首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   23篇
  免费   0篇
化学   3篇
数学   1篇
物理学   19篇
  2002年   2篇
  2001年   1篇
  2000年   1篇
  1994年   2篇
  1993年   3篇
  1992年   3篇
  1988年   3篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1981年   1篇
  1975年   1篇
排序方式: 共有23条查询结果,搜索用时 15 毫秒
1.
Simultaneous total column amounts of a number of minor and trace atmospheric gases above the South Pole in December 1980 and December 1986 have been deduced from analysis of high resolution solar absorption spectra recorded (by F. J. M. and F. H. M.) from Amundsen-Scott South Pole Station. These spectra also contain some limited information on the vertical profiles of the observed atmospheric gases.The data sets were recorded with a Bomem Michelson-type interferometer and analyzed with a spectral least-squares fitting procedure, utilizing the best available spectroscopic line parameters and absorption cross sections. Because the same instrument, line parameters, and analysis method have been used in analyzing the December 1980 and December 1986 data sets, the precision in comparing the column amounts from these two dates is rather high, about 10–20% for the stronger absorbing gases. For this reason, it has been possible to quantify or determine upper limits for differences between the December 1980 and December 1986 total column amounts, of a number of atmospheric gases including O3, N2O, HNO3, CO2, CH4, and CF2C1 2 (CFC 12). In addition, vertical column amounts for a number of atmospheric gases covered only in the December 1986 observations have been derived, including HC1, NO, NO2, and C2H6. Some of these results will be discussed here. The HC1 measurements are especially interesting since the observed amounts are higher than expected from observations made at lower latitudes in the northern and southern hemispheres.  相似文献   
2.
3.
The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO3 perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good example of these properties is (La1−2x Pr x Ca x )MnO3 (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for understanding the structural, transport and magnetic properties are discussed in detail.  相似文献   
4.
We have extended our analysis of the (010) vibrational state of H2S, this time using Watson's A-reduced Hamiltonian (through P8 terms) in the I′ rotational representation. We have determined separate sets of (010) upper state constants for each isotopomer (H232S, H233S, and H234S) by fitting the ν2 spectral lines, keeping the ground state constants fixed to the values determined by Flaud, Camy-Peyret, and Johns. Determinable coefficients for H232S and a slightly revised set of ν2 line assignments for H233S and H234S are also reported.  相似文献   
5.
A.K.Gupta  D.G.Kabe 《东北数学》2000,16(4):405-410
§ 1.Introduction WearegivenkindependentWishartdensitiesofthe (p +q)× (p +q)randomsymmetricpositivedefinitematricesG1,… ,Gktobeg(Gi) =Kexp -12 trR- 1i Gi Gi12 (ni- q-p- 1) ,(1 )wherei=1 ,… ,k,andRidenotesthepopulationcorrelationmatrixofthei thpopulationandKasagenericletterdenote…  相似文献   
6.
The infrared absorption spectrum of ν2 of H2Se in the region from 885 to 1347 cm?1 was obtained with a resolution limit of 0.025 cm?1 on the University of Denver 50-cm FTIR spectrometer system. We have assigned 1604 lines for the six isotopomers of H2Se, including 25 lines for the H274Se isotopomer, and have analyzed them using Watson's A-reduced Hamiltonian in the Ir rotational representation. Ground state constants for each of the five most abundant isotopomers were obtained from fits of microwave transitions combined with weighted averaged ground state combination differences formed from the infrared bands (010), (020), (100), and (001). Upper state constants for each of the five most abundant isotopomers were obtained from least-squares fits of the spectral lines of ν2, keeping the ground state constants fixed to the values determined from our ground state fits. An alternate set of ground state constants together with isotopic mass adjustment constants for all six isotopomers was determined by simultaneously fitting all available microwave transitions and infrared ground state combination differences. Keeping this set of ground state constants fixed, a single set of upper state constants and isotopic mass adjustment constants for the ν2 band was determined by a simultaneous fit of infrared spectral lines from all six isotopomers.  相似文献   
7.
The infrared absorption spectrum of ν2 of H2S in the region from 1000 to 1500 cm?1 was obtained with a resolution limit of <0.05 cm?1 on the University of Denver 50-cm FTIR spectrometer system. We have assigned 387 lines due to H232S, 75 lines due to H234S, and 15 lines due to H233S, and have analyzed them using Typke's reduction of Watson's Hamiltonian. Slightly revised ground-state constants for the 32 isotope were obtained from a simultaneous fit of the microwave transitions observed by Helminger, Cook, and De Lucia, combined with weighted averaged ground-state combination differences formed from the infrared bands (010), (020), (100), (001), (110), (011), (210), and (111). The standard deviation for the fit was 0.0018 cm?1 for the infrared data and 0.000032 cm?1 for the microwave lines. Upper-state constants for the 32 isotope were obtained from a least-squares fit of the spectral lines of ν2, keeping the ground-state constants fixed to the values determined by the combination difference fit. The standard deviation of the (010) line fit was 0.0017 cm?1 for the 32 isotope. Ground-state and upper-state isotopic mass adjustment constants were determined in a simultaneous fit of lines of H233S and H234S, keeping the ground-state and upper-state constants for the 32 isotope fixed.  相似文献   
8.
The SCRIBE (Stratospheric CRyogenic Interferometer Balloon Experiment) system was flown August 10, 1986, over eastern New Mexico. Because the SCRIBE sensor is a liquid nitrogen cooled interferometer, absolute radiance data were obtained with good resolution (0.1 cm–1) and high sensitivity. The normal field of view was reduced to ~0.2° (80 m on the ground) by a 12' Dall-Kirkham telescope, and was steered by remote control using television cameras boresighted with the infrared sensor. The stabilized viewing allowed staring at selected features for considerable periods of time. The data sets thus include spectra of different terrain features, as well as substantially different atmospheric paths to one feature. Both the data and the SCRIBE equipment are described.  相似文献   
9.
1988 lines of ozone have been observed in the atmospheric spectrum in the region 1060 to 1220 cm?1, 1394 of them have been assigned to the ν1 band, and 480 to the ν3, particularly corresponding to ΔK?1 = 2. The analysis has been performed using the Watson Hamiltonian, taking account of the strong Coriolis coupling between the 001 and 100 levels. The constants for the latter two states, the spectra and a listing of the observed and calculated wave-numbers, with their assignment, are given. In addition, 114 lines of the “hot” band (ν1 + ν2) ? ν2 have been observed and assigned and are reported.  相似文献   
10.
High-resolution (0.02 cm?1) infrared atmospheric spectra were used for a new analysis of the ν2 and 2ν2-ν2 bands of ozone and for generating a new line parameters compilation. Samples of the spectra and the analysed lines are presented.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号