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排序方式: 共有370条查询结果,搜索用时 15 毫秒
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BZ Packard 《Canadian Metallurgical Quarterly》1994,1222(2):159-163
Previously, it was shown that Oncoimmunin-M (OI-M), a recently identified tumor cell-derived 36 kDa protein, is able both to inhibit the proliferation of the human promyelocytic leukemic cell line HL-60 while maintaining viability in culture and to induce a bimodal distribution of CD11b, the alpha chain of the integrin MAC-1, on the cell surface (Packard, B.Z. and Komoriya, A. (1993) J. Biol. Chem. 268, 6356-6363). Now, data which reveal that exposure of HL-60 cells to this factor also brings about an increase in the mean level of surface expression of CD11c, the alpha chain of another leukocyte integrin (p150,95), but leaves CD11a, the alpha chain of the third leukointegrin (LFA-1), virtually unchanged (< 10%) are presented. Comparison of motility studies of OI-M-treated HL-60 bulk populations with control bulk populations demonstrates coinduction of CD11b and CD11c surface upregulation with chemotactic responsiveness to a gradient of the chemoattractant human C5a. Separation of motile from nonmotile cell subpopulations after exposure to C5a further reveals that individual cells which respond to this chemoattractant express increased levels of both CD11b and CD11c relative to unresponsive cells. These data correlate the upregulation of leukointegrins MAC-1 and p150,95 by a tumor cell-derived protein on a preterminally differentiated myeloid cell with chemotactic responsiveness to human C5a. 相似文献
3.
Prostaglandins act through specific receptors to stimulate cyclic AMP formation which inhibits platelet activation and relaxes vascular smooth muscle. We have used RT-PCR combined with Southern blot analysis to determine the subtypes of prostaglandin receptor on platelets. Platelets expressed the EP4 rather than the EP2 prostaglandin EP receptor subtype, whereas vascular smooth muscle cells predominantly expressed the EP2 receptor. The IP receptor, which binds prostacyclin and couples to stimulation of adenylyl cyclase, and three isoforms of the inhibitory EP3 receptor were equally expressed in platelets, HEL cells and umbilical artery smooth muscle cells. The EP3-II isoform showed variation in level of expression among the three cell types. As a positive control for the presence of platelet RNA, PCR was performed using primers specific for the alpha chain of the platelet membrane glycoprotein Ib. As a negative control for the absence of T and B cell contamination in the platelet RNA, PCR was performed using primers specific for the cell specific cluster determinants CD2 (a T-cell marker) and CD20 (a B-cell marker). The finding that platelets express both stimulatory and inhibitory prostaglandin receptors provides confirmation of a homeostatic model of regulation of platelet adenylyl cyclase previously proposed. 相似文献
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Many mothers with children under age 6 are employed and it is not usually feasible for a parent to stay home with a child who is mildly ill. Such ill children likely remain in child day care programs. The extent to which this occurs and the management of these children in family day care was studied. Over the course of a year, 1 to 3 visits were made to 714 family day care homes in order to survey providers. With enrollments ranging between 0 and 18 children per day care home at the time of each visit, information on 3,630 "child enrollment days" was collected. The median age of children in care was 2 years. An average of 16% of all children were ill on any one day (with seasonal variation); 1% were injured. Of ill children, 82% attended day care that day, 49% had contacted a physician about that illness, and 28% were administered a medication at the day care setting. Twenty-one percent of children receiving medication in day care had no contact with a physician for that illness. These data show that mild childhood illnesses are routinely managed by child day care providers. Physicians who traditionally limit their illness-management education to parents need to recognize the health education and consultation needs of day care providers. 相似文献
6.
I. E. Ginzburg V. M. Zhigalkin S. V. Zhigalkin E. V. Plyusnina V. N. Semenov O. M. Usoltseva A. I. Chanyshev 《Journal of Mining Science》1998,34(6):482-490
Conclusions We have carried out an experimental study of the inelastic properties of solids with simple and complex loadings, producing
pure shear strains and the subsequent imposition of strain states of pure shear.
Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk. Translated from Fiziko-Tekhnicheskie Problemy
Razrabotki Poleznykh Iskopaemykh, No. 6, pp. 16–26, November–December, 1998. 相似文献
1. | The data from experiments with biaxial tension on a specimen of the zirconium alloy E-110 demonstrate the presence of initial anisotropy of the elastic deformation and strength properties. |
2. | The test specimens have three orthogonal planes of elastic symmetry of the material, directed respectively along the axis of the specimen, along the tangential direction to the cylinder generatrix, and along the radial direction. These are the principal axes. The elastic constants were determined in the direction of these axes. |
3. | We have pointed out a trajectory of preliminary simple and complex loading that leads to an increase of strength and deformation properties of the material in one of the principal directions of the stress tensor, in comparison with the analogous properties in the case of simple loading. Such a trajectory consists of loading accompanied by partial unloading in one of the directions of preliminary plastic deformation, interruption of the increase of plastic strains in this direction, and an excess of the magnitude of the second principal stress over the first. |
4. | Regardless of the prehistory of simple and complex loading of the initially orthotropic material, accompanied by partial unloading in the direction of the preliminary plastic deformation, a repeated simple loading σ z =2σϕ, equivalent to the action of pure shear with the imposition of hydrostatic pressure, leads to a change in the deformation properties, i.e., to isotropic strengthening of the material. The onset of plasticity in such a repeated simple loading is determined by the stress intensity at the end of the first section of the preliminary loading trajectory, and the point at which this onset occurs is independent of the magnitude of the second principal stress and the intensity of stresses at the end of the second section of complex loading of the preliminary loading trajectory. This indicates that the onset and development of plastic strains along specific slip areasT is determined solely by the magnitude of the maximum tangential stress, and is independent of plastic slips along the other areasT 12 orT 23. |
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D'Humières D Ginzburg I Krafczyk M Lallemand P Luo LS 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2002,360(1792):437-451
This article provides a concise exposition of the multiple-relaxation-time lattice Boltzmann equation, with examples of 15-velocity and 19-velocity models in three dimensions. Simulation of a diagonally lid-driven cavity flow in three dimensions at Re = 500 and 2000 is performed. The results clearly demonstrate the superior numerical stability of the multiple-relaxation-time lattice Boltzmann equation over the popular lattice Bhatnagar-Gross-Krook equation. 相似文献
9.
以两种方法合成了10个取代苯甲酸葡萄糖酯类化合物,一是相转移催化法,二是在三忆胺的存在下,取代苯甲酸与溴代葡萄糖反应,该种合成糖酯的方法未见文献报道,取代苯甲酸葡萄糖酯的结构由IR、MS、^1H NMR和元素分析确认。对化合物的抗病毒活性测试结果发现,其中有两个化合物具有一定的抑制TMV的活性。 相似文献
10.
N. S. Ginzburg A. M. Malkin N. Yu. Peskov A. S. Sergeev 《Technical Physics Letters》2006,32(10):896-900
A new scheme of feedback in a free-electron maser (FEM), which is based on the mutual scattering of propagating and quasi-cutoff (trapped) modes on a periodic Bragg structure, is considered. The trapped mode makes possible self-excitation of the system, while the energy exchange in a stationary generation regime is almost entirely determined by the interaction with a synchronous propagating wave. Using the proposed method, it is possible to improve mode selectivity with respect to the transverse index and accordingly decrease the working wavelength. 相似文献