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1.
固体推进剂高过载冲击动态力学性能研究   总被引:5,自引:0,他引:5  
王宁飞  魏卫 《火炸药学报》2002,25(1):19-21,15
综述了近年来固体推进剂受过载冲击时动态学响应研究的各种方法,分析对比了各种研究方法的优劣,讨论了未来固体推进剂受冲击载荷时动态力学性能研究的方向。  相似文献   

2.
综述了国内外无机纳米材料研究的成果与进展,对各种金属与非金属无机纳米材料的种类、具有各种特异性能和用途作了系统的介绍,并系统地阐述了无机纳米材料的各种物理或化学的制备技术,讨论了各种制备方法的特点、适用范围以及国内外在无机纳米材料制备方法研究上的进展,并介绍了目前国内常用的一些无机纳米材料的表征方法及其特点和应用。  相似文献   

3.
赵薇娜  陈利民 《塑料工业》2007,35(B06):58-60
分析了引起塑料压力管道发生力学破坏的各种影响因素,指出了快速应力开裂的危害性;概述了国内外塑料压力管道快速应力开裂研究的各种实验方法,并分析了各种方法的优缺点,对其发展方向进行了预测。  相似文献   

4.
1,3-丙二醇合成方法研究   总被引:9,自引:0,他引:9  
介绍了1,3-丙二醇的三种主要生产方法;丙烯醛法,环氧乙烷法和微生物法,指出各种生产工艺的步骤及合成路线,并详细探讨了各种生产方法的催化剂使用及研究进展情况。而且对各种方法进行了比较,指出各种生产法的优缺点及国内适用情况。提出国内生产1,3-丙二醇的基础和未来1,3-丙二醇的研究方向。  相似文献   

5.
通过对各种化学试剂的研究,并对各种仪表的使用技术进步比较试验,对聚乙烯的液位仪表进行了彻底改造,取得了较好的效果。  相似文献   

6.
反应精馏过程模拟研究进展   总被引:16,自引:0,他引:16  
对均相反应精馏和非均相催化精馏过程的各种模拟计算方法进行了评述,分析了各种算法的优缺点和适用范围,指明了目前研究中存在的不足和今后的发展方向。  相似文献   

7.
纳米Y2O3的液相制备法   总被引:7,自引:0,他引:7  
介绍了纳米Y2O3的各种液相制备法,概述了各种方法的特点与研究新进展。  相似文献   

8.
对制备聚合氯化铝的主要制备技术研究进行了评述,分析了各种制备方法的优缺点,并展望了聚合氧化铝研究重点及发展方向。  相似文献   

9.
固体酸催化合成苯甲酸正丁酯   总被引:3,自引:0,他引:3  
论述了利用对甲苯磺酸,磺化苯磷酸锆,六水三氯化铁,氧化亚锡,十二水合硫酸铁铵,一水硫酸氢钠,固体超强酸和杂多酸等各种固体催化剂催化合成苯甲酸正丁酯的方法。研究发现:各种催化剂的催化效果良好,酯收率达74%以上,有的甚至达97.8%。同时对各种催化剂的催化机理进行了初步探讨,对各种固体酸的催化效果也进行了比较。  相似文献   

10.
对特辛基酚合成机理及其催化剂评价   总被引:1,自引:0,他引:1  
本文综合了对特辛基酚的合成机理,介绍了各种催化剂的基本性能,并对各种催化剂作出了工业应用的评价,同时反映了当前国内对辛基酚开发、研究和生产的概况。  相似文献   

11.
为了探究不同岩性、不同级配机制砂对混凝土性能的影响,对三种不同岩性机制砂混凝土及天然河砂混凝土的工作性和抗压强度进行研究。此外,对比分析了四种混凝土在干湿循环制度下的抗硫酸盐侵蚀性能。结果表明,天然河砂混凝土的工作性优于机制砂混凝土,钙质机制砂混凝土的工作性略好于硅质机制砂混凝土。机制砂混凝土的抗压强度优于天然河砂混凝土,在硫酸盐侵蚀循环作用下的力学性能变化趋势与天然河砂混凝土基本一致。在相同级配条件下,机制砂混凝土的抗蚀系数高于天然河砂混凝土;机制砂岩性并不会对混凝土抗硫酸盐侵蚀性能带来负面影响。级配良好的机制砂可以增强混凝土抗压强度和抗硫酸盐侵蚀性能。  相似文献   

12.
The measurement of functionality of protein food ingredients has developed somewhat haphazardly, probably due to the wide range of proteins used as ingredients and the diversity of foods. Studies of the physiochemical properties of proteins should enable prediction of a proteins response to process environments and prove more fruitful than many of the empirical measurements of functionality. The effects of pH, salt type and concentration on the phase behaviour of the oilseed globulin and arachin, demonstrates the complexity of protein solubility and the inadequacies of simple tests that have arisen. Studies of the effects of salts and conditioning on meat fibres, coupled with measurement of the location of water in pellets from water holding tests enable the latter to be applied with increased confidence. Comparison of the endothermic transitions observed on heating with the development of storage and loss moduli allow the contributions of domains of skeletal muscle myosin to gel structure to be investigated.  相似文献   

13.
Six electrophysiologically active aromatic compounds, viz., anisole, benzaldehyde, veratrole, guaiacol, phenylacetonitrile, and phenol, were identified in the volatiles of older-adult male desert locust. Young adults and females of all age groups produced none or only trace quantities of these compounds. Comparison of the aggregation responses of young and older adults to the crude, older-adult, volatile extract and different synthetic blends of the six compounds showed that the aggregation pheromone system of the adult gregarious locust consists of phenylacetonitrile, guaiacol, phenol, and benzaldehyde. Like the crude volatile extract of older males, neither the synthetic blend of the six compounds nor the adult pheromone blend evoked any significant aggregation responses from nymphs. These results confirm our previous report of sexual differentiation in the production of adult aggregation pheromone in the desert locust and of the evidence of two distinct aggregation pheromone systems in the two stages of the insect.  相似文献   

14.
Molecular mechanics modelling is used to calculate the energies of interaction, hence the molecular level energy of adhesion at the interface with crystalline cellulose I of three different photopolymerizable primers and of a polyester varnish at the interface with the primer/cellulose assembly. The energy of interactions for just one of the primers with the statistically most common conformation of amorphous cellulose has also been obtained for comparison. Experimental results of adhesion by a standard peel test and by thermomechanical analysis, in which the effect of viscoelastic energy dissipation by crack tip propagation has been respectively minimized or is not present, hence in which the energy of interfacial interaction is nothing else but the work of adhesion, correlated well with the energies of interaction calculated by molecular mechanics. An equation correlating the energy of interaction at each finish/cellulose interface with the deflection derived by thermomechanical analysis, and with the number of internal bond rotational degrees of freedom as well as the degree of networking of the finish, has been derived and is presented. A relationship between the intrinsic fracture energy Go and the molecular mechanics-derived energy of interaction at the interface equating this to the square of the work of adhesion is obtained and is presented.  相似文献   

15.
16.
Isoprenoids and phenolics, major metabolites of important browse species, are reviewed in regard to concentrations, distribution within tissues, and between species. Seasonal variation of specific substances and changes with age of the plant are also considered. The distribution of substances may affect food selection and feeding behavior of animals. Wild mammalian herbivores tend to avoid plant parts rich in these substances, in spite of high nutritional content of the plant tissue. Possible mechanisms for defense by plants against depredation by mammalian herbivores are discussed within the framework of the plants' biochemistry.  相似文献   

17.
使用共沉淀法制备负载Cu催化剂。通过添加碱土金属Sr,对Cu催化剂进行了改性,以提高Cu催化剂在果糖加氢制备甘露醇过程中的活性和选择性。采用ICP-MS、TEM、XRD、H2-TPR、XPS和CO2-TPD等对所制备的催化剂进行了系统表征。结果表明:Sr的添加能增大催化剂的比表面积,促进活性组分Cu的分散,从而提高了催化剂的活性,并且增加了催化剂的碱性,使果糖优先形成β-呋喃糖中间体,从而提高了甘露醇的选择性。在果糖浓度为1.1 mol·L-1、催化剂用量为反应物质量的6%、反应温度为373 K、反应氢压为4.0 MPa、Cu/Sr原子比为7∶1的反应条件下,果糖转化率为99%,甘露醇的选择性为79%。催化剂循环使用了20次,其催化稳定性基本保持不变。  相似文献   

18.
密封界面的泄漏机理是机械密封研究与应用的焦点问题之一,涉及泄漏通道表征、粗糙表面的接触力学模型、界面微观形貌变化以及介质流体在泄漏通道中的流动阻力等问题。回顾了近几十年国内外接触式机械密封泄漏通道模型的研究,深入分析了G-W模型、M-B模型和Persson模型3种粗糙表面接触力学模型的贡献和存在的问题,提出了一种基于逾渗理论的泄漏通道新模型;探讨了密封界面的分形参数、泄漏通道的流动阻力以及密封界面的有限尺寸效应对泄漏特性的影响,指出孔隙连通贯穿界面和流体流经贯穿通道的流动阻力小是密封界面产生泄漏的成因,以及泄漏通道的形成和泄漏通道内的流体流动特性是泄漏机理研究的主要方向。  相似文献   

19.
Experimental trials of the water hydrolysis of bagasse to produce xylose, arabinose and glucose were conducted using a temperature-controlled microwave digester. The experimental variables were temperature, ratio of water mass to bagasse mass, type of bagasse material and reaction time. The pH of the liquid and concentration of dissolved xylose, arabinose and glucose were measured at the completion of each trial. Kinetic modelling of the global rates of formation of monosaccharide products was performed using schemes based on earlier researchers’ models of acid hydrolysis using mineral acids. For the most plentiful product, xylose, the most accurate kinetic model of the global reactions was determined to be two parallel pathways for hydrolysis of xylan to xylose followed by a single pathway for xylose decomposition. The calculated activation energies of the reactions were within the range reported by other researchers for the hydrolysis of a range of lignocellulosic materials using mineral acids.  相似文献   

20.
The rate of hydrolysis of the abundant foliar protein, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPC), in enzymatically active gut fluid ofManduca sexta larvae is very rapid and is unaffected by the presence of tannic acid, even when tannic acid is present in the incubation mixture in amounts in excess of the amount of RuBPC. When this protein is dissolved in the denatured gut fluids ofM. sexta larvae orSchistocerca gregaria nymphs, large amounts of tannic acid must be added to bring about the precipitation of significant quantities of protein. The ability of insect gut fluid to prevent the formation of insoluble tannin-protein complexes is due to the presence of surfactants. On the basis of our results and a review of the findings of other investigators, we argue that there is no evidence that tannins reduce the nutritional value of an insect's food by inhibiting digestive enzymes or by reducing the digestibility of ingested proteins and, further, that the failure of tannins to interfere with digestion is readily explained on the basis of well-documented characteristics of the digestive systems of herbivorous insects. In challenging the currently popular notion that tannins are digestibility-reducing substances, we do not challenge the general utility of either the apparency theory or resource availability theory of plant defense. In debating the merits of these two analyses of plant-herbivore interactions, however, the demise of tannins as all-purpose, dose-dependent, digestibility-reducing defensive substances must be taken into account.  相似文献   

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