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排序方式: 共有434条查询结果,搜索用时 15 毫秒
1.
Holographic interferometry is proposed to detect the change in the mechanical responses of reed stems growing in eutrophic, as compared with those in healthy, water bodies. The detection of the difference in behaviour could be a sensitive way to index the degree of eutrophication. An interferometric method based on holomicroscopic moiré is developed and preliminary results obtained are presented. 相似文献
2.
We present a theoretical analysis of corrugated long-period gratings in planar waveguides. In particular, we calculate the transmission spectra for both the TE and TM polarizations and highlight the polarization-independence conditions. 相似文献
3.
R. M. Sawant R. K. Rastogi N. K. Chaudhuri 《Journal of Radioanalytical and Nuclear Chemistry》1998,238(1-2):203-206
The paper presents a radiokinetic study on the appearance and growth of*Fe2S3,*Fe(OH)3,*Fe2(C2O4)3,*Fe(IO3)3 crystals in a colloidal medium of agar and gelatine. The values of the diffusion constants through gels of55+59Fe3+ radioactive cations and of the rate of global growth process of these crystals in agar or gelatine were calculated using
the experimental data. A new method for the determination of the starting time for the complex nucleation process was proposed.
The formation rate of crystals under study decreases in the order:*Fe(OH)3>*Fe(IO3)3>*Fe2S3>*Fe2(C2O4)3, in agar medium and*Fe(OH)3>*Fe(IO3)3>*FeC2O4)3>*FeS3, in gelatine medium. 相似文献
4.
A new acyl anion addition reaction between acylsilanes and alpha,beta-unsaturated conjugate acceptors promoted by a nucleophilic organic catalyst has been disclosed. The 1,4-dicarbonyl products produced in this reaction are highly useful synthons. Neutral carbenes (or zwitterions) generated in situ from commercial thiazolium salts are used as effective catalysts for the reaction which is in contrast to established anionic catalysts typically employed to promote the required Brook rearrangement (1,2-silyl shift from carbon to oxygen) involved in the reported reaction. This process successfully utilizes acylsilanes as tunable acyl anion progenitors and is tolerant of a wide range of structural diversity on the acylsilane or the conjugate acceptor. 相似文献
5.
R. P. Rastogi Kehar Singh Ram Shabd B. M. Upadhyay 《Journal of colloid and interface science》1981,80(2):402-411
Electrical properties of cholesterol interfaces have been investigated. For this purpose electroosmotic and hydrodynamic permeation of water, sodium chloride, barium chloride, aluminum chloride, and urea solutions across a cholesterol plug have been investigated. Dependence of electroosmotic permeability on concentration of electrolytes has also been studied. Electrophoretic mobility of cholesterol particles of known size distribution and dispersed in solutions of varying concentrations of electrolytes and urea has also been studied. The data have been used to estimate ζ potentials in order to have a plausible picture of the electrical double layer at the cholesterol/ solution interfaces. 相似文献
6.
Subphase conditions have been optimized to obtain stable organophosphorous hydrolase (OPH-EC 3.1.8.1) as Langmuir films. The Langmuir film was characterized by surface pressure and surface potential-area isotherms and UV-Vis spectroscopy in situ. The interaction of an organophosphorous compound, namely Paraoxon, with the OPH film was investigated for various surface pressures. The stability of the monolayer and the evidence of the enzyme activity at air-water interface support the use of enzyme LB films as biosensor. 相似文献
7.
A. K. Rastogi S. Mishra A. K. Tiwari 《International Journal of Infrared and Millimeter Waves》1995,16(3):601-614
Dispersion characteristics and wave impedance for the even and odd modes of the broad side coupled dielectric image guides are computed by using mode matching techniques. Dispersion curves for broadside image guide are plotted for various dielectric materials and dimensional parameters as a function of frequency. Normalized electric field for dominant electric field component E of TM even and odd modes for various half spacings between two dielectric slabs of broadside coupled image guide have been plotted. Polysterene ( r=2.56) and Stycast ( r=3.4) have been used as dielectric materials in fabricating broadside coupled image guide. This broadside coupled dielectric guide is very convenient as compared to the other dielectric guides. Since in case of broadside coupled image guide the dielectric slab can be bonded to the side metallic walls using some low loss adhesive material, while in other coupled dielectric guides the dielectric slab have to be supported by some low dielectric constant material (Eccofoam with r=1.02) to maintain the proper distance of side metallic walls from the dielectric slab. Since this structure is symmetrical, this configuration can be analysed in terms of even and odd mode phase velocities. The difference in these even and off mode phase velocities can be used to determine the coupling between coupled dielectric slab. Various couplers in this configuration can be realised. 相似文献
8.
S.K. Agarwal R.P. Rastogi H. Van Koningsveld K. Goubitz G.J. Olthof 《Tetrahedron》1980,36(10):1435-1438
A novel natural product, microphyllone, has been isolated from Ehretia microphylla2 together with baurenol and ursolic acid. Spectroscopic techniques, derivative formation and finally X-ray diffraction have been utilized in the structure elucidation of microphyllone. The structure appears to be 4a, 5, 8,8a - tetrahydro -11,14- dihydroxy-7-methyl-4a-(3-methyl-2-butenyl)-5, 8a-o-benzeno-1, 4-naphthoquinone. 相似文献
9.
K. P. Madhusudanan Mohan Prasad Shri Nivas Rastogi D. Fraisse 《Journal of mass spectrometry : JMS》1985,20(11):680-684
The nucleophilic substitution reaction under NH3 chemical ionization (CI) conditions in cis- and trans-1,2-dihydroxybenzosuberans (1–4) has been studied with the help of ND3 CI and metastable data. The results indicate that in the parent diols 1 (cis) and 2 (trans), the substitution ion [MsH]+, is produced mainly by the loss of H2O from the [MNH4]+ ion (SNi reaction) while in their 7-methoxy derivatives 3 and 4, the ion-molecule reaction between [M? OH]+ and NH3 seems to be the major pathway for the formation of [MsH]+. The substitution ion from 1 and 2 and the [MH]+ ion from trans-1-amino-2-hydroxybenzosuberan give similar collision-induced dissociation mass-analysed ion kinetic energy spectra. Interestingly, their diacetates do not undergo the substitution reaction. 相似文献
10.
Devendra K. Rastogi Suresh K. Sahni Vidya B. Rana Satendra K. Dua 《Transition Metal Chemistry》1978,3(1):56-60
Summary Dimeric manganese(II)and iron(II)complexes, (ML)2, derived from benzoyl hydrazones ofo-hydroxyaryl aldehydes and ketones arc described and characterised by elemental analyses and by conductance, molecular weight, magnetic, electronic and i.r. spectral measurements. The dimeric nature of the complexes is revealed by i.r. spectra which show bands atca. 885 Mn2+ and 820 cm–1 Fe2+, characteristic of ring vibrations. The i.r. spectra reveal the terdentate nature of the ligands. The electronic spectra in dimethylformamide are consistent with the tetrahedral nature of the complexes. The appreciable lowering in
eff is attributed to the presence of exchange interactions between two paramagnetic atomsvia oxygen bridges.Reprints of this article are not available. 相似文献