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麻竹叶抑菌活性成分的分离鉴定 被引量:6
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作者 谢碧霞 陆志科 《中南林学院学报》 CAS CSCD 北大核心 2005年第5期10-14,共5页
对麻竹叶抑菌活性成分进行了分离鉴定,结果表明:将麻竹叶干粉加70%乙醇抽提至色淡,抽提液浓缩后经石油醚萃取,水相过聚酰胺柱,用水和70%乙醇洗脱,醇洗部回收溶剂经60℃低温干燥,得红棕色结晶性粉末;该物质经真空层析、聚酰胺层析、得单... 对麻竹叶抑菌活性成分进行了分离鉴定,结果表明:将麻竹叶干粉加70%乙醇抽提至色淡,抽提液浓缩后经石油醚萃取,水相过聚酰胺柱,用水和70%乙醇洗脱,醇洗部回收溶剂经60℃低温干燥,得红棕色结晶性粉末;该物质经真空层析、聚酰胺层析、得单一色斑;在聚酰胺柱色谱中呈单一吸收峰,经高压液相色谱检验,单一主峰面积比例为97.75%;用盐酸镁粉检出其为黄酮化合物;经酸水解。用硅胶薄板层析检出有木糖;用UV+vis光谱法及化学法对其结构进行分析,其分子结构为黄酮醇类,该化合物具有较强抑菌活性, 酸水解后抑菌活性升高。 展开更多
关键词 经济林 麻竹叶 纯化 分于结构 抑菌作用
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氨基磺酸盐系超塑化剂研制 被引量:3
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作者 张师恩 卞葆芝 张云理 《混凝土》 CAS CSCD 北大核心 2006年第11期30-33,共4页
依据表面活性剂的分子结构性能,研究了以氢氧化钠为催化剂,以对氨基苯磺酸钠、苯酚及甲醛等为原料,直接缩聚成氨基磺酸盐系超塑化剂的配方及工艺参数。其产品超塑化性能良好,分子结构稳定,存放两年无交联现象。
关键词 氨基磺酸盐 超塑化剂 表面活性剂 分于结构 合成试验 临界状态 稳定性
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Structural Analysis and Design of Steel Connections Using Component-Based Finite Element Model
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作者 Lubomir Sabatka Frantisek Wald +2 位作者 Jaromir Kabelac Drahoslav Kolaja Martin Pospisil 《Journal of Civil Engineering and Architecture》 2015年第8期895-901,共7页
This paper introduces CBFEM (component-based finite element model) which is a new method to analyze and design connections of steel structures. Design focused CM (component model) is compared to FEM (finite eleme... This paper introduces CBFEM (component-based finite element model) which is a new method to analyze and design connections of steel structures. Design focused CM (component model) is compared to FEM (finite elements models). Procedure for composition of a model based on usual production process is used in CBFEM. Its results are compared to those obtained by component method for portal frame eaves moment connection with good agreement. Design of moment resistant column base is demonstrated by a case loaded by two directional bending moments and normal force. Interaction of several connections in one complex joint is explained in the last example. This paper aims to provide structural engineers with a new tool to effectively analyze and design various joints of steel structures. 展开更多
关键词 Steel structures structural connections finite element model component model analytical model design model.
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An Approach to Underwater Image Enhancement Based on Image Structural Decomposition 被引量:11
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作者 JI Tingting WANG Guoyu 《Journal of Ocean University of China》 SCIE CAS 2015年第2期255-260,共6页
Underwater imaging posts a challenge due to the degradation by the absorption and scattering occurred during light propagation as well as poor lighting conditions in water medium Although image filtering techniques ar... Underwater imaging posts a challenge due to the degradation by the absorption and scattering occurred during light propagation as well as poor lighting conditions in water medium Although image filtering techniques are utilized to improve image quality effectively, problems of the distortion of image details and the bias of color correction still exist in output images due to the complexity of image texture distribution. This paper proposes a new underwater image enhancement method based on image struc- tural decomposition. By introducing a curvature factor into the Mumford_Shah_G decomposition algorithm, image details and struc- ture components are better preserved without the gradient effect. Thus, histogram equalization and Retinex algorithms are applied in the decomposed structure component for global image enhancement and non-uniform brightness correction for gray level and the color images, then the optical absorption spectrum in water medium is incorporate to improve the color correction. Finally, the en- hauced structure and preserved detail component are re.composed to generate the output. Experiments with real underwater images verify the image improvement by the proposed method in image contrast, brightness and color fidelity. 展开更多
关键词 underwater image image structural decomposition image enhancement RETINEX
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Structure-based design of hexahydropyrimidin-5-ols as novel non-peptidic β-secretase inhibitors
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作者 周博 牛彦 +6 位作者 邹晓民 许凤荣 袁悦 王超 高海飞 刘鹏 徐萍 《Journal of Chinese Pharmaceutical Sciences》 CAS 2010年第5期341-345,共5页
Based upon the crystal structure of a previously reported fragment hit that binds to Corresponding author. β-secretase, a novel series of non-peptidic small-molecule β-secretase inhibitors, namely hexahydropyrimidin... Based upon the crystal structure of a previously reported fragment hit that binds to Corresponding author. β-secretase, a novel series of non-peptidic small-molecule β-secretase inhibitors, namely hexahydropyrimidin-5-ols, along with two series of their analogues, were rationally designed through structural modification. The CADD study was performed and revealed good expectation. Inhibitory activities of the corresponding structural cores were tested, which provided further support for our design approach. 展开更多
关键词 β-Secretase inhibitors Hexahydropyrimidin-5-ols Structure-based drug design Computer-aided drug design
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