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排序方式: 共有76条查询结果,搜索用时 31 毫秒
61.
Mustafa İlhan Mete Kaan Ekmekçi Abdullah Demir Halil Demirer 《Journal of fluorescence》2016,26(5):1637-1643
Undoped and PbNb2O6:Eu3+ (1.0 ≤ x ≤ 6.0 mol%) phosphors were synthesized at 1100 °C for 3.5 h by the conventional solid state reaction method. Synthesized PbNb2O6:Eu3+ phosphors were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and Photoluminescence (PL) analyses. The PL spectra showed series of excitation peaks between 350 and 430 nm due to the 4f–4f transitions of Eu3+. For 395.0 nm excitation, emission spectra of Eu3+ doped samples were observed at 591 nm (orange) and 614 nm (red) due to the 5D0 → 7F1 transitions and 5D0 → 7F2 transitions, respectively. PL analysis results also showed that the emission intensity increased by increasing Eu3+ ion content. No concentration quenching effect was observed. The CIE chromaticity color coordinates (x,y) of the PbNb2O6:Eu3+ phosphors were found to be in the red region of the chromaticity diagram. 相似文献
62.
Lakshmi V.R. Babu Syamala Trimbak B. Mete Ramakrishna G. Bhat 《Tetrahedron letters》2018,59(34):3288-3291
FeCl3·6H2O/triethylsilane composite catalyst system is successfully developed for the selective conjugate reduction of carbon-carbon double bond of Michael acceptor-alkylidene-β-keto esters and alkylidene-1,3-diketones under mild reaction conditions to afford the corresponding saturated β-keto esters and 1,3-diketones. The process involves the iron-catalyzed hydrosilylation, followed by in situ hydrolysis of silyl enol ether. The optimal reaction conditions include 20?mol% of FeCl3·6H2O and triethylsilane in dichloromethane at room temperature. A broad range of substrates undergoes the reduction in 1, 4-selective manner to afford the corresponding saturated compounds in excellent yields. 相似文献
63.
1-Aryl-3-phenethylamino-1-propanone hydrochlorides 1-10, which are potentialpotent cytotoxic agents, were synthesized via Mannich reactions using paraformaldehyde,phenethylamine hydrochloride as the amine component and acetophenone, 4'-methyl-, 4'-methoxy-, 4'-chloro-, 4'-fluoro-, 4'-bromo-, 2',4'-dichloro-, 4'-nitro-, 4'-hydroxyacetophenone or 2-acetylthiophene as the ketone component. Yields were in the87-98 % range. Of the compounds synthesized, compounds 2, 6-8 and 10 were new. Theoptimum reaction conditions were investigated by changing the mol ratios of the reactants,the solvents and the acidity levels using 1 and 10 as representative targets. It was observedthat the best mol ratio of the ketone, paraformaldehyde and phenethylamine hydrochloridewas 1:1.2:1 (compared with a 2:2.1 ratio), and the most suitable reaction medium wasethanol containing concentrated hydrochloric acid (compared with only ethanol or nosolvent). This study may serve as a guide for the conditions of the reactions to synthesizecompounds having similar chemical structures. 相似文献
64.
We investigate new Clairaut conditions for anti-invariant submersions from Sasakian and Kenmotsu manifolds onto Riemannian manifolds. We prove that there do not exist Clairaut anti-invariant submersion admitting vertical Reeb vector field in case of the total manifold is Sasakian. Several illustrative examples are also included. 相似文献
65.
An expedient direct and regioselective thiocyanation of phenols, anilines and heterocycles is described. Transformation is realized via the direct CH functionalization under transition metal free conditions at ambient temperature in excellent yields. Method proved to be monoselective and variety of functional groups tolerated the reaction conditions. The practicality of the protocol is demonstrated in gram scale synthesis of a precursor of PPAR δ agonist in excellent yield. 相似文献
66.
Mustafa İlhan Mete Kaan Ekmekçi Rıza Gürcan Oraltay Ali Sadi Başak 《Journal of fluorescence》2017,27(1):199-203
Undoped and Nd3+ doped lutetium niobate phases have been prepared by a conventional solid state reaction method using lutetium acetate and niobium oxide at 1250 °C for 6 h. X-ray diffraction patterns of the 6 mol% Lu3NbO7 sample exhibited a cubic fluorite single phase. Phase structure exhibited interesting crystallization behaviour depending on increasing Nd3+ concentration which led to a Lu3NbO7 single phase formation during the heat treatment process. SEM investigations were also in agreement with the XRD results. Morphologies of Nd3+ doped lutetium niobate powders exhibited oval like shapes and grain sizes varied between 0.3 and 5 μm. Near-infrared luminescence properties of Nd3+ doped Lu3NbO7 were also studied. 1.06 μm laser transition characteristics of Nd3+ doped lutetium niobate have been observed. Concentration quenching phenomenon was not detected depending on increasing Nd3+ doping concentrations at room temperature. 相似文献
67.
Mete Bakir Jacob L. Meyer Andre Sutrisno James Economy Iwona Jasiuk 《Journal of polymer science. Part A, Polymer chemistry》2018,56(24):1595-1603
The glass transition is a genuine imprint of temperature-dependent structural relaxation dynamics of backbone chains in amorphous polymers, which can also reflect features of chemical transformations induced in macromolecular architectures. Optimization of thermophysical properties of polymer nanocomposites beyond the state of the art is contingent on strong interfacial bonding between nanofiller particles and host polymer matrix chains that accordingly modifies glass transition characteristics. Contemporary polymer nanocomposite configurations have demonstrated only marginal glass transition temperature shifts utilizing conventional polymer matrix and functionalized nanofiller combinations. We present nanofiller-contiguous polymer network with aromatic thermosetting copolyester nanocomposites in which carbon nanofillers covalently conjugate with cure advancing crosslinked backbone chains through functional end-groups of constituent precursor oligomers upon an in situ polymerization reaction. Via thoroughly transformed backbone chain configuration, the polymer nanocomposites demonstrate unprecedented glass transition peak broadening by about 100 °C along with significant temperature upshift of around 80 °C. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1595–1603 相似文献
68.
The duality between the robust (or equivalently, model independent) hedging of path dependent European options and a martingale optimal transport problem is proved. The financial market is modeled through a risky asset whose price is only assumed to be a continuous function of time. The hedging problem is to construct a minimal super-hedging portfolio that consists of dynamically trading the underlying risky asset and a static position of vanilla options which can be exercised at the given, fixed maturity. The dual is a Monge–Kantorovich type martingale transport problem of maximizing the expected value of the option over all martingale measures that have a given marginal at maturity. In addition to duality, a family of simple, piecewise constant super-replication portfolios that asymptotically achieve the minimal super-replication cost is constructed. 相似文献
69.
70.
K. S. Adhav V. G. Mete R. S. Thakare A. M. Pund 《International Journal of Theoretical Physics》2011,50(1):164-170
Field equations in the presence of wet dark fluid distribution are obtained in general relativity with the aid of Einstein-Rosen
cylindrically symmetric metric. 相似文献