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881.
With the aim of discovering new bioactive pesticides for crop protection, a series of novel sulfidecontaining amide derivatives A were efficiently synthesized via a strategy of modifying the “amide” structure of anthranilic diamide insecticides. The single-crystal structures of A2-3 and A4-5 were firstly reported. The bioassay results showed that most of the synthesized compounds display moderate to high insecticidal activities. Particularly, some sulfone-containing compounds, e.g., A2-3, A3-3 a... 相似文献
882.
883.
本文研究了在盐酸溶液中砷(Ⅲ)—碘酸钾—溴化钾—甲基红褪色反应及影响褪色速度的因素,建立了动力学分光光度法测定水样中微量砷(Ⅲ)的新方法。方法灵敏度为2.4×10-9克砷(Ⅲ)/毫升,测定范围0~11微克砷(Ⅲ)/25毫升,并具有操作简便、快速,分析结果稳定,分析费用低廉等 相似文献
884.
Karger-Kocsis J. Moskala E. J. Shang P. P. 《Journal of Thermal Analysis and Calorimetry》2001,63(3):671-678
The toughness of amorphous copolyester sheets was assessed by the essential work of fracture (EWF) concept. While the yielding-related
work of fracture terms did not change significantly, the necking-related parameters strongly decreased with decreasing entanglement
density of the copolyesters having different amounts of cyclohexylenedimethylene (CHDM) units in their backbones. Furthermore, copolyesters with high CHDM content and thus less entanglement density showed full recovery of the necked region beyond the glass transition temperature,
i.e. the ‘plastic’ zone in the related specimens formed by cold drawing and not by true plastic deformation. By contrast,
the copolyester with negligible amount of CHDM did not show this shape recovery. Modulated differential scanning calorimetry (MDSC) revealed that the necking in the latter
system was accompanied by strain-induced crystallization. The superior work hardening in the necking stage of the respective
poly(ethylene terephthalate) (PET) specimens can thus be ascribed to stretching of the entanglement network with superimposed crystallization.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
885.
Traditionally there do not exist integralinvariants for a nonconservative system in the phasespace of the system. For weak nonconservative systems,whose dynamical equations admit adjoint symmetries, there exist Poincare and Poincare-Cartanintegral invariants on an extended phase space, wherethe set of dynamical equations and their adjointequations are canonical. Moreover, integral invariantsalso exist for pseudoconservative dynamical systemsin the original phase space if the adjoint symmetriessatisfy certain condtions. 相似文献
886.
Nonlinear Dynamics - Vector visibility graph (VVG) is an algorithm that transforms multivariate time series into directed complex networks. However, at present, the researches of VVG mainly focus... 相似文献
887.
The interval-valued q-rung dual hesitant linguistic (IVq-RDHL) sets are widely used to express the evaluation information of decision makers (DMs) in the process of multi-attribute decision-making (MADM). However, the existing MADM method based on IVq-RDHL sets has obvious shortcomings, i.e., the operational rules of IVq-RDHL values have some weaknesses and the existing IVq-RDHL aggregation operators are incapable of dealing with some special decision-making situations. In this paper, by analyzing these drawbacks, we then propose the operations for IVq-RDHL values based on a linguistic scale function. After it, we present novel aggregation operators for IVq-RDHL values based on the power Hamy mean and introduce the IVq-RDHL power Hamy mean operator and IVq-RDHL power weighted Hamy mean operator. Properties of these new aggregation operators are also studied. Based on these foundations, we further put forward a MADM method, which is more reasonable and rational than the existing one. Our proposed method not only provides a series of more reasonable operational laws but also offers a more powerful manner to fuse attribute values. Finally, we apply the new MADM method to solve the practical problem of patient admission evaluation. The performance and advantages of our method are illustrated in the comparative analysis with other methods. 相似文献
888.
Potassium methyl siliconate(PMS) was investigated as a simple physicochemical modification in aged paper using silane coupling technique. The PMS-based solution was shown to favor penetration in the cellulose fibers on the paper with suitable uptakes being achieved at low concentrations. The studies of the physicochemical properties of the treated paper(mechanical strength and alkalinity) demonstrated that, besides the required deacidification feature and high level of alkali reserves, the immersion treatment by PMS allowed the enhancement of the mechanical intensities of paper arising from the interaction between Si―OH generated in hydrolysis of PMS and C―OH of cellulose on the paper. Adding ethanol into PMS solution could significantly improve mechanical properties of the aged paper treated by the formula apart from modifying the flatness of the paper. Optimized treatment process was achieved by altering the ratio of ethanol to water in PMS-based solutions. Contact angle measurements indicated the occurrence of hydrophobic character of the papers in immersion treatment with PMS-based solutions. The easy availability of the materials and simplicity of the method rendered it convenient for treatment for aged paper documents. 相似文献
889.
以低不饱和度环氧丙烷聚醚三元醇与L型及DL型丙交酯为原料, 合成了不同单体物质的量比的聚醚与聚乳酸嵌段共聚物. 采用FTIR, 1H NMR, GPC对共聚物的结构进行了表征; 用DSC, DTA对共聚物的玻璃化转变温度、熔点及热分解温度进行了研究. 结果表明, 丙交酯在聚醚多元醇端羟基的引发下发生开环反应, 得到聚环氧丙烷L型乳酸(POLLA)或聚环氧丙烷DL型乳酸(PODLA)二嵌段共聚物. POLLA二嵌段共聚物具有结晶能力, 且随着L型聚乳酸链段的增长而增强. PODLA二嵌段共聚物为非晶态聚合物. 两种共聚物的玻璃化转变温度与共聚物的组成有关, 其值介于聚醚和聚乳酸玻璃化转变温度之间. 与聚醚三元醇相比, 二嵌段共聚物的耐热性得到提高, 其热分解温度提高了30~60 ℃, 约为235~262 ℃. 共聚物的结构和组成对材料的热降解机制有很大影响. PODLA在高温区发生热氧化降解. 相似文献
890.
Zhigang Shi Yuting Bai Xuebo Jin Xiaoyi Wang Tingli Su Jianlei Kong 《Entropy (Basel, Switzerland)》2022,24(3)
The prediction of time series is of great significance for rational planning and risk prevention. However, time series data in various natural and artificial systems are nonstationary and complex, which makes them difficult to predict. An improved deep prediction method is proposed herein based on the dual variational mode decomposition of a nonstationary time series. First, criteria were determined based on information entropy and frequency statistics to determine the quantity of components in the variational mode decomposition, including the number of subsequences and the conditions for dual decomposition. Second, a deep prediction model was built for the subsequences obtained after the dual decomposition. Third, a general framework was proposed to integrate the data decomposition and deep prediction models. The method was verified on practical time series data with some contrast methods. The results show that it performed better than single deep network and traditional decomposition methods. The proposed method can effectively extract the characteristics of a nonstationary time series and obtain reliable prediction results. 相似文献