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61.
Gordon R Brolo AG McKinnon A Rajora A Leathem B Kavanagh KL 《Physical review letters》2004,92(3):037401
Strong polarization dependence is observed in the optical transmission through nanohole arrays in metals. It is shown that the degree of polarization is determined by the ellipticity and orientation of the holes; the polarization axis lies perpendicular to the broad edge of the ellipse. Furthermore, the depolarization ratio shows a squared dependence on the aspect ratio of the holes, which is discussed in terms of coupling into and out of the surface plasmon modes. The observed results will be useful for tailoring the polarization behavior of metallic nanophotonic elements in many applications, including surface plasmon enhanced optical sensing and ultrafast optical switching. 相似文献
62.
The barriers to rotation about the C? N bond in eighteen substituted N,N-dimethylbenzamides have been determined by complete line shape analysis of the NMR spectra of the N,N-dimethyl protons. The barriers have been correlated with the substituent constants σ and σ+. It has been shown that polar solvents increase the barrier in N,N-dimethylbenzamide. Acid catalysis of rotation about the amide C? N bond in N-(p-N,N-dimethylcarboxamidobenzyl)-pyridinium bromide has been investigated. 18O exchange studies show that catalysis is due to N-protonation rather than the formation of a tetrahedral intermediate. The rate of rotation is a function of the Hammett acidity function, H0, and the water activity, and it is shown that proton exchange between the N- and O-protonated species involves the intermediacy of a water molecule. The differences in chemical shifts for the non-equivalent N, N-dimethyl groups of the benzamides are also a function of the substituents. Possible explanations of this phenomenon are discussed. 相似文献
63.
Summary Ultra high molecular mass (> 7 million dalton) polystyrenes are prone to degradation in size exclusion chromatography. In gradient elution reversed phase HPLC they do not elute visibly on small particle size porous supports. However, large diameter C18 pellicular particles were successfully employed for reversed phase study of ultra high molecular mass (15 million dalton) polystyrenes without polymer degradation during elution. Although retention for the lower molecular mass polystyrenes was lower than on small diameter porous particles, the medium high molecular mass polystyrenes (0.5–1 million dalton) showed similar retention. The addition of small diameter porous particles in small quantities, to the large diameter pellicular particles, increased the amount of retention of the low molecular mass polystyrenes without affecting the higher molecular mass polystyrenes. 相似文献
64.
L.W. Mitchell R.W. Kavanagh M.E. Sevior C.I.W. Tingwell D.G. Sargood 《Nuclear Physics A》1985,443(3):487-498
The yield of γ-rays from the reaction 42Ca(α, γ)46Ti has been measured as a function of bombarding energy over the range Eα = 3.42–5.62 MeV and from 42Ca(α, pγ)45Sc over the range Eα = 4.06–5.92 MeV, and the yield of protons from the reaction 42Ca(α, p)45Sc has been measured over the range Eα = 4.78–5.92 MeV. Cross sections for all three reactions have been extracted from the data and compared with global statistical-model calculations. The agreement is good. Thermonuclear reaction rates under stellar conditions appropriate for silicon burning are calculated and their significance for the approach to and bridging of the mass-45 bottleneck in the upward flow of nucleosynthesis is discussed. 相似文献
65.
Allowed β+ decay branches from 25AI, 37K, 38K and 39Ca have been sought by observation of delayed γ-radiation. The precision of previously known branches has been increased and improved limits obtained for unobserved branches. 相似文献
66.
S. Arutjunjan R. Mnatzakanjan M. S. Malinowski G. Hamann O. L. Baril G. A. Megrdichian H. Düll J. W. Alexejewski K. G. Tárassowa W. I. Kusnetzow A. Wada I. Kawai F. Raschig S. Ueno T. Suzuki W. C. Hughes H. N. Wilson C. H. Bosanquet Hellmut Müller C. R. Barnicoat F. Kavanagh V. Lang H. Staudinger E. Husemann W. N. Haworth H. Machemer 《Analytical and bioanalytical chemistry》1939,117(11-12):425-433
67.
Surface plasmon sensor based on the enhanced light transmission through arrays of nanoholes in gold films 总被引:5,自引:0,他引:5
Brolo AG Gordon R Leathem B Kavanagh KL 《Langmuir : the ACS journal of surfaces and colloids》2004,20(12):4813-4815
Arrays of nanoholes in a gold film were used to monitor the binding of organic and biological molecules to the metallic surface. This technique is particularly sensitive to surface binding events because it is based upon the resonant surface plasmon enhanced transmission through the array of nanoholes. The sensitivity was found to be 400 nm per refractive index unit, which is comparable to other grating-based surface plasmon resonance (SPR) devices. The array of nanoholes is well suited for dense integration in a sensor chip. Furthermore, the optical geometry is collinear, which simplifies the alignment with respect to the traditional Kretschmann (reflection) arrangement for SPR sensing. 相似文献
68.
Summary The reversed phase behaviour of high molecular mass polystyrenes was investigated on a C18 bonded phase column using acetonitrile
as the polar mobile phase component and dichloromethane, chloroform and carbon tetrachloride, as separate nonpolar components.
Solvent solubility compositions, elution compositions and resolutions of the various molar mass polystyrenes were measured
and compared for each of the three mobile phases. Anomalous behaviour of the polystyrenes was not observed in any of the three
mobile phases and only minor differences in resolution were observed. By comparing these results with previously published
work, it is suggested that any mobile phase component that is both nonpolar and a good solvent for the polymer can be combined
with acetonitrile for effective separations of polystyrenes by mass and that it is the poor solvent component of the mobile
phase that is responsible for the anomalous behaviour that is sometimes observed in this type of chromatography. 相似文献
69.
Paul Kavanagh 《Tetrahedron letters》2004,45(1):121-123
A superior synthetic route to 4,4′-diamino-2,2′-bipyridine has been developed. This procedure compares favorably with existing methods, producing 4 times the yield previously reported. In addition, mild reaction conditions are utilized, allowing a considerably more efficient production, and subsequent purification, of the diamino complex. 相似文献
70.
Treatment of 2-(toluene-4-sulfonyl)-2,3,4,4a,5,6-hexahydro-1H-[2]pyrindin-6-ol 10, accessed from the diastereoselective Luche reduction of a Pauson-Khand derived bicylic cyclopentenone, with a catalytic amount of (1,5-cyclooctadiene)(pyridine)(tricyclohexylphosphine)iridium(I) hexafluorophosphate 1 (Crabtree's catalyst) under a hydrogen atmosphere resulted in the formation of 4-(toluene-4-sulfonyl)-2-oxa-4-azatricyclo[5.2.1.0(3,8)]decane 12 as a single diastereoisomer. This process is likely to proceed via an initial Ir(I)-mediated isomerization of the alkene to form an N-sulfonyl enamine 11, followed by cyclization. Evidence to support this came when, after short reaction periods, 11 was isolated, characterized spectroscopically, and on resubmission to the reaction conditions formed 12. 相似文献