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71.
G. De Polsi C. Cabeza A.C. Marti C. Masoller 《The European physical journal. Special topics》2013,222(2):501-510
We propose a novel method of symbolic time-series analysis aimed at characterizing the regular or chaotic dynamics of coupled oscillators. The method is applied to two identical pendulums mounted on a frictionless platform, resembling Huygens’ clocks. Employing a transformation rule inspired in ordinal analysis [C. Bandt and B. Pompe, Phys. Rev. Lett. 88, 174102 (2002)], the dynamics of the coupled system is represented by a sequence of symbols that are determined by the order in which the trajectory of each pendulum intersects an appropriately chosen hyperplane in the phase space. For two coupled pendulums we use four symbols corresponding to the crossings of the vertical axis (at the bottom equilibrium point), either clock-wise or anti-clock wise. The complexity of the motion, quantified in terms of the entropy of the symbolic sequence, is compared with the degree of chaos, quantified in terms of the largest Lyapunov exponent. We demonstrate that the symbolic entropy sheds light into the large variety of different periodic and chaotic motions, with different types synchronization, that cannot be inferred from the Lyapunov analysis. 相似文献
72.
Lucía Álvarez-Rodríguez Prof. Dr. Javier A. Cabeza Dr. Pablo García-Álvarez Prof. Dr. Mar Gómez-Gallego Laura González-Álvarez Alba D. Merinero Prof. Dr. Miguel A. Sierra 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(6):1588-1594
The formation of the five-membered-ring germylene complexes [M(CO)5{Ge(tBu2bzamC(OEt)Me)tBu}] ( 3M ; M=Cr, W), which occurs readily at room temperature from the germylene Ge(tBu2bzam)tBu ( 1 t Bu ) and Fischer carbenes [M(CO)5{C(OEt)Me}] ( 2M ; M=Cr, W), has been found to be reversible. Upon heating at 60 °C, complexes 3M undergo epimerization to an equilibrium mixture of 3M and 3′M . At that temperature, the chromium epimers (but not the tungsten ones) release CO to end in the mixed germylene–Fischer carbene complexes [Cr(CO)4{C(OEt)Me}{Ge(tBu2bzam)tBu}] (cis- 4Cr and trans- 4Cr ). The latter decompose at 120 °C to [Cr(CO)5{Ge(tBu2bzam)tBu}] ( 6Cr ). Because the formation of cis- 4Cr and trans- 4Cr from 3Cr or 3′Cr requires the presence of free 1 t Bu and 2Cr in the reaction solutions, the reactions of 1 t Bu with 2M to give 3M (and 3′M at 60 °C) should be reversible. This proposal has been proven by germylene-exchange crossover reactions in which free 1 t Bu and [M(CO)5{Ge(tBu2bzamC(OEt)Me)CH2SiMe3}] ( 5′M ; M=Cr, W) were formed when complexes 3M were treated at room temperature with the germylene Ge(tBu2bzam)CH2SiMe3 ( 1tmsm ). A clear differential behavior between N-heterocyclic carbenes (NHCs) and amidinatogermylenes ( 1 t Bu and 1tmsm ) in their reactivity against group 6 metal Fischer carbene complexes is demonstrated. The higher electron-donor capacity of amidinatogermylenes with respect to NHCs and the bias of the former to get involved in ring expansion processes are responsible for this differential behavior. 相似文献
73.
This work is a continuation of our studies on experimental measurements of physical properties on binary mixtures of the ionic liquid (IL) family 1-alkyl-3-methyl imidazolium tetrafluoroborate (CnMIM-BF4) with water and ethanol. Here, we present density for the ternary system Butyl-MIM-BF4 + ethanol + water at two temperatures (298.15 K and 323.15 K) and seven pressures (from 0.1 to 30 MPa). It should be noted that BMIM-BF4 is the only IL of the family CnMIM-BF4 that can be mixed with water and ethanol in all range of concentrations at room conditions. From the density data measured in function of pressure and temperature other important derived thermodynamic properties can be calculated, such us excess molar volumes, isothermal compressibility, isobaric expansion and the thermal pressure coefficients. These properties for selected ternary mixtures will be discussed and compared with data from the scarce number of published results for similar ternary mixtures with this same IL. 相似文献
74.
The reactions of [Ru(3)(CO)(12)] with four aromatic diazines have been studied in THF at reflux temperature. With phthalazine (L(1)), the compound [Ru(3)(μ-κ(2)N(2)N(3)-L(1))(μ-CO)(3)(CO)(7)] (1), which contains an intact phthalazine ligand in an axial position bridging an Ru-Ru edge through both N atoms, is initially formed but it reacts with more phthalazine to give [Ru(3)(κN(2)-L(1))(μ-κ(2)N(2)N(3)-L(1))(μ-CO)(3)(CO)(6)] (2), in which a π-π stacking interaction between the aromatic rings of both ligands determines their position in cluster axial sites on the same face of the Ru(3) triangle. With quinazoline (HL(2)), the cyclometalated hydrido decacarbonyl derivative [Ru(3)(μ-H)(μ-κ(2)N(3)C(4)-L(2))(CO)(10)] (3) is initially produced but it partially decarbonylates under the reaction conditions to give [Ru(6)(μ-H)(2)(μ-κ(2)N(3)C(4)-L(2))(μ(3)-κ(3)-N(1)N(3)C(4)-L(2))(CO)(19)] (4), which results from the displacement of a CO ligand of 3 by the uncoordinated N(1) atom of another molecule of 3. With 4,7-phenanthroline (H(2)L(3)), the stepwise formation of the cyclometalated derivatives [Ru(3)(μ-H)(μ-κ(2)N(4)C(3)-HL(3))(CO)(10)] (5) and two isomers of [Ru(6)(μ-H)(2)(μ(4)-κ(4)N(4)C(3)N(7)C(8)-L(3))(CO)(20)] (6a, 6b) takes place. In compounds 6a and 6b, two Ru(3)(μ-H)(CO)(10) trinuclear units are symmetrically (C(2) in 6a or C(S) in 6b) bridged by a doubly-cyclometalated 4,7-phenanthroline ligand. With 2,3'-bipyridine (HL(4)), two products have been isolated, [Ru(3)(μ-H)(μ-κ(2)N(3')C(4')-L(4))(CO)(10)] (7) and [Ru(3)(μ-H)(μ-κ(3)N(2)N(3')C(2')-L(4))(CO)(9)] (8). While compound 7 contains an N(3')C(4')-cyclometalated 2,3'-bipyridine, in compound 8 an N(3')C(2')-cyclometalation is accompanied by the coordination of the N(2) atom of the remaining pyridine fragment. The structures of compounds 2, 3, 4, 6a and 8 have been determined by X-ray diffraction crystallography. 相似文献
75.
The adsorption of 1,3-butadiene (BD) on the Pd/Ni(1 1 1) multilayers has been studied using the VASP method in the framework of the density functional theory (DFT). The adsorption on two different configurations of the Pdn/Nim(1 1 1) systems were considered. The most stable adsorption sites are dependent on the substrate composition and on the inclusion or not of spin polarization. On Pd1Ni3(1 1 1) surface, di-π-cis and 1,2,3,4-tetra-σ adsorption structures are the most stable for non-spin polarized (NSP) and spin polarized (SP) levels of calculation, respectively. Conversely, on Pd3Ni1(1 1 1) surface, the 1,2,3,4-tetra-σ adsorption structure is the most stable for both NSP and SP levels, respectively. The magnetization of the Pd atoms strongly modifies the adsorption energy of BD and its most stable adsorption mode. On the other hand, as a consequence of BD adsorption, the Pd magnetization decreases. The smaller adsorption energies of BD and 1-butene on the Pd1Ni3(1 1 1) surface than on Pd(1 1 1) can be associated to the strained Pd overlayer deposited on Ni(1 1 1). 相似文献
76.
Prof. Dr. Javier A. Cabeza Dr. Pablo García-Álvarez Prof. Dr. Mar Gómez-Gallego Laura González-Álvarez Alba D. Merinero Prof. Dr. Miguel A. Sierra 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(9):2222-2225
The silylenes Si(tBu2bzam)R (tBu2bzam=N,N′-bis(tertbutyl)benzamidinate; R=mesityl, CH2SiMe3) attack the Ccarbene atom of the Fischer alkynyl(ethoxy)carbene complex [W(CO)5{C(OEt)C2Ph}] to give, after a striking rearrangement, zwitterionic σ-allenyl complexes in which the original carbene C atom forms part of the allene C3 fragment and also of a Si-C-N-C-N five-membered ring after insertion into a Si−N bond of the original amidinatosilylene. These remarkable allenyl products, which contain two stereogenic groups, are selectively formed as single diastereomers. 相似文献
77.
The chiral compound (H2cydiampy)[RuCl3(p‐cymene)]2 has been obtained in high yield by treating [RuCl2(p‐cymene)]2 with an excess of hydrochloric acid in the presence of one equivalent of N,N′‐bis‐(6‐methylpyrid‐2‐yl)‐(1R,2R)‐1,2‐diaminocyclohexane (cydiampy). It crystallizes in the chiral tetragonal space group P43212, with half of the atoms of the dication related to the other half by a crystallographic C2 axis that also makes equivalent the two anionic metal moieties. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
78.
79.