排序方式: 共有12条查询结果,搜索用时 15 毫秒
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Cletus A D'Souza Vikramjit Chopra Richard Varhol Yuan-Yun Xie Slavita Bohacec Yongjun Zhao Lisa LC Lee Mikhail Bilenky Elodie Portales-Casamar An He Wyeth W Wasserman Daniel Goldowitz Marco A Marra Robert A Holt Elizabeth M Simpson Steven JM Jones 《BMC neuroscience》2008,9(1):1-14
Background
We have recorded responses from single neurons in murine visual cortex to determine the effectiveness of the input from the two murine cone photoreceptor mechanisms and whether there is any unique selectivity for cone inputs at this higher region of the visual system that would support the possibility of colour vision in mice. Each eye was stimulated by diffuse light, either 370 (strong stimulus for the ultra-violet (UV) cone opsin) or 505 nm (exclusively stimulating the middle wavelength sensitive (M) cone opsin), obtained from light emitting diodes (LEDs) in the presence of a strong adapting light that suppressed the responses of rods.Results
Single cells responded to these diffuse stimuli in all areas of striate cortex. Two types of responsive cells were encountered. One type (135/323 – 42%) had little to no spontaneous activity and responded at either the on and/or the off phase of the light stimulus with a few impulses often of relatively large amplitude. A second type (166/323 – 51%) had spontaneous activity and responded tonically to light stimuli with impulses often of small amplitude. Most of the cells responded similarly to both spectral stimuli. A few (18/323 – 6%) responded strongly or exclusively to one or the other spectral stimulus and rarely in a spectrally opponent manner.Conclusion
Most cells in murine striate cortex receive excitatory inputs from both UV- and M-cones. A small fraction shows either strong selectivity for one or the other cone mechanism and occasionally cone opponent responses. Cells that could underlie chromatic contrast detection are present but extremely rare in murine striate cortex. 相似文献3.
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Reily MD Robosky LC Manning ML Butler A Baker JD Winters RT 《Journal of the American Chemical Society》2006,128(38):12360-12361
A new NMR chemical shift standard and pH indicator, difluorotrimethylsilanylphosphonic acid (DFTMP), is described, and the utility of this reagent is demonstrated for in situ determination of pH in complex biofluids. The pH dependence of this reagent allows accurate in situ determination of aqueous solution pH to within an RMSE of 0.02 pH units over a pH range of 5 to 8. Advantages of this reagent over previously described pH-sensitive components include (1) lack of metal binding affinity, (2) minimal disturbance of endogenous spectral regions, and (3) the potential to function as a multinuclear pH indicator and chemical shift reference point for 19F, 1H, and 31P nuclei. This reagent will be generally useful for NMR experiments on biological systems where the pH needs to be accurately measured at the moment of data acquisition. 相似文献
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Epitaxial La1−x
Pb
x
MnO3 (LPMO) thin films, grown on (100) SrTiO3 substrates by laser ablation technique at different temperatures between 600 and 850°C, have been characterized for electrical
and magnetic properties. The temperature dependence of resistivity showed that the metal-insulator transition temperature
(T
MI) decreases with increasing substrate temperature, which has been attributed to decrease in Pb content in the filsm. The YBa2Cu3O
x
/La1−x
MnO3 heterostructures, exhibiting both superconductivity and ferromagnetism, have been fabricated. 相似文献
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Let f, g: (Rn, 0) (Rp, 0) be two C map-germs. Then f and gare C0-equivalent if there exist homeomorphism-germs h and lof (Rn, 0) and (Rp, 0) respectively such that g = l f h1.Let k be a positive integer. A germ f is k-C0-determined ifevery germ g with jk g(0) = jk f(0) is C0-equivalent to f. Moreover,we say that f is finitely topologically determined if f is k-C0-determinedfor some finite k. We prove a theorem giving a sufficient conditionfor a germ to be finitely topologically determined. We explainthis condition below. Let N and P be two C manifolds. Consider the jet bundle Jk(N,P) with fiber Jk(n, p). Let z in Jk(n, p) and let f be suchthat z = jkf(0). Define
Whether (f) < k depends only on z, not on f. We can thereforedefine the set
Let Wk(N, P) be the subbundle of Jk(N, P) with fiber Wk(n, p).Mather has constructed a finite Whitney (b)-regular stratificationSk(n, p) of Jk(n, p) Wk(n, p) such that all strata aresemialgebraic and K-invariant, having the property that if Sk(N,P) denotes the corresponding stratification of Jk(N, P) Wk(N, P) and f C(N, P) is a C map such that jkf is multitransverseto Sk(N, P), jkf(N) Wk(N, P) = and N is compact (or f is proper),then f is topologically stable. For a map-germ f: (Rn, 0) (Rp, 0), we define a certain ojasiewiczinequality. The inequality implies that there exists a representativef: U Rp such that jkf(U 0) Wk (Rn, Rp = and suchthat jkf is multitransverse to Sk (Rn, Rp) at any finite setof points S U 0. Moreover, the inequality controlsthe rate jkf becomes non-transverse as we approach 0. We showthat if f satisfies this inequality, then f is finitely topologicallydetermined. 1991 Mathematics Subject Classification: 58C27. 相似文献
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Strife RJ Robosky LC Garrett G Ketcha MM Shaffer JD Zhang N 《Rapid communications in mass spectrometry : RCM》2000,14(4):250-260
The analysis of data within multi-generational, genealogical, electrospray ionization/MS(n) fragmentation maps is discussed in reference to the structure elucidation of morphinans, an important class of pharmacological compounds. Various general approaches to separate and understand observed processes are discussed. These include: (1) Simple synthetic schemes incorporating deuterium and (13)C into morphinans to study later-generation, O-methyl group migration; (2) labeling to understand 'intense' signals for even-electron to odd-electron ion 'switching' events; (3) gas phase 'synthesis' of proposed MS(3) ions via an independent route, using chemical ionization (CI) MS/MS of naphthalenes and analysis via a bench-top El/Cl ion trap; (4) a useful synthetic paradigm for generating proposed carbonium ion structures at MS(4) via electrospray ionization (ESI) of easily synthesized amines; (5) the analysis of an oxidation product and correlation of MS(n) data of a switched, odd-electron species with electron ionization and low-pressure, low-energy charge exchange data; and (6) a new way of summarizing MS(n) data. Copyright -Copyright 2000 John Wiley & Sons, Ltd. 相似文献