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41.
We present light scattering results from two different fluid mixtures undergoing phase separation next to a glass interface. We observe a characteristic length scale L, which coarsens as a function of time L ∼ t3/2. This growth is faster than any observed previously in bulk samples. The physical process responsible for it is the formation of a wetting layer of one of the two coexisting phases next to the interface. We discuss recent theoretical attempts to explain the fast kinetic mode. 相似文献
42.
Paul Cumming Milan Scheidegger Dario Dornbierer Mikael Palner Boris B. Quednow Chantal Martin-Soelch 《Molecules (Basel, Switzerland)》2021,26(9)
Hallucinogens are a loosely defined group of compounds including LSD, N,N-dimethyltryptamines, mescaline, psilocybin/psilocin, and 2,5-dimethoxy-4-methamphetamine (DOM), which can evoke intense visual and emotional experiences. We are witnessing a renaissance of research interest in hallucinogens, driven by increasing awareness of their psychotherapeutic potential. As such, we now present a narrative review of the literature on hallucinogen binding in vitro and ex vivo, and the various molecular imaging studies with positron emission tomography (PET) or single photon emission computer tomography (SPECT). In general, molecular imaging can depict the uptake and binding distribution of labelled hallucinogenic compounds or their congeners in the brain, as was shown in an early PET study with N1-([11C]-methyl)-2-bromo-LSD ([11C]-MBL); displacement with the non-radioactive competitor ketanserin confirmed that the majority of [11C]-MBL specific binding was to serotonin 5-HT2A receptors. However, interactions at serotonin 5HT1A and other classes of receptors and pleotropic effects on second messenger pathways may contribute to the particular experiential phenomenologies of LSD and other hallucinogenic compounds. Other salient aspects of hallucinogen action include permeability to the blood–brain barrier, the rates of metabolism and elimination, and the formation of active metabolites. Despite the maturation of radiochemistry and molecular imaging in recent years, there has been only a handful of PET or SPECT studies of radiolabeled hallucinogens, most recently using the 5-HT2A/2C agonist N-(2[11CH3O]-methoxybenzyl)-2,5-dimethoxy- 4-bromophenethylamine ([11C]Cimbi-36). In addition to PET studies of target engagement at neuroreceptors and transporters, there is a small number of studies on the effects of hallucinogenic compounds on cerebral perfusion ([15O]-water) or metabolism ([18F]-fluorodeoxyglucose/FDG). There remains considerable scope for basic imaging research on the sites of interaction of hallucinogens and their cerebrometabolic effects; we expect that hybrid imaging with PET in conjunction with functional magnetic resonance imaging (fMRI) should provide especially useful for the next phase of this research. 相似文献
43.
Benjamin P. Cumming Sukanta Debbarma Barry Luther-Davies Min Gu 《Applied physics. B, Lasers and optics》2012,109(2):227-232
We demonstrate compensation for the spherical aberration due to the refractive index mismatch that occurs when a laser beam is focused into a thick arsenic trisulfide (As $_2$ S $_3$ ) film with a high numerical aperture objective. The effects of the aberration at different focal depths on the point spread function have been calculated numerically and the axial response method shown to be a useful measure for compensating the spherical aberration. We show that with the addition of adaptive optics based on a spatial light modulator, the aberration can be significantly reduced, resulting in an increase in peak intensity by a factor of 2.4 and a decrease in axial elongation by a factor of 2.2. 相似文献
44.
T. Westphal G. Bergmann A. Bertolini M. Born Y. Chen A. V. Cumming L. Cunningham K. Dahl C. Gr?f G. Hammond G. Heinzel S. Hild S. Huttner R. Jones F. Kawazoe S. K?hlenbeck G. Kühn H. Lück K. Mossavi J. H. P?ld K. Somiya A. M. van Veggel A. Wanner B. Willke K. A. Strain S. Go?ler K. Danzmann 《Applied physics. B, Lasers and optics》2012,106(3):551-557
The AEI 10 m prototype interferometer facility is currently being constructed at the Albert Einstein Institute in Hannover, Germany. It aims to perform experiments for future gravitational wave detectors using advanced techniques. Seismically isolated benches are planned to be interferometrically interconnected and stabilized, forming a low-noise testbed inside a 100 m3 ultra-high vacuum system. A well-stabilized high-power laser will perform differential position readout of 100 g test masses in a 10 m suspended arm-cavity enhanced Michelson interferometer at the crossover of measurement (shot) noise and back-action (quantum radiation pressure) noise, the so-called Standard Quantum Limit (SQL). Such a sensitivity enables experiments in the highly topical field of macroscopic quantum mechanics. In this article we introduce the experimental facility and describe the methods employed; technical details of subsystems will be covered in future papers. 相似文献
45.
We present a mass-conservative vertex-centred finite volume method for efficiently solving the mixed form of Richards’ equation
in heterogeneous porous media. The spatial discretisation is particularly well-suited to heterogeneous media because it produces
consistent flux approximations at quadrature points where material properties are continuous. Combined with the method of
lines, the spatial discretisation gives a set of differential algebraic equations amenable to solution using higher-order
implicit solvers. We investigate the solution of the mixed form using a Jacobian-free inexact Newton solver, which requires
the solution of an extra variable for each node in the mesh compared to the pressure-head form. By exploiting the structure
of the Jacobian for the mixed form, the size of the preconditioner is reduced to that for the pressure-head form, and there
is minimal computational overhead for solving the mixed form. 相似文献
46.
47.
48.
Several new liquid crystalline compounds comprising Schiff's-base cinnamate cores and fluorocarbon alkoxy tails of varying lengths have been synthesized and characterized. The thermal properties of these materials are compared to those of their hydrocarbon analogues. The results show that fluorination stabilizes the crystalline phase, quite unexpectedly destabilizes the Sc phase, and for two of the compounds produces extraordinarily stable SA phases. 相似文献
49.
G A O'Brien D V Cumming C W Pattison J M Corbett M J Dunn M H Yacoub 《Electrophoresis》1991,12(7-8):570-575
Skeletal muscle has an inherent plasticity which allows it to undergo fibre type transformation when induced by a specific stimulus. Electrical stimulation has been used here to induce transformation of a predominantly fast type skeletal muscle towards a slow, more fatigue-resistant phenotype, which is more suitable for use in long-term cardiac assistance. Muscle samples from animals electrically stimulated for periods up to 6 months have been analysed by electrophoresis for myosin heavy chain (MHC) and myosin light chain (MLC) fast and slow isoforms. Densitometry and computer analysis have been used to determine the pattern of transformation of the different myosin subunits over this time period. MHC and MLC 2 fast to slow isoform switching preceded that of the alkali light chains (MLC1 and MLC3). After 3 months of stimulation the MHC slow isoform was found to have doubled in concentration relative to the unstimulated control muscle and by 4 months accounted for almost 50% of the total MHC content. The slow isoform accounted for 75% of the MLC2 after 4 months of stimulation. The protein products of mRNA isolated from stimulated muscle samples, translated in vitro and separated by electrophoresis, showed that transformation at the mRNA level preceded that at the protein level. By 2-4 weeks of stimulation MLC2 slow isoform mRNA represented over 60% of the total MLC2 mRNA population. An understanding of the molecular structure of muscle during transformation provides insight into its haemodynamic performance in cardiac assistance. 相似文献
50.
An electrode assembly suitable for voltammetric analysis of very small sample volumes, in vitro or (vivo), has been constructed inside a catheter. Well-defined differential pulse current peaks have been obtained for acetaminophen, chlorpromazine and ascorbic acid at the submillimolar concentration level. Voltamperograms recorded for rhesus monkey blood in vivo and in vitro were similar. 相似文献