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51.
52.
Theoretical predictions of solubility, typically accomplished by comparing the chemical potential of pure solid and solution, currently suffer from a lack of accuracy. We suggest an alternative method for predicting solubility based on molecular dynamics simulations of the behaviour of a small seed crystalline cluster probe in solutions of varying concentrations. The size dynamics of a properly chosen seed cluster that dissolves in unsaturated solutions and grows in size in supersaturated solutions is indicative of the saturation point. This approach is illustrated by its application to NaCl in water. 相似文献
53.
系统研究了表面润湿法合成β沸石的体系中,干晶种、润湿态晶种、异晶晶种(Y沸石、ZSM 5沸石)以及碱处理β沸石晶种在此晶化体系中的作用.采用β沸石产品及异晶作晶种时,可使产品的相对结晶度稍有提高,但对沸石微晶核的结构导向作用不明显.经浓碱液处理20min后的β沸石产品(碱处理晶种)作晶种引入晶化体系后,可以显著提高产品的相对结晶度,降低模板剂的用量,缩短晶化诱导期,成为表面润湿法合成β沸石体系的有效晶种形式. 相似文献
54.
浙江分布的中国种子植物特有属研究 总被引:5,自引:1,他引:4
郑朝宗 《浙江大学学报(理学版)》1998,25(2):75-80
浙江分布的中国种子植物特有属有49 属, 含63 种, 隶属于30 科, 其中有3 属为浙江特有属;在49 属
中, 单种属29 个, 少种属10 个, 多种属10 个;特有属的特征概括为:单种特有属的比例大, 木本属占优势、
具有相对的原始或古老性和珍稀濒危性以及具有明显的温带性质;浙西北山区, 特别是西天目山是中国
特有属在浙江的分布中心;浙江与全国各省区的共有属的关系为华东(46 属)>华中(36 属)>华南(32)
>西北(16 属), 而与东北和华北两地的关系很少有联系;浙江与毗邻省份的特有属相似性分析, 其与江西
和安徽的关系比与福建和江苏更为密切. 相似文献
55.
56.
The concept of using magnetic particles (seeds) as the implant for implant assisted-magnetic drug targeting (IA-MDT) was analyzed in vitro. Since this MDT system is being explored for use in capillaries, a highly porous (ε∼70%), highly tortuous, cylindrical, polyethylene polymer was prepared to mimic capillary tissue, and the seeds (magnetite nanoparticles) were already fixed within. The well-dispersed seeds were used to enhance the capture of 0.87 μm diameter magnetic drug carrier particles (MDCPs) (polydivinylbenzene embedded with 24.8 wt% magnetite) under flow conditions typically found in capillary networks. The effects of the fluid velocity (0.015–0.15 cm/s), magnetic field strength (0.0–250 mT), porous polymer magnetite content (0–7 wt%) and MDCP concentration (C=5 and 50 mg/L) on the capture efficiency (CE) of the MDCPs were studied. In all cases, when the magnetic field was applied, compared to when it was not, large increases in CE resulted; the CE increased even further when the magnetite seeds were present. The CE increased with increases in the magnetic field strength, porous polymer magnetite content and MDCP concentration. It decreased only with increases in the fluid velocity. Large magnetic field strengths were not necessary to induce MDCP capture by the seeds. A few hundred mT was sufficient. Overall, this first in vitro study of the magnetic seeding concept for IA-MDT was very encouraging, because it proved that magnetic particle seeds could serve as an effective implant for MDT systems, especially under conditions found in capillaries. 相似文献
57.
Sasaki S 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2008,84(2):31-57
The physiological characteristics of the dominant tree species in the tropical rain forest mainly belonging to dipterocarps as well as the environmental conditions especially for the light in the forest were studied to establish the silvicultural system for the forest regeneration in the tropical South Asia. The flowering patterns of the dipterocarp trees are usually irregular and unpredictable, which make difficult to collect sufficient seeds for raising the seedlings. The field survey revealed the diverged features of the so-called gregarious or simultaneous flowering of various species of this group. Appropriate conditions and methods for the storage of the seeds were established according to the detailed analyses of the morphological and physiological characteristics of the seeds such as the low temperature tolerance and the moisture contents. The intensity and spectra of the light in the forest primarily determine the growth and the morphological development of the seedlings under the canopy. Based on the measurements of the diffused light at the sites in the tropical forest in the varying sunlight, the parameters such as "the steady state of the diffuse light" and "the turning point" were defined, which were useful to evaluate the light conditions in the forest. To improve the survival of the transplanted seedlings, a planting method of "the bare-root seedlings", the seedlings easy to be handled by removal of all leaves, soil and pots, was developed. Its marked efficiency was proved with various dipterocarps and other tropical trees by the field trial in the practical scale. Tolerance of the various species to the extreme environmental conditions such as fires, acid soils and drought were examined by the experiments and the field survey, which revealed marked adaptability of Shorea roxburghii as a potential species for regeneration of the tropical forests. 相似文献
58.
采用铝溶胶晶种引入、结合相分离的方法制备了具有三维贯通多级孔道结构的大孔氧化铝材料。采用扫描电镜(SEM)、X射线衍射(XRD)、N2吸附-脱附、压汞、核磁共振波谱(NMR)等测试方法对所得材料进行了表征。结果表明,该氧化铝材料具有200-600 nm的均匀分布且贯通的连续大孔孔道,经550℃焙烧即可得到结晶态γ-氧化铝。大孔氧化铝比表面积达到366 m2/g,具有以5 nm及400 nm为中心的较为集中的介孔-大孔多级孔道分布。焙烧后的样品中,铝具有四、六两种配位状态。制备过程中,聚环氧乙烷(PEO)作为诱导剂引发固-液两相分离,形成具有三维贯通多级孔道结构大孔氧化铝,而凝胶中引入铝溶胶时,AlOOH晶粒与铝交联水合物均相伴生,在凝胶过程诱导铝交联水合物转变为AlOOH,最终使大孔氧化铝在较低的焙烧温度即可转化为γ-氧化铝。 相似文献
59.
The present study reports the first phytochemical investigation of the seed kernels of Manilkara bidentata (Balata) harvested in Trinidad, W.I. Gas chromatography–mass spectrometry (GC-MS) analysis of the n-hexane, chloroform, ethyl acetate, ethanol and methanol extracts showed a total of 39 components. 2,6,10,14,18-pentamethyl-2,6,10,14,18-eicosapentaene (74.93%), 9-octadecenoic acid, (Z)- 2,3-dihydroxypropyl ester (79.98%), (Z)-ethyl oleate (92.75%), Z,E-2-methyl-3,13-octadecadien-1-ol (80.51%) and 5-(hydroxymethyl)-2-furancarboxyaldehyde (50.32%) were the major constituents identified in the n-hexane, chloroform, ethyl acetate, ethanol and methanol extracts, respectively. The extracts showed the presence of several bioactive components and provides reference data for further research of its active constituents. 相似文献
60.
Wenna Zhou Zhenzhen Yuan Gang Li Jian Ouyang Yourui Suo 《Natural product research》2018,32(8):892-897
In this study, a valid method was established for the isolation and purification of flavone glycosides from Hippophae rhamnoides L. seed residues using high-speed counter-current chromatography in one step, with a solvent system of ethyl acetate-methanol-n-butyl alcohol-water (9:1:0.5:9, v/v/v/v). A total of 28.8 mg compound I and 57.3 mg compound II were obtained from 200 mg of flavone H-glycosides rich extract, with purities of 98.3 and 96.4%, respectively. The structures of two compounds were identified by MS and NMR. 3-O-β-D-Sophorosylkaempferol-7-O-{3-O-[2(E)-2,6-dimethyl-6-hydroxyocta-2,7-dienoyl]}-α-L-rhamnoside is compound I and compound II named hippophanone is a new compound were identified by MS and NMR. The method was efficient and convenient, which could be used for the preparative separation of flavone glycosides from H. rhamnoides L. seed residues. 相似文献