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排序方式: 共有2093条查询结果,搜索用时 15 毫秒
41.
CP Coppola JR Gosche M Arrese B Ancowitz J Madsen J Vanderhoof BL Shneider 《Canadian Metallurgical Quarterly》1998,115(5):1172-1178
OBJECTIVES: Major operative trauma like aorta-coronary bypass operation may lead to postoperative immunodisturbance, putting the patient at an increased risk for infection and sepsis. The monocyte/macrophage system and the endotoxin receptor CD14 are important in the early recognition and elimination of invading bacteria. The aim of this study was to analyze changes in membrane-associated CD14 and soluble CD14 during and after cardiac involving cardiopulmonary bypass. METHODS: We studied numbers of leukocytes, monocytes, and monocyte subpopulations, expression of monocyte membrane-associated CD14 and plasma levels of soluble CD14 in 10 patients (63 +/- 8 years of age), who underwent elective cardiopulmonary bypass. RESULTS: Cardiopulmonary bypass induced marked postoperative monocytosis, which was maximal 20 hours after the operation (485 +/- 242 cells/microl before, 1080 +/- 264 cells/microl 20 hours after surgery). Expression of membrane-associated CD14 on classical CD14++ monocytes decreased significantly by 40%, reaching a nadir 20 hours after surgery (p < 0.05). At the time of maximal membrane-associated CD14 suppression, the levels of soluble CD14 measured by enzyme-linked immunosorbent assay were clearly increased (3.2 +/- 1.0 microg/ml before versus 5.6 +/- 1.0 microg/ml 20 hours after, p < 0.001). No significant change of the percentage of small (alpha) and large (beta) forms of soluble CD14 was found. CONCLUSIONS: Cardiopulmonary bypass leads to reduced membrane-associated CD14 expression on peripheral blood monocytes and increased levels of soluble CD14 through shedding or secretion of membrane-associated CD14 from the cell surface. These findings indicate that bypass is associated with significant monocyte activation. 相似文献
42.
ABSTRACT Multi-functional radial jet reattachment blow boxes deliver a dry air into the pockets of the dryer section of a paper machine by impinging directly onto the unsuppned sheet in the open diaw. The air flow also maintains or improves the sheet swbility. The iadial jet reattachment blow box technology pmvides a significant enhancement in drying rates. The theoretical drying results are presented in terms of average drying rates, moisture and temperature pmfiles along the drying section with and without the presence of the multi-functional radial jet reaaachment blow boxes. The thcorclical results indicate that enhancements of drying rates within the range of 8% to 25% are feasible depending on ihe operating conditions and machine configuration. 相似文献
43.
Dos Santos OF Rodrigues SC Sipahi GM Scolfaro LM da Silva EF 《Nanoscale research letters》2011,6(1):175
The electrical conductivity σ has been calculated for p-doped GaAs/Al0.3Ga0.7As and cubic GaN/Al0.3Ga0.7N thin superlattices (SLs). The calculations are done within a self-consistent approach to the theory by means of a full six-band Luttinger-Kohn Hamiltonian, together with the Poisson equation in a plane wave representation,
including exchange correlation effects within the local density approximation. It was also assumed that transport in the SL
occurs through extended minibands states for each carrier, and the conductivity is calculated at zero temperature and in low-field
ohmic limits by the quasi-chemical Boltzmann kinetic equation. It was shown that the particular minibands structure of the
p-doped SLs leads to a plateau-like behavior in the conductivity as a function of the donor concentration and/or the Fermi
level energy. In addition, it is shown that the Coulomb and exchange-correlation effects play an important role in these systems,
since they determine the bending potential. 相似文献
44.
Dunsmore CJ Malone KJ Bailey KR Wear MA Florance H Shirran S Barran PE Page AP Walkinshaw MD Turner NJ 《Chembiochem : a European journal of chemical biology》2011,12(5):802-810
Cyclophilin A (CypA) is a member of the immunophilin family of proteins and receptor for the immunosuppressant drug cyclosporin A (CsA). Here we describe the design and synthesis of a new class of small-molecule inhibitors for CypA that are based upon a dimedone template. Electrospray mass spectrometry is utilised as an initial screen to quantify the protein affinity of the ligands. Active inhibitors and fluorescently labelled derivatives are then used as chemical probes for investigating the biological role of cyclophilins in the nematode Caenorhabditis elegans. 相似文献
45.
The authors describe two software tools used for teaching logic design and analysis and basic computer organization in the introductory course on computer engineering at the authors' department. The first computer-aided instruction tool described is a schematic capture, simulation, and logic animation package targeted for teaching combinational and sequential logic concepts. The tool incorporates logic animation capability rather than waveform displays, which allows students to view and control logic values propagating throughout the entire network. The second tool teaches computer organization, including microprogramming concepts, by means of the graphical display of an instructional microprocessor architecture in which users are allowed to view and control internal registers, memory locations, and microcontrol store. Both of the computer-aided instructional tools run on UNIX workstations, with graphics displays, local hard-disk mass storage, and mouse input 相似文献
46.
G.J. Hutchings R. Wells S. Feast M.R.H. Siddiqui D.J. Willock F. King C.H. Rochester D. Bethell P.C.B. Page 《Catalysis Letters》1997,46(3-4):249-254
Modification of zeolite H-Y by dithiane oxides (2-R-1,3-dithiane 1-oxide, R = H, CH3, C6H5) is shown to enhance significantly its activity for the acid-catalysed gas phase dehydration of butan-2-ol. The rate enhancement
is observed for catalysts that are prepared using two commercial samples of zeolite H-Y. The origin of this effect is examined
using in situ FTIR spectroscopy and 27Al and 29Si MAS NMR spectroscopy studies of the modified zeolite. The rate enhancement is considered to result from a specific interaction
between the dithiane oxide modifier with both the extra-framework and framework aluminium in the zeolite.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
47.
Granule impact deformation has long been recognised as important in determining whether or not two colliding granules will coalesce. Work in the last 10 years has highlighted the fact that viscous effects are significant in granulation. The relative strengths of different formulations can vary with strain rate. Therefore, traditional strength measurements made at pseudo-static conditions give no indication, even qualitatively, of how materials will behave at high strain rates, and hence are actually misleading when used to model granule coalescence. This means that new standard methods need to be developed for determining the strain rates encountered by granules inside industrial equipment and also for measuring the mechanical properties of granules at these strain rates. The constitutive equations used in theoretical models of granule coalescence also need to be extended to include strain-rate dependent components. 相似文献
48.
49.
Brian Lawn David Marshall Rishi Raj Greg Hirth Trevor Page Julie Yeomans 《Journal of the American Ceramic Society》2021,104(1):23-26
Crystalline quartz has long been identified as among the weakest of abundant crustal minerals. This weakness is particularly evident around the α–β phase inversion at 573°C, in which Si–O bonds undergo a displacive structural transformation from trigonal to hexagonal symmetry. Here we present data using indentation testing methodologies that highlight the precipitous extent of the transformational weakening. Although the indentations are localized over relatively small specimen contact areas, the data quantify the essential deformation and fracture properties of quartz in a predominantly (but not exclusively) compressive stress field, at temperatures and pressures pertinent to conditions in the earth's crust. 相似文献
50.
Joanna Dojillo-Mooney Jonathan E. Page Murray B. Isman G. H. Neil Towers 《Journal of chemical ecology》1999,25(6):1369-1382
The larvae of a rare noctuid moth, Lasionycta wyatti, were found to be associated with the stems and roots of Ambrosia chamissonis, a species found along sandy beaches in western North America. High-performance liquid chromatographic (HPLC) analyses of L. wyatti larvae and their frass revealed significant amounts of thiarubrines, secondary compounds characteristic of this host plant. Artificial diet studies showed that thiarubrines were well tolerated by these larvae. These same diets, however, were toxic to larvae of Manduca sexta and inhibited larval growth of Spodoptera litura. Even in the presence of simulated sunlight, artificial diets containing thiarubrines did not affect larvae of L. wyatti. However, dietary incorporation of thiophenes, natural UV-activated breakdown products of thiarubrines, was deleterious to larvae of L. wyatti. 相似文献