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41.
M. Barron 《Applied Acoustics》1984,17(3):165-181
Though computer-generated low crest-factor signals can now be produced and processed to derive the impulse response of auditoria, the use of impulsive signals remains the simplest and, in many cases, a fully viable technique. The advantages of a uni-polar half-cycle sine wave test signal are discussed and compared with those of the bi-polar single-cycle signal. The particular requirements for visual display of the impulse response are reviewed, as are the signal requirements and analysis options for objective measures involving integrated energy. In each case the implications are considered of interference between reflections which arrive simultaneously. 相似文献
42.
43.
E. N. Barron 《Journal of Optimization Theory and Applications》1983,41(4):573-586
We consider the minimization of the mean-square deviation of a prescribed function from the class of monotone functions. Two problems are considered. The first problem places no restriction on the initial value of the controls, while the second problem assumes that all the control functions must start at a fixed initial value. Optimal controls are exhibited in both problems. Finally, we consider the situation with general payoff and dynamics and give the heuristic characterization of the value function for such problems. 相似文献
44.
Stuart J. Corr Lisa O'Reilly Eoghan P. Dillon Andrew R. Barron Patrick J. McNally 《Journal of Raman spectroscopy : JRS》2011,42(12):2085-2088
Poly(vinylpyrrolidone)‐stabilized silver nanoparticles deposited onto strained‐silicon layers grown on graded Si1−xGex virtual substrates are utilized for selective amplification of the Si–Si vibration mode of strained silicon via surface‐enhanced Raman scattering spectroscopy. This solution‐based technique allows rapid, highly sensitive and accurate characterization of strained silicon whose Raman signal would usually be overshadowed by the underlying bulk SiGe Raman spectra. The analysis was performed on strained silicon samples of thickness 9, 17.5 and 42 nm using a 488 nm Ar+ micro‐Raman excitation source. The quantitative determination of strained‐silicon enhancement factors was also made. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
45.
Catherine S. Branch Laura G. van Poppel Simon G. Bott Andrew R. Barron 《Journal of chemical crystallography》1999,29(9):993-996
The molecular structure of (tBu)3Al[O=C(OPh)2] has been determined. The increase in the C=O bond distance [1.258(4) Å] when compared to free O=C(OPh)2 [1.191(3) Å], is presented in respect to the activating ability of aluminum Lewis acids. Crystal data: monoclinic, P21/n, a = 10.653(2), b = 18.486(4), c = 14.551(3) Å, = 108.07(3)°, and V = 2724.3(9) Å3 for Z = 4. 相似文献
46.
Post‐Synthetic Ligand Exchange in Zirconium‐Based Metal–Organic Frameworks: Beware of The Defects! 下载免费PDF全文
Dr. Marco Taddei Dr. Russell J. Wakeham Athanasios Koutsianos Dr. Enrico Andreoli Prof. Andrew R. Barron 《Angewandte Chemie (International ed. in English)》2018,57(36):11706-11710
Post‐synthetic ligand exchange in the prototypical zirconium‐based metal–organic framework (MOF) UiO‐66 was investigated by in situ solution 1H NMR spectroscopy. Samples of UiO‐66 having different degrees of defectivity were exchanged using solutions of several terephthalic acid analogues in a range of conditions. Linker exchange only occurred in defect‐free UiO‐66, whereas monocarboxylates grafted at defect sites were found to be preferentially exchanged with respect to terephthalic acid over the whole range of conditions investigated. A 1:1 exchange ratio between the terephthalic acid analogue and modulator was observed, providing evidence that the defects had missing‐cluster nature. Ex situ characterisation of the MOF powders after exchange corroborated these findings and showed that the physical‐chemical properties of the MOF depend on whether the functionalisation occurs at defective sites or on the framework. 相似文献
47.
Three‐Dimensional Branched and Faceted Gold–Ruthenium Nanoparticles: Using Nanostructure to Improve Stability in Oxygen Evolution Electrocatalysis 下载免费PDF全文
Dr. Lucy Gloag Dr. Tania M. Benedetti Dr. Soshan Cheong Dr. Yibing Li Dr. Xuan‐Hao Chan Prof. Lise‐Marie Lacroix Prof. Shery L. Y. Chang Dr. Raul Arenal Dr. Ileana Florea Dr. Hector Barron Dr. Amanda S. Barnard Dr. Anna M. Henning Prof. Chuan Zhao Prof. Wolfgang Schuhmann Prof. J. Justin Gooding Prof. Richard D. Tilley 《Angewandte Chemie (International ed. in English)》2018,57(32):10241-10245
Achieving stability with highly active Ru nanoparticles for electrocatalysis is a major challenge for the oxygen evolution reaction. As improved stability of Ru catalysts has been shown for bulk surfaces with low‐index facets, there is an opportunity to incorporate these stable facets into Ru nanoparticles. Now, a new solution synthesis is presented in which hexagonal close‐packed structured Ru is grown on Au to form nanoparticles with 3D branches. Exposing low‐index facets on these 3D branches creates stable reaction kinetics to achieve high activity and the highest stability observed for Ru nanoparticle oxygen evolution reaction catalysts. These design principles provide a synthetic strategy to achieve stable and active electrocatalysts. 相似文献
48.
Laura G. van Poppel Simon G. Bott Andrew R. Barron 《Journal of chemical crystallography》2001,31(9-10):417-420
The structure of [(tBu)2Al(3,5-Me2py)]2(μ-O) has been determined as a consequence of the preferential hydrolytic cleavage of an Al–O versus an Al–C bond from the hydrolysis of the quinone bridged compound, [(tBu)2Al(3,5-Me2py)]2(μ-OC6H4O). The Al–O distance is 1.710(1) Å and the Al–O–Al angle is 180° because of crystallographic symmetry. Crystal data: triclinic, P $\overline 1$ , a = 9.334(2) Å, b = 10.639(2) Å, c = 10.661(2) Å, α = 112.65(3)°, β = 93.84(3)°, γ = 115.84(3)°, V = 843.4(3) Å3, Z = 1, R = 0.0581, R w = 0.1674. 相似文献
49.
C. Jeff Harlan Simon G. Bott Andrew R. Barron 《Journal of chemical crystallography》1998,28(8):649-651
Reaction of AlH3[N(CH2CH2)3CH] with hexamethyltrisiloxane, (OSiMe2)3, gives rise to the bis-quinuclidine complex AlH3[N(CH2CH2)3CH]2, which has been characterized by 1H and 13C NMR spectroscopy and X-ray crystallography. The molecular structure of AlH3[N(CH2CH2)3CH]2 consists of a trigonal bipyramidal aluminum with axial coordination of the quinuclidine ligands. Crystal data: orthorhombic, space group Pbcn, a = 10.6895(9), b = 12.266(1), c = 12.3794(9) Å, V = 1623.2(2) Å3, and Z = 4. 相似文献
50.
Cullen T. Vogelson Christopher L. Edwards Andrew N. Kobylivker Star B. Chacko Cristin E. Moran Kathryn Dalton Shawn M. Stewart Brian C. Werner Simon G. Bott Andrew R. Barron 《Journal of chemical crystallography》1998,28(11):815-824
The molecular structures of Al(tfac)3 (1), Co(tfac)3 (2) (H-tfac = 1,1,1-trifluoroacetylacetone) and Cu(H2O)(fod)2 (3) (H-fod = 1,1,1,2,2,3,3-hepta-fluoro-7,7-dimethyloctane-4,6-dione) have been determined. The metal coordination spheres in compounds 1 and 2 are essentially the same as the respective M(acac)3 derivatives. Despite the isomorphous nature of the structures of compounds 1 and 2, the identity of the nearest intermolecular van der Waals contacts are altered by minor changes in the metal coordination sphere. The geometry about copper in compound 3 is close to that of an ideal square bipyramid with the -diketonate ligands occupying the basal plane. The water ligand in each molecule of compound 3 is hydrogen bonded to an oxygen of a -diketonate ligand on an adjacent molecule resulting in the formation of dimers, which form rods along the y-axis due to weak C–F···Cu interactions. Crystal data: (1) orthorhombic, Pca21, a = 14.949(3), b = 19.806(4), c = 13.624(3) Å, V = 4033(1) Å3, and Z = 8, and (2) orthorhombic, Pca21, a = 14.930(3), b = 19.620(4), c = 13.540(3) Å, V = 3966(1) Å3, and Z = 8,; (3) monoclinic, P21/c, a = 12.447(3), b = 10.486(2) c = 21.980(4) Å, = 102.65(3)°, V = 2799(1) Å3, and Z = 4. 相似文献