排序方式: 共有43条查询结果,搜索用时 15 毫秒
31.
This study compared recovery of fecal coliform bacteria from sewage by Colilert-18 and Standard Methods 9222D (membrane-Fecal Coliform medium) in accordance with the U.S. Environmental Protection Agency (EPA) Alternative Test Protocol (ATP). Samples were collected from 10 different wastewater treatment plants in the northeastern United States and tested in a single laboratory. Twenty replicates of each sample were analyzed by each method, and 200 positive and 200 negative responses were confirmed for each method. Recovery of fecal coliforms by Colilert-18 was significantly higher than (8 of 10 sites) or statistically equivalent to (1 of 10 sites) recovery by the reference method (Standard Methods 9222D) for samples from all but one site. Both methods had low false-positive rates (< 2%); however, the false-negative rate observed with Standard Methods 9222D (21.5%) was substantially higher than that observed with Colilert-18 (7%). The accuracy rates of the two methods were calculated as 96.5 and 88.9% for Colilert-18 and Standard Methods 9222D, respectively. The results of this study demonstrate that Colilert-18 meets the acceptance criteria for alternative methods specified in the EPA ATP. 相似文献
32.
33.
Alves GA Amato S Anjos JC Appel JA Bracker SB Cremaldi LM Darling CL Dixon RL Errede D Fenker HC Gay C Green DR Jedicke R Kaplan D Karchin PE Kwan S Leedom I Lueking LH Luste GJ Mantsch PM de Mello Neto JR Metheny J Milburn RH de Miranda JM da Motta Filho H Napier A d'Olivera AB Rafatian A dos Reis AC Reucroft S Ross WR Santoro AF Sheaff M Souza MH Spalding WJ Stoughton C Streetman ME Summers DJ Takach SF Wu Z 《Physical review letters》1992,69(22):3147-3150
34.
Abstract —The transient oxidation and subsequent reduction of P700+ in spinach chloroplasts has been monitored by flash photolysis-electron spin resonance spectroscopy in the presence of various donors and acceptors. In general, the results obtained correlate well with results on Photosystem I subchloroplast particles, with two major differences. For Type A and B intact chloroplasts in the presence of 3-(3, 4-dichlorophenyl)-1, 1-dimethylurea (DCMU), the electron acceptor methyl viologen has no effect on the decay kinetics. This phenomenon is interpreted in terms of a functioning cyclic electron flow path around Photosystem I. Also, the photoresponse of Signal I depends on the length of the photolyzing flash. This is interpreted in terms of the existence of a primary electron donor to P700+ with a transfer time of ? 10 μs. 相似文献
35.
Abstract —Transient decay kinetics of Signal I in spinach subchloroplast particles have been studied in the presence of artificial donors [5-methyl phenazonium methyl sulfate (PMS), 2, 6-dichlorophenolindophenol (DPIP), N, N, N', N'-tetramethyl-p-phenylenediamine (TMPD) and ascorbate], artificial acceptors [benzyl viologen (BV) and methyl viologen (MV)] and various natural donor and acceptor moieties, using the technique of flash photolysis-electron spin resonance spectroscopy. The results are discussed in the framework of three mechanisms for reduction of P700+: (1) direct electron return from the primary acceptor to P700+, (2) cyclic electron flow via an electron carrier, and (3) noncvclic electron flow. 相似文献
36.
Aitala EM Amato S Anjos JC Appel JA Ashery D Banerjee S Bediaga I Blaylock G Bracker SB Burchat PR Burnstein RA Carter T Carvalho HS Costa I Cremaldi LM Darling C Denisenko K Fernandez A Gagnon P Gerzon S Gobel C Gounder K Granite D Halling AM Herrera G Hurvits G James C Kasper PA Kondakis N Kwan S Langs DC Leslie J Lichtenstadt J Lundberg B Manacero A MayTal-Beck S Meadows B de Mello Neto JR Milburn RH de Miranda JM Napier A Nguyen A d'Oliveira AB O'Shaughnessy K Peng KC Perera LP Purohit MV 《Physical review letters》1996,76(3):364-367
37.
Bizau J Esteva J Cubaynes D Wuilleumier FJ Blancard C La Fontaine AC Couillaud C Lachkar J Marmoret R Remond C Bruneau J Hitz D Ludwig P Delaunay M 《Physical review letters》2000,84(3):435-438
Photoionization of Xe4+ to Xe7+ ions was studied by combining an electron cyclotron resonance ion source with synchrotron radiation. Multiconfiguration Dirac-Fock calculations were performed to interpret the data. Many autoionization lines were measured and identified, resulting from excitation of a 4d electron into nf and np orbitals followed by Auger decay of the excited states. Continuum photoionization is negligible for the higher members of the isonuclear series. 相似文献
38.
A biology teacher's acceptance or rejection of evolutionary theory as a scientifically valid explanation is potentially important to the role that evolution takes in the high school biology curriculum. Due to the nature of available instrumentation, our understanding of teacher acceptance of this complex overreaching biological theory may be incomplete or confounded. This paper describes the development and validation of the Measure of Acceptance of the Theory of Evolution (MATE)—a 20-item Likert-scaled instrument that assesses teachers' overall acceptance of evolutionary theory. Chronbach alpha reliability of the MATE is also reported. 相似文献
39.
Alves GA Amato S Anjos JC Appel JA Astorga J Bracker SB Cremaldi LM Dagenhart WD Darling CL Dixon RL Errede D Fenker HC Gay C Green DR Jedicke R Karchin PE Kennedy C Kwan S Lueking LH de Mello Neto JR Metheny J Milburn RH de Miranda JM da Motta Filho H Napier A Passmore D Rafatian A dos Reis AC Ross WR Santoro AF Sheaff M Souza MH Spalding WJ Stoughton C Streetman ME Summers DJ Takach SF Wallace A Wu Z 《Physical review letters》1996,77(12):2392-2395
40.
Pearson P Kepert CM Deacon GB Spiccia L Warden AC Skelton BW White AH 《Inorganic chemistry》2004,43(2):683-691
We report two new synthetic routes to the dinuclear Ru(I) complexes, [Ru(I)(2)(RCO(2))(CO)(4)(N( wedge )N)(2)](+) (N( wedge )N = 2,2'-bipyridine or 1,10-phenanthroline derivatives) that use RuCl(3).3H(2)O as a starting material. Direct addition of the bidentate diimine ligand to a methanolic solution of [Ru(CO)(2)Cl(2)](n) and sodium acetate yielded a mixture of [Ru(I)(2)(MeCO(2))(CO)(4)(N( wedge )N)(2)](+) (N( wedge )N = 4,4'-dmbpy, and 5,6-dmphen), and [Ru(II)(MeCO(2))(2)(CO)(2)(N( wedge )N)] (N( wedge )N = 4,4'-dmbpy and 5,5'-dmbpy). Single-crystal X-ray studies confirmed that the Ru(II) complexes had a trans-acetate-cis-carbonyl arrangement of the ligands. In contrast, the use of sodium benzoate resulted in the unexpected formation of a Ru-C bond producing ortho-cyclometalated complexes, [Ru(II)(O(2)CC(6)H(4))(CO)(2)(N( wedge )N)], where N( wedge )N = bpy or phen. A second approach used ligand exchange between a bidentate ligand (N( wedge )N) and the pyridine ligands of [Ru(I)(RCO(2))(CO)(2)(py)](2) to convert these neutral complexes into [Ru(I)(2)(RCO(2))(CO)(4)(N( wedge )N)(2)](+). This method, although it involved more steps, was applicable for a wider variety of diimine ligands (R = Me and N( wedge )N = 4,4'-dmbpy, 5,5'-dmbpy, 5,6-dmphen; R = Ph and N( wedge )N = bpy, phen, 5,6-dmphen). 相似文献