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41.
Wall-mounted roughness features, such as ribs, are often placed along the walls of a channel to increase the convective surface
area and to augment heat transfer and mixing by increasing turbulence. Depending on the relative roughness size and orientation,
the ribs also have varying degrees of increased pressure losses. Designs that use ribs to promote heat transfer encompass
the full range of having only a few streamwise ribs, which do not allow fully developed flow conditions, to multiple streamwise
ribs, which do allow the flow to become fully developed. The majority of previous studies have focused on perturbing the geometry
of the rib with little attention to the spatially and temporally varying flow characteristics and their dependence on the
Reynolds number. A staggered rib-roughened channel study was performed using time-resolved digital particle image velocimetry
(TRDPIV). Both the developing (entry region) and a fully developed region were interrogated for three Reynolds numbers of
2,500, 10,000, and 20,000. The results indicate that the flow was more sensitive to Reynolds number at the inlet than within
the fully developed region. Despite having a similar mean-averaged flowfield structure over the full Reynolds number range
investigated, the population and distribution of coherent structures and turbulent dissipation within the fully developed
region were also found to be Reynolds number dependent. Exploring the time-accurate flow characteristics revealed that in
addition to vortices shed from the rib shear layer, the region of the rib wake was governed by a periodic process of bursting
of the wake vortices resulting in the intermittent ejection of the inter-rib recirculation region into the core flow. This
periodic process was the driving mechanism resulting in mixing and heat transfer augmentation. A quadrant-splitting burst
analysis was also performed to determine the characteristic frequency and duration of inter-rib bursting as well as the wake
shedding frequency, both of which were determined to be Reynolds number dependent. 相似文献
42.
43.
Accuracy of out-of-plane vorticity estimation from in-plane experimental velocity measurements is investigated with particular
application to digital particle image velocimetry (DPIV). Simulations of known flow fields are used to quantify errors associated
with amplification of the velocity measurement noise and method bias error due to spatial sampling resolution. A novel, adaptable,
hybrid estimation scheme combining implicit compact finite difference and Richardson extrapolation schemes is proposed for
improved vorticity estimation. The scheme delivers higher-order truncation error with less noise amplification than an explicit
second order finite difference scheme. Finally, a complete framework for predicting, a priori, the random, bias, and total
error of the vorticity estimation on the basis of the error of the resolved velocities and the choice of differentiation scheme
is developed and presented.
A portion of this work was presented at ASME IMECE 2003 conference
An erratum to this article is available at . 相似文献
44.
45.
Pavlos Tzermias 《Archiv der Mathematik》2010,95(1):19-24
We prove that the torsion part of the Mordell–Weil group of the Jacobian of a Fermat curve over a cyclotomic field is contained
in the kernel of a certain isogeny. This provides a natural analogue of a similar result on Jacobians of Fermat quotient curves. 相似文献
46.
47.
Pavlos Sinopoulos 《Aequationes Mathematicae》2003,66(1-2):164-179
48.
Hafez IT Paraskeva CA Klepetsanis PG Koutsoukos PG 《Journal of colloid and interface science》2011,363(1):145-156
A new method for the consolidation of loose sand formations has been developed. The method involves in situ precipitation of a composite calcium phosphate-polyelectrolyte salt that binds together with loose sand grains, thus resulting to their consolidation. Three different polyelectrolytes (PE) were tested, i.e., polyacrylic acid (PAA), polyallylamine hydrochloride (PAH), and polyethylenimine (PEI). The effect of PE tested on the thermodynamics and the kinetics of precipitation of calcium phosphate salts was investigated. Three types of experiments were done. Investigation of the adsorption of PE on either hydroxyapatite (Ca(5)(PO(4))(3)OH, HAP) crystals or on sand grains. Measurement of the kinetics of heterogeneous nucleation of HAP on the solid substrates and the mechanical properties of the obtained crystals in batch experiments of low and high supersaturation solutions, respectively. Evaluation of the consolidation in sand packs in order to investigate the effectiveness of the method. The crystallization rates, R(p), on HAP crystals in the presence of the PE tested were found in the order R(p)(PAA)>R(p)(PEI)>R(p)(PAH), while nucleation and crystal growth on silicate sand took place only in the absence of adsorbed PE. PAH favored strongly the consolidation process, whereas PEI and PAA resulted in the formation of poorly consolidated grain agglomerates. 相似文献
49.
Violeta Kourbeli Eleni Chontzopoulou Kalliopi Moschovou Dimitrios Pavlos Thomas Mavromoustakos Ioannis P. Papanastasiou 《Molecules (Basel, Switzerland)》2021,26(15)
The protozoan diseases Human African Trypanosomiasis (HAT), Chagas disease (CD), and leishmaniases span worldwide and therefore their impact is a universal concern. The present regimen against kinetoplastid protozoan infections is poor and insufficient. Target-based design expands the horizon of drug design and development and offers novel chemical entities and potential drug candidates to the therapeutic arsenal against the aforementioned neglected diseases. In this review, we report the most promising targets of the main kinetoplastid parasites, as well as their corresponding inhibitors. This overview is part of the Special Issue, entitled “Advances of Medicinal Chemistry against Kinetoplastid Protozoa (Trypanosoma brucei, Trypanosoma cruzi and Leishmania spp.) Infections: Drug Design, Synthesis and Pharmacology”. 相似文献
50.
Talia A. Shmool Laura K. Martin Liem Bui-Le Ignacio Moya-Ramirez Pavlos Kotidis Richard P. Matthews Gerhard A. Venter Cleo Kontoravdi Karen M. Polizzi Jason P. Hallett 《Chemical science》2021,12(27):9528
Understanding protein folding in different environmental conditions is fundamentally important for predicting protein structures and developing innovative antibody formulations. While the thermodynamics and kinetics of folding and unfolding have been extensively studied by computational methods, experimental methods for determining antibody conformational transition pathways are lacking. Motivated to fill this gap, we prepared a series of unique formulations containing a high concentration of a chimeric immunoglobin G4 (IgG4) antibody with different excipients in the presence and absence of the ionic liquid (IL) choline dihydrogen phosphate. We determined the effects of different excipients and IL on protein thermal and structural stability by performing variable temperature circular dichroism and bio-layer interferometry analyses. To further rationalise the observations of conformational changes with temperature, we carried out molecular dynamics simulations on a single antibody binding fragment from IgG4 in the different formulations, at low and high temperatures. We developed a methodology to study the conformational transitions and associated thermodynamics of biomolecules, and we showed IL-induced conformational transitions. We showed that the increased propensity for conformational change was driven by preferential binding of the dihydrogen phosphate anion to the antibody fragment. Finally, we found that a formulation containing IL with sugar, amino acids and surfactant is a promising candidate for stabilising proteins against conformational destabilisation and aggregation. We hope that ultimately, we can help in the quest to understand the molecular basis of the stability of antibodies and protein misfolding phenomena and offer new candidate formulations with the potential to revive lost therapeutic candidates.Probing the energy landscape and thermodynamics of biomolecules for drug design. 相似文献