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以硅胶球为基质键合γ-GOPS并各接枝上具有络合功能的三种配体,邻位氨基吡啶、间酰氨基吡啶及对酰氨基吡啶,再和TiCl_4络合成固载化的Lewis酸催化剂,将这些催化剂进行缩醛、缩酮及酯化反应,有很好的催化活性,重复使用多次不失效.本文在合成此类催化剂的过程中利用热失重(TG)法及等离子光谱法(ICP)等检测方法对合成此类催化剂的每一步进行跟踪检测,得到键合反应,开环反应及络合反应过程中的键合量,开环相量和TiCl_4络合量的定量数据.对固载化催化剂表面的接枝量有所了解,从而可进一步检测此类催化剂的催化效应并得到一些启示. 相似文献
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A convenient one‐step synthesis of 5‐aryl uracils has been developed. The procedure involves heating ethyl 3‐hydroxy‐2‐arylpropenate with urea at 130°C, followed by base‐catalyzed cyclization. The method is simple and high yielding. 相似文献
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本文用热分析、元素分析及溶液吸附三种方法,对不同浓度的γ-GOPS水溶液与硅球表面接枝键合相的系列样品进行接枝度的测定。认为热分析方法是测定硅胶表面接枝度的适用方法。元素分析误差大,数值偏高。溶液吸附法只能作为比较对硅胶表面接枝量大小的相对方法。 相似文献
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Plasmonic Hotspots in Air: An Omnidirectional Three‐Dimensional Platform for Stand‐Off In‐Air SERS Sensing of Airborne Species
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Gia Chuong Phan‐Quang Dr. Hiang Kwee Lee Hao Wen Teng Charlynn Sher Lin Koh Barnabas Qinwei Yim Dr. Eddie Khay Ming Tan Wee Lee Tok Dr. In Yee Phang Prof. Dr. Xing Yi Ling 《Angewandte Chemie (International ed. in English)》2018,57(20):5792-5796
Molecular‐level airborne sensing is critical for early prevention of disasters, diseases, and terrorism. Currently, most 2D surface‐enhanced Raman spectroscopy (SERS) substrates used for air sensing have only one functional surface and exhibit poor SERS‐active depth. “Aerosolized plasmonic colloidosomes” (APCs) are introduced as airborne plasmonic hotspots for direct in‐air SERS measurements. APCs function as a macroscale 3D and omnidirectional plasmonic cloud that receives laser irradiation and emits signals in all directions. Importantly, it brings about an effective plasmonic hotspot in a length scale of approximately 2.3 cm, which affords 100‐fold higher tolerance to laser misalignment along the z‐axis compared with 2D SERS substrates. APCs exhibit an extraordinary omnidirectional property and demonstrate consistent SERS performance that is independent of the laser and analyte introductory pathway. Furthermore, the first in‐air SERS detection is demonstrated in stand‐off conditions at a distance of 200 cm, highlighting the applicability of 3D omnidirectional plasmonic clouds for remote airborne sensing in threatening or inaccessible areas. 相似文献
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Xu Peng Liang Juan Cao Xiaoyong Tang Jingen Gao Juan Wang Liying Shao Wei Gao Qinwei Li Wei Teng Zhaogang 《Research on Chemical Intermediates》2016,42(12):8321-8328
Research on Chemical Intermediates - In this paper, we demonstrate a facile electroless plating method for fabricating silver nanoparticles deposited onto hollow mesoporous silica microspheres... 相似文献
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根据在线监测的需要,把反应所需的溶液输送管道化,因其为一稳定流动体系,流速恒定,故在测定时仅需控制阀门的开关时间即可达到控制流量的目的,而开关时间的长短及先后顺序在单片机的控制下按预先设置的程序进行.pHS-2C型酸度计运行易于稳定,在3-5s的跳动后,即趋于稳定,当程序进行到读数工步时,设有16s的时间间隔,既可达到读数准确又可使程序操作步骤分明(读数时数码管明亮).单片机的工作程序通过微机的键盘和显示器的界面输入,这样可根据实验条件、生产现场操作条件的变化修改程序和运行参数,操作灵活,适应性强,移植性好. 相似文献
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We simulated the translocation process of a polymer chain from a source container to a drain container through a short nanochannel. We utilized the bond fluctuation model coupled with Monte Carlo dynamics in our simulations. The calculation results show that the excluded volume effect significantly affects the polymer's translocation time tau. This time depends nonmonotonically on the polymer length N. For a fixed nanochannel length, tau decreases when the polymer length increases. tau, however, increases when the polymer length exceeds a certain threshold. This observation differs from those predicated for a Gaussian chain. In this paper, we will further present our findings to explain this phenomenon. The knowledge we gain from this research can enhance the understanding of complex transport processes in many biological systems. 相似文献
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We have developed a convenient two-step procedure for the synthesis of 3-ethoxycarbonyl indoles from commercially available materials. The two-step procedure involves the synthesis of 2-aryl-3-hydroxypropenoic acid ester, followed by a catalytic reduction. This method is efficient, simple, and selective. 相似文献
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An RP-HPLC method was developed for the first time to simultaneously determine five major compounds in Polygonum cuspidatum, namely resveratrol, polydatin, anthraglycoside B, emodin and physcion with UV detection at 306 nm. The column was an Agilent Zorbax SB-C18 (250 × 4.6 mm i.d., 5 μm). The separation was carried out with a gradient program. The mobile phase was acetonitrile–water (containing 0.1% formic acid) at a flow rate of 1.0 mL min?1. The standard curve was rectilinear in the range of 2.04–62.96 μg mL?1 (r = 0.9998) for resveratrol, 20.13–239.7 μg mL?1 (r = 0.9998) for polydatin, 7.19–71.92 μg mL?1 (r = 1.0000) for anthraglycoside B, 2.68–83.68 μg mL?1 (r = 0.9998) for emodin and 0.60–14.37 μg mL?1 (r = 0.9997) for physcion. The recoveries of the markers were 96.0, 106.5, 97.8, 97.9 and 98.1%, respectively. The relative standard deviation of intra-day and inter-day were less than 5.0 and 2.3%. This method was simple, accurate and reproducible. The developed method was successfully applied to analyze five compounds in P. cuspidatum of 20 commercial brands. 相似文献