阿城区森林鼠害及其治理措施

通过多年的森林调查数据,本文查清了阿城辖区内森林鼠类及其分布,并从营林措施,强化法制意识,合理区划、分类施策,建立完善的监测体系四个方面提出了森林鼠害监测预警及防治措施.     

济南建邦黄河公路大桥主桥斜拉桥辅助墩顶超重主梁施工控制措施

济南建邦黄河大桥主桥是一座三塔、双索面的预应力混凝土梁斜拉桥,跨度布置为53.5＋56.5＋2×300＋56.5＋53.5m,中塔处为塔梁墩固结。主梁采用前支点挂篮进行施工,边跨合龙段位于过渡墩与辅助墩之间,中边跨合龙有一定难度。墩助墩顶主梁较重,施工难度大,本文主要介绍了该桥辅助墩顶超重主梁施工的方法及控制的措施。     

Preparation and characterization of urea-formaldehyde resin-sodium montmorillonite intercalation-modified poplar

To improve its overall performance, fast-growing poplar was modified using the vacuum-pressure-vacuum impregnation method with a urea-formaldehyde resin-sodium montmorillonite intercalation as the modification solution. The results showed that considerable amounts of urea-formaldehyde resin and montmorillonites entered the poplar tracheid, and some entered the microporous wood. These substances formed bonds with the active groups in timber, causing reduced crystallinity in the amorphous region of the poplar, a decreased level of free hydroxyl, and an enhanced association with hydroxyl and ether bonds. The density, dimensional stability, and mechanical properties of poplar were markedly improved. The best results were obtained with 14% sodium montmorillonite and 20% ureaformaldehyde resin: the bending resistance, compressive resistance, and elastic modulus increased by 19.37%, 30.24%, and 50.06%, respectively. With elevated levels of sodium montmorillonite, the impact toughness and wear rate decreased.     

贡嘎山海螺沟冰川退缩区土壤序列矿物组成变化

阐明土壤中矿物随时间变化的机制是理解矿物风化和土壤发育的基础。利用X射线衍射法对贡嘎山海螺沟冰川退缩区土壤矿物组成随成土作用时间变化进行了定量分析。结果表明,冰川退缩区成土母质的矿物组成同质性较高,以硅酸盐矿物为主(约90%),包括:斜长石(28.5%)、石英(24.5%)、黑云母、钾长石、普通辉石、角闪石、绿泥石、蛭石;并有少量碳酸盐矿物,如方解石(8%)、白云石(2.3%);以及磷酸盐矿物磷灰石(2.1%)。退缩区土壤的矿物组成总体呈新发育土壤特征,随着成土年龄的增加,方解石逐渐被风化成为草酸钙石,角闪石、黑云母、磷灰石和绿泥石含量逐渐降低,长英质矿物的相对含量有所增加。成土作用中矿物组成的变化受植被原生演替和土壤p H的影响,快速发育的植被导致土壤p H迅速降低,风化程度增强。     

中国土壤有机碳密度和储量的估算与空间分布分析

基于 1∶40 0万的《中华人民共和国土壤图》和第二次土壤普查数据 ,运用地理信息系统技术 ,对中国土壤有机碳密度及储量做出估算 ,并且分析了土壤有机碳密度的空间分布差异。结果表明 :10 0cm深度的土壤有机碳密度介于 1 19kgm- 2 到 176 46kgm- 2 之间 ,2 0cm深度的土壤有机碳密度介于 0 2 7kgm- 2 到53 46kgm- 2 之间 ;10 0cm和 2 0cm深度的土壤有机碳储量分别为 84 4Pg (1Pg =10 15 g)和 2 7 4Pg ;土壤有机碳密度具有高度的空间变异性 ,东北地区、青藏高原的东南部、云贵高原等森林、草甸分布的地区有机碳密度最高 ,准噶尔盆地、塔里木盆地、阿拉善高原与河西走廊、柴达木盆地等沙漠化地区的土壤有机碳密度最低 ;土壤有机碳密度的空间分布主要受气候、植被以及人类活动的影响     

Bimodal grain-size distribution of Chinese loess, and its palaeoclimatic implications

Grain-size analysis indicates that Chinese loess generally shows a bimodal distribution with a coarse and a fine component. The coarse component, comprising the main part of the loess, has pronounced kurtosis and is well sorted, which is interpreted to be the product of dust storms generated by low-altitude northwesterly winds. Its grain-size reflects the strength of the low-altitude circulation in the dust seasons of the year, and its percentage provides an indicator of the source area aridity and the frequency of dust storms. Conversely, the fine component has a wide grain-size range and is poorly sorted. Sedimentary illustrations based on the grain-size distribution characteristics of bulk samples and of detrital quartz suggest that the fine component probably represents the background dust load of the atmosphere and is mainly transported by high-altitude westerly airstreams. Its grain-size provides an estimate of the westerly air stream intensity. The coarse and fine components of a loess sample can be mathematically separated by fitting a designated mathematical distribution function to the measured grain-size data, and this procedure constitutes an approach for reconstructing the palaeowind system of Northern China.     

L195柴油机用雾化器喷水节油研究

在L195柴油机进气管适当位置,安装一个特制的不锈钢雾化器,用它喷出一定量的雾化软水,参与气缸内燃烧,可提高柴油机的性能。根据柴油机的工况,可以控制所需的较佳喷水量。     

以天然沸石为烘干介质烘干玉米的研究

用固体介质烘干谷物是当代谷物烘干探讨的方向之一。利用二次旋转回归设计方法,进行了天然沸石和湿玉米的混合干燥实验,以及天然沸石的加热脱水实验。建立了干燥参数与干燥性能指标间的数学模型。用非线性约束优化方法找出了最佳干燥参数。     

酵母菌对果蔬采后病害防治的研究进展

该文对酵母菌对果蔬采后病害防治的研究现状进行了综述，其中包括防治效果、防治机理、防治的优势及最新研究成果。许多酵母菌对果蔬采后病害具有明显的抑制作用，酵母菌抑制霉菌的机理主要在于营养与空间的竞争、对病原菌的直接寄生作用及诱导寄主产生抗病性。酵母菌与其它生防微生物相比，具有拮抗效果好、不产生毒素、可以和化学杀菌剂共同使用等优点。使用生物工程技术改造拮抗酵母菌从而提高其生防效果，是酵母菌对果蔬采后生物防治的最新研究领域。该文还指出了酵母菌对果蔬采后生物防治存在的问题，并对未来的研究提出了新的思路。     

晋西黄土残源沟壑区不同林分暴雨产流产沙作用分析

 通过对晋西黄土残塬沟壑区不同林分的径流场近6年的定位观测,分析林分对产流产沙的影响。结果表明:由山杨、油松、虎棒子、绣线菊、黄刺梅形成的次生林及虎榛子灌木林林分暴雨时产流产沙远较其他林分少;林草型林草带状间作、草林型林草带状间作和果园有较好的水土保持功能;低质量整地的果农复合经营模式暴雨时产流产沙较其他类型多,但在细致整地后其产流产沙明显减少;刺槐纯林林分郁闷度大、林下草本和枯落物量大,则暴雨时产流产沙少。