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排序方式: 共有63条查询结果,搜索用时 21 毫秒
21.
Robert Chiarelli Andr Jeunet Josette Michon Pierre Michon Claude Morat Andr Rassat Hans Ulrich Sieveking 《Magnetic resonance in chemistry : MRC》1980,13(3):216-217
Several nitroxide biradicals have been studied by electron spin resonance, in cyclohexane solution at ?10°C and in toluene solution at ?150°C. The ESR spectra change when the sample orientation in the spectrometer cavity is changed: under favourable circumstances oriented spectra are obtained. 相似文献
22.
A simple, economical and accurate technique, based on the different dielectric constants of solids and gases, has been developed to determine instantaneous, in-situ void fractions and particle velocities in gas-powder streams. Two different electrode configurations were investigated for sensitivity and flow-regime dependency. Stationary, as well as high speed cinematographic, calibrations were performed. The technique is suitable for process control. 相似文献
23.
H. R. Irons 《Czechoslovak Journal of Physics》1971,21(4-5):500-502
Ni-Fe-Au films can be made by vacuum evaporation from a single melt since Au has an evaporation rate comparable to that of Ni and Fe. In films 400 Å thick the addition of Au does not changeH
c
, butH
k
increases 0·1 Oe per 1% Au until 10% Au is reached and then remains constant for Au percentages up to 26%. The change ofH
k
with substrate deposition temperature is about the same as for Ni-Fe films (–0·01 Oe/°C). Films with 8% Au have the same skew as Ni-Fe films when made at a substrate temperature of 300 °C, but for Ni-Fe-Au films the change of skew with substrate temperature is about one fourth that of Ni-Fe films. The small area dispersion is reduced by a factor of 2 to 3 for Au additions of 4 to 26 percent. 相似文献
24.
25.
Mikhail Reibarkh Thomas P. Wyche Josep Saurí Tim S. Bugni Gary E. Martin R. Thomas Williamson 《Magnetic resonance in chemistry : MRC》2015,53(12):996-1002
Utilization of 2H, 13C, and 15N isotopically labeled proteins and peptides is now routine in biomolecular NMR investigations. The widespread availability of inexpensive, uniformly 13C enriched glucose now makes it possible to isolate uniformly 13C labeled natural products from microbial fermentation. We now wish to describe an approach for the rapid structural characterization of uniformly 13C labeled natural products that avoids the pitfalls of relying on parameters typically employed in biomolecular NMR studies. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
26.
Romain Sallio Stéphane Lebrun Francine Agbossou-Niedercorn Christophe Michon Eric Deniau 《Tetrahedron: Asymmetry》2012,23(13):998-1004
Two alternative synthetic approaches to a variety of enantioenriched 6-arylated piperidin-2-ones have been developed. The first one is based on the hydrogenation of suitably arylated chiral cyclic enehydrazides. The second approach relies on the asymmetric catalytic hydrogenation of the corresponding N-alkylated precursors. 相似文献
27.
Gelatin gel properties have been studied through the evolution of the storage [G()] and the loss [G()] moduli during gelation or melting near the gel point at several concentrations. The linear viscoelastic properties at the percolation threshold follow a power-law G()G() and correspond to the behavior described by a rheological constitutive equation known as the Gel Equation. The critical point is characterized by the relation: tan = G/G = cst = tan ( · /2) and it may be precisely located using the variations of tan versus the gelation or melting parameter (time or temperature) at several frequencies. The effect of concentration and of time-temperature gel history on its variations has been studied. On gelation, critical temperatures at each concentration were extrapolated to infinite gel times. On melting, critical temperatures were determined by heating step by step after a controlled period of aging. Phase diagrams [T = f(C)] were obtained for gelation and melting and the corresponding enthalpies were calculated using the Ferry-Eldridge relation. A detailed study of the variations of A with concentration and with gel history was carried out. The values of which were generally in the 0.60–0.72 range but could be as low as 0.20–0.30 in some experimental conditions, were compared with published and theoretical values. 相似文献
28.
Dr. Paul Bamborough Dr. Chun‐wa Chung Dr. Emmanuel H. Demont Dr. Rebecca C. Furze Dr. Andrew J. Bannister Dr. Ka Hing Che Dr. Hawa Diallo Clement Douault Dr. Paola Grandi Prof. Tony Kouzarides Dr. Anne‐Marie Michon Darren J. Mitchell Dr. Rab K. Prinjha Dr. Christina Rau Dr. Samuel Robson Robert J. Sheppard Dr. Richard Upton Dr. Robert J. Watson 《Angewandte Chemie (International ed. in English)》2016,55(38):11382-11386
ATAD2 is a cancer‐associated protein whose bromodomain has been described as among the least druggable of that target class. Starting from a potent lead, permeability and selectivity were improved through a dual approach: 1) using CF2 as a sulfone bio‐isostere to exploit the unique properties of fluorine, and 2) using 1,3‐interactions to control the conformation of a piperidine ring. This resulted in the first reported low‐nanomolar, selective and cell permeable chemical probe for ATAD2. 相似文献
29.
The aim of this study is to provide a structural damping solution for space applications to enhance mission performance of honeycomb structures. Classical particle dampers are enclosures partially filled with small metallic or glass spheres, attached to a vibrating structure. The induced damping mechanism is mainly due to frictional losses and collision effects. This paper deals with replacing classical hard particles with soft hollow ones. This study is oriented toward experimental investigations and theoretical validation in order to distinguish dissipation phenomena. The experimental approach first relies on identifying the damping in small honeycomb samples filled with particles. Instead of dissipation by friction and impact, the elliptical shape of the measured hysteresis loops highlights that visco-elastic behavior is dominant with these specific soft particle dampers. Then, experimental and numerical validations are performed on aluminum honeycomb cantilever beams filled with particles. To take into account the effect of the particles, equivalent oscillators, based on the previous experimental damping identification, are added to a finite element model. These kinds of particle dampers are highly nonlinear as a function of excitation frequency and amplitude. It is shown that good damping efficiency is achieved across a large frequency range with low impact on structure stiffness. This paper suggests a convenient method to model the structural damping induced by soft hollow particles. 相似文献
30.
On the multifractal analysis of measures 总被引:16,自引:0,他引:16
The multifractal formalism is shown to hold for a large class of measures. 相似文献