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131.
异珊瑚原始隔壁数目、后生隔壁的增生部位和方式以及隔壁的排布系列的研究,是探讨异珊瑚的起源、演化和分类的基本前提。通过对3隔壁的Triphyllia和4隔壁的Quadratphyllia二属的研究,结合生物体对称的原则,提出异珊瑚原始隔壁为2条,并认为异珊瑚的后生隔壁发育在原始隔壁所分隔的左右两侧部体腔内缘部位,长隔壁呈树枝状拓布或者末端达中心向某一方面扭曲连接形成轴管构造。依据后生隔壁在体腔内的繁生能力、增殖数量、发生部位、排布方式、分化程度、隔壁始端在外壁中的埋植类型和末端在中心部位的连接类型等方面的不同,异珊瑚隔壁增生大致可划分为7个布系列。  相似文献   
132.
介绍了交流变频调速CD-2B型岩心钻机研制情况,技术参数,主要特点及型式检验,生产试验等情况。  相似文献   
133.
四川省房屋建筑易损性研究   总被引:3,自引:0,他引:3  
研究房屋建筑易损性特征是防震减灾工作必不可少的环节之一,本文通过对多年工作的系统总结,得出四川省不同地区的房屋建筑易损性矩阵,全省房屋建筑抗震性能总体水平不高,这是造成地震灾害加重的主要原因之一,随着经济发展实力的提高,适当提高全省房屋建筑抗震设防水平可大大减轻特别是中强地震所造成的经济损失。  相似文献   
134.
范家参 《地震研究》2002,25(1):48-52
地壳由半无限大的基岩上一层厚度为H^-的表土层组成,入射地震波为垂直的SH波,产生水平地面运动。当浅源大地震发生时,在极震区以外行波传播产生地面运动将使地壳介质有非线性的有限弹性变形。用小参数摄动法使非线性控制方程为线性化的小参数各阶控制方程,得出头两阶线性控制方程的解析解。  相似文献   
135.
从井孔周围地下水开采量变化、大气降雨补给量变化、农田灌溉用水量变化、矿井塌方、涌水、排水和地震活动等影响因素入手 ,对 1999年至 2 0 0 0年间介休井水位的 2次突降原因进行了调查。通过初步分析 ,表明介休井水位阶降型异常具有一定的震兆性质 ,其水位的缓慢上升与突然阶降意味着介休地区断裂活动在加速。其地震预测的意义是未来一段时间山西地震带内有发生MS≥ 5 0级地震可能  相似文献   
136.
Temporal sequential analyses of the hydrological observational data in the Tarim Basin over the last forty years revealed an annual increase of 2× 107m3 in the water quantities at the three headstreams of the upper courses and an annual decrease of 3 × 107m3 in the water flow from Alaer, which is on the upper main stream. A prediction of the trends indicates that there can be severe situations under which intermittent water interceptions occur. By means of approximate estimations on vegetative water consumption through phreatic evaporation combined with a quota assessment, the ecological water demands required to maintain the ecological environment in the mainstream area over the three different targeted years of 2005, 2010 and 2030 are defined as standing at 31.86 × 108m3, 36.27 × 108m3 and 41.04 × 108m3 respectively. Ecological fragility indexes are established on the basis of the selection of environmental sensitivity factors. Rational evaluations give proof that the lower reaches of the mainstream have already turned into zones where their ecological environments are gravely damaged. Multi-objective optimization should be conducted and protective schemes be framed within the threshold limits of the bearing capacities of water resources and the environment  相似文献   
137.
Based on remote sensing information sources including B/W aerial photos of 1983, pseudo-color aerial photos of 1992 and JERS-1/OPS VNIR image of 1996, vegetation types of Yingbazha, in the middle reaches of the Tarim River Basin in Xinjiang, China are mapped using ARC/INFO and related software. The changes in vegetation areas and distribution conditions are analyzed. As a result of natural and human influences, vegetation changes have temporal and spatial characteristics. According to the principles of landscape ecology and geographical information science, the landscape changes are indicated. Moreover, the remote sensing and GIS techniques are integrated to study vegetation and its landscape.  相似文献   
138.
Because of the human exploitation and utilization of water resources in the Tarim Basin, the water resources consumption has changed from mainly natural ecosystem to artificial oasis ecosystem, and the environment has changed correspondingly. The basic changes are: desertification and oasis development coexist, both “the human being advance and the desert retreat” and “the desert advance and the human being retreat” coexist, but the latter is dominant. In the upper reaches, water volume drawing to irrigated agricultural areas has increased, artificial oases have been enlarging and moving from the deltas in the lower reaches of many rivers to the piedmont plains. In the middle and lower reaches of the Tarim River, the stream flow has decreased, old oases have declined, natural vegetations have been degenerating, desertification has been enlarging, and the environment has deteriorated. The transition regions, which consist of forestlands, grasslands and waters between the desert and the oases, have been decreasing continuously, their shelter function to the oases has been weakened, and the desert is threatening the oases seriously.  相似文献   
139.
A lot of slow fluctuations of water level have been observed in the original recording maps of subsurface fluid in Well Shuozhou, Shanxi Province. Some typical recording maps of the “precursors” are introduced in the paper and the features of the “precursors” recorded by the well are analyzed. The results show that 38% strong earthquakes possess this kind of record, which has a fluctuation period arranging from several to tens of minutes and appear mostly two days before the earthquakes. Moreover, the mechanism, transmission and responding conditions of well water level are discussed, as well as the scientific meaning and practical value of the “precursor” of the well water level in earthquake predictions. Foundation item: State Natural Science Foundation of China (19973011).  相似文献   
140.
Early Yanshanian magmatic suites predominate absolutely in the Nanling granite belt. They consist mainly of monzogranite and K-feldspar granite. There occur associations of early Yanshanian A-type granitoids (176 Ma-178 Ma) and bimodal volcanic rocks (158 Ma-179 Ma) in southern Jiangxi and southwestern Fujian in the eastern sector of the granite belt and early Yanshanian basalts (177 Ma-178 Ma) in southern Hunan in the central sector of the belt. Both the acid end-member rhyolite in the bimodal volcanic rock association and A-type granitoids in southern Jiangxi have the geochemical characteristics of intraplate granitic rocks and the basic end-member basalt of the association is intraplate tholeiite, while the basaltic rocks in southern Hunan include not only intraplate tholeiite but also intraplate alkali basalt. Therefore the early Yanshanian magmatic suites in the Nanling region are undoubtedly typical post-orogenic rock associations. Post-orogenic suites mark the end of a post-collision or late orogenic event and the initiation of Pangaea break-up, indicating that a new orogenic Wilson cycle is about to start. Therefore it may be considered that the early Yanshanian geodynamic settings in the Nanling region should be related to post-orogenic continental break-up after the Indosinian orogeny and the break-up did not begin in the Cretaceous.  相似文献   
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