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101.
一类含扩散项的Nicholson苍蝇模型解的渐近行为及其Hopf分支 总被引:1,自引:0,他引:1
本文研究了一类含扩散项的Nicholson苍蝇模型在Neumann边值条件下解的渐近行为和Hopf分支,得到了其正解收敛于不同平衡点的充分条件和由平衡点分支出Hopf分支的充分条件. 相似文献
102.
Two new 8,4′-oxynorneolignans were produced by elicitation of Echinacea purpurea cell suspension cultures with yeast elicitor. Their structures with an unusual (hydroxy)acetyl group were elucidated by spectroscopic methods including gas chromatography (GC) and electrospray ionization (ESI) mass spectrometry. 相似文献
103.
Fractional Differentiation in Passive Vibration Control 总被引:4,自引:0,他引:4
From a single-degree-of-freedom model used to illustrate the concept ofvibration isolation, a method to transform the design for suspensioninto a design for robust controller is presented. Fractionaldifferentiation is used to model viscoelastic behaviour of suspension.The use of fractional differentiation not only permits optimisation ofjust four suspension parameters, showing the `compactness' of thefractional derivative operator, but also leads to robustness ofsuspension performance to uncertainty of the sprung mass. As an example,an engine suspension is studied. 相似文献
104.
广义中心-细鞍点的若干公式 总被引:2,自引:0,他引:2
In this paper, a problem of center-weak focus of a general system of degree n is transformed into a problem of generalized center-weak saddle. It offers: (1) the calculating formula of the saddle values of the former 4 orders in the general system of degree three; (2) some calculating formulae of the saddle values in the general homogeneous system of degree n.
The problem of center-focus(saddle) plays an important role in the qualitative theory of ordinary differential equations. However, since the calculations are difficult, the results have not been satisfactory. On the basis of the author's work, Northeast. Math. J., 13(4)(1997), 487-494, the paper offers some calculating formulae of the saddle values. 相似文献
105.
《Arabian Journal of Chemistry》2022,15(11):104302
Traditional Chinese medicine (TCM) is the key to unlock treasures of Chinese civilization. TCM and its compound play a beneficial role in medical activities to cure diseases, especially in major public health events such as novel coronavirus epidemics across the globe. The chemical composition in Chinese medicine formula is complex and diverse, but their effective substances resemble “mystery boxes”. Revealing their active ingredients and their mechanisms of action has become focal point and difficulty of research for herbalists. Although the existing research methods are numerous and constantly updated iteratively, there is remain a lack of prospective reviews. Hence, this paper provides a comprehensive account of existing new approaches and technologies based on previous studies with an in vitro to in vivo perspective. In addition, the bottlenecks of studies on Chinese medicine formula effective substances are also revealed. Especially, we look ahead to new perspectives, technologies and applications for its future development. This work reviews based on new perspectives to open horizons for the future research. Consequently, herbal compounding pharmaceutical substances study should carry on the essence of TCM while pursuing innovations in the field. 相似文献
106.
We have performed Monte Carlo simulations of hard spheres under gravity. Vertical boundaries are hard walls, which are well separated with each other. On the other hand, the periodic boundary condition is imposed in the horizontal direction. While we previously reported enhancement of crystallinity as well as crystallization due to gravity, we present here the results that demonstrate the succession of a defect. In case that the crystal formed at the bottom of the system includes kinds of stacking disorders for the (0 0 1) growth, twin band structure develops as mediated by a stacking disorder succeeded in the crystal formed in the fluid region which lies on the bottom crystal. In case that the stacking structure along horizontal direction changes from the (1 1 1) stacking to the (0 0 1) stacking, twin band structure in the (0 0 1) stacking region develops as succeeded in the crystal transformed. The twin band structure also becomes large with its upward growth. 相似文献
107.
Kikuo Miyokawa Masayuki Itoh Takummi Etoh Setsuko Kinoshita Isao Masuda 《Thermochimica Acta》1985,96(1):227-234
Kinetic and thermodynamic aspects of the axial base dissociation of solid Co(salen) (X-py) complexes, X = H (1), 3-Me (2), 4-Me (3), 3,4-Me2 (4), 3,5-Me2 (5), 3-NH2 (6), 3-Cl (7), 3-CN (8), 4-CN (9), have been investigated by means of TG-DSC and isothermal weight-loss measurements. These adducts endothermically dissociate the axial base giving rise to the oxygen-active Co(salen) complex. The axial base dissociation reactions fit the contracting disc equation and the kinetic compensation effect is observed for all the adducts excepting Adducts 4–6. For the remaining adducts the kinetic and thermodynamic stabilities of the Co-(X-py) bond are found to increase linearly with increasing Hammett's substitution constants of X except for Adducts 3 and 9. These results are discussed in terms of the σ and π interactions between cobalt(II) and substituted pyridine. Factors dominating the kinetic bond stability are briefly discussed. 相似文献
108.
由聚苯胺粒子组成的电流变液的研究 总被引:6,自引:1,他引:6
由经碱处理的掺杂态聚苯胺(PAn)制得高介电常数的半导体PAn粒子,将其悬浮于电绝缘油可组成电流变液,讨论了电流变(ER)液的静态屈服应力(τ_s),电流密度等性能与PAn的介电常数(ε_p),导电率(σ),体积分数和应用电场强度的关系。对导电率相同的PAn粒子,用氨水处理的PAn粒子ε_p较用NaOH液处理的高,前者在σ足够低如σ≤1.0×10 ̄(-7)/cm时,ER液的τ_s随偶极系数的平方(β ̄2)的增大而呈现非线性增加;后者ER液的τ_s随β ̄2的增大出现一最大值.结果表明:由聚苯胺粒子可组成高电流变活性的无水ER液. 相似文献
109.
Photosynthetic suspension cultures of higher plants offer an alternative approach to biomass production, potentially yielding
cellulosic material and protein on a continuous year-round basis. A bench-top hybrid photobioreactor was developed to study
photomixotrophic and photoautotrophic growth of Glycine max as a model system. Maximum biomass doubling times for photomixotrophic
and photoautotrophic growth were 1.87 and 3.92 d, respectively. The presence of exogenous sugars resulted in photomixotrophic
growth, reduced chlorophyll levels, and a reduction in photosynthetically-evolved oxygen. Depletion of carbohydrates from
the medium coincided with the beginning of stationary phase and an increase in oxygen evolution by the cells. A second growth
phase, prolonging cell viability, could be initiated by increasing the carbon dioxide from 2 to 5%, just before the onset
of stationary phase. Biomass from bioreactor cultured cells proved resistant to enzymatic attack without pretreatment. Composition
of the biomass was 7.8% lignin, 20.7% α-cellulose, 23% hemicellulose, 5.5% starch, 14.5% protein and 6.5% nucleic acids. 相似文献
110.
交联聚乙烯基吡咯烷酮的合成及其性能研究 总被引:2,自引:0,他引:2
以乙烯基吡咯烷酮(NVP)为单体,二乙烯基苯为交联剂,AIBN为引发剂,采用悬浮聚合法合成了性能稳定的交联聚乙烯基吡咯烷酮(PVPP),研究了聚合温度,引发剂用量,交联剂用量和反应气氛等因素对产率,溶胀性能和吸附性能的影响,并用红外光谱和扫描电镜等对产物的结构、性能和表面形貌进行了表征。 相似文献