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排序方式: 共有188条查询结果,搜索用时 609 毫秒
111.
Brandon J. O'Neill David H. K. Jackson Anthony J. Crisci Carrie A. Farberow Fengyuan Shi Ana C. Alba‐Rubio Junling Lu Paul J. Dietrich Xiangkui Gu Christopher L. Marshall Peter C. Stair Jeffrey W. Elam Jeffrey T. Miller Fabio H. Ribeiro Paul M. Voyles Jeffrey Greeley Manos Mavrikakis Susannah L. Scott Thomas F. Kuech James A. Dumesic 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2013,125(51):14068-14068
112.
Igor V. Chernushevich Samuel I. Merenbloom Suya Liu Nic Bloomfield 《Journal of the American Society for Mass Spectrometry》2017,28(10):2143-2150
Orthogonal injection time-of-flight (orthoTOF) mass spectrometry (MS) is the most prevalent form of TOFMS, owing to its greater control over incoming ion energy, the ability to correct for aberrations in incoming ion velocity and position, and its ability to provide an entire mass spectrum within a single scan. However, the duty cycle of orthoTOFMS is low compared with scanning analyzers, which can have 100% duty cycle when measuring a single type of ion. Typical duty cycles for orthoTOFMS range from 1% to 30%, depending on instrument geometry. Generally, as instrument resolution increases, duty cycle decreases. Additionally, the greatest duty cycle is achieved for the highest m/z ion recorded in the spectrum, and decreases for all other ions as a function of m/z. In a prior publication [Loboda, A.V.; Chernushevich, I.V. J. Am. Soc. Mass Spectrom. 20, 1342–1348 (20)], a novel trapping/release method for restoring the duty cycle of a V-geometry orthoTOFMS to near 100% (referred to as “Zeno pulsing”) was presented. Here, we apply that method to a W-TOF geometry analyzer with analog detection. Across a m/z range of 100–2000, sensitivity gains of ~5–20 are observed, for total ion currents approaching ~107 ions·s?1. Zeno pulsing, or similar strategies for restoring duty cycle, will continue to be important as instrument resolution in orthoTOFMS is increased through the use of ion mirrors. 相似文献
113.
Y. Y. C. Yeung Lam Ko P. Cosquer P. Pellon J. Hamelin R. Carrie 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):523-526
Abstract Diels Alder reaction provides an easy and general access to functionalized Δ3 phosphabenzenes after aromatization with the possibilities of introducing the functional group either with the diene or the phosphaalkene. 相似文献
114.
Dudzinski KM Brown SJ Lammers M Lucke K Mann DA Simard P Wall CC Rasmussen MH Magnúsdóttir EE Tougaard J Eriksen N 《The Journal of the Acoustical Society of America》2011,129(1):436-448
Deployment of any type of measuring device into the ocean, whether to shallow or deeper depths, is accompanied by the hope that this equipment and associated data will be recovered. The ocean is harsh on gear. Salt water corrodes. Currents, tides, surge, storms, and winds collaborate to increase the severity of the conditions that monitoring devices will endure. All ocean-related research has encountered the situations described in this paper. In collating the details of various deployment and recovery scenarios related to stationary passive acoustic monitoring use in the ocean, it is the intent of this paper to share trouble-shooting successes and failures to guide future work with this gear to monitor marine mammal, fish, and ambient (biologic and anthropogenic) sounds in the ocean-in both coastal and open waters. 相似文献
115.
Ping Liu Thomas J. Lanza Jr.James P. Jewell Carrie P. JonesWilliam K. Hagmann Linus S. Lin 《Tetrahedron letters》2003,44(49):8869-8871
A highly active catalyst system for the heteroarylation of acetone has been identified. The coupling between the in situ generated tributyltin enolate of acetone and a variety of heteroaromatic bromides, chlorides, and triflates in the presence of this catalyst system provided arylacetones in good yields. 相似文献
116.
Ikanovic M Rudzinski WE Bruno JG Allman A Carrillo MP Dwarakanath S Bhahdigadi S Rao P Kiel JL Andrews CJ 《Journal of fluorescence》2007,17(2):193-199
A novel assay was developed for the detection of Bacillus thuringiensis (BT) spores. The assay is based on the fluorescence observed after binding an aptamer-quantum dot conjugate to BT spores. The in vitro selection and amplification technique called SELEX (Systematic Evolution of Ligands by EXponential enrichment) was used in
order to identify the DNA aptamer sequence specific for BT. The 60 base aptamer was then coupled to fluorescent zinc sulfide-capped,
cadmium selenide quantum dots (QD). The assay is semi-quantitative, specific and can detect BT at concentrations of about
1,000 colony forming units/ml. 相似文献
117.
118.
In this study, Saccharomyces cerevisiae yeast lysate is used to demonstrate how a simple wash procedure can improve IEF of IPG strips passively rehydrated in the presence of NaCl. By performing three 10 min washes after IPG strip rehydration and before IEF, corresponding second-dimensional gels from strips containing NaCl look similar to control strips while the second-dimensional gels of unwashed strips contains streaks and spaces devoid of protein. Up to 500 mM NaCl was added to the yeast lysate and successfully focused following this wash regime. Protein loss due to the washes was determined to be minimal by comparing replicates of washed and unwashed strips and analyzing the densities of their corresponding second-dimensional gel spots. In the event of unknown salt contamination, indicated by low voltage during focusing, it is possible to stop focusing, wash the strips, and then continue focusing with acceptable second dimension results. 相似文献
119.
120.
Cedervall PE Dey M Li X Sarangi R Hedman B Ragsdale SW Wilmot CM 《Journal of the American Chemical Society》2011,133(15):5626-5628
We present the 1.2 ? resolution X-ray crystal structure of a Ni-methyl species that is a proposed catalytic intermediate in methyl-coenzyme M reductase (MCR), the enzyme that catalyzes the biological formation of methane. The methyl group is situated 2.1 ? proximal of the Ni atom of the MCR coenzyme F(430). A rearrangement of the substrate channel has been posited to bring together substrate species, but Ni(III)-methyl formation alone does not lead to any observable structural changes in the channel. 相似文献