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2，5-呋喃二甲酸（2，5-FDCA）是生物可降解聚呋喃二甲酸乙二醇酯（PEF）的单体，目前尚未形成廉价的制备技术，其中用己糖二酸脱水环合制备2，5-FDCA是一条具有发展潜力的路线。针对此路线中副产物定性不准确、反应路径研究不完善等问题，通过高效液相色谱、高分辨质谱、核磁共振和傅里叶变换红外光谱分析，开展了副产物定性工作，确定反应体系中的2个主要副产物为糠酸和3-羟基-6-羧基-2-吡喃酮（HOCA）。在硫酸催化下不同己糖二酸脱水环合的反应路径相似，半乳糖二酸易生成副产物HOCA，而葡萄糖二酸钙易生成主产物2，5-FDCA。结合文献报道，提出了己糖二酸脱水环合制备2，5-FDCA可能的完整反应路径。研究工作可为己糖二酸脱水环合制备2，5-FDCA的高效催化体系开发和工业化生产提供指导。

Copyright of Chinese Journal of Tissue Engineering Research / Zhongguo Zuzhi Gongcheng Yanjiu is the property of Chinese Journal of Tissue Engineering Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Computational Mechanics / Jisuan Lixue Xuebao is the property of Chinese Journal of Computational Mechanics Editorial Office, Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Southeast University / Dongnan Daxue Xuebao is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Frontiers of Computer Science & Technology is the property of Beijing Journal of Computer Engineering & Applications Journal Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Computer Engineering & Applications is the property of Beijing Journal of Computer Engineering & Applications Journal Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Objective] The aims of this study are to clarify the topographic gradient effect of land spatial function change for Dongting Lake Basin, and provide scientific basis for the construction of new land spatial pattern, the implementation and supervision of land spatial planning, and the promotion of regional coordinated development. [Methods] Based on multi-source data, from the perspective of Production-Living-Ecological functions, and the methods of function merging, atlas, standard deviation ellipse and terrain position were used to reveal the spatio-temporal characteristics of the spatial functions of the basin since 1990, and discussthe terrain gradient effect of spatial function changes, so as to clarify the distribution pattern of local land and spatial resources. [Results] The service state of the land-spatial function in Dongting Lake Basin were divided into dominant, important, secondary and non-dominant types. Since 1990, the land area dominated by production and living functions had increased slowly, while the land dominated by ecological functions had tended to shrink. The functional change areas concentrated in Dongting Lake area, Xiangjiang River Basin and other areas, showed pointed distribution characteristics. The changes of production, living and ecological functions all showed significant directional distribution patterns. The land with dominant and important production and living functions tended to distribute in low terrain gradients, while the land with dominant ecological functions concentrated in high terrain gradient areas. The terrain was important factor for the formation of spatial and temporal heterogeneity of land functions in Dongting Lake Basin. Most of the lands with dominant production and living functions and lands with secondary ecological functions were stable maps, and the map with repeated changes of production and ecological functions fluctuated first and then decreased with the growth of shape index. [Conclusion] The land spatial planning and management of Dongting Lake Basin should comprehensively consider the terrain gradient effect to promote the efficient allocation of land resources in this basin. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Computational Mechanics / Jisuan Lixue Xuebao is the property of Chinese Journal of Computational Mechanics Editorial Office, Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effects of two grinding aids, glycerol and sodium pyrophosphate, on the grinding kinetic behavior of 0.074~2mm quartz pure mineral in the material were systematically investigated by using batch wet ball milling experiments. Based on the grain size distribution characteristics of grinding products, m order grinding kinetic models of quartz in the grinding process were established. The influence of the amount of grinding aid on the kinetic parameters and grinding speed of quartz was analyzed. The results show that the quartz grinding process conformes to the m order grinding dynamics model. With the increase of the dosage of glycerol and sodium pyrophosphate， the kinetic parameter k decreases first and then increases, and the kinetic parameter m increases first and then decreases. The maximum value is reached when the dosage of grinding aids is 0.3%~0.5%. Under the same grinding conditions, the grinding speed of 0.45~1mm particle size is the maximum. [ABSTRACT FROM AUTHOR]

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Yellow River is the property of Editorial Board of Yellow River and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Zhejiang University (Science Edition) is the property of Journal of Zhejiang University (Science Edition) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The sediment deposited by the external flood into the main channel will weaken the flow capacity of the channel, causing the water body to overflow the top and overflow the embankment, which will seriously affect the stability of the embankment slope. The effects of sediment concentration in external flood on the transverse and vertical distribution of flow velocity, sedimentation process and sedimentation morphology in the main channel were studied by physical model test. The results show that the middle of the main channel is less affected by the external flood and the resistance of the channel side wall, and the flow velocity is larger. On the contrary, the flow velocity near the flood mouth and the channel side wall is smaller. The flow velocity increases with the decrease of water depth in a certain depth range, and decreases when it is near the surface. With the increase of external flood sediment concentration, the sediment deposition thickness increases, and the initial position of sediment deposition and the maximum position of sediment deposition thickness are closer to the upstream of the main channel. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study attempted to identify the differences in runoff changes of two rivers in the south and north of China's north-south transitional zone. The linear regression test and the cumulative anomaly method were applied to detect temporal variations in runoff at Wuhou and Wushan stations in the sources of Hanjiang River and Weihe River from 1975 to 2015. The elasticity coefficient method based on the Budyko hydrothermal balance equation was applied to quantify the attributions of climate change and land surface changes. The results show that the annual runoff at Wuhou in Hanjiang River shows a slightly decreasing trend, whereas runoff at Wushan Station shows a significant decreasing trend. Abrupt changes are detected in 1990 and 1993 respectively. Runoff in both watersheds shows high sensitivity to climate change, especially in the source of the Hanjiang River, its runoff shows high sensitivity to the changes of precipitation. The changes in precipitation, potential evapotranspiration and land surface contribute 65.23%, 6.02% and 28.75% respectively to the runoff changes in the source of the Hanjiang River and 24.51%, 26.62% and 48.87% respectively in the source of the Weihe River. Furthermore, the runoff in the source of the Weihe River is highly influenced by human activities comparing to that in the source of Hanjiang River. [ABSTRACT FROM AUTHOR]

Copyright of Coatings & Protection / Tuceng yu Fanghu is the property of Coating & Protection Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Shanghai Land & Resources / Shanghai Guotu Ziyuan is the property of Editorial Board of Shanghai Land & Resources and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Northeastern University (Social Science) / Dongbei Daxue Xuebao (Shehui Kexue Ban) is the property of Dongbei Daxue and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Yellow River is the property of Editorial Board of Yellow River and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Northeastern University (Natural Science) is the property of Dongbei Daxue Xuebao and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Northeastern University (Social Science) / Dongbei Daxue Xuebao (Shehui Kexue Ban) is the property of Dongbei Daxue and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Journal of Clinical Hepatology / Linchuang Gandanbing Zazhi is the property of Journal of Clinical Hepatology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)