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941.
During the induction of gamete-producing gametangia, induced gametophytes were collected at 4 days intervals (0,4,8,12 d) and total RNAs were isolated by CsCl gradient ultracentrifugation. Some stage-specific expressed mRNAs were identified by differential display of mRNAs from different developing stages of the gametophytes. The cDNA of one specific mRNA was verified, cloned and sequenced. This gene was specifically expressed during 4 days of induction, and had partial homologous sequence with tobacco IAA-binding protein gene. It suggests that this cDNA may represent a gene which is related to the IAA regulating function during the development of the gametophytes.
相似文献942.
943.
软岩的强度—变形—时间之间关系的试验分析 总被引:6,自引:4,他引:2
对软岩和有不连续面的软岩试样进行一系列固结不排水三轴压缩和蠕变试验,测定并分析了它们在正常固结和超固结状态下的应变软化性状、蠕变特性和残余强度的变化规律。探讨了软岩中存在的不连续面对应力-应变关系、残余强度特性和蠕变应变速率的影响。 相似文献
944.
本文初步总结了市场经济国家的商业性地勘工作主要特点,对我国今后开发商业性地勘地作所要解决的问题做了探讨,并就冶金地质队伍如何更好地适应今后商业性地质工作提出了建议。 相似文献
945.
构造应力作用下流体运动的动力学分析——构造流体动力学 总被引:18,自引:0,他引:18
本文从流体动力学的基本规律出发,应用渗流力学、岩土力学及弹性力学的理论及方法,推导出了考虑应力状态的可变形介质中流体运动的动力学方程,由该方程可以看出:应力状态是影响流体运动的一个非常重要的因素,它通过3种方式来影响流体的运动,其一是:应力的作用改变介质的渗透性能,从而影响流体运动;其二是:平均正应力的变化速率影响介质的含流体能力,它以源汇项的形式反映在方程中;其三是:应力的作用影响流场的初始状态及边界状态,通过影响定解条件反映在动力学方程中,从而影响运动特征。构造应力场对流体运动的最终影响是这3方面作用 相似文献
946.
947.
INVESTIGATION OF STATUS AND DEMAND ON PUBLIC SERVICE OF EARTHQUAKE DISASTER MITIGATION IN CHINA 下载免费PDF全文
In order to make a comprehensive and systematic evaluation of the status and demands of public service of earthquake disaster mitigation, we launched an investigation with Social Opinion Polling Center of National Bureau of Statistics on the current situation of public service of earthquake disaster mitigation and the demands for it in 2018. The investigation was conducted for 18~75-year-old residents for both urban and rural areas in 31 provinces of China mainland using the Computer Assisted Telephone Interview(CATI)method and 20 078 valid samples were received in total. The questionnaire mainly includes two parts: the current situation assessment and the demand survey. The assessment of public service status consists of five indicators: earthquake emergency drill, knowledge publicity of earthquake prevention and disaster reduction, acquisition of earthquake information, reliability of information released by earthquake agencies, and overall satisfaction. The results indicate that only 27.4% of public have participated the earthquake emergency drill, and 73.5% of public have learned some knowledge about earthquake prevention and disaster reduction in different level. It shows that rural residents have a lower level of scientific knowledge of earthquake disaster mitigation although the rural residents have a higher level of satisfaction. Meanwhile, 82.9% of the public are very concerned about earthquake-related information, and the earthquake information acquisition convenience score is 81.51 points(the full score is 100 points). At present, TV is still the most popular way to obtain the earthquake-related information, besides that, network and the new media app such as Wechat and Weibo play a more and more important role. In terms of the reliability of official information published by the earthquake administration, the score is 83.69 points which indicates that the public tend to believe in official departments. Furthermore, the degree of satisfaction evaluation of public service of earthquake disaster mitigation is marked 76.44 points which shows that there is still much room for improvement. The more educated the public, the less satisfied they are with the public service of earthquake prevention and disaster reduction. The results also show that 51.81% of the public are willing to obtain earthquake warning information at their own expense. As for the demand, the most expectative services for the public are post-earthquake rescue and reconstruction, earthquake warning, and house earthquake resilience test. The results of the investigation may provide some reference for the government to provide better services of earthquake disaster mitigation and to make scientific knowledge popularization in a more scientific way. 相似文献
948.
广武新灌区春小麦土壤水分变化规律研究 总被引:1,自引:0,他引:1
通过对广武新灌区春小麦土壤水分的垂直变化、季节变化和时空变化的研究,将广武新灌区0~100cm土层划分为活跃层、贮水层、阻隔层和无效水分层,为寻找新灌区节水途径奠定了基础。 相似文献
949.
研究了华北地区几次大震周围的较小区域内和较大区域内的b值变化.发现了较小区域内的b值随时间先升高后逐步降低,直至最低值,震前又有所回升才发震;较大区域内的b值随时间的变化,在大震前有个明显的峰值期,其峰值期的长短与大震震级有关. 另外,研究了b值从大震震中向外随区域扩展的变化,发现b值从震中向外有逐步增高的趋势.在大震震中附近有个低b值区域,其外围有个高b值区域. 相似文献
950.
关于黄土碳酸盐与气候环境关系探讨 总被引:1,自引:0,他引:1
黄土中碳酸盐与气候环境密切相关。从碳酸盐的成因看,干冷的气候利于原生碳酸盐的保存,而温湿的气候使大量的次生碳酸盐产生。碳酸盐的存在形式与降水量多少有关,降水量大可形成结核层和钙板等,而降水量小则形成各种胶膜。胶膜中各种不同形态的方解石胶膜又可反映不同的气候条件。黄土一古土壤中形成的碳酸盐实际上在古土壤期形成的碳酸盐要高于黄土期形成的,只是由于古土壤期强烈的风化淋溶作用,大量的碳酸盐从古土壤中淀积到下伏的黄土层中。黄土中CaCO3的淀积可分为连续淀积和不连续淀积两类。依据淀积深度和降水量的关系,可建立二者定量的关系。从黄土碳酸盐的不同方面,得到其与气候环境关系较为全面的认识。 相似文献