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31.
The concerned azooximes (L1OH, 1) are of type p-X-C6H4C(N2Ph)(NOH) (X = H, Me, Cl). The reaction of [Re(MeCN)Cl3(PPh3)2] with [Ag(L1OH)(L1O)] in cold dichloromethane-acetonitrile solvent has furnished the green colored ionized azoimine complex [ReV(O)Cl(PPh3)2(L1)](PF6), 2. In effect L1O- has undergone oxidative addition, the oxygen atom being transferred to the metal site. Upon treatment of [ReV(NPh)Cl3(PPh3)2] with L1OH in solution, the neutral azoimine complex [ReV(NPh)Cl3(L1H)], 3, resulted due to the spontaneous transfer of the oxime oxygen atom to a PPh3 ligand, which is eliminated as OPPh3. In contrast, the oxime of 2-acetylpyridine (L2OH, 4) did not undergo oxygen atom transfer and simply afforded the imine-oxime complex [ReV(NC6H4Y)Cl2(PPh3)(L2O)], 5, upon reacting with [ReV(NC6H4Y)Cl3(PPh3)2] (Y = H, Me, Cl). The spectral and electrochemical properties of 2, 3, and 5 and the structures of three representative compounds are reported. In the cation of 2 (X = H) the two PPh3 ligands lie trans to each other and the equatorial plane is defined by the five-membered azoimine chelate ring and the oxo and chloro ligands. The oxo ligand which forms a model triple bond (Re-O length 1.616(6) A) lies cis to the imine-N atom. In 3 (X = Cl) the ReCl3 fragment has meridional geometry and the imido nitrogen lies trans to the imine nitrogen of the planar azoimine chelate ring. In 5 x H2O (Y = Me), the Cl, oximato-N, and P atoms define an equatorial plane and the pyridine-N lies trans to the imido-N. The water of crystallization is hydrogen bonded to the oximato oxygen atom (O...O, 2.829(5) A). Reaction models in which chelation of the azooxime precedes oxygen atom transfer are proposed on the basis of oxophilicity of trivalent rhenium, Lewis acid activity of pentavalent rhenium, electron withdrawal by the azo group, and observed relative disposition of ligands in products. 相似文献
32.
A. K. Chakravorty 《Journal of Thermal Analysis and Calorimetry》1993,39(3):289-299
TMA/DTMA with DTA studies on the thermal changes of kaolinite were performed with special emphasis on the crystallization behaviour of amorphous SiO2. The results of four different physical techniques (semiquantitative XRD, DTA, TMA and DTMA) were clearly in good agreement with the fact that the 1420°C exotherm in DTA is due to silica crystallization.Thanks to Dr. B. K. Sarkor, Director of the Institute for his kind permission to publish the paper and to Mr. D. K. Ahosh for his needful suggestions. 相似文献
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L. Chatterjee G. Das A. Chakravorty R. Goswami S. K. Mondal 《Hyperfine Interactions》1993,82(1-4):143-148
Interesting surprises in some exotic atom kinetics have been reported recently. These involve muonic atom transfer cross sections, nuclear pion capture and theq 1s effect in CF. These can be explained if the exotic atom population contains a contributing fast component. Such fast atoms can be formed by radiative continuum to bound transitions of fast (keV) muons or pions. Cross sections for formation of such fast pionic and muonic atoms and their velocity distributions are reported. The possibility of these processes competing with the thermalisation channels and contributing effectively to the exotic atom population is discussed. 相似文献
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S. Bhattacharyya S. K. Saha M. Chakravorty B. M. Mandal D. Chakravorty K. Goswami 《Journal of Polymer Science.Polymer Physics》2001,39(16):1935-1941
The frequency‐dependent conductivity of interpenetrating polymer network composites of polypyrrole (PPy) and poly(vinyl acetate) (PVAc) synthesized by FeCl3‐impregnated PVAc films being dipped into solutions of pyrrole in water was investigated over a frequency range of 100 Hz to 2 MHz and a temperature range of 110–300 K. For specimens with a PPy content less than the percolation threshold, the quantum mechanical tunneling of electrons was the conduction mechanism. For specimens with a higher PPy content, correlated barrier hopping of electrons appeared to be operative. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1935–1941, 2001 相似文献
37.
The synthesis of dibenzoazocine framework through palladium-mediated reductive Mizoroki-Heck cyclization has been described. The procedure is simple, straightforward, and regioselective. 相似文献
38.
Summary The Hirshfeld population analysis scheme which carves the molecular density into atomic density contributions is tested. This method does not require a reference to basis sets or their respective locations, but is based on a different physical and mathematical footing. The advantage of this method is that, when the molecular deformation density converges to the true solution, the computed net charges will necessarily converge. This method also allows a straightforward definition for local moments. About 36 molecules have been used to compute the conventional Mulliken and Löwdin population analyses with STO3G, 6311G** and Dunning-Hay split valence basis sets. These results have been compared to the estimates provided by the Hirshfeld model. The charges found in the Hirshfeld method are smaller than those from the other methods. 相似文献
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S. Bhattacharyya S. K. Saha D. Chakravorty 《Journal of Polymer Science.Polymer Physics》2000,38(9):1193-1200
Conductivity relaxation spectra of interpenetrating network conducting composites of polypyrrole (PPy) and poly(styrene‐co‐butyl acrylate) (SBA) have been analysed on the basis of coupling model developed by Ngai. The macroscopic activation energy obtained from coupling model using the stretch exponent β compares favourably with the tunnel energy estimated from the overlapping large polaron tunnelling (OLPT) model. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1193–1200, 2000 相似文献