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101.
Andrew J. Saterlay Shelley J. Wilkins Christiaan H. Goeting John S. Foord Richard G. Compton Frank Marken 《Journal of Solid State Electrochemistry》2000,4(7):383-389
The use of boron-doped diamond has a considerable impact in electrochemistry owing to the wide potential range accessible,
low background currents, extreme hardness, and the ease of chemical modification of diamond surfaces. It is shown here that,
although the electrodeposition of silver metal is known to yield very poorly adhering films with a poor electrical contact,
a silver oxysalt deposit formed on anodically pre-treated diamond surfaces adheres strongly with good electrical contact.
The deposit is stable even in the presence of ultrasound. Voltammetric and XPS studies reveal that the silver oxide deposit,
in contrast to the silver metal deposit, is efficiently stripped from the diamond surface by applying a sufficiently negative
potential. The silver oxysalt Ag7O8NO3, deposited onto two types of boron-doped diamond electrodes, a 50 μm thick polycrystalline thin film deposited on a tungsten
substrate and a polished free standing diamond plate, is shown to act as an electrocatalyst for oxygen evolution and for the
oxidation of toluene. This development opens up the possibility of boron-doped diamond being applied as an inert and conducting
substrate material for a wide range of oxidic materials, which can then be utilised as active electrocatalysts at high applied
potentials.
Received: 17 March 2000 / Accepted: 10 April 2000 相似文献
102.
John A. Castoro Paul V. Rucker Charles L. Wilkins 《Journal of the American Society for Mass Spectrometry》1992,3(4):445-450
Internal energy deposition into iron pentacarbonyl positive ions undergoing surface-induced dissociation (SID) in a Fourier transform mass spectrometer is estimated from the abundances and known critical energies of the product fragment ions. A narrow energy distribution, comparable to that reported in earlier BQ and tandem quadrupole SID studies of the same compound, is observed. As judged by the ratio of fragment ions to incident parent ions observed, SID of iron pentacarbonyl in the 3 T Fourier transform mass spectrometer is more efficient, but results in lower conversion of laboratory to internal energy. This may be a result of the more shallow collision incidence angle employed in the Fourier transform mass spectrometer measurements (a few degrees), which contrasts with the 32–60° collision angles used in the earlier BQ and tandem quadrupole mass spectrometry studies. Collision-induced dissociation with He under single collision conditions is also reported, Not unexpectedly, conversion of kinetic to internal energy was lower than found in a previous Fourier transform mass spectrometer study of the iron pentacarbonyl cation employing argon as collision gas under multiple collision conditions. 相似文献
103.
Michael S. Kahr Charles L. Wilkins 《Journal of the American Society for Mass Spectrometry》1993,4(6):453-460
Addition of silver nitrate to nonpolar hydrocarbon polymer solutions prior to their analysis by laser desorption Fourier transform mass spectrometry is shown to allow efficient silver ion chemical ionization. High-quality mass spectra are thus obtained for polymers, such as polystyrene, polyisoprene, polybutadiene, and polyethylene, that previously failed to yield useful mass spectra using conventional laser desorption. Accurate mass measurement experiments and isotopic ratios verify that the spectra are those of silver-attached oligomer ion distributions. Mass measurement errors for complete oligomer distributions average between 3 and 12 ppm for oligomers with masses between 400 and 6000 D whereas unit mass resolution is maintained throughout the entire spectral range. 相似文献
104.
Wilkins SB Spencer PD Hatton PD Collins SP Roper MD Prabhakaran D Boothroyd AT 《Physical review letters》2003,91(16):167205
We report the first direct resonant soft x-ray scattering observations of orbital ordering. We have studied the low temperature phase of La0.5Sr1.5MnO4, a compound that displays charge and orbital ordering. Previous claims of orbital ordering in such materials have relied on observations at the manganese K edge. These claims have been questioned in several theoretical studies. Instead we have employed resonant soft x-ray scattering at the manganese L(III) and L(II) edges which probes the orbital ordering directly. Energy scans at constant wave vector are compared to theoretical predictions and suggest that at all temperatures there are two separate contributions to the scattering: direct orbital ordering and strong cooperative Jahn-Teller distortions of the Mn3+ ions. 相似文献
105.
Trinkle DR Hennig RG Srinivasan SG Hatch DM Jones MD Stokes HT Albers RC Wilkins JW 《Physical review letters》2003,91(2):025701
We propose a new direct mechanism for the pressure driven alpha-->omega martensitic transformation in pure titanium. A systematic algorithm enumerates all possible pathways whose energy barriers are evaluated. A new, homogeneous pathway emerges with a barrier at least 4 times lower than other pathways. The pathway is shown to be favorable in any nucleation model. 相似文献
106.
Roberson LB Kowalik J Tolbert LM Kloc C Zeis R Chi X Fleming R Wilkins C 《Journal of the American Chemical Society》2005,127(9):3069-3075
At moderate temperatures in flowing gas, pentacene undergoes a disproportionation reaction to produce 6,13-dihydropentacene (DHP) and a series of polycondensed aromatic hydrocarbons, including the previously unknown peripentacene (PP). The process requires activation by heating to 320 degrees C and is possibly catalyzed by impurities such as DHP, 6,13-pentacenequinone (PQ), Al, or Fe found in the starting materials. These impurities also result in a decrease in the intrinsic field-effect mobility (FEM) of pentacene crystals. Subsequent purifications remove such impurities, thus inhibiting the formation of the disproportionation products and increasing the FEM of pentacene (2.2 cm(2)/Vs). These results clarify the importance of purification of semiconductive materials for measurements of intrinsic mobility and optimal device performance. 相似文献
107.
P. D.?Spencer M. E.?Ghazi S. B.?Wilkins P. D.?HattonEmail author S. D.?Brown D.?Prabhakaran A. T.?Boothroyd 《The European Physical Journal B - Condensed Matter and Complex Systems》2005,46(1):27-32
We present high resolution X-ray measurements
characterising the charge stripe order state in the
La2-xSrxNiO4 system with x = 0.20, 0.225 and 0.25. We
find that in the x = 0.20, 0.225 and 0.25 systems the charge
stripe order exists in a charge stripe glass characterised by
weak, poorly correlated incommensurate charge stripes in contrast
to the strong well correlated charge stripes in the commensurate
x = 1/3 system. No stabilisation of the charge order was
observed at the next possible commensurate value of ε= 0.25. A comparison with high energy X-ray measurements suggested
that the charge order may exist in a charge stripe glass in the
bulk in the doping region x = 0.20 - 0.33. Finally at low
temperature there was an initial increase in the intensity and
correlation not observed with neutron measurements and it appears
to be an effect that X-rays are sensitive to but neutrons are not. 相似文献
108.
Michael P. Coogan Li-ling Ooi Derek S. Wilkins 《Journal of organometallic chemistry》2005,690(7):1861-1865
The Pauson-Khand reaction of 2-ethynyl aniline gives the expected cyclopentenone product, with the aniline alpha to the ketone. Treatment with organocuprates gives not the simple conjugate addition product, but the indole derived from an addition-cyclisation-nucleophilic attack sequence. 相似文献
109.
E. Reichmanis R. Gooden C. W. Wilkins H. Schonhorn 《Journal of polymer science. Part A, Polymer chemistry》1983,21(4):1075-1083
Ortho-nitrobenzyl cholate esters have been successfully used as photosensitive components in solution inhibition deep UV photoresists. The photochemical behavior of a variety of substituted o-nitrobenzyl cholate derivaties has been examined and resist sensitivity is related to the quantum yield of the reaction. The most efficient system examined is o, o′-dinitrobenzyl cholate/P(MMA-MMA), where the quantum yield of photoreaction is 0.2 and resist sensitivity is ca. 150 mJ/cm2 for a 1.5 μm film. The mode of resist behaviour on irradiation and development is also reported. 相似文献
110.