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1.
干旱胁迫对胡麻游离脯氨酸累积的影响   总被引:2,自引:1,他引:2  
用PEG-6000高渗溶液模拟干旱胁迫,研究了干旱胁迫对胡麻累积游离脯氨酸的影响实验结果表明,在相同时间内,干旱胁迫强度越大累积游离脯氨酸量越多;在胁迫强度相同条件下的一定范围内,随着处理时间的延长累积游离脯氨酸量越来越多;最多累积量为对照的11.5倍这一结果与前人在小麦、水稻、高粱等作物上所得结果一致,证明游离脯氨酸是胡麻幼苗的渗透调节物质,累积游离脯氨酸是胡麻幼苗对干旱环境的适应性表现.  相似文献   

2.
采用普通硅酸盐水泥和矿渣硅酸盐水泥,分别配制了水灰比在0.45~0.60范围内的混凝土试件,采用加速腐蚀试验研究了在海水侵蚀后,其强度、重量损失随时间变化的规律及原因,并为试件损伤状态定量化解析提供了试验数据。结果表明,在相同的试验条件下,矿渣硅酸盐水泥混凝土耐久性优于普通硅酸盐水泥混凝土;混凝土试件的抗蚀系数为0.8时与美国ASTM标准规定的强度损失25%的界限值吻合较好。  相似文献   

3.
本文针对美国《水和废水标准检验法》中酚的分离测定条件的选定不恰当,进行了实验研究.结果表明,只有当pH≤1时蒸馏的水样,4—AAP光度法测定挥发酚方可在pH7.9条件下进行;若在pH4时蒸馏的水样,测定挥发酚只能在pH10条件下进行  相似文献   

4.
本文针对美国《水和废水标准检验法》中酚的分离测定条件的选定不恰当,进行了实验研究。结果表明,只有当pH≤1时蒸馏的水样,4-AAP光度法测定挥发酚方可在pH7.9条件下进行;其在pH4时蒸馏的水样,测定挥发酚只能在pH10条件下进行。  相似文献   

5.
超声波强化大黄中蒽醌的双相水解工艺研究   总被引:2,自引:0,他引:2  
以游离蒽醌得率为指标,探讨了超声波强化大黄中蒽醌双相水解工艺的主要因素。在此基础上,用正交实验优化了用超声波法强化大黄中蒽醌双相水解的工艺条件。实验结果表明,影响游离蒽醌得率的主次因素为:提取温度〉超声功率〉硫酸体积分数〉提取时间。最佳工艺条件为:硫酸体积分数为15%,超声波提取时间为60min.超声功率为150W,超声波提取温度为40℃。  相似文献   

6.
盐溶液侵蚀环境下混凝土耐久性的研究   总被引:1,自引:0,他引:1  
张玉敏  马静  矫强 《应用科技》2003,30(10):55-58
采用普通硅酸盐水泥和矿渣硅酸盐水泥,分别配制了水灰比在0.45-0.60的混凝土试件,采用加速腐蚀试验研究了在盐溶液侵蚀后,其强度、重量损失随时问变化的规律及原因,并为试件损伤状态定量化解析提供了试验数据.结果表明,在相同的试验条件下,矿渣硅酸盐水泥混凝土耐久性优于普通硅酸盐水泥混凝土;混凝土试件的抗蚀系数为0.8时,与美国ASTM标准规定的强度损失25%的界限值吻合较好.  相似文献   

7.
从硫化锌氧压酸浸渣中提取硫磺的工艺研究   总被引:2,自引:0,他引:2  
褚丽娟 《科学技术与工程》2011,11(27):6661-6664,6687
采用硫化铵法从硫化锌氧压酸浸渣中回收单质硫,分别考察了在浸出过程中硫化铵浓度、浸出时间、液固比与浸出温度对硫浸出率的影响和蒸馏过程中蒸馏温度与保温时间对硫析出率的影响,从而得到回收硫磺的最佳工艺参数:硫化铵浓度2.5 mol/L,浸出时间10 min,液固比6:1,浸出温度25℃;蒸馏温度90℃,蒸馏保温时间30 min。在此工艺条件下进行全工艺条件实验,结果表明硫磺回收率在95.8%以上,硫磺纯度在99.16%以上且质量符合GB/T 2449—2006工业硫磺合格品标准。  相似文献   

8.
本文给出了等热流条件下热绕流运动密度场的加权残数解,并且在一给定的工况下计算了相应的密度场,所得结果与数值解及实验情况相吻合.该解法具有解析结构清楚、计算工作量小的特点.  相似文献   

9.
固定化细胞发酵—膜蒸馏耦合生产乙醇的研究   总被引:3,自引:0,他引:3  
对固定化酿酒酵母细胞发酵与膜蒸馏耦合生产乙醇进行了实验研究,首先实验测定了平板蒸膜馏器的分离性能以及游离酵母细胞发酵动力学和固定化酵线细胞发酵动力学,然后将游离细胞发酵罐及固定化细胞反应器分别与平板膜蒸馏装置相耦合成膜生物反应器,对固定化细胞发酵-膜蒸馏分离乙醇耦合过程进行了研究。在游离酵母细胞发酵中,间歇培养13h发酵液中乙醇质量浓度,酵母细胞密度(单位体积发酵液内细胞个数)和葡萄糖转化率,乙醇  相似文献   

10.
大豆异黄酮甙元提取工艺的研究   总被引:6,自引:0,他引:6  
采用先酸水解、后碱水解的方法从大豆中提取游离型大豆异黄酮甙元成分,并通过单因素实验和正交实验确定了碱水解的最佳提取工艺条件.结果表明,碱水解的最佳条件是:pH8.75、温度50℃、提取时间90min,此条件下大豆异黄酮甙元的提取率为44.3%,粗提品纯度为19.9%.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

13.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

14.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

15.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

16.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

17.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

18.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

19.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

20.
For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the  相似文献   

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