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排序方式: 共有275条查询结果,搜索用时 15 毫秒
61.
R. Bambha D. C. Hutchings M. J. Snelling P. Likamwa A. Miller A. L. Moretti R. W. Wickman K. A. Stair T. E. Bird J. A. Cavaillès D. A. B. Miller 《Optical and Quantum Electronics》1993,25(12):S965-S971
Picosecond excite-probe studies are performed on a single quantum well waveguide modulator giving a direct measure of the escape of photogenerated carriers from a quantum well. Both the effects of exciton saturation and external field screening are observed in the transient transmission change. The results are consistent with the escape of carriers by thermionic emission. 相似文献
62.
Effect of Acute Exposure to Hydrogen Peroxide on the Production of Phytoplankton and Bacterioplankton in a Mesohumic Lake 总被引:1,自引:0,他引:1
Abstract— Active oxygen species such as hydrogen peroxide are produced as a result of UV radiation interaction with natural organic matter and can build up to high concentrations in many aquatic environments. Although the resulting oxidizing potential may affect biological materials and processes, the ecological effects have not yet been studied in any detail. We examined the influence of hydrogen peroxide exposure on phytoplankton and bacterioplankton production in Lac Cromwell, a small humic lake in the Laurentian Hills (Quebec, Canada). A range of hydrogen peroxide concentrations were added to natural samples that were incubated in situ; results indicate that even small amounts of added hydrogen peroxide (50 n M inhibited bacterial production in this lake. A 100 n M addition inhibited bacteria by as much as 40%. On the other hand, low concentrations of added hydrogen peroxide usually stimulated photosynthesis. Catalase addition to eliminate hydrogen peroxide from water usually stimulated bacterial production but had no effect on algal carbon fixation. If these results represent true changes in growth rate, they indicate very different sensitivities of phytoplankton and bacteria to oxidative stress. 相似文献
63.
64.
Leveraging the Knorr Pyrazole Synthesis for the Facile Generation of Thioester Surrogates for use in Native Chemical Ligation 下载免费PDF全文
Dillon T. Flood Jordi C. J. Hintzen Michael J. Bird Philip A. Cistrone Jason S. Chen Dr. Philip E. Dawson 《Angewandte Chemie (International ed. in English)》2018,57(36):11634-11639
Facile synthesis of C‐terminal thioesters is integral to native chemical ligation (NCL) strategies for chemical protein synthesis. We introduce a new method of mild peptide activation, which leverages solid‐phase peptide synthesis (SPPS) on an established resin linker and classical heterocyclic chemistry to convert C‐terminal peptide hydrazides into their corresponding thioesters via an acyl pyrazole intermediate. Peptide hydrazides, synthesized on established trityl chloride resins, can be activated in solution with stoichiometric acetyl acetone (acac), readily proceed to the peptide acyl pyrazoles. Acyl pyrazoles are mild acylating agents and are efficiently exchanged with an aryl thiol, which can then be directly utilized in NCL. The mild, chemoselective, and stoichiometric activating conditions allow this method to be utilized through multiple sequential ligations without intermediate purification steps. 相似文献
65.
Abe F Albrow MG Amendolia SR Amidei D Antos J Anway-Wiese C Apollinari G Areti H Atac M Auchincloss P Azfar F Azzi P Bacchetta N Badgett W Bailey MW Bao J de Barbaro P Barbaro-Galtieri A Barnes VE Barnett BA Bartalini P Bauer G Baumann T Bedeschi F Behrends S Belforte S Bellettini G Bellinger J Benjamin D Benlloch J Bensinger J Benton D Beretvas A Berge JP Bertolucci S Bhatti A Biery K Binkley M Bird F Bisello D Blair RE Blocker C Bodek A Bokhari W Bolognesi V Bortoletto D Boswell C Boulos T 《Physical review D: Particles and fields》1996,53(3):1051-1065
66.
Abe F Albrow MG Amendolia SR Amidei D Antos J Anway-Wiese C Apollinari G Areti H Atac M Auchincloss P Azfar F Azzi P Bacchetta N Badgett W Bailey MW Bao J de Barbaro P Barbaro-Galtieri A Barnes VE Barnett BA Bartalini P Bauer G Baumann T Bedeschi F Behrends S Belforte S Bellettini G Bellinger J Benjamin D Benlloch J Bensinger J Benton D Beretvas A Berge JP Bertolucci S Bhatti A Biery K Binkley M Bird F Bisello D Blair RE Blocker C Bodek A Bokhari W Bolognesi V Bortoletto D Boswell C Boulos T 《Physical review D: Particles and fields》1996,53(7):3496-3505
67.
Abe F Albrow MG Amidei D Antos J Anway-Wiese C Apollinari G Areti H Atac M Auchincloss P Azfar F Azzi P Bacchetta N Badgett W Bailey MW Bao J de Barbaro P Barbaro-Galtieri A Barnes VE Barnett BA Bartalini P Bauer G Baumann T Bedeschi F Behrends S Belforte S Bellettini G Bellinger J Benjamin D Benlloch J Bensinger J Benton D Beretvas A Berge JP Bertolucci S Bhatti A Biery K Binkley M Bird F Bisello D Blair RE Blocker C Bodek A Bokhari W Bolognesi V Bortoletto D Boswell C Boulos T Brandenburg G 《Physical review letters》1995,74(15):2900-2904
68.
C.W. Bird H.I. Butler M.P.L. Caton E.C.J. Coffee C.J. Hardy T.W. Hart H.J. Mason 《Tetrahedron letters》1985,26(34):4101-4104
The synthesis is described of (±)-6a-oxo-6,9-methano-15-hydroxyprosta-5,13-dienoic acids as stable analogues of prostacyclin with blood platelet aggregation inhibiting activity. 相似文献
69.
J. Lowe S.H. Chew J.M. Nelson C.E. Waltham G.J. Pyle G.T.A. Squier S. Baird C.J. Batty P. Sharman P. Bird A.S. Clough K.R. Parker 《Nuclear Physics B》1982,209(1):16-28
The reaction K?p → Λγ, produced by K? stopping in a liquid hydrogen target, has been studied using a NaI(Tl) gamma-ray spectrometer. The branching ratio is based on 1355 events assigned to this branch. This is in conflict with a previous experiment, but agrees with one of the two published calculations, when recent values for the coupling constants and scattering amplitudes are used. 相似文献
70.
David B. Capps Orson D. Bird Edward F. Elslager Zoe B. Gavrilis Jane A. Roush Paul E. Thompson John W. Vaitkus 《Journal of heterocyclic chemistry》1968,5(3):355-369
The preparation of a variety of novel 1-aryl-4,6-diamino-1,2-dihydro-s-triazines is described. These compounds exhibit an array of contrasting effects on intestinal helminths, bacteria, and dihydrofolic reductase. It is concluded that potent anthelmintic activity among the dihydro-triazines is not dependent solely on the bulky-substituent hypothesis advanced by other investigators, and indeed cannot reliably be predicted on this basis. 相似文献