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131.
Femtosecond Excitonic Relaxation Dynamics of Perovskite on Mesoporous Films of Al2O3 and NiO Nanoparticles
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Hung‐Yu Hsu Chi‐Yung Wang Amir Fathi Jia‐Wei Shiu Chih‐Chun Chung Po‐Shen Shen Prof. Dr. Tzung‐Fang Guo Prof. Dr. Peter Chen Prof. Dr. Yuan‐Pern Lee Prof. Dr. Eric Wei‐Guang Diau 《Angewandte Chemie (International ed. in English)》2014,53(35):9339-9342
The excitonic relaxation dynamics of perovskite adsorbed on mesoporous thin films of Al2O3 and NiO upon excitation at 450 nm were investigated with femtosecond optical gating of photoluminescence (PL) via up‐conversion. The temporal profiles of emission observed in spectral region 670–810 nm were described satisfactorily with a composite consecutive kinetic model and three transient components representing one hot and two cold excitonic relaxations. All observed relaxation dynamics depend on the emission wavelength, showing a systematic time–amplitude correlation for all three components. When the NiO film was employed, we observed an extent of relaxation proceeding through the non‐emissive surface state larger than through the direct electronic relaxation channel, which quenches the PL intensity more effectively than on the Al2O3 film. We conclude that perovskite is an effective hole carrier in a p‐type electrode for NiO‐based perovskite solar cells showing great performance. 相似文献
132.
This paper presents an analysis of the coupled vibration of asymmetric core structures in tall buildings. The governing equation
of free vibration and its corresponding eigenvalue problem, which is a set of equations for laterally flexural vibrations
in two different directions coupled by a warping-St. Venant torsional vibration, are derived. Based on the Calerkin method,
a generalized approximate method is developed for the analysis of coupled vibration and thus proposed for determining the
natural frequencies and mode shapes of the structure in triply-coupled vibration. The results of the proposed method for the
example structure show good agreement with those of the FEM analysis. The proposed method has been shown to provide a simple
and rapid, yet accurate, means for coupled vibration analysis of core structures. 相似文献
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134.
For an integer k > 0, a graph G is k-triangular if every edge of G lies in at least k distinct 3-cycles of G. In (J Graph Theory 11:399–407 (1987)), Broersma and Veldman proposed an open problem: for a given positive integer k, determine the value s for which the statement “Let G be a k-triangular graph. Then L(G), the line graph of G, is s-hamiltonian if and only L(G) is (s + 2)-connected” is valid. Broersma and Veldman proved in 1987 that the statement above holds for 0 ≤ s ≤ k and asked, specifically, if the statement holds when s = 2k. In this paper, we prove that the statement above holds for 0 ≤ s ≤ max{2k, 6k − 16}. 相似文献
135.
The product pair correlation of the title reaction was measured with rotational selection for both the vibrationally ground CD3(nu = 0) and umbrella-excited CD3(nu2 = 2) products. A striking linear relationship was found between the rotational energy of the selected CD3 product and the correlated kinetic energy release (or the average vibrational energy of the DF coproduct). Such a linearly correlated (or anticorrelated) dependence appears to be stronger for CD3(nu2 = 2,N) than for CD3(nu = 0,N). The mechanistic implication of the observation is that the rotational motion N of the CD3 product tends to lie antiparallel to the orbital angular momentum l' of the two departing products. The dependency on the K quantum number--the projection of N on the top axis--is, on the other hand, less significant yet noticeable. 相似文献
136.
The title reaction was investigated under crossed-beam conditions at three different collision energies, E(c) = 8.4, 2.76 and 1.46 kcal mol(-1). The combination of using a (2 + 1) resonance-enhanced multiphoton ionization for tagging state-specific CD(3) products and exploiting a time-sliced velocity imaging for ion detection allows us to reveal the coincident information of the two product pairs in a state-correlated manner. The pair-correlated results are reported for the two product vibrators -- (v(2) = 0, v'), (v(2) = 1, v'), (v(2) = 2, v') and (v(2) = 3, v')-and the dynamics attributes we examined include product state distributions, energy disposals and angular distributions. Together with our earlier communications, a rather complete picture of the correlated dynamics of the title reaction emerges. One of the major findings, the anti-correlated excitations of the two product vibrators at all four energies of this study, can qualitatively be understood by kinematics arguments. 相似文献
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138.
The paper studies a discrete counterpart of Gerber et al. (2006). The surplus of an insurance company (before dividends) is modeled as a time-homogeneous Markov chain with possible changes of size +1,0,−1,−2,−3,…. If a barrier strategy is applied for paying dividends, it is shown that the dividends-penalty identity holds. The identity expresses the expected present value of a penalty at ruin in terms of the expected discounted dividends until ruin and the expected present value of the penalty at ruin if no dividends are paid. For the problem of maximizing the difference between the expected discounted dividends until ruin and the expected present value of the penalty at ruin, barrier strategies play a prominent role. In some cases an optimal dividend barrier exists. The paper discusses in detail the special case where the distribution of the change in surplus does not depend on the current surplus (so that in the absence of dividends the surplus process has independent increments). A closed-form result for zero initial surplus is given, and it is shown how the relevant quantities can be calculated recursively. Finally, it is shown how optimal dividend strategies can be determined; typically, they are band strategies. 相似文献
139.
Panpan Li Hing Chan Shiu‐Lun Lai Maggie Ng Mei‐Yee Chan Vivian Wing‐Wah Yam 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(27):9186-9192
A new class of four‐coordinate donor‐acceptor fluoroboron‐containing thermally activated delayed fluorescence (TADF) compounds bearing a tridentate 2,2′‐(pyridine‐2,6‐diyl)diphenolate (dppy) ligand has been successfully designed and synthesized. Upon varying the donor moieties from carbazole to 10H‐spiro[acridine‐9,9′‐fluorene] to 9,9‐dimethyl‐9,10‐dihydroacridine, these boron derivatives exhibit a wide range of emission colors spanning from blue to yellow with a large spectral shift of 2746 cm?1, with high PLQYs of up to 96 % in the doped thin film. Notably, vacuum‐deposited organic light‐emitting devices (OLEDs) made with these boron compounds demonstrate high performances with the best current efficiencies of 55.7 cd A?1, power efficiencies of 58.4 lm W?1 and external quantum efficiencies of 18.0 %. More importantly, long operational stabilities of the green‐emitting OLEDs based on 2 with half‐lifetimes of up to 12 733 hours at an initial luminance of 100 cd m?2 have been realized. This work represents for the first time the design and synthesis of tridentate dppy‐chelating four‐coordinate boron TADF compounds for long operational stabilities, suggesting great promises for the development of stable boron‐containing TADF emitters. 相似文献
140.
Idiopathic autoimmune hemolytic anemia (AIHA) is a rare hematological disease typically characterized by extracellular hemolysis. An unusual case of AIHA with interesting magnetic resonance imaging (MRI) appearances is presented. Possible explanations for the MRI findings are discussed. 相似文献