonstrate that the effect of breakup on fusion is coherent, like coupling to any nonelastic channel. 相似文献
7.
Tawara H Doke T Hayashi T Kikuchi J Kyan A Nagaoka S Nakano T Takahashi S Terasawa K Yoshihira E 《Radiation measurements》2002,35(2):119-126
The LET distributions during the Space Shuttle missions STS-84 (altitude 270-412 km, average 375 km; inclination angle, 51.6 degrees) and STS-91 (altitude 328-397 km, average 373 km; inclination angle, 51.6 degrees) were measured using CR-39 plastic nuclear track detectors. A correction for the dip-angle dependence of the track-formation sensitivity of the CR-39 plates was applied to the data analysis. The absorbed doses and the dose equivalents around RRMD Detector Units, estimated from the LET distributions in the LET region of 4-200 keV/micrometers, fluctuated with standard deviations of +/- 21% to +/- 35% in both flight experiments. The LET distributions obtained from the CR-39 plates agreed well with that obtained from RRMD-II in STS-91. However, the particle fluxes obtained from RRMD-III in STS-84 and STS-91 were two or three times higher than those obtained from RRMD-II and the CR-39 plates. It was concluded that the LET distributions obtained from RRMD-II and the CR-39 plates in the present flight experiments did not include the contribution of target-fragmented secondary heavy particles produced by low-LET particles, such as relativistic or semi-relativistic protons and helium ions, whereas RRMD-III was able to detect these secondary particles because of its low triggering level. 相似文献
8.
Doke T Hayashi T Kikuchi J Sakaguchi T Terasawa K Yoshihira E Nagaoka S Nakano T Takahashi S 《Radiation measurements》2001,33(3):373-387
Dosimetric measurements on the Space Shuttle Missions STS-84, -89 and -91 have been made by the real-time radiation monitoring device III (RRMD-III). Simultaneously, another dosimetry measurement was made by the Dosimetry Telescope (DOSTEL) on STS-84 and by the tissue-equivalent proportional counter (TEPC) on STS-91. First, the RRMD-III instrument is described in detail and its results summarized. Then, the results of DOSTEL and TEPC are compared with those of the RRMD-III. Also, the absorbed doses obtained by TLD (Mg2SiO4) and by RRMD-III on board STS-84 and -91 are compared. 相似文献
9.
Ever since it was proposed more than three decades ago, the nuclear optical model has been very successful in interpreting
a large body of nucleon-induced nuclear reaction data in terms of a complex nucleon-nucleus potential. Rapid progress both
in the experimental measurements and the theoretical developments in the last two decades has led to a better understanding
of this nucleon-nucleus optical potential. From the parameter-fitting phenomenological stage, the optical model has come a
long way and it is now possible to calculate the nucleon-nucleus optical potential in a reasonable way starting from the fundamental
nucleon-nucleon interaction. Excellent reviews on various aspects of the optical model exist in the literature for proton
energies above 10 MeV. The present article is an attempt to review comprehensively the status of the proton-nucleus optical
potential at low proton energies, below the Coulomb-barrier, for target nuclei with mass numbers lying between 40 and 130.
The sets of phenomenological optical potential derived mostly from (p, n) reaction data are reviewed and their applicabilities discussed. The neutron-nucleus optical model is referred to wherever
it is relevant. Microscopic calculations for one case is carried out and compared with the corresponding phenomenological
values. 相似文献
10.
Light charged particles emitted in heavy-ion induced reactions, their spectra and angular distributions measured over a range
of energies, carry the signature of the underlying reaction mechanisms. Analysis of data of light charged particles, both
inclusive and exclusive measured in coincidence with gamma rays, fission products, evaporation residues have yielded interesting
results which bring out the influence of nuclear structure, nuclear mean field and dynamics on the emission of these particles. 相似文献