大型地下厂房围岩三维粘弹塑性数值模拟

目前,地下工程围岩尤其是大型岩石地下工程围岩的粘弹塑性分析研究少见报道。针对这种情况,本文根据西原粘弹塑性流变模型相关理论开发了hhu-vp流变计算软件,以用于大型岩石地下工程围岩粘弹塑性流变数值模拟分析;并以一简单算例与软件FLAC-3D比较,结果偏差在容许范围内。将其应用于水布垭大型地下洞室围岩流变研究中,对该地下洞室的施工开挖及支护处理过程进行了模拟,提出了支护处理意见,并对其运营期的长期稳定性作出了评价。     

Dynamics of grass–clover mixtures—An analysis of the response to management with the PROductive GRASsland Simulator (PROGRASS)

A dynamic plot-scale model PROGRASS was developed to simulate the seasonal and inter-annual dynamics of productive, cut grass/clover mixtures in response to management, and specifically to examine the role of root development on grass/clover interactions. The model was parameterized by virtue of data for dry matter yield, leaf area index, root mass, soil mineral N uptake and biological N fixation from a long-term field trial in north-eastern Switzerland. It was tested using 5 years of independent data for yield and clover fraction from a field experiment with two management regimes carried out on the Swiss Central Plateau. The results of transient simulations indicated that under intensive fertilization grass dominance was initiated by preferential allocation of assimilates to the roots. The rapid growth of the grass root system lowered the substrate C:N ratio, favouring carbon allocation to the shoot, which eventually provided competitive advantages with respect to light interception. Under extensive management, limited N acquisition capacity of the grass root system maintained preferential allocation to the roots, limiting shoot development in the grass and leading to clover dominance. Co-existence regimes with dominance by one of the components were also found in equilibrium experiments, with a transition regime from clover to grass dominance for annual N applications in the range 100–200 kg N ha⁻¹ y⁻¹ that reflected adjustments of the root system to fertilization. It is concluded that the dynamics of grass/clover mixtures is driven by negative and positive feedbacks in the soil–plant system that are strongly controlled by root development and therefore by the allocation patterns of the grass component.     

接种根瘤菌和菌根真菌对三叶草生长及对土壤Pb2+吸收的影响

采用盆栽实验,设计了不接种(CK)、接种根瘤菌、接种丛枝菌根真菌、双接种根瘤菌和菌根真菌4种处理,探讨了三叶草的生长情况及对土壤中Pb2+吸收的影响。结果表明:三叶草对Pb具有一定的吸收能力,两次采样中,CK处理三叶草Pb浓度分别为15.38mg/kg和15.57mg/kg,均为各处理中最高;接种根瘤菌可明显提高三叶草生物量,接种菌根真菌能明显减少三叶草对土壤中Pb的吸收。接种根瘤菌和菌根真菌减少三叶草对Pb2+的吸收和向地上部运输。     

处理日本遗弃在华化学武器专用透气防毒服的研究

本文针对日本遗弃在华化学武器的性质和特点,根据销毁工程对个人防护装备的需求．通过对目前国内外主要透气防毒材料的比较分析,提出了专用透气防毒服内外层纺织材料的技术性能指标和要求．为专用透气防毒服的研制做了前期技术准备。     

污泥堆肥施用于草坪草栽培：Zn和Cu的分布特征

为了探索污泥堆肥中重金属在土壤一植物系统中的积累与转移特性,通过温室盆栽实验,分析了污泥堆肥对草坪草高羊茅、黑麦草和白三叶生物量积累的情况,研究了污泥堆肥中Zn和Cu在植物和土壤中的分布特征。结果表明,污泥堆肥施用可以有效促进3种草坪草的积累生物量,在0～6kg／m2的污泥堆肥施用量范围内,草坪草的生物量积累随着施用量的增加而提高。土壤中Zn和Cu的含量随污泥堆肥施加量的增加而增大,85％以上的Zn和Cu残留在土壤中。污泥堆肥中的Zn和Cu均可以被植物吸收,随着污泥堆肥施用量的增加,草坪草对Zn和Cu的吸收量增大,但当污泥堆肥施用量超过一定阈值时,草坪草吸收zn和cu不再增加,甚至减少;对于不同的草坪草,这一阈值有所不同。植物对zn和cu的吸收量只占土壤中zn和cu减少量的5％左右。根据生物富集系数（BCF）的计算结果推测,污泥堆肥的施用对土壤环境的影响大于对植物体内累积zn和Cu的影响。     

Heat and carbon dioxide generated by honeybees jointly act to kill hornets

We have found that giant hornets (Vespa mandarinia japonica) are killed in less than 10 min when they are trapped in a bee ball created by the Japanese honeybees Apis cerana japonica, but their death cannot be solely accounted for by the elevated temperature in the bee ball. In controlled experiments, hornets can survive for 10 min at the temperature up to 47°C, whereas the temperature inside the bee balls does not rise higher than 45.9°C. We have found here that the CO₂ concentration inside the bee ball also reaches a maximum (3.6 ± 0.2%) in the initial 0–5 min phase after bee ball formation. The lethal temperature of the hornet (45–46°C) under conditions of CO₂ concentration (3.7 ± 0.44%) produced using human expiratory air is almost the same as that in the bee ball. The lethal temperature of the honeybee is 50–51°C under the same air conditions. We concluded that CO₂ produced inside the bee ball by honeybees is a major factor together with the temperature involved in defense against giant hornets.     

泡囊丛枝菌根对红三叶草根际土壤磷酸酶活性的影响

以三叶草为材料,利用三室隔网培养方法,研究了缺磷土壤上施用植酸时接种３种泡囊丛枝菌根真菌（Ｇｌｏｍｕｓ ｍｏｓｓｅａｅ,Ｇｌｍｏｕｓ ｖｅｒｓｉｆｏｒｍｅ,Ｇｉｇａｓｐｏｒａ ｍａｒｇａｒｉｔａ）对根际土壤酸性磷酸酶和碱性磷酸酶活性的影响。三叶草生长６０ｄ后,收获测定距根表不同距离土壤中的磷酸酶活性,结果表明,接种菌根真菌增加了根际土壤酸性和碱性磷酸酶活性,Ｇｉｇａｓｐｏｒａ ｍａｒｇａｒｉｔａ菌     

染织排水对日本青鳉幼鱼和胚胎的毒性效应

采用日本青鳉幼鱼及胚胎暴露评估染织排水的毒性效应.4个测试水样采自染织工厂排水口.96 h急性毒性试验表明:1和2号水样对幼鱼急性毒性效应不明显,3和4号水样对幼鱼具有急性毒性效应,毒性单位分别为0.47、0.53、9.93和1.68TUa,1和2号水样为微毒,3号水样为中毒,4号水样为低毒.14 d胚胎幼鱼慢性毒性试...     

氯化镉、灭多威和硝基苯对日本青鳉(Oryzias latipes) 行为抑制的生物应急监测

研究了氯化镉、灭多威和硝基苯对孵化以后7d左右日本青鳉(Oryzias latipes)行为毒性。结果表明,在不同污染物中,随暴露浓度的增加,第1尾日本青鳉产生行为抑制的时间逐渐缩短,并且半数行为抑制时间(time ofhalf behavior inhibition,THBI,Y)随暴露浓度(X)呈现幂指数关系Y=aXb,其中20相似文献   

乡村政治视角下战时河南难民迁移特点

因特殊的时间、地点等因素,乡村政治视角下战时河南难民迁移,具有一定特点:战时河南难民迁移数量位居全国之首,并且迁移的时间相对集中,混乱中又带有一定的规律性;安土重迁的特性使得这一时期的难民迁移又具有一定的保守性;另外,造成战时难民迁移的原因除战争外,自然灾害亦是重要因素,同时,这一时期的河南难民迁移还具有全国战时人口迁移的特点。