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31.
罗建辉 《湖南大学学报(自然科学版)》1990,17(2)
本文将便于应用的胡海昌方程推广到各种常见的中厚板理论.广义胡海昌方程解的结构与弹性理论所得的结果一致. 相似文献
32.
T-cell tolerance by clonal anergy in transgenic mice with nonlymphoid expression of MHC class II I-E 总被引:26,自引:0,他引:26
T-cell reactivity to the class II major histocompatibility complex I-E antigen is associated with T-cell antigen receptors containing the V beta gene segments V beta 17a and V beta 5. Mice expressing I-E with the normal tissue distribution (on B cells, macrophages, dendritic cells and thymic epithelium) induce tolerance to self I-E by clonal deletion in the thymus. By contrast, we find that transgenic INS-I-E mice that express I-E on pancreatic beta-cells, but not in the thymus or peripheral lymphoid organs, are tolerant to I-E but have not deleted V beta 5- and V beta 17a-bearing T cells. Moreover, whereas T-cell populations from nontransgenic mice proliferate in response to receptor crosslinking with V beta 5- and V beta 17a-specific antibodies, T cells from INS-I-E mice do not. Thus, our experiments provide direct evidence that T-cell tolerance by clonal paralysis does occur during normal T-cell development in vivo. 相似文献
33.
Class II major histocompatibility complex (MHC) gene expression in the mouse is generally limited to thymic epithelium and bone marrow-derived cells such as B lymphocytes and cells of the macrophage/dendritic cell lineage (M phi/DC). Class II-bearing B lymphocytes and M phi/DC possess antigen presenting cell (APC) function; that is, they can stimulate T lymphocytes reactive to either antigen plus MHC or foreign MHC alone. To assess whether non-bone-marrow-derived cells can acquire APC function and elicit graft rejection through expression of class II, we studied transgenic pancreatic islet beta cells that express a foreign class II (I-E) molecule. In vivo, grafts of I-E+ transgenic islets into I-E- naive hosts are not rejected unless the host is primed by an injection of I-E+ spleen cells. In vitro, the I-E+ beta cells are unable to stimulate T lymphocytes reactive to I-E plus a peptide antigen. Paradoxically, they induce antigen specific unresponsiveness in the T cells. We propose that expression of class II on non-lymphoid cells may serve as an extrathymic mechanism for maintaining self tolerance. 相似文献
34.
CUIHong ZHAOChunsheng QINYu ZHENGXiangdong ZHENGYongguang CHANChuenYu CHANLoYin 《科学通报(英文版)》2004,49(2):167-174
A new method based on mass fluxes and observed ozone profiles was developed to estimate crosstropopause ozone flux. Using this method, we estimated the cross-tropopause ozone flux in a stratospheric-tropospheric exchange event that occurred over East Asia in March 2001.The result revealed that the ozone flux across the tropopause in this event was an order of magnitude higher than the global and hemispheric average. Compared to the traditional method using a linear relationship between ozone mixing ratio and potential vorticity near the tropopause, the cross-tropopause ozone flux evaluated with ozonesonde data was somewhat higher, although the orders of the two values were the same. 相似文献
35.
Highly precise 40Ar-39Ar dating results demonstrate that the ages of potash-rich volcanic rocks in western Shandong Province are 114.7–124.3 Ma,
and that of the lamprophyres is 119.6 Ma. The potash-rich volcanic rocks have relatively high (87Sr÷86Sr)i ratios (0.708715–0.711418) and distinctly negative εnd values (−11.47–−17.54), and are enriched in radiogenic lead (206Pb÷204Pb=17.341−17.622, 207Pb÷204Pb=15.525−15.538, 208Pb÷204Pb = 37.563−37.684). Similarly, the lamprophyres also have quite low εnd values (−11.57–−19.64). Based on the fact that the Sr, Nd and Pb isotopic compositions of potash-rich volcanic rocks are
very consistent with that of the clinopyroxene separates, and by integrating comprehensive analyses of their tectonic settings,
and extensive comparisons of the Sr, Nd isotopic compositions with that of the related simultaneous rocks, it is concluded
that the potash-rich volcanic rocks and lamprophyres in western Shandong Province were most possibly derived from the partial
melting of enriched mantle which was caused by source contamination and metasomatism of subducted continental crustal materials. 相似文献
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M. Katar W. -K. Lo M. Nagpal H. Maisel 《Cellular and molecular life sciences : CMLS》1980,36(4):416-418
Summary The cytoskeletal proteins of the vertebrate lens fibre cell comprise polypeptides ranging in mol.wt from 43,000 to 250,000 daltons. The main intermediate filament polypeptide of the pickerel, Northern frog, chick, bovine, and human lens has a mol.wt of 54,000 daltons. Peptide analysis revealed that the chick 54,000 dalton protein was more similar to the bovine protein than to the pickerel protein.Supported by grants EY 01417 (H. Maisel) and HD-06390 (J.C. Brown, University of Virginia, Charlottesville) from the National Institutes of Health, U.S.P.H.S. 相似文献
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