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51.
Ketan D. Mulmuley Hariharan Narayanan Milind Sohoni 《Journal of Algebraic Combinatorics》2012,36(1):103-110
We point out that the positivity of a Littlewood?CRichardson coefficient $c^{\gamma}_{\alpha, \beta}$ for sl n can be decided in strongly polynomial time. This means that the number of arithmetic operations is polynomial in n and independent of the bit lengths of the specifications of the partitions ??,??, and ??, and each operation involves numbers whose bitlength is polynomial in n and the bit lengths ??,??, and ??. Secondly, we observe that nonvanishing of a generalized Littlewood?CRichardson coefficient of any type can be decided in strongly polynomial time assuming an analogue of the saturation conjecture for these types, and that for weights ??,??,??, the positivity of $c^{ 2\gamma}_{2\alpha, 2\beta}$ can (unconditionally) be decided in strongly polynomial time. 相似文献
52.
Conducting polyaniline doped with polymeric acids was synthesized by a in situ chemical polymerization method. The synthesized polymers were characterized by using UV‐Visible, FT‐IR spectroscopy and SEM analysis. Thermal stability of these polymers was evaluated by using TGA/DSC analysis. Among the three polymeric acids used for doping purpose, poly(vinyl sulphonic acid) doped polyaniline is found to be more conducting than those doped with other acids. From the temperature dependent conductivity measurements, an increase in conductivity with increase in temperature was observed. 相似文献
53.
Arun K. Kalkar Vineeta D. Deshpande Milind J. Kulkarni 《Journal of Polymer Science.Polymer Physics》2010,48(10):1070-1100
The article deals with the melting and nonisothermal crystallization behavior of neat poly (phenylene sulphide) (PPS) and its composites with a thermotropic liquid crystalline polymer (TLCP)—Vectra A950, prepared by melt mixing and probed by differential scanning calorimetry. The various macrokinetic models namely, the Ozawa, the modified Avrami, the Tobin, and the Mo models were applied to describe the crystallization kinetics under nonisothermal conditions. The kinetic crystallizabilty of PPS/TLCP composites calculated using the approach of Ziabicki varies depending on these two composite composition‐induced effects. Similarly Mo model predicts that to obtain a higher degree of crystallizabilty for PPS/TLCP composites, a higher cooling rate should be used. The effective energy barrier based on the differential isoconversional method of Friedman is found to be an increasing function of relative degree of melt conversion. The effect is explained in terms of nucleation theory proposed by Wunderlich to crystallization of polymers. The Lauritzen–Hoffman parameters are estimated using G = 1/t0.5 effective activation energy equation proposed by Vyazovkin and Sbirrazzuoli. The Kg values estimated from latter equations are more comparable with values obtained using isothermal crystallization data than 1/t0.5 method. Furthermore, the kinetic analysis using this equation shows a regime transition from regime II to regime III for 100/00, 90/10, 80/20 PPS/TLCP composites, basically attributed to reduced mobility of PPS chains in composites. This regime II to III transition is accompanied by a morphological transition from defective spherulitic sheaf‐like structures to ordered sheaf‐like structures. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1070–1100, 2010 相似文献
54.
Laxmi Kathawate Yogesh Shinde Ravi Yadav Umesh Kasabe Milind Nikalje Sunita Salunke-Gawali 《Journal of Thermal Analysis and Calorimetry》2014,115(3):2319-2330
Thermal and spectral studies of reactions between 2-hydroxy-1,4-naphthoquinone (lawsone) and sodium metal (Lw-1, Lw-1A, Lw-1B), CH3COONa (Lw-2), NaOH (Lw-3), KOH (Lw-4), K2CO3 (Lw-5), Tris buffer (Lw-6), ammonia (Lw-7) are studied. Red solids of Lw-1 to Lw-7, Lw-1A, and Lw-1B were isolated and are characterized by elemental analysis, FT-IR, 1H NMR and UV–Visible spectroscopy. FT-IR spectra of Lw-1A and Lw-1B show, ν OH of adsorbed as well as coordinated water molecules between 3,600–3,100 cm?1 and decrease in ν C=O frequency of lawsone ligand. The benzenoid ring protons C(5)H, C(8)H, C(6)H and C(7)H in Lw-1A and Lw-1B show upfield shift in 1H NMR spectra. Hypsochromic shift and bathochromic shift is observed to π–π* transition band (~329 nm) and charge transfer band (~455 nm), respectively in UV–Visible spectra of all compounds. Pyrolytic decomposition of all compounds is studied by nonisothermal TG studies in air. Step I in all compounds leads to loss of adsorbed water molecules. Decomposition of lawsone anion in all compounds occurs in two or more steps. Thermodynamically Lw-1 to Lw-7, Lw-1A and Lw-1B are different compounds and their decomposition mechanisms are varied. The respective metal oxide residue viz. (Na2O or K2O) obtained after complete decomposition of Lw-1 to Lw-5, Lw-1A, and Lw-1B, is analyzed by powder X-ray diffraction. The adsorbed as well as coordinated water molecules are revealed by DTA and DSC studies as endothermic peak at ~100 °C. Decomposition mechanisms for lawsone anion are proposed based on LC–MS, GC–MS, and TG studies. Thermal and spectral studies reveal the coordination of lawsone ligand in its naphthosemiquinone form with alkali metal ions. 相似文献
55.
Single step polymerization of poly(o‐toluidine) was carried out by using ammonium persulphate as an oxidizing agent. Formation of the conducting emeraldine salt phase of the polymer was confirmed by the UV‐visible and FT‐IR spectroscopic analysis. The elemental composition of the polymer was evaluated by using a CHNS analyzer. Thermal stability of these polymers was investigated by the thermogravimetric analysis. Among the three polymeric acids used for doping purposes, poly(acrylic acid) doped material was found to show less thermal stability compared to poly(styrene sulphonic acid) and poly(vinyl sulphonic acid) doped poly(o‐toluidine). 相似文献
56.
We explored the interactions of gas molecules such as H2, CH4, C2H4, C2H6, CO2, and CS2 sandwiched by two pyrazine (Pz) molecules, which were employed as a model of organic linker in the Hofmann-type metal?Corganic framework (MOF). The MP2.5/aug-cc-pVTZ method was employed here, because this method presents almost the same binding energy as that calculated by the CCSD(T)/aug-cc-pVDZ with MP2.5-evaluated basis set extension effects to aug-cc-pVTZ basis set. The binding energy of the gas molecule increases in the order H2?<?CH4?<?CO2?<?C2H4????C2H6?<?CS2. The energy decomposition analysis of the interaction energy indicates that the electrostatic term presents the largest contribution to the interaction energy at the Hartree?CFock level. However, the dispersion interaction provides dominant contribution to the total binding energy at correlated level. We newly found a linear correlation between the z-component of polarizability of gas molecules and dispersion energy, where the z-axis was taken to be perpendicular to two Pz rings. These results are useful for understanding and predicting the binding energy of the gas molecule with the organic linkers of MOF. 相似文献
57.
Abstract An analytical model for the initial transverse stiffness of a sinusoidally corrugated plate is derived, incorporating deformations due to extension, shear, and bending. A nondimensional plot is developed for determining transverse stiffness based on thickness and corrugation for a range of plate geometries. This model shows that for most corrugated plates the transverse stiffness is dramatically decreased from that of an uncomigated plate of the same thickness. For thin plates, a simple approximate polynomial expression for initial transverse stiffness is obtained. For thick plates with a small degree of corrugation, transverse stiffness is not negligible relative to longitudinal stiffness. The exact model is verified using a linear-elastic two-dimensional finite element model. 相似文献
58.
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60.
Sanjay P. Kamble Onkar Manjarekar Ravi Mawale Bhaskar D. Kulkarni Naresh Chowdary Milind Y. Gupte Prashant P. Barve 《国际化学动力学杂志》2012,44(9):624-634
The transition metal complex catalyzed transvinylation of carboxylic acid with vinyl acetate monomer is of significant interest to industry. The palladium complex catalyzed transvinylation of lauric acid using vinyl acetate monomer is a reversible reaction. In present article, design of experiments (DOE) statistics is used to study effects of various operating parameters on transvinylation of lauric acid. The kinetic parameters forward and backward rate constants and the thermodynamic parameters such as equilibrium constant and energy of activation of the transvinylation of lauric acid were estimated using the Dynochem model. The optimum operating parameters for the transvinylation of lauric acid were then predicted using the Dynochem model and verified by performing the actual experiments to validate the model. It was found that the experimental results match with the predicted one. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 624–634, 2012 相似文献