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排序方式: 共有1081条查询结果,搜索用时 687 毫秒
991.
992.
Hanjun Sun Ibrahim Halil
ner Tao Wang Tao Zhang Oleksandr Selyshchev Christof Neumann Yubin Fu Zhongquan Liao Shunqi Xu Yang Hou Andrey Turchanin Dietrich R. T. Zahn Ehrenfried Zschech Inez M. Weidinger Jian Zhang Xinliang Feng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(30):10476-10482
Conjugated polymers featuring tunable band gaps/positions and tailored active centers, are attractive photoelectrode materials for water splitting. However, their exploration falls far behind their inorganic counterparts. Herein, we demonstrate a molecular engineering strategy for the tailoring aromatic units of conjugated acetylenic polymers from benzene‐ to thiophene‐based. The polarized thiophene‐based monomers of conjugated acetylenic polymers can largely extend the light absorption and promote charge separation/transport. The C≡C bonds are activated for catalyzing water reduction. Using on‐surface Glaser polycondensation, as‐fabricated poly(2,5‐diethynylthieno[3,2‐b]thiophene) on commercial Cu foam exhibits a record H2‐evolution photocurrent density of 370 μA cm?2 at 0.3 V vs. reversible hydrogen electrode among current cocatalyst‐free organic photocathodes (1–100 μA cm?2). This approach to modulate the optical, charge transfer, and catalytic properties of conjugated polymers paves a critical way toward high‐activity organic photoelectrodes. 相似文献
993.
The reductive coupling of cyclic imides and ω-amidoesters with benzophenones by Zn-TiCl4 in THF and subsequent acid-catalyzed dehydration gave 5-diarylmethylene-1,5-dihydropyrrol-2-ones A, 6-diarylmethyl-2-pyridones B, and ω-(diarylmethylene)lactams C. In a similar manner, 3-((benzyloxy)carbonyl)amino substituted A, B, and C were synthesized from the corresponding 3-((benzyloxy)carbonyl)amino cyclic imides and ω-((benzyloxy)carbonyl)amino-ω-amidoesters prepared from L-aspartic and L-glutamic acids. In addition, 4- and 5-((benzyloxy)carbonyl)amino substituted C were also obtained by the same procedures from 2-((benzyloxy)carbonyl)amino-ω-amidoesters prepared from L-asparagine and L-glutamine, respectively. 相似文献
994.
利用高温管式炉开展城市污泥(SS)与四种塑料(PE、PP、PS和PVC)混合热解实验,分别得到四种生物炭(SSCPE、SSCPP、SSCPS和SSCPVC),研究了生物炭中重金属(Cr、Mn、Ni、Cu、Zn、As、Cd和Pb)含量、残余率、BCR形态和TCLP浸出毒性特征,并开展潜在生态风险评估。结果表明,添加不同塑料与污泥混合热解能够降低除Cd以外重金属的残余率。与污泥单独热解所得生物炭(SSC)相比,添加PE、PP和PS能够促进生物炭中的重金属向相对稳定态(F3+F4)转化,实现固化稳定;添加PVC仅对生物炭中Cr和As有固化稳定作用,对其他重金属有明显活化作用。四种生物炭中的重金属浸出量低于GB5085.3-2007浸出毒性鉴别标准规定的限值,生态风险均明显地降低至轻微风险水平,表明添加PE、PP、PS和PVC与污泥混合热解所得生物炭的应用不会带来新的环境风险,这为污泥与废塑料协同处置工艺提供了良好的理论支撑。 相似文献
995.
In the present study, super-capacitive behavior of spinel Zn-Co oxides (with different Zn+2/Co+2 mol ratio) has been thoroughly investigated. The spinel of transition metal oxides with different morphologies has been synthesized with hydrothermal method on Ni foam as substrate layer. The specific capacitance of the Zn-Co oxide electrode prepared at 180 °C for 5 h with different Zn+2/Co+2 mol ratios of 1:0, 2:1, 1:1, 1:2, 0:1 were investigated and measured 405, 842, 726, 1237, 705 F g?1, respectively at 50 mV s?1 scan rate. Zn-Co oxide with Zn+2/Co+2 mol ratio of 1:2 was also synthesized at two different temperatures of 120 and 150 °C for 5 h with the specific capacitance of 1147, 917 F g?1 at 50 mV s?1 scan rate, respectively. Among the obtained data, the sample with Zn+2/Co+2 mol ratio of 1:2 prepared at 180 °C for 5 h possessed highest specific capacitance. The cyclic life of this electrode showed 92% capacitance retention after 1000 cycle of charge-discharge. All results revealed that Zn-Co oxides had excellent supercapacitive properties due to multiple oxidation states and fast ion/electron transfer at the surface of electrode which could be offered as suitable devices for energy storage applications. 相似文献
996.
In this study, the influences of thin film thickness and post-annealing process on the magnetic properties of CoFeB thin films were investigated. The angular dependency and linewidth of the ferromagnetic resonance signal were used to explore the magnetic behavior of sputtered single-layer and trilayer thin film stacks of CoFeB. A micromagnetic simulation model was employed based on the metropolis algorithm comprising the demagnetizing field and in-plane induced uniaxial anisotropy terms with all relevant contributions. Our results reveal that the direction of magnetization changes from in-plane to out-of-plane as a result of the annealing process and induces a perpendicular magnetic anisotropy in the 1-nm thick CoFeB thin film. The ferromagnetic resonance (FMR) linewidth can be defined well by the intrinsic Gilbert damping effect and the magnetic inhomogeneity contribution in both as-grown and annealed samples. The difference between the linewidths of the single and trilayer film is mainly caused by the spin pumping effect on damping which is associated with the interface layers. 相似文献
997.
昔格达地层性质特殊,强度低,遇水极易崩解,在地质构造与水力作用下,极易发生滑塌。在调查研究的基础上,介绍了文武坡喇嘛溪沟重力侵蚀作用下昔格达地层滑坡的地层岩性、地质构造等工程地质条件及地表水、地下水等水文地质条件,重点分析了滑坡形成原因及影响因素,认为滑坡发生的易发斜坡坡度、坡角与高度,并按坡度对斜坡按危险性分成了3级,得出了滑坡易发坡度,为滑坡稳定性评价提供了依据,最后提出了适合于地质条件的填方反压结合排水沟的整治措施。 相似文献
998.
An alternative way of estimating the durability of structural plastics under stresses = const 0.4-0.8f(f is the failure stress) based on test data obtained in multiple rectangular loading-rest cycles is proposed. It is also suggested to employ the decrease in the instantaneous elastic modulus as a criterion for evaluating the residual service life of plastic parts and structures and elucidating the reasons for their early failure. For the first time, a possibility of considerably increasing the durability and endurance of structural plastics under short pulsed loadings with relatively long interruptions at the initial stage of stress concentration is considered. The cases of a significantly increased endurance of plastics caused by long interruptions after some fatigue loading by high-frequency tension cycles with a zero maximum stress are explained. First experimental confirmations of an increased durability and endurance of microcomposites subjected to short pulsed loadings alternating with long interruptions are obtained. The evolution of the effect of the loading-rest modes on the durability of massive specimens, microcomposites, and dry fibrous reinforcing fillers is demonstrated with examples of a glass-fabric laminate, a microcomposite, and a nonimpregnated glass strand. 相似文献
999.
Roussel F Saidi S Guittard F Geribaldi S 《The European physical journal. E, Soft matter》2002,8(3):283-288
The thermophysical properties of fluorinated acrylate homopolymers are investigated by differential scanning calorimetry (DSC)
and optical microscopy and discussed in terms of relative lengths of the fluorinated chain and the hydrocarbon spacer between
the acrylate moiety and the fluorinated chain. These compounds exhibit an intrinsic microphase-separation (Isotropic+Isotropic
morphology) occurring between the fluorinated chains and the acrylate polymer backbone. It is shown that the enthalpy of mixing
is a function of the length of the lateral fluorocarbon chains. The thermophysical behaviour of these materials may be regarded
as demixed systems exhibiting an Upper Critical Solution Temperature. The photopolymerization process of one of the monomer
is studied by isothermal photocalorimetry. High acrylate double-bond conversion and fast curing rates were obtained thus demonstrating
the promising use of these materials for coating and film processing applications using UV-curing techniques.
Received 30 January 2002 相似文献
1000.
Recent experiments have demonstrated that the dynamics in liquids close to the glass transition temperature is strongly heterogeneous.
The characteristic size of these heterogeneities has been measured to be a few nanometers at T
g. We extend here a recent model for describing the heterogeneous nature of the dynamics which allows both to derive this length
scale and the right orders of magnitude of the heterogeneities of the dynamics close to the glass transition. Our model allows
then to interpret quantitatively small probes diffusion experiments.
Received 29 March 2002 and Received in final form 11 November 2002
RID="a"
ID="a"e-mail: long@lps.u-psud.fr 相似文献