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排序方式: 共有223条查询结果,搜索用时 15 毫秒
191.
L. Tandon E. Hastings J. Banar J. Barnes D. Beddingfield D. Decker J. Dyke D. Farr J. FitzPatrick D. Gallimore S. Garner R. Gritzo T. Hahn G. Havrilla B. Johnson K. Kuhn S. LaMont D. Langner C. Lewis V. Majidi P. Martinez R. McCabe S. Mecklenburg D. Mercer S. Meyers V. Montoya B. Patterson R. A. Pereyra D. Porterfield J. Poths D. Rademacher C. Ruggiero D. Schwartz M. Scott K. Spencer R. Steiner R. Villarreal H. Volz L. Walker A. Wong C. Worley 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(2):467-473
The goal of nuclear forensics is to establish an unambiguous link between illicitly trafficked nuclear material and its origin.
The Los Alamos National Laboratory (LANL) Nuclear Materials Signatures Program has implemented a graded “conduct of operations”
type analysis flow path approach for determining the key nuclear, chemical, and physical signatures needed to identify the
manufacturing process, intended use, and origin of interdicted nuclear material. This analysis flow path includes both destructive
and non-destructive characterization techniques and has been exercized against different nuclear materials from LANL’s special
nuclear materials archive. Results obtained from the case study will be presented to highlight analytical techniques that
offer the critical attribution information. 相似文献
192.
Recently, we reported that the natural product derrubone exhibits Hsp90 inhibitory activity. Due to its unique architectural scaffold and proposed rapid assembly, the synthesis of this natural product was pursued with the aim of identifying structure--activity relationships. Synthesis of the natural product was accomplished in eight highly convergent steps, which led to a facile method for the construction of related compounds. Biological evaluation of derrubone and its analogues identified several compounds that exhibit low micromolar inhibitory activity against breast and colon cancer cell lines. 相似文献
193.
Hastings CJ Fiedler D Bergman RG Raymond KN 《Journal of the American Chemical Society》2008,130(33):10977-10983
The tetrahedral assembly [Ga4L6](12-) [L = N,N-bis(2,3-dihydroxybenzoyl)-1,5-diaminonaphthalene) encapsulates a variety of cations, including propargyl enammonium cations capable of undergoing the aza Cope rearrangement. For propargyl enammonium substrates that are encapsulated in the [Ga4L6](12-) assembly, rate accelerations by factors of up to 184 compared with the background reaction rate were observed. After rearrangement, the product iminium ion is released into solution and hydrolyzed, allowing for catalytic turnover. The activation parameters for the catalyzed and uncatalyzed reaction were determined, revealing that a decrease in the entropy of activation is responsible for the observed rate enhancements. The catalyzed reaction exhibits saturation kinetics: the rate data obeyed the Michaelis-Menten model of enzyme kinetics, and competitive inhibition using a nonreactive guest was demonstrated. 相似文献
194.
Troy A Baudino Alex McFadden Charity Fix Joshua Hastings Robert Price Thomas K Borg 《Microscopy and microanalysis》2008,14(2):117-125
Patterning of cells is critical to the formation and function of the normal organ, and it appears to be dependent upon internal and external signals. Additionally, the formation of most tissues requires the interaction of several cell types. Indeed, both extracellular matrix (ECM) components and cellular components are necessary for three-dimensional (3-D) tissue formation in vitro. Using 3-D cultures we demonstrate that ECM arranged in an aligned fashion is necessary for the rod-shaped phenotype of the myocyte, and once this pattern is established, the myocytes were responsible for the alignment of any subsequent cell layers. This is analogous to the in vivo pattern that is observed, where there appears to be minimal ECM signaling, rather formation of multicellular patterns is dependent upon cell-cell interactions. Our 3-D culture of myocytes and fibroblasts is significant in that it models in vivo organization of cardiac tissue and can be used to investigate interactions between fibroblasts and myocytes. Furthermore, we used rotational cultures to examine cellular interactions. Using these systems, we demonstrate that specific connexins and cadherins are critical for cell-cell interactions. The data presented here document the feasibility of using these systems to investigate cellular interactions during normal growth and injury. 相似文献
195.
196.
Abstract— The reaction of luciferase-bound flavin hydroperoxide with both I-1 H and 1–2 H decanal has been examined at 2°C in both low (0.01 M ) and high (0.35 M ) phosphate buffer, pH 7, where the kinetics and deuterium isotope effects are quite different. Upon reaction in both buffers there are rapid (<2 ms) increases in absorption at both 380 and W nm, followed by decay over the subsequent seconds and minutes. The changes at 380 nm exhibit a primary isotope effect and are rapid compared to bioluminescence, indicating that the scission of the aldehyde C — H bond occurs prior to the step responsible for populating the electronically excited state. However, the final absorbance change at 600 nm decays in parallel to bioluminescence under the several different conditions studied, suggesting the involvement of a long-wavelength absorbing flavin species in the production of, the excited state. Evidence is also presented indicating that under certain conditions there may be two (sequential) steps, each of which exhibits a primary isotope effect involving the same H atom. 相似文献
197.
Somov A Schwartz AJ Abe K Abe K Adachi I Aihara H Anipko D Arinstein K Asano Y Aulchenko V Aushev T Aziz T Bahinipati S Bakich AM Balagura V Bay A Bedny I Belous K Bitenc U Bizjak I Blyth S Bondar A Bozek A Bracko M Brodzicka J Browder TE Chang MC Chang P Chao Y Chen A Chen WT Cheon BG Chistov R Choi SK Choi Y Choi YK Chuvikov A Cole S Dalseno J Dash M Dragic J Drutskoy A Eidelman S Epifanov D Gabyshev N Garmash A Gershon T Go A Gokhroo G Golob B Hara K Hara T Hastings NC Hayasaka K Hayashii H 《Physical review letters》2006,96(17):171801
We have measured the branching fraction , longitudinal polarization fraction f(L), and CP asymmetry coefficients A and S for B(0) --> rho(+) rho(-) decays with the Belle detector at the KEKB e(+) e(-) collider using 253 Fb(-1) of data. We obtain B = [22.8 +/- 3.8(stat)(+2.3)(-2.6)(syst)] x 10(-6), f(L) = 0.941 (+0.034)(-0.040)(stat) +/- 0.030(syst). A = 0.00 +/- 0.30(stat) +/- 0.09(syst) and S = 0.08 +/- 0.09(syst). These values are used to constrain the Cabibbo-Kobayashi-Maskawa phase ; the solution consistent with the standard model is phi(2) = (88 +/- 17) degrees or 59 degrees < phi(2) < 115 degrees at 90% C.L. 相似文献
198.
Shangbing Ai Xinfu Chen Stuart P. Hastings 《Transactions of the American Mathematical Society》2006,358(7):3169-3206
We study , where , , and is sufficiently small, on an interval with boundary conditions at . All solutions with an independent number of oscillations are analyzed. Existence of complicated patterns of layers and spikes is proved, and their Morse index is determined. It is observed that the results extend to with and also to an infinite interval.
199.
200.
I.U. Heilmann J.M. Hastings G. Shirane A.J. Heeger A.G. MacDiarmid 《Solid State Communications》1979,29(6):469-471
Inelastic neutron scattering measurements of Hg-chain excitations in Hg3?σAsF6 are presented. Below Tc = 120 K, where the Hg-ions develop an ordered sublattice, a small but well-defined gap in the Hg-chain dispersion develops at finite q. The response of the Hg-chains does not involve an elastic component indicating the absence of defect or impurity-interactions along the chains. 相似文献