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排序方式: 共有154条查询结果,搜索用时 21 毫秒
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Aguilar-Arevalo AA Bazarko AO Brice SJ Brown BC Bugel L Cao J Coney L Conrad JM Cox DC Curioni A Djurcic Z Finley DA Fleming BT Ford R Garcia FG Garvey GT Green C Green JA Hart TL Hawker E Imlay R Johnson RA Kasper P Katori T Kobilarcik T Kourbanis I Koutsoliotas S Laird EM Link JM Liu Y Liu Y Louis WC Mahn KB Marsh W Martin PS McGregor G Metcalf W Meyers PD Mills F Mills GB Monroe J Moore CD Nelson RH Nienaber P Ouedraogo S Patterson RB Perevalov D Polly CC Prebys E Raaf JL Ray H Roe BP 《Physical review letters》2007,98(23):231801
The MiniBooNE Collaboration reports first results of a search for nu e appearance in a nu mu beam. With two largely independent analyses, we observe no significant excess of events above the background for reconstructed neutrino energies above 475 MeV. The data are consistent with no oscillations within a two-neutrino appearance-only oscillation model. 相似文献
126.
An international intercomparison exercise for the determination of purified microcystin-LR and microcystins in cyanobacterial field material 总被引:6,自引:0,他引:6
Fastner J Codd GA Metcalf JS Woitke P Wiedner C Utkilen H 《Analytical and bioanalytical chemistry》2002,374(3):437-444
The comparability of current microcystin analysis methods has been evaluated in an international intercomparison exercise. The focus was on the analysis of microcystins by high-performance liquid chromatography coupled with ultraviolet or photodiode-array detection (HPLC-PDA/UV), currently the most widespread method for microcystin analysis, but the exercise was open for other methods such as enzyme-linked immunosorbent assay (ELISA), protein phosphatase inhibition assay (PPA) and high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS).Thirty-one laboratories from 13 countries participated in the study. For a microcystin-LR (MC-LR) standard solution (S1) of undisclosed quantity, and for a field sample (S3) from a natural cyanobacterial bloom, repeatabilities between 4 and 15% and reproducibilities between 24 and 49% were obtained. No significant differences between single methods were found for S1 and S3, except for a significantly higher repeatability value of ELISA for S1. However, the analysis of microcystins in the field sample (S3) by HPLC-PDA/UV was significantly more variable than for the standard solution (S1). Both the extraction and the analysis of the microcystins appeared to contribute to this variability.It is concluded that standard MC-LR (S1) can be measured with adequate precision by all participating laboratories independently of the method used. With respect to the different methods used the results for the field sample can also be regarded as satisfactory, but clearly showed the need for improvement by standardisation between laboratories. Furthermore, quantification with in-house standards compared to quantification using the supplied MC-LR standard indicated that routine microcystin analysis in laboratories may be also influenced by the variability of available standards, emphasising the need for the production of certified reference materials (CRM). 相似文献
127.
An efficient fiberoptic interface system was developed to convert a Gary 14 H spectrophotometer into a fiberoptic instrument. This new spectrophotometer can be used to study the UV-visible and near-IR absorption spectroscopy of radioactive samples and wastes in a confined environment. 相似文献
128.
Frenkel AI Pease DM Budnick JI Metcalf P Stern EA Shanthakumar P Huang T 《Physical review letters》2006,97(19):195502
Structural transformations around both V and Cr atoms in (V1-xCrx)2O3 across its metal-insulator transition (MIT) at x approximately 0.01 are studied by extended x-ray absorption fine-structure technique. Our new results for Cr made possible by the use of a novel x-ray analyzer that we developed reveal the substitutional mechanism of Cr doping. We find that this system has a buckled structure with short Cr-V and long V-V bonds. This system of bonds is disordered around the average trigonal lattice ascertained by x-ray diffraction. Such local distortions can result in a long range strain field that sets in around dilute Cr atoms in microscopic regions. We suggest that such locally strained regions should be insulating even at small x. The possibility of local insulating regions within a metallic phase, first suggested by Rice and Brinkman in 1972, remains unaccounted for in modern MIT theories. 相似文献
129.
We present a programmable multitap microwave photonic filter with an arbitrary phase response operating over a broad bandwidth. Complex coefficient taps are achieved by optical line-by-line pulse shaping on a 10 GHz flat optical frequency comb using a novel interferometric scheme. Through high-speed real-time measurements, we demonstrate programmable chirp control of a waveform via phase filtering. This achievement enables us to compress broadband microwave signals to their corresponding bandwidth-limited pulse duration. 相似文献
130.
Park IH Schnetzer S Green J Sakamoto S Sannes F Stone R Trentalange S Vinson J Bacala A Imlay R Kirk P Lim J McNeil RR Metcalf W Cheng CP Li J Li YK Mao ZP Xu YT Zhu YC Abashian A Gotow K Low EH Mattson ME Naito F Piilonen L Sterner KL Lusin S Rosenfeld C Wang AT Wilson S Frautschi M Kagan H Kass R Trahern CG Ko W Lander RL Maeshima K Malchow RL Smith JR Sparks K Williams MC Abe K Fujii Y Higashi Y Kim SK Kurihara Y Maki A Nozaki T Omori T Sagawa H Sakai Y Sugimoto Y Takaiwa Y Terada S 《Physical review letters》1989,62(15):1713-1716