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111.
An amniocentesis was performed at 13.3 weeks' gestation for advanced maternal age. A mosaic sex chromosome pattern was found: of 50 cells examined, 34 had a 45,X karyotype. In 14 cells with a modal number of 46, a recognizable Y was substituted by a small non-fluorescent marker. C-banding identified the marker as an isodicentric in 12 cells. In two cells, the non-fluorescent marker appeared to be monocentric and looked like a non-fluorescent del (Yq), but could have been an isodicentric Y with inactivation of one of the centromeres. Two cells with a modal number of 47 showed two copies of the monocentric marker. Fluorescent in situ hybridization with an alpha satellite Y-specific centromeric probe confirmed the Y-chromosome origin of the markers and allowed for more accurate prenatal diagnostic information. 相似文献
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浅谈炼油企业的水资源利用 总被引:1,自引:0,他引:1
水资源短缺和水资源不能得到有效利用的问题严重制约我国经济的可持续发展,并将引起生态环境退化、人居环境恶化、争水矛盾日益突出等社会和环境问题。针对炼油企业水资源利用的现状和存在的问题进行了分析,结合当前企业的实际情况,在节水和废水资源再利用等方面做了初步的探讨。 相似文献
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J. J. Jesudason R. H. Marchessault T. Saito 《Journal of Polymers and the Environment》1993,1(2):89-98
The synthetic analogue of a bacterially produced polyester, poly(-hydroxybutyrate) (PHB) was synthesized from racemic -butyrolactone using anin situ trimethyl aluminum-water catalyst. The polymer was fractionated into samples differing in molecular weight and isotactic diad content. The latter was closely related to degree of crystallinity. The biodegradation of these fractions were examined by monitoring mass loss over time in the presence of anAlcaligenes faecalis T1 extracellular bacterial poly(-hydroxybutyrate) depolymerase. The fraction with high isotactic diad tacticity content showed little or no degradation over a 50 hour incubation period, whereas the fraction of intermediate isotactic diad content degraded in a continuous steady fashion at a rate that was less than that for bacterial PHB. The low isotactic diad fraction underwent a rapid initial degradation, followed by no further mass loss. The presence of stereoblocks in the polymer structure of the various fractions was an influence on the degree of susceptibility towards degradation and is related to sample crystallinity. 相似文献
118.
本文从近几年来宜宾市工业及生活废水等排放情况及水环境质量的监测资料,阐述了我市流域水污染状况与可持续发展面临的主要问题,提出了水资源保护对策,以促进社会经济可持续发展。 相似文献
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Traditional knowledge and practices are important in prudent resource use and biodiversity conservation. The implications of modernization and changing lifestyle are discussed in the context of agriculture and resource use, the two sectors in which maximum modernization has occurred. The information was gathered through observations and structured interviews over three years (July 1996 to July 1999) of field work in the western Himalaya. It was observed that forest based subsistence agriculture has given way to the market dependant cash crop cultivation. That apart from loss of genetic diversity, has also resulted in the degradation of forests. The use of wild plants in the day-to-day activities has also declined and dependence on high value market products has increased. Currently, wild plants are used only if no other cheap substitute is available in the market or if the use is economically beneficial to the people. Thus, the knowledge gathered through ages of experience is eroding because of the activities geared for short-term economic benefits which, in long run, may not be sustainable. 相似文献
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广州茶文化旅游资源的开发利用 总被引:7,自引:1,他引:7
作者立足于广州的茶文化,首先从社会普同性、文化信息共有性、文化模式的整合性等三个方面分析得出茶文化是广州民俗旅游资源的重要组成部分,并在此基础上对广州茶文化进行了分类,论述了其民俗旅游资源价值。最后,作者对开发广州茶文化旅游资源提出了一些建议。 相似文献