Yongnan Li  Shu-Wei Huang  Bowen Li  Hao Liu  Jinghui Yang  Abhinav Kumar Vinod  Ke Wang  Mingbin Yu  Dim-Lee Kwong  Hui-Tian Wang  Kenneth Kin-Yip Wong  Chee Wei Wong 《光：科学与应用（英文版）》2020,(2):244-253

Femtosecond mode-locked laser frequency combs have served as the cornerstone in precision spectroscopy, all-optical atomic clocks, and measurements of ultrafast...  相似文献   

    

Zhu WM  Liu AQ  Zhang XM  Tsai DP  Bourouina T  Teng JH  Zhang XH  Guo HC  Tanoto H  Mei T  Lo GQ  Kwong DL 《Advanced materials (Deerfield Beach, Fla.)》2011,23(15):1792-1796

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Zhang L  Yu JC  Mo M  Wu L  Kwong KW  Li Q 《Small (Weinheim an der Bergstrasse, Germany)》2005,1(3):349-354

In this study we demonstrate that one-dimensional (1D) nanostructured lead telluride (PbTe) can be synthesized in a hydrothermal reaction between lead foil and tellurium powder. The resulting materials were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The formation of the 1D structure can be explained by an in situ hydrothermal rolling-up mechanism whereby PbTe is formed hydrothermally and deposited on the lead substrate. The lead underneath the PbTe layer is then selectively etched by a cetyltrimethylammonium bromide solution, thus allowing the PbTe to roll up into 1D structures. This method can be extended to prepare other 1D tellurides, including CdTe, Cu(2)Te, and Ag(2)Te.  相似文献   

    

W Nadler  T Huang  DL Stein 《Canadian Metallurgical Quarterly》1996,54(4):4037-4047

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GS Cooper  A Chak  AF Connors  DL Harper  GE Rosenthal 《Canadian Metallurgical Quarterly》1998,36(4):462-474

OBJECTIVES: The effectiveness of upper endoscopy in unselected patients with upper gastrointestinal hemorrhage has not been well studied. This study was undertaken to identify factors associated with the performance of early endoscopy (ie, within 1 day of hospitalization) and, after adjusting for these factors, to determine associations between early endoscopy and in-hospital mortality, length of stay, and performance of surgery. METHODS: Subjects in this observational cohort study were 3,801 consecutive admissions with upper gastrointestinal hemorrhage to 30 hospitals in a large metropolitan region. Demographic and clinical data were abstracted from hospital records. A multivariable model based on factors that potentially could relate to the decision to perform endoscopy was developed to determine the propensity (0 to 100%) for early endoscopy in each patient. RESULTS: Early endoscopy was performed in 2,240 patients (59%), and although it was not associated with mortality after adjusting for severity of illness among all patients, it was associated with a higher risk of death for patients in the lowest propensity group. Early endoscopy was associated with a lower likelihood of upper gastrointestinal surgery in all patients and in the two highest propensity groups and with a shorter length of stay in the entire cohort and in all subgroups. CONCLUSIONS: In the absence of specific contraindications, early endoscopy should be considered because of associated reductions in length of stay and surgical intervention. Further studies are needed to identify subgroups in whom the procedure may be associated with adverse effects on survival.  相似文献   

    

SC Hsu  CD Hazuka  R Roth  DL Foletti  J Heuser  RH Scheller 《Canadian Metallurgical Quarterly》1998,20(6):1111-1122

Both the sec6/8 complex and septin filaments have been implicated in directing vesicles and proteins to sites of active membrane addition in yeast. The rat brain sec6/8 complex coimmunoprecipitates with a filament composed of four mammalian septins, suggesting an interaction between these complexes. One of the septins, CDC10, displays broad subcellular and tissue distributions and is found in postmitotic neurons as well as dividing cells. Electron microscopic studies showed that the purified rat brain septins form filaments of 8.25 nm in diameter; the lengths of the filaments are multiples of 25 nm. Glutaraldehyde-fixed rat brain sec6/8 complex adopts a conformation resembling the letter \"T\" or \"Y\". The sec6/8 and septin complexes likely play an important role in trafficking vesicles and organizing proteins at the plasma membrane of neurons.  相似文献   

    

BF Kammen  DE Elder  DL Fraker  ES Siegelman 《Canadian Metallurgical Quarterly》1998,171(3):721-723

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SY Shiao  DL Novotny 《Canadian Metallurgical Quarterly》1998,17(4):78-79

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DL Boger  J Zhou  B Winter  PA Kitos 《Canadian Metallurgical Quarterly》1995,3(12):1579-1593

The synthesis and evaluation of two key analogs 3 and 4 of the potent antitumor antibiotics deoxybouvardin (1) and RA-VII (2) which contain fundamental modifications in the tetrapeptide subunit are described. Unlike the natural products, these agents 3 and 4, which substitute (Gly)4 and (Gly)3 for the D-Ala-Ala-NMe-Tyr(OMe)-Ala tetrapeptide subunit, adopt conformations in which the central amide in the cycloisodityrosine subunit adopts its inherently preferred trans stereochemistry and both were found to be biologically inactive.  相似文献   

    

F Doi  DD Chi  BB Charuworn  AJ Conrad  J Russell  DL Morton  DS Hoon 《Canadian Metallurgical Quarterly》1996,65(4):454-459

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