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排序方式: 共有2047条查询结果,搜索用时 296 毫秒
91.
92.
Yun‐Hsuan Huang Shu‐Hsien Huang Wei‐Chi Chao Chi‐Lan Li Yun‐Ying Hsieh Wei‐Song Hung Der‐Jang Liaw Chien‐Chieh Hu Kueir‐Rarn Lee Juin‐Yih Lai 《Polymer International》2014,63(8):1478-1486
To improve the pervaporation performance in separating an aqueous ethanol solution, polyamide thin‐film composite (TFC) membranes (m‐tolidine‐H‐TMC/mPAN) were prepared through the interfacial polymerization reaction between trimesoyl chloride (TMC) and 2,2'‐dimethylbenzidine hydrochloride (m‐tolidine‐H) on the surface of a modified polyacrylonitrile (mPAN) membrane. The effects of the feed ethanol concentration on the pervaporation performance and the durability of m‐tolidine‐H‐TMC/mPAN TFC membranes were investigated. To choose the optimal mPAN membrane as the TFC substrate, the effect of hydrolysis time on the chemical properties and separation performance of an mPAN substrate was also studied. An appropriate hydrolysis time of 15 min was chosen to obtain the mPAN substrate due to the corresponding high permeation flux. The m‐tolidine‐H‐TMC/mPAN TFC membrane exhibited a high pervaporation performance for ethanol dehydration. A positron annihilation lifetime spectroscopy experiment was used to estimate the mean free‐volume radius of the m‐tolidine‐H‐TMC polyamide selective layer, which lay between the radii of the water and ethanol molecules. © 2013 Society of Chemical Industry 相似文献
93.
Solution‐processable and electroactive aromatic polyamides with 3,5‐bis(trifluoromethyl)triphenylamine moiety 下载免费PDF全文
New fluorine‐containing, triphenylamine‐based diamine and dicarboxylic acid monomers, namely 3,5‐bis(trifluoromethyl)‐4′,4″‐diaminotriphenylamine and 3,5‐bis(trifluoromethyl)‐4′,4″‐dicarboxytriphenylamine, were synthesized and polymerized with commercially available aromatic dicarboxylic acids and diamines, respectively, leading to two series of aromatic polyamides, 5a–h and 7a–e . Most of the polyamides were amorphous and readily soluble in many common organic solvents and could be solution‐cast into transparent, flexible and strong films with good mechanical properties. The polyamides had useful levels of thermal stability associated with high glass transition temperatures of 273–305 °C and 10% weight‐loss temperatures in excess of 500 °C. Cyclic voltammograms of films of polymers 5a–h on indium–tin oxide‐coated glass substrates exhibited reversible oxidation redox couples with E1/2 around 1.15 V versus Ag/AgCl in tetrabutylammonium perchlorate/acetonitrile solution, accompanied by a color change from colorless neutral state to reddish brown oxidized state. The 7 series polymers displayed a higher oxidation potential and less electrochemical stability as compared to the 5 series analogues. © 2017 Society of Chemical Industry 相似文献
94.
Hung‐Yu Chien 《中国工程学刊》2013,36(3):527-532
Abstract Even though there have been many research studies on proxy signature schemes, only Shao's proxy multi‐signature scheme is based on the factoring problem (FAC). Unfortunately, Shao's scheme requires sequential signing operations and strict order of the modulus. It is not practical and not efficient. We, therefore, based on RSA cryptosystems, propose new proxy‐protected mono‐signature and proxy‐protected multi‐signature schemes. In contrast to their counterparts, our scheme allows parallel signing operations and also improves the signers’ computational performance. 相似文献
95.
Protein therapy exhibits several advantages over small molecule drugs and is increasingly being developed for the treatment of disorders ranging from single enzyme deficiencies to cancer. Cell-penetrating peptides (CPPs), a group of small peptides capable of promoting transport of molecular cargo across the plasma membrane, have become important tools in promoting the cellular uptake of exogenously delivered proteins. Although the molecular mechanisms of uptake are not firmly established, CPPs have been empirically shown to promote uptake of various molecules, including large proteins over 100 kiloDaltons (kDa). Recombinant proteins that include a CPP tag to promote intracellular delivery show promise as therapeutic agents with encouraging success rates in both animal and human trials. This review highlights recent advances in protein-CPP therapy and discusses optimization strategies and potential detrimental effects. 相似文献
96.
Estimation of illuminant chromaticity based on highlight detection for face images with varying illumination 下载免费PDF全文
Illuminant chromaticity estimation is required in the fields of the tracking and recognition of human faces, compensation and detection of skin color, image reproduction, and color constancy. This article proposes a simple and effective method to estimate the illuminant chromaticity using highlights from the face region. We first select the candidate points through the detection of highlights around the leftmost pixel of the rg chromaticity space from the facial images under various illuminant conditions and then estimate the illuminant chromaticity by averaging the chromaticities of the candidate points. To enhance the illuminant chromaticity estimation accuracy, we propose a more elaborate estimation method, which effectively readjusts the candidate points of the highlight regions according to the conditions derived from two ethnic and three illuminant groups. The experiment results show that our proposed method reliably estimates the illuminant chromaticity under various color temperatures and illuminant directions. © 2012 Wiley Periodicals, Inc. Col Res Appl, 39, 188–199, 2014 相似文献
97.
This study investigates electromigration in Bi2Te3 thermoelectric (TE) material systems and the effectiveness of the diffusion barrier under current. The Peltier effect on the interfacial reaction was decoupled from the effect of electromigration. After connecting p- and n-type Bi2Te3 to Sn3Ag0.5Cu (SAC305) solders, different current densities were applied at varying temperatures. The Bi2Te3 samples were fabricated by the spark plasma sintering technique, and an electroless nickel-phosphorous (Ni-P) layer was deposited at the solder/TE interfaces. The experimental results confirm the importance of the Ni diffusion barrier in joint reliability. Intermetallic compound layers (Cu,Ni)6Sn5 and NiTe formed at the solder/Ni-P and Ni-P/substrate interfaces, respectively. The experimental results indicate that the mechanism of NiTe and (Cu,Ni)6Sn5 compound growth was dominated by the Peltier effect at high current density. When the current density was low, the growth of NiTe was affected by electromigration but the changes of thickness for (Cu,Ni)6Sn5 were not obvious. 相似文献
98.
99.
Siang Chen Wu Pi Fen Lu Yu Chien Lin Pei Chung Chen Chi Mei Lee 《International Journal of Hydrogen Energy》2012
Photobiological H2 production is a promising method for renewable energy development. An innovative system that co-cultivating Rhodopseudomonas palustris WP3-5 and Anabaena sp. CH3 was carried out to estimate the effect of co-cultivation on H2 production enhancement. H2 production prolongation and enhancement were observed due to the light and metabolic compatibility of these two strains. Co-culture system served by acetate and fructose as carbon source can accumulate H2 in 140.8 mL, almost double than the sum of individuals. Moreover, the enhancement of H2 production was significantly affected by the mixed ratio of two strains. The mixed ratio (WP3-5:CH3) of 1:2 showed a highest H2 production rate in 44.8 mL-H2/L-culture/h, and both 2:1 and 1:2 exhibited a relatively high substrate conversion efficiency during the latest period of cultivation, whereas the mixed ratio of 1:1 and 3:1 only revealed a prolongation in H2 production due to metabolic compatibility of two strains. 相似文献
100.
This study used ultrasonic scanning to investigate the contact between end-mill cutters and workpieces. This method is novel for endmills and has not been applied before. Contact shapes were disclosed and a comparison of contact images and areas was made from the experimental results. It is not a dynamic or online monitoring during the cutter machining process. Instead, it is only a static measurement because the objective is to provide the information for users to know the area size of a worn end-mill cutter. The 2D maps show an apparent change not only in area sizes but also in contact shapes for the used endmills. The 3D maps disclose the information for which region is in light or heavy contact. 相似文献