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排序方式: 共有126条查询结果,搜索用时 0 毫秒
121.
Michael C Breadmore Wojciech Grochocki Umme Kalsoom Mnica N. Alves Sui Ching Phung Masoomeh Tehrani Rokh Joan M. Cabot Alireza Ghiasvand Feng Li Aliaa I. Shallan Aemi S. Abdul Keyon Ala A. Alhusban Hong Heng See Alain Wuethrich Mohamed Dawod Joselito P Quirino 《Electrophoresis》2019,40(1):17-39
One of the most cited limitations of capillary and microchip electrophoresis is the poor sensitivity. This review continues to update this series of biannual reviews, first published in Electrophoresis in 2007, on developments in the field of online/in‐line concentration methods in capillaries and microchips, covering the period July 2016–June 2018. It includes developments in the field of stacking, covering all methods from field‐amplified sample stacking and large‐volume sample stacking, through to isotachophoresis, dynamic pH junction, and sweeping. Attention is also given to online or in‐line extraction methods that have been used for electrophoresis. 相似文献
122.
Adding ultrasonic vibrations to drilling process results in an advanced hybrid machining process, entitled “vibration drilling”. This study presents the design and fabrication of a vibration drilling tool by which both rotary and vibrating motions are applied to drill simultaneously. High frequency and low amplitude vibrations were generated by an ultrasonic transducer with frequency of 19.65 kHz. Ultrasonic transducer was controlled by a MPI ultrasonic generator with 3 kW power. The drilling tool and workpiece material were HSS two-flute twist drill and Al2024-T6, respectively. The aim of this study was investigating on the effect of ultrasonic vibrations on built-up edge, surface quality, chip morphology and wear mechanisms of drill edges. Therefore, these factors were studied in both vibration and ordinary drilling. Based on the achieved results, vibration drilling offers less built-up edge and better surface quality compared to ordinary drilling. 相似文献
123.
Hossein Reza Darabi Mohammad Hashemi Karouei Mohammad Jafar Tehrani Kiomars Aghapoor Mitra Ghasemzadeh Bernhard Neumüller 《Supramolecular chemistry》2013,25(6):462-469
Novel pinacolophanes tethered by methyl and ethyl chains were synthesised and characterised. The stereochemistry of these small-sized cyclophanes was determined by NMR spectral data as well as by single-crystal X-ray analysis. Intramolecular hydrogen bondings in the crystal structure of the molecules play an important role in holding their configuration, while the intermolecular hydrogen bondings lead to a designed arrangement of the molecules. The stereoselective transformation of pinacolophanes to stilbenophanes in improved yield is also reported. 相似文献
124.
We study generalized solutions of the nonlinear wave equation
utt−uss=au+−bu−+p(s,t,u), 相似文献
125.
We consider the question of existence of positive solutions for a class of elliptic problems in all of having a noncoercive linear part and a sign-changing nonlinearity of the form . Received December 20, 1999 / Accepted July 17, 2000 /Published online November 9, 2000 相似文献
126.
Carsten E. Seyfert Christoph Porten Dr. Biao Yuan Selina Deckarm Dr. Fabian Panter Dr. Chantal D. Bader Janetta Coetzee Felix Deschner Dr. Kamaleddin H. M. E. Tehrani Prof. Dr. Paul G. Higgins Prof. Dr. Harald Seifert Prof. Dr. Thomas C. Marlovits Dr. Jennifer Herrmann Prof. Dr. Rolf Müller 《Angewandte Chemie (International ed. in English)》2023,62(2):e202214094
Over recent decades, the pipeline of antibiotics acting against Gram-negative bacteria is running dry, as most discovered candidate antibiotics suffer from insufficient potency, pharmacokinetic properties, or toxicity. The darobactins, a promising new small peptide class of drug candidates, bind to novel antibiotic target BamA, an outer membrane protein. Previously, we reported that biosynthetic engineering in a heterologous host generated novel darobactins with enhanced antibacterial activity. Here we utilize an optimized purification method and present cryo-EM structures of the Bam complex with darobactin 9 (D9), which served as a blueprint for the biotechnological generation of twenty new darobactins including halogenated analogs. The newly engineered darobactin 22 binds more tightly to BamA and outperforms the favorable activity profile of D9 against clinically relevant pathogens such as carbapenem-resistant Acinetobacter baumannii up to 32-fold, without observing toxic effects. 相似文献