排序方式: 共有21条查询结果,搜索用时 0 毫秒
1.
2.
伊洛河流域是我国原始农业发展最早地区之一,也是水利开发较早地区之一,本文探讨这一地区水利开发的历史过程,并总结人类改造利用的经验教训.文章分为四个部分:一、简要地论述了影响伊洛河水利开发的历史的自然因素和社会经济因素.二、论述了历史时期伊洛河水利开发的大势.三、就历史时期伊洛河水利开发的三个主要方面,即漕运、灌溉、防洪作进一步的探讨.四.论述了在水利开发的历史过程中,由于人类活动,对伊洛河的水系变迁带来的影响.文章最后认为:伊洛河水利开发的历史,其趋势与这一地区社会经济发展的趋势基本上是一致的.水利开发中以漕运最有影响,开发地区主要在伊洛河水中下游的河谷地带,尤其是洛阳附近,这样的情况,主要是受社会经济,尤其是受洛阳城市发展的影响.从历史发展并结合现状来看,今后本区的水利开发应以灌溉为主,适当兼顾航运、防洪、城市用水等. 相似文献
3.
4.
5.
The solubilities of ammonium chloride in aqueous ammonia decreased first and then increased with increasing ammonia concentrations, but the mechanism of this phenomenon has not been clarified. In the present work, the ATR-FTIR and Raman spectroscopy were employed to investigate the corresponding mechanism. The spectra analysis was focused on the region between 2500 and 4000 cm-1. It was firstly discovered that the N-H???N hydrogen bonds between ammonium ions and ammonia molecule was mainly formed in the NH4Cl-NH3-H2O system with concentrations higher than 10% ammonia, but N-H???O hydrogen bonds between ammonium ions and water molecule took advantage in the system with lower ammonia concentrations. Correspondingly, the phenomena of hydrogen bonding redshift and blueshift was observed respectively compared in NH3?H2O solution. Moreover, the hydrogen bonding structure of the saturated solution was obtained by means of MD simulation. The present work provides some theoretical basis for the separation of ammonium potassium chloride. 相似文献
6.
地电场日变幅与地电暴分析 总被引:2,自引:1,他引:1
利用昌黎台地电场资料分析地电场日变幅季节变化特征,显示有季节效应,EW、SN测向夏季日变幅地震最大,而出现最小值的季节两测向表现不一。分析认为,与地电场观测信号的复杂多样性有关。地电暴可以记录到磁暴急始变幅、初相、主相的变化形态,但由于电场和磁场之间存在一阶差分的关系,并不是所有地电暴都和地磁暴变化一致,甚至有些地电暴没有变化形态,而是出现高频上下起伏的脉冲形式。利用多台地电场资料,对同一个K指数为7的磁暴进行急始变幅、扰动最大变幅分析,结果显示,各台不尽相同,可能与台址介质的电性结构有关。 相似文献
7.
8.
9.
10.
根据昌黎地震台3年多的实际观测资料,对208#CTM—DI磁通门经纬仪的稳定性进行了初步分析,结果显示:仪器格值标定和稳定性良好,但零场漂移S0较大,应予调整。反映磁通门探头磁轴不重合度的水平角度δ和垂直角度ε总体较稳定。 相似文献