排序方式: 共有102条查询结果,搜索用时 15 毫秒
71.
华录松下革新QC小组 《电子质量》2002,(9)
TT压入机生产节拍慢,不良率高严重影响TT压入机的生产性,使线体的生产能力远远满足不了市场的要求。小组成员为提高TT压入机生产性,从TT压入机的生产节拍和不良率两方面入手,分别制定目标,分析原因,确定要因,采取对策,最终实现目标取得很好的经济效益和无形效益。 相似文献
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以SiO2、活性炭(AC)和Al2O3为载体,采用浸渍法制备了Ni-V-O系负载光催化剂.考察了样品的光谱特征,并在紫外光下评价了样品在甲醇和CO2光催化反应巾的性能;通过吡啶吸附FIIR和UV-Vis分析,结合反应测试结果,比较了催化剂载体对产物选择件的影响.XRD结果表明,在系列催化剂中,SiO2载体上的镍、钒粒子分散程度最高.吡啶吸附FIIR结果显示,系列催化剂表面存在L酸中心;相同的活性组分由于载体不同,所得到的负载催化剂表面酸度不同.负载催化剂表面L酸强度顺序为:Ni-V-O/SiO2>Ni-V-O/Al2O3>Ni-V-O/AC.不同酸度的催化剂,其上的羰基化产物甲酸甲酯(MF)和碳酸二甲酯(DMC)的选择性也不同.催化剂的表面酸强度是影响羰基产物选择性的主要因素. 相似文献
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采用浸渍法制备了Ni-Ti-O/SiO2催化剂,在紫外光照射下,考察了甲醇和CO2光催化羰基化反应性能,并通过原位红外光谱,XPS和MS等表征分析了可能的反应机理。实验结果表明,Ni-Ti-O/SiO2催化剂对甲醇和CO2光催化作用较显著,在180min反应时间内,甲醇的转化率达到了24.9%,羰基化产物的选择性超过了60%;结合催化剂表征结果推断,O-C.-O-和CH3OC(O).或许是甲醇和CO2羰基化反应的重要中间体。 相似文献
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中药黄连饮片活性成分分布的检测研究 总被引:2,自引:0,他引:2
为了实现中药饮片的活性成分空间分布检测,有效地对药用部位进行质量评价,以中药黄连饮片为研究对象,运用光谱成像分析技术进行检测.首先获取检品的荧光光谱立方体,根据中药鉴定学知识,人工提取3个不同组织结构处的光谱曲线;进而运用主成分分析法重构光谱图像,将3个不同组织结构的特征差异集中于前几个主成分图中;最后采用阈值法对第一主成分图像进行分割,获得了不同组织结构的空间分布情况及各组织结构有效成分的相对含量.实验结果显示光谱成像技术可以提供中药饮片有效成分的空间分布状态,为人药部位的选择提供依据,且检测过程无损、快速. 相似文献
75.
应用自行设计的液晶光谱成像装置对不同地方居群的钩藤叶进行透射光谱检测分析。绘制特征曲线,构建成像特征图谱,并对钩藤叶的特征光谱进行聚类分析。分析结果显示:钩藤叶的成像特征光谱相似度及其聚类分析对钩藤亲缘关系的判定结果与植物分类学鉴定结果相一致。说明光谱成像分析技术可应用于探讨钩藤亲缘关系。应用光谱成像分析技术设计的液晶光谱成像系统可对中药进行快速无损检测。同一样品可反复进行多次实验,实验操作方法简便快捷。可为中药研究提供新的检测方法。 相似文献
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Houttuynoids A-E (1-5), a new type of flavonoid with houttuynin tethered to hyperoside, and their presumed biosynthetic precursor hyperoside (6) were isolated from the whole plant of Houttuynia cordata. Their structures were elucidated by analysis of 1D and 2D NMR. A hypothetical biogenetic pathway for houttuynoids A-E was proposed. Compounds 1-5 exhibited potent anti-HSV (herpes simplex viruses) activity. 相似文献
77.
Peng JB Zhang QC Kong XJ Zheng YZ Ren YP Long LS Huang RB Zheng LS Zheng Z 《Journal of the American Chemical Society》2012,134(7):3314-3317
Four 52-metal-ion 3d-4f cluster complexes featuring a common core of Ln(42)M(10) (Ln = Gd(3+), Dy(3+); M = Co(2+/3+), Ni(2+)) were obtained through self-assembly of the metal ions templated by mixed anions (ClO(4)(-) and CO(3)(2-)). Magnetic studies revealed that the Gd(42)Co(10) and Gd(42)Ni(10) clusters exhibit the largest magnetocaloric effect (MCE) among any known 3d-4f complexes. Replacement of Gd(3+) ions with anisotropic Dy(3+) ions caused significant changes in the magnetic behavior of the clusters; both Dy(42)Co(10) and Dy(42)Ni(10) displayed slow relaxation of the magnetization. 相似文献
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Zeng R Chen YB Shao XX Shieh CH Miller K Tran H Xia QC 《Rapid communications in mass spectrometry : RCM》2003,17(17):1995-2004
Digests from ten gel bands containing low abundance proteins were analyzed by both matrix-assisted laser desorption/ionization ion trap (MALDI-IT) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) methods. MALDI-TOF techniques were able to identify only one protein from all 10 gel bands, while MALDI-IT identified eight proteins from the same 10 bands. The ability to perform MS/MS experiments with a MALDI-IT instrument leads to protein identifications based on both peptide molecular mass and sequence information, and is much less prone to errors and uncertainties introduced by peptide fingerprinting methodologies in which protein identification is based on peptide molecular masses alone. 相似文献