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排序方式: 共有48条查询结果,搜索用时 15 毫秒
1.
In the present paper, we study the rate of convergence in simultaneous approximation for the Bézier variant of the Baskakov-Beta operators by using the decomposition technique of functions of bounded variation. 相似文献
2.
Geometrical parameters associated with N-H ... N types of hydrogen bonds have been analysed using crystal structure data on
nucleic acids, amino acids and related compounds. Histograms depicting the frequency distribution of N-H ... N length (l) and H-N ... N angle (θ) have been drawn and conclusions on the favoured geometry of such bonds have been arrived at. The
distribution ofl shows a pronounced maximum in the range between 2.9? and 3.0? with an overall average of 2.98 ?. The θ distribution shows
a pronounced maximum for the hydrogen bond angle in the range 0°-10°, with a rapid fall-off in frequency for nonlinear hydrogen
bonds. The frequency shows a cos6θ dependence as compared to cos2θ dependence term used earlier to predict the angular dependence of hydrogen bond potential energy in proteins and polypeptides. 相似文献
3.
R. K. Sinha A. Dhal P. Agarwal S. Kumar Monika B. B. Singh R. Kumar P. Bringel A. Neusser R. Kumar K. S. Golda R. P. Singh S. Muralithar N. Madhavan J. J. Das K. S. Thind A. K. Sinha I. M. Govil R. K. Bhowmik J. B. Gupta P. K. Joshi A. K. Jain S. C. Pancholi L. Chaturvedi 《The European Physical Journal A - Hadrons and Nuclei》2006,28(3):277-281
High-spin states in 79Rb were populated in the reaction
at E(beam) = 60 MeV. The lifetimes of the excited states of the
positive-parity yrast band and of the
negative-parity band in 79Rb were measured by the Doppler Shift Attenuation Method. The deduced transition quadrupole moments Qt are found to have a decreasing trend with rotational frequency for both the bands, consistent with those found experimentally
in neighbouring nuclei.
An erratum to this article is available at . 相似文献
4.
M. M. Dhingra G. Govil C. L. Khetrapal K. Venkata Ramiah 《Proceedings Mathematical Sciences》1965,62(2):90-96
Proton magnetic resonance studies of the solutions of (a) 2-amino, 3-methyl pyridine and (b) 2-amino, 6-methyl pyridine in carbontetrachloride show that in these molecules there is an equilibrium between monomers and hydrogen-bonded dimers. The equilibrium constants for the two cases have been obtained. Evidence has also been obtained to show that chloroform forms hydrogen bond with the ring nitrogen of these compounds. These NMR results have been compared with those obtained earlier from infra-red studies. 相似文献
5.
A. Dhal R. K. Sinha D. Negi T. Trivedi M. K. Raju D. Choudhury G. Mohanto S. Kumar J. Gehlot R. Kumar S. Nath S. S. Ghugre R. P. Singh J. J. Das S. Muralithar N. Madhavan J. B. Gupta A. K. Sinha A. K. Jain I. M. Govil R. K. Bhowmik S. C. Pancholi L. Chaturvedi 《The European Physical Journal A - Hadrons and Nuclei》2012,48(3):1-10
The odd mass nucleus 137Pm has been studied to high spins through the 109Ag(32S, 2p2n)137Pm reaction at an incident beam energy of 150 MeV. The de-exciting ??-rays were detected using an array of 18 Compton suppressed clover detectors. The level scheme of 137Pm has been extended up to $J^\pi = \tfrac{{43}} {2}^ -$ and excitation energy of E x ? 6 MeV with the observation of 42 new gamma transitions. The linear polarization (IPDCO) measurements for the ??-ray transitions have been done for the first time. The spin and parity assignments for most of the reported levels have been made using these results and the coincidence angular anisotropy (RDCO) measurements. The nuclear shape evolution is discussed in the light of Total Routhian Surface (TRS) and Cranked Shell Model (CSM) calculations. 相似文献
6.
Girjesh Govil 《应用光谱学评论》2013,48(1):47-78
There are several reasons why nuclear magnetic resonance (NMR) studies in gases are important. At low pressures the interactions in the gas phase are essentially governed by two body collisions. It is therefore possible to study the intermolecular forces between two molecules approaching one another during collision from their influence on the chemical shifts of the nuclei of the molecules under considerations. The experimental measurements allow one to learn how the chemical shift is perturbed because of the presence of other molecules. This knowledge can then be transferred to interpret solvent effects in condensed phases and for detection of any solvent-solute interactions in such systems. 相似文献
7.
Prashansa Agrawal Girjesh Govil Ritu Barthwal 《Magnetic resonance in chemistry : MRC》2009,47(5):390-397
The complexes of adriamycin–d‐(TGATCA)2 and 4′‐epiadriamycin–d‐(CGATCG)2 are studied by one‐ and two‐dimensional 31P nuclear magnetic resonance spectroscopy (NMR) at 500 MHz in the temperature range 275–328 K and as a function of drug to DNA ratio (0.0–2.0). The binding of drug to DNA is clearly evident in 31P? 31P exchange NOESY spectra that shows two sets of resonances in slow chemical exchange. The phosphate resonances at the intercalating steps, T1pG2/C1pG2 and C5pA6/C5pG6, shift downfield up to 1.7 ppm and that at the adjacent step shift downfield up to 0.7 ppm, whereas the central phosphate A3pT4 is relatively unaffected. The variations of chemical shift with drug to DNA ratio and temperature as well as linewidths are different in each of the two complexes. These observations reflect change in population of BI/BII conformation, stretching of backbone torsional angle ζ, and distortions in O? P? O bond angles that occur on binding of drug to DNA. To the best of our knowledge, there are no solution studies on 4′‐epiadriamycin, a better tolerated drug, and binding of daunomycin or its analogue to d‐(TGATCA)2 hexamer sequence. The studies report the use of 31P NMR as a tool to differentiate various complexes. The specific differences may well be the reasons that are responsible for different antitumor action of these drugs due to different binding ability and distortions in DNA. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
8.
9.
R. K. Sinha A. Dhal P. Agarwal S. Kumar Monika B. B. Singh R. Kumar P. Bringel A. Neusser R. Kumar K. S. Golda R. P. Singh S. Muralithar N. Madhavan J. J. Das K. S. Thind A. K. Sinha I. M. Govil R. K. Bhowmik J. B. Gupta P. K. Joshi A. K. Jain S. C. Pancholi L. Chaturvedi 《The European Physical Journal A - Hadrons and Nuclei》2006,29(2):253-253
10.
S. S. Dharmatti F.A.Sc. G. Govil C. R. Kanekar C. L. Khetrapal Y. P. Virmani 《Proceedings Mathematical Sciences》1962,56(2):71-85
The high resolution proton magnetic resonance spectra of AB, ABC and ABCD systems in fourteen coumarins have been studied. Chemical shifts and spin coupling constants for the protons in various positions in the benzo-α-pyrone ring have been obtained. The spectrum of coumarin confirms the ethylenic nature of double bond between carbon atoms in positions 3 and 4. The chemical shifts for the phenyl protons are in conformity with the reactivities of the coumarins at various positions in the ring. A linear relation has been observed between the chemical shift for proton in 8 position in various 6 substituted coumarins and the Hammett’s constants (σ) for substituents in themeta position. The NMR spectra offer a very convenient method for distinguishing between 3 and 4 substituted coumarins on account of the large chemical shift for the protons in positions 3 and 4. The results do not substantiate resonance of the naphthalene type in coumarin as suggested to explain its dipole moment. 相似文献