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The Science of Nature -     

我国环保基础设施建设融资的ABS方式

本文阐述了我国环保基础设施建设资金短缺的情况，指出必须利用金融创新为环保融资服务，ＡＢＳ融资就是其中的一种方法。本文介绍了ＡＢＳ融资方式的涵义，并提出了其在环保基础设施融资方面所具有的优势，即保障国家安全、降低融资风险、降低融资成本、筹资前景广阔和改善公司财务状况，同时，也指出了使用ＡＢＳ方式进行融资的所应当注意的一些问题，即保障可预期的现金流问题以及风险管理问题，并针对这些问题提出了相应的解决对     

Cells of the connective tissue differentiate and migrate into pollen sacs

In angiosperms, archesporial cells in the anther primordium undergo meiosis to form haploid pollen, the sole occupants of anther sacs. Anther sacs are held together by a matrix of parenchyma cells, the connective tissue. Cells of the connective tissue are not known to differentiate. We report the differentiation of parenchyma cells in the connective tissue of two Gordonia species into pollen-like structures (described as pseudopollen), which migrate into the anther sacs before dehiscence. Pollen and pseudopollen were distinguishable by morphology and staining. Pollen were tricolpate to spherical while pseudopollen were less rigid and transparent with a ribbed surface. Both types were different in size, shape, staining and surface architecture. The ratio of the number of pseudopollen to pollen was 1:3. During ontogeny in the connective tissue, neither cell division nor tetrad formation was observed and hence pseudopollen were presumed to be diploid. Only normal pollen germinated on a germination medium. Fixed preparations in time seemed to indicate that pseudopollen migrate from the connective tissue into the anther sac.