排序方式： 共有24条查询结果，搜索用时 203 毫秒
1.
正 INTRODUCTION Ⅰ.General Principles Theoretically speaking, under the normal cycle of erosion rivers tend to adjust themselves to structure as the cycle advances and complete adjustment should 相似文献
2.
杭州湾大型底栖动物季节分布及环境相关性分析 总被引：2，自引：1，他引：1
对杭州湾大型底栖动物进行了夏(2006年7-8月)、冬(2006年12月-2007年1月)、春(2007年4月)、秋(2007年10-11月)季调查,分析了大型底栖动物的季节分布及其与环境的关系。结果表明:本海域四季共鉴定出113种大型底栖动物,多毛类、软体动物和甲壳类是该海域大型底栖动物的主要类群;主要优势种为双鳃内卷齿蚕、西方似蛰虫和多鳃卷吻沙蚕等多毛类。方差分析表明,除甲壳类丰度外,杭州湾大型底栖动物群落参数无显著季节差异,群落分析表明,杭州湾群落特点比较单一,未分辨出显著差异的群落;丰度/生物量比较法分析表明,秋季杭州湾海域受到了污染的扰动;典范对应分析表明,多毛类主要受物理因子(如温度、盐度、水深等)影响,而软体动物、甲壳类和其他类动物主要受生物化学因子(如叶绿素、总有机碳、浮游生物等)影响。从典范对应分析的结果,可以推断出杭州湾大型底栖动物受自然环境特征的影响较人类活动的影响大。 相似文献
3.
Impulsive force of debris flow on a curved dam 总被引：8，自引：0，他引：8
Although Sabo dams are an efficient method for river and basin management, traditional Sabo dams have a great impact on ecology and landscape. Moreover, such dams are hit and often damaged by great impulsive force when they block the debris flow. Therefore, alternative shapes for Sabo dam deserve thorough investigation. In this investigation, a curved dam was designed by changing the upstream-dam-surface geometric shape to reduce the impulsive force of the debris flow, with enhanced stability and reduced concrete mass being the anticipated outcomes. In this study, the flume and laboratory facilities simulated the impulsive force of the debris flow to the Sabo dams. Three geometric forms, including vertical, slanted and curved Sabo dams, were used to determine the impulsive force. Impulsive force theories of the debris flow were derived from the momentum equation and the Bernoulli equation. In these, the impulsive force was balanced by the friction force of the Sabo dam and the opposite force of the load cell behind the dam as it was hit by the debris flow. Positive correlations were found when comparing the experimental data with the theoretical results. These findings suggest that our impulsive force theory has predictive validity with regard to the experimental data. The results from both theory and experimental data clearly show that curved darns were sustained less force than the other darns under the same debris flow. This comparison demonstrates the importance of curved geometry for a well-designed Sabo dam. 相似文献
4.
TING YING H.MA 《地质学报》1940,(Z1)
The geological events happened since the beginning of the building of theraised coral reefs may be summarized as follows: 1. The period of the formation of raised coral reefs seems to coincidewith the last interglacial stage, at least in Asia. This will be termed the"Tateyama Reef Stage." In this period it was not the climate of the wholeworld, but the location of latitude that was different from that of present.Latitudes of places in Asia were about 5 degrees nearer to the equator than theyare now. The... 相似文献
5.
TING YING H.MA 《地质学报》1938,(Z1)
Some years have elapsed since I began my studies on both fossil andrecent reef-building corals.Intensive as well as extensive investigations 相似文献
6.
The region of Malung and Chutsing was first visited by V. K.Ting as far back as 1914. Besides reconnaissance mapping a considerablenumber of fossils were collected. These were sent to C. D. Walcott ofthe Smithsonian Institution, who, together with Kirk, McEwan and 相似文献
7.
Helioseismic techniques such as ring-diagram analysis have often been used to determine the subsurface structural differences
between solar active and quiet regions. Results obtained by inverting the frequency differences between the regions are usually
interpreted as the sound-speed differences between them. These in turn are used as a measure of temperature and magnetic-field
strength differences between the two regions. In this paper we first show that the “sound-speed” difference obtained from
inversions is actually a combination of sound-speed difference and a magnetic component. Hence, the inversion result is not
directly related to the thermal structure. Next, using solar models that include magnetic fields, we develop a formulation
to use the inversion results to infer the differences in the magnetic and thermal structures between active and quiet regions.
We then apply our technique to existing structure inversion results for different pairs of active and quiet regions. We find
that the effect of magnetic fields is strongest in a shallow region above 0.985R
⊙ and that the strengths of magnetic-field effects at the surface and in the deeper (r<0.98R
⊙) layers are inversely related (i.e., the stronger the surface magnetic field the smaller the magnetic effects in the deeper layers, and vice versa). We also find that the magnetic effects in the deeper layers are the strongest in the quiet regions, consistent with the
fact that these are basically regions with weakest magnetic fields at the surface. Because the quiet regions were selected
to precede or follow their companion active regions, the results could have implications about the evolution of magnetic fields
under active regions. 相似文献
8.
9.
1967年8月30日,曾在我国四川省甘孜藏族自治州炉霍县境内,发生了一次M=6.8级地震.震中位置是北纬31°.6,东经100°.3。地震发生后,立即进行了现场考察,对该地区的地震发展趋势作出了估计。当时若根据康定一甘孜断裂带所作的蠕变曲线估计,则该地区地震能量已基本释放完毕(图 相似文献
10.
We use five-day helioseimic data from the Taiwan Oscillation Network to study the flow around a sunspot, NOAA 7887. The p-mode oscillations in an annular region centered at the sunspot are decomposed into the modes propagating toward and away from the sunspot. We find that the frequency of an outgoing mode is greater than that of the corresponding incoming mode. This indicates that the plasma is flowing outward from the sunspot. The outflow velocity is estimated to be about 40–80 m s-1. 相似文献