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991.
992.
In this paper, we study a generalized Nicholson??s Blowflies model with feedback control and multiple time-varying delays. Under proper conditions, we employ a novel proof to establish some criteria to guarantee the global exponential convergence and permanence of this model. Moreover, we give two examples to illustrate our main results. 相似文献
993.
Complex new materials from simple chemistry: Combining an amino‐substituted polysiloxane and carboxylic acids
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Yong He Hui Zhao Miao Yao Richard G. Weiss 《Journal of polymer science. Part A, Polymer chemistry》2017,55(23):3851-3861
Changes in rheological, adhesive, and swelling properties of quaternary salts, made by adding one of eight mono‐ or six α,ω‐alkanedioic acids (the latter with two to six or nine carbon atoms) to 6‐7PSil (a polysiloxane with 6%–7% of the monomer units contain a 3‐aminopropyl group) have been correlated with the salt structures. The simple acid‐base chemistry initiates drastic changes in the bulk properties of the materials that depend on the amount and type of the added acid. Thus, the quaternized forms of the 6‐7PSil have significantly enhanced viscoelastic and adhesive properties compared to those of the initial polysiloxane, and they can swell selectively liquids based on their polarity. Also, interpenetrating networks have been made in situ by photopolymerization of salts with vinylic carboxylic acids. DFT calculations on model systems consisting of dimethylammonium α,ω‐alkanedioate salts with two to six carbon atoms provide insights into the interactions responsible for the unexpected dependence of the properties of the 6‐7PSil salts on the chain lengths of the diacids. The potential for applying the methodologies described here to systems with other amino‐substituted polymers and other acid types is noted. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3851–3861 相似文献
994.
Wei Zhao Yi Zhang Xiao Wang Xiaowen Hu Feng Liu Thomas P. Russell Guofu Zhou 《Journal of polymer science. Part A, Polymer chemistry》2018,56(20):1369-1375
Block copolymer (BCP) films with long-range lateral ordering and orientation are crucial for many applications. Here, we report a simple, versatile strategy based on a solution casting procedure, to produce millimeter thick film of BCPs with highly oriented nanostructures. Transmission electron microscope (TEM), small angle X-ray scattering (SAXS), and Hansen solubility parameters were used to study the morphology and interactions of the system. A variety of BCP-solvent pairs were investigated. Factors including set-up geometry, BCP characteristics, solvent evaporation, surface tension, and interactions, such as solvent-BCP, solvent-substrate, and BCP-substrate were examined. A mechanism is proposed to describe the observed long-range lateral ordering and orientation in films up to 1 mm in thickness. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1369–1375 相似文献
995.
996.
We present a high power red-green-blue (RGB) laser light source based on cascaded quasi-phasematched wavelength conversions
in a single stoichiometric lithium tantalate. The superiority of the experimental setup is: the facula of the incident beam
is elliptical to increase interaction volume, and the cavity was an idler resonant configuration for realizing more efficient
red and blue light output. An average power of 2 W of quasi-white-light was obtained by proper combination of the RGB three
colors. The conversion efficiency for the power of the quasi-white-light over pump power reached 36%. This efficiency and
powerful RGB laser light source has potential applications in laser-based projection display et al. 相似文献
997.
Yingshuai Zhao Xiaobo Zhao Zuo-Jun Max Shen 《The Journal of the Operational Research Society》2016,67(9)
A behavioural study on the newsvendor problem without demand distribution knowledge or realized demands is conducted. We configure a censored-information scenario, where only sales data in history are provided. With laboratory experiments, we analyse participants ordering levels and ordering oscillations over time. It is observed that participants perform a significant learning process in the censored-information scenario. Moreover, we find that participants make orders by anchoring on the previous-period sales and adjusting to an adapted inventory level. On the basis of the observations, we propose an exponential-type learning (EXP) model to describe the behaviour of decision makers. Comparing with a chasing model that is popularly used in the full-information scenario, the EXP model is more recommended in the censored-information scenario. 相似文献
998.
Ytterbium, erbium, aluminum tri-doped zinc oxide crystal was synthesized, which can turn color from red to green up-conversion luminescence through adjusting aluminum content. When the aluminum concentration reached 4?mol%, the color of up-conversion emission first turn from red to green. Meanwhile, the ratio of red to green emission reduced from 25.32 to 0.26, and the coordinates of chromaticity coordinate calculation changes from (0.5749, 0.3378) to (0.2190, 0.7169) with aluminum concentration range from 0 to 4?mol%. The up-conversion emission peaks at 521, 542, and 660?nm of sample originate from the transitions of 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2 of erbium ions, respectively. X-ray diffraction patterns perform the better crystallization degree with increasing aluminum concentration. The scanning electron microscopy images show the porous and lamellar structures with different aluminum concentrations. A convenient but effective design to obtain ytterbium, erbium, aluminum tri-doped zinc oxide up-conversion luminescence is reported, which can turn color from red to green. 相似文献
999.
1000.
Jin Wang HongLei Zhan LiPing He Kun Zhao HuiBin Lü KuiJuan Jin GuoZhen Yang 《中国科学:物理学 力学 天文学(英文版)》2016,59(11):114221
正Dear Editors,The evaluation of the oil-gas resources’potential depends on the characterization of reservoirs.The geometry of the pore-crack structures and the compositions of the pore walls have influence on hydrocarbon production about capillarity and permeability[1].Besides,it has been known that the adsorption phenomenon in micro-structure plays a significant role in oil-gas reservoirs.Some techniques have been applied to characterize conventional and unconventional reservoirs, 相似文献