桉木浆纤维多孔结构的分形分析

采用低温氮吸附法测量了桉木浆纤维的内部孔隙结构。结果表明,桉木浆纤维表面密布孔洞,孔隙分布以中孔为主,有一定量的大孔,微孔数量有限。原子力显微镜（AFM）观察也证实这一点。在低温氮吸附实验的基础上,把分形理论用于分析桉木浆纤维的孔结构,发现桉木浆纤维具有分形特征,其分形维数为2.82,分维数接近3,说明植物纤维表面较为粗糙,是密布孔洞。桉木浆纤维分形维数与其保水值等宏观性质有密切的关系。     

高效FTP搜索引擎的设计与实现

为了解决传统FTP搜索引擎对检索结果优化程度不够而造成的检索质量低的问题,在对FTP用户查询日志进行统计分析的基础上,采用双字节倒排索引、检索结果自动分类以及查询自动纠错等技术设计了一种高性能的智能化FTP搜索引擎.双字节倒排是对文件名中每两个字节建立倒排索引表,自动分类是对检索结果按主题划分为层次结构,查询自动纠错是以用户查询日志中的高频查询词为数据源构建拼写错误词典.试验结果表明,该方案能够有效地提高FTP搜索引擎的文件检索效率与质量.     

黎平木生真菌资源及其生态

报道了黎平自然保护区的木生真菌72种;其中食用菌22种,药用菌18种,木腐菌30种和毒菌2种。     

农业科技推广模式中的激励机制研究——以新疆生产建设兵团为例

新疆生产建设兵团农业科技推广模式是独具特色的市场导向下政府主导的推广模式.其有效性取决于农业科技推广模式中的激励机制,一方面通过农业科技推广者收入与推广效益挂钩的收入分配制度,增强其推广农业科技意愿和推广能力:另一方面通过农业科技应用者岗位技术工资与科技培训挂钩的科技培训制度,增强其接受农业科技推广的意愿和能力.     

Features of intervertebral disc degeneration in rat’s aging process

Objective: The age-related change is important part of degenerative disc disease. However, no appropriate animal model or objective evaluation index is available. This study aimed to investigate the features of intervertebral disc degeneration in aging process of rats. Methods: 22-month-old Sprague-Dawley (SD) rats were used as spontaneously occurring intervertebral disc degeneration models and 6-month-old rats as young controls. Expression of collagen types II and X was measured by immunohistochemistry. Degenerations of intervertebral discs were scored according to Miyamoto’s method. Numbers and areas of afferent vascular buds were measured. The thicknesses of non-calcified and calcified layers were measured and statistically analyzed. Results: There were less collagen type II expression and more collagen type X expression in the calcified layer of the cartilage endplates and nucleus pulposus in the rats of the aged group than in the young control. There were fewer and smaller afferent vascular buds in the rats of the aged group than in the young control group. The ratio of the non-calcified to the calcified layers in the rats of the aged group significantly decreased, compared with that of the young control group (P<0.01). Conclusion: Rats can spontaneously establish intervertebral disc age-related degeneration. The expression of collagen types II and X, numbers and areas of afferent vascular buds, the ratio of the non-calcified to the calcified layers, and water and glycosaminoglycan contents in the nucleus pulposus are sensitive indexes of intervertebral disc degeneration.     

后现代主义文化语境下李白文化的尴尬处境

李白文化的地位是崇高的、影响是深远的,不过,李白文化当前正面临着前所未有的挑战。本文运用后现代主义文化理论对李白文化的现实处境进行研究,剖析当前李白文化所处的尴尬处境,分析其原因,并尝试提出解决问题的思路,进而探讨李白文化在后现代主义思潮下的走向。     

基于STL的斜壁结构支撑及自动生成算法

为进一步降低熔丝沉积成形设备的运行成本,同时提高成形效率,设计一种斜壁结构的支撑,基于STL模型提出并实现其自动生成算法.实验证明该支撑结构与常用直壁结构支撑相比,不仅能够有效辅助零件实体的成形过程,而且能够尽可能地减少支撑材料消耗量和成形时间.算法实用可靠,已成功集成至Power RP软件支撑模块中.     

面向SBA的综合集成决策支持系统

为了解决面向装备虚拟采办(SBA)的多层次与多维度复杂系统的决策问题,提出了一种基于定性定量综合集成的决策策略.在建立了包括协同控制管理支撑服务平台、SBA研讨决策综合集成服务、SBA研讨决策信息服务等的体系基础设施服务的基础上,设计并实现了面向SBA、基于综合集成的智能决策支持系统,该系统通过SBA决策任务一体化数据/信息/知识/模型表征、同步一异步决策、研讨内容管理及决策优选等具体功能.在研讨厅的环境中,利用智能体技术和全方位集成机制获得具体采办决策任务的满意解.     

超导电感储能脉冲输出电路设计及其关键问题

针对电感脉冲输出容易产生高电压,而且一般的断路开关也不易快速切断大电流这两个问题,提出了用模块化技术和脉冲变压器降低断路开关的开断电流,用金属氧化锌阀片(MOV)保护超导电感上的过电压的技术方案.以超导电感脉冲输出的单模块电路为对象,重点分析了氧化锌避雷器(由MOV组成)的U1mA(MOV通过1 mA电流时两端的电压)对脉冲输出波形的影响,提出了U1mA的选择原则.同时讨论了断路开关的开断时间对脉冲输出的影响.实验验证了此单模块电路的脉冲输出效果.     

Skin collagen fiber-based radar absorbing materials

By using skin collagen fiber (CF) as raw material,Schiff base structure containing CF (Sa-CF) was synthesized through CF-salicylaldehyde reaction.Then a novel radar absorbing material (Fe-Sa-CF) was prepared by chelating reaction between Sa-CF and Fe 3+.The coaxial transmission and reflection method was used to analyze the complex permittivity and complex magnetic permeability of these CF-based materials,and the radar cross section (RCS) method was used to investigate their radar absorbing properties in the frequency range of 1.0-18.0 GHz.Experimental results indicated that the conductivity of CF increased from initial 1.08×10-11 to 2.86×10-6 S/cm after being transferred into Fe-Sa-CF,and its dielectric loss tangent (tanδ) in the frequency range of 1.0-17.0 GHz also increased.These facts suggest that the Fe-Sa-CF is electric-loss type radar absorbing material.In the frequency range of 3.0-18.0 GHz,Sa-CF (1.0 mm in thickness) exhibited somewhat radar absorbing property with maximum radar reflection loss (RL) of-4.73 dB.As for Fe-Sa-CF,the absorbing bandwidth was broadened,and the absorbing intensity significantly increased in the frequency range of 1.0-18.0 GHz where a maximum radar RL of-9.23 dB was observed.In addition,the radar absorbing intensity of Fe-Sa-CF can be further improved by increasing membrane thickness.When the thickness reached to 2.0 mm,the RL values of Fe-Sa-CF were-15.0-18.0 dB in the frequency range of 7.0-18.0 GHz.Consequently,a kind of novel radar absorbing material can be prepared by chemical modification of collagen fiber,which is characterized by thin thickness,low density,broad absorption bandwidth and high absorption intensity.