排序方式： 共有157条查询结果，搜索用时 15 毫秒
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<正>一、种植品种目前种植面积较大、产量和品质表现较好的品种是"珍珠"番石榴。它在北方温室表现出很好的适应性:植株生长快速,种植当年可开花挂果,产量高,栽培管理容易,土壤适应性广,抗病性强,果实风味好。 相似文献
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不同品种和氮肥条件下水稻根系主要几何参数动态量化 总被引：3，自引：1，他引：2
目的建立基于生物量的水稻根系主要几何参数动态模型,为水稻功能-结构模型的研究奠定基础。方法于2008和2009年设置3个品种[两优108(V1,杂籼)、86优8(V2,杂粳)和南粳43(V3,常规粳稻)]和2个氮肥水平盆栽试验获取根系形态及根干重等指标,采用SPSSv13.0与Excel2007处理试验数据,RMSE检验模型。结果利用2008年观测资料,通过分析不同品种与施肥处理下水稻单株总根长及根直径与生物量间的定量关系,建立了基于生物量的水稻单株总根长动态模型;根据立体几何原理,构建了基于生物量的水稻总根体积与总根表面积动态模型。经2009年独立试验资料检验,单株总根长、总根体积及总根表面积的实测值与模拟值的RMSE分别为490.660cm/plant、131.859cm2/plant和2.532cm3/plant,说明模型拟合度较好。结论所建水稻根系主要几何参数模型具有一定机理性、解释性和通用性,对水稻功能-结构模型研究及水稻可视化奠定了基础。 相似文献
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水稻单株产量与根系主要几何属性的定量关系 总被引：1，自引：0，他引：1
为揭示水稻单株产量与不同生育阶段根系主要几何属性的定量关系。以两优108(杂交籼稻)、86优8(杂交粳稻)和南粳43(常规粳稻)为材料,设施肥(N:每盆3.6 g;P2O5:每盆0.8 g;K2O:每盆3.6 g)与不施肥2个水平,共6个处理,采用塑料桶土培。在试验观测的基础上,建立回归模型及模型统计量,结果表明拔节期至灌浆末期水稻单株产量与单株总根长及单株总根表面积之间的定量关系以二次模型较好,分蘖初期至拔节期根系几何属性与单株产量关系则以三次模型拟合较好;单株产量与根系各参数相关分析结果表明单株总根长、总根表面积及总根体积的增加有利于提高产量。 相似文献
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研究了开放接入网络中带宽分配的公平性问题.将最大〖CD*2〗最小公平算法应用到双向SLA带宽调度算法中,给出了一种基于EPON的易于实现的双向SLA公平带宽调度算法.以用户SLA为首要SLA,以业务提供商的SLA为次要SLA,通过带宽分配和调整,实现了双向公平的带宽分配.仿真实验表明,双向SLA算法实现了业务提供商和用户的公平性需求,具有合理性和可用性. 相似文献
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[目的]研究水培空心菜净化和资源化利用畜禽养殖粪便沼液的可行性,为畜禽养殖沼气工程的沼液净化处理和资源化利用提供科学依据.[方法]在不同稀释倍数的鸡粪沼液中栽培空心菜,研究其对沼液中氨氮(NHrN)、总氮(TN)、总磷(TP)、化学需氧量(COD)的削减能力及沼液浓度对水培空心菜生长的影响;并通过在鸡粪沼液中添加华南农大叶菜A配方各营养元素,探讨鸡粪沼液作为水培营养液的限制因子.[结果]不同稀释倍数的鸡粪沼液经空心菜生长吸收后,各项污染物浓度均有不同程度的消减,定植21d后,各处理NH3-N均达GB 18596-2001的排放浓度要求,以稀释6倍的去除率最高(81.61%);COD、TP和TN均以稀释9倍的去除率最高,分别为78.16%、87.00%和87.96%.稀释12倍鸡粪沼液水培的空心菜植株全重最重(4.83 g/株);不同稀释倍数沼液水培的空心菜还原糖含量均高于华南农大叶菜A配方处理,但沼液水培空心菜易引起Pb、Hg、Cr等重金属在植株体内的过量积累.鸡粪沼液中添加KH2PO4和KNO3,水培的空心菜植株高度、地上部分重和植株全重等指标均表现较优,K可能为空心菜生长的限制因子.[结论]水培空心菜可有效降低沼液中污染物浓度;沼液可作为水培蔬菜的营养液资源化利用,但实际生产中仍需进行必要的养分调控使植物更好生长,并根据植物不同生长阶段对K的需求作进一步调整. 相似文献
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The particle swarm optimization (PSO) algorithm developed in recent years is a stochastic optimization algorithm based on swarm intelligence. It possesses advantages such as being a simple concept, ease of implementation and low resource occupation. The PSO algorithm was adopted to solve the problem of size optimization of truss structures with stress and displacement constraints. We present the basic principle of the original PSO algorithm in detail, and then introduce a constriction coefficient to modify it. Moreover, reasonable values of the coefficients are proposed for the modified PSO algorithm. Several classical problems are solved using the modified PSO algorithm, and the results compared with those using traditional optimization algorithms and genetic algorithms. Numerical results show that the modified PSO algorithm has good convergence and stability, and can be applied to the size optimization of truss structures. 相似文献
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In order to study the compressive failure characteristics of layered rock mass and build the corresponding theoretical model, the fast lagrangian method was adopted to address numerical simulation of the layered rock mass under tri axial compression. The relationship between compressive strength and inclination of structure plane was analyzed, and a theoretical model was proposed to describe their relationship. The test data from the foreign references were described by the theoretical model and the relationship between loading velocity and the compressive strength was analyzed. It was shown that, the fitting model can well describe the strength characteristics of stratified rock mass, which was validated by the numerical test and laboratory test. And the compressive strength of rock mass increased linearly with the increase of loading velocity. 相似文献
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The effects of magnesium stress on the growth and photosynthetic character of cucumber seedlings are studied at various temperatures using artificial climate box. This is done to investigate the functional mechanism of magnesium in cucumbers. The results show that at low temperature, magnesium stress evidently inhibits plant growth, while at suitable temperatures it decreases the plant diameter, total number of leaves, leaf area, and dry weight of the above ground parts, and increases the plant height and root/shoot ratio. Excessive magnesium promotes below ground cucumber growth. The value of chlorphyl A/chlorophyl B (Chla/Chlb) increases more under conditions of magnesium deficiency than under magnesium excess. The Chla, Chlb and Cxc content decreases when magnesium is deficient, increase when excessive magnesium exists at suitable temperatures, but decreases if excessive magnesium exists at low temperatures. Pn and Gs decrease under magnesium stress, and are at the lowest level when excessive magnesium exists at low temperatures. The effects of magnesium stress on Ci, WUE, Tr and Ls vary at different magnesium concentrations and temperatures. The main factor limiting photosynthesis of cucumber seedlings is non stomata factor when magnesium is deficient, but is a stomata factor if there is excessive magnesium. 相似文献