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排序方式: 共有2096条查询结果,搜索用时 15 毫秒
1.
微型通用串行总线(Micro-USB)作为PC机及各类数码产品的主流接口,因其具有携带方便、传输速度快、易于扩展、总线供电等优点,尤其是其特殊的传输线模型,使其在通用计算机、嵌入式系统为主要应用领域的各种数字系统和设备中得到了广泛的应用,并获得制造商及用户的高度认可,具有广阔的发展前景. 相似文献
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介绍了时间的基本概念以及国际上常用的几种时标,描述了闰秒的定义及调整原理,最后给出闰秒在通信网的应用要求。 相似文献
4.
Sharmin Sultana M.A Motalib Hossain Nina Nizar Ahmad Naquiah 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2018,35(9):1662-1673
Gelatin is widely used in pharmaceuticals as a protective coating, such as soft and hard capsule shells. However, the animal source of gelatin is a sensitive issue because certain gelatins such as porcine and bovine gelatins are not welcome in Halal, Kosher and Hindus’ consumer goods. Recently, we have documented DNA barcoding and multiplex PCR platforms for discriminating porcine, bovine and fish gelatins in various fish and confectionary products; but those assays were not self-authenticating and also not tested in highly refined pharmaceutical products. To address this knowledge gap, here we report a self-authenticating multiplex PCR-restriction fragment length polymorphism (RFLP) assay to identify animal sources of various gelatin in pharmaceutical capsules. Three different restriction enzymes, BsaAI, Hpy188I and BcoDI were used to yield distinctive RFLP patterns for gelatin-based bovine (26, 94 bp), fish (97, 198 bp) and porcine (17, 70 bp) DNA in control experiments. The specificity was cross-tested against 16 non-target species and the optimised assay was used to screen gelatin sources in 30 halal-branded pharmaceuticals capsule shells. Bovine and porcine DNA was found in 27 and 3 of the 30 different capsules products. The assay was suitable for detecting 0.1 to 0.01 ng total DNA extracted from pure and mixed gelatins. The study might be useful to authenticate and monitor halal, kosher, vegetarian and Hindu compliant pharmaceuticals, foods and cosmetics. 相似文献
5.
半参数回归模型的泛补偿最小二乘估计 总被引:1,自引:0,他引:1
本文首先提出泛补偿最小二乘法:接着,使用该法考虑半参数回归模型,得到了参数及非参数的估计。然后,将泛补偿最小二乘法与补偿最小二乘法进行了比较;最后用模拟的算例说明了该方法的有效性。 相似文献
6.
采用多目标优化的方法,优化接轴的主要尺寸参数。在不改变接轴外径和材质的条件下,使叉头和扁头的承载能力趋于相等。优化后的接轴,不但结构合理,而且还可以显著地提高接轴的综合承载能力。 相似文献
7.
Nandita Elizabeth Paulose 《Journal of Adhesion Science and Technology》2018,32(9):931-946
The effect of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) on the bond strength and durability of the resin-dentin interface using a three-step etch-and-rinse and a universal adhesive (UA) system was investigated. Additionally, the effect of dry and wet bonding on the interface created by UA was evaluated. Investigations carried out were scanning electron microscopy (SEM) evaluation, interfacial nanoleakage expression (NE) and micro-tensile bond strength (μ-TBS) testing. Dentin surfaces of sound molars were acid-etched, pretreated with 0.3 M EDC followed by adhesive application and restored with composite incrementally. Resin-dentin beams for μ-TBS testing and resin-dentin slabs for SEM and NE were sectioned. At 24 h, pre-treatment with EDC did not significantly change the μ-TBS and NE of any of the adhesives compared to their respective controls. There is a significant decrease in the μ-TBS and significant increase in NE after 1 yr of storage compared to the 24 h results. UA in dry bonding conditions pretreated with EDC had higher μ-TBS values than its control. Pre-treatment of acid-etched dentin with 0.3 M EDC for 1 min enhanced the bond strength and durability of the resin-dentin interface created by the tested adhesives. Application of UA in a wet bonding technique appeared less effective than dry bonding technique. 相似文献
8.
The free energies of mixing a series of water-soluble polymers with cellulose were calculated using the UNIFAC (universal functional group activity coefficients) algorithm, and the results were correlated with measurements of polymer/cellulose adhesion. The more negative the minimum free energy of mixing, the greater the measured adhesion. Adhesion was quantified by single-lap shear test in which regenerated cellulose films were laminated with aqueous polymer. The results are relevant to the use of adsorbed water-borne polymers to strengthen cellulose fiber–fiber bonds in paper. The calculations did not anticipate the exceptional strength-enhancing properties of carboxymethyl cellulose, nor did they predict molecular-weight effects. Nevertheless, the approach may have utility as a general tool to relate polymer chemistry to adhesion performance. 相似文献
9.
制造系统通用作业计划与蚁群算法优化 总被引:9,自引:0,他引:9
分析了基本作业方式的“通用-特例”关系,提出了全面研究上述基本作业方式的通用作业计划的概念,建立了通用作业计划非连接图模型及基于蚁群算法的优化方法。算例研究假定一制造系统包含开放作业、异顺序作业、混杂流水作业三种作业方式,将其按照通用作业计划方式采用蚁群算法进行优化,所得的近优加工流程时间显著优于采用穷举法对三种作业方式分别优化所得的最优解。 相似文献
10.
在“万工显”上运用坐标平移和旋转原理测量小弦长大圆弧半径的方法——“旋转法”,不但可以在圆弧轮廓上均匀地选择测量点,进行多点测量,而且能直接测出半径偏差,既扩大了“万工显”的测量范围,又提高了圆弧半径的测量准确度。误差分析表明,“旋转法”的准确度比“弓弦法”的准确度高近8倍,特别对于小弦长大圆弧半径的测量,更显示其优越性。 相似文献