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51.
Intense terahertz pulses by four-wave rectification in air 总被引:6,自引:0,他引:6
We describe a new four-wave rectification method for the generation of intense, ultrafast terahertz (THz) pulses from gases. The fundamental and second-harmonic output of an amplified Ti:sapphire laser is focused to a peak intensity of ~5x10(14)W/cm (2) . Under these conditions, peak THz fields estimated at 2 kV/cm have been observed; the measured power spectrum peaks near 2 THz. Phase-dependent measurements show that this is a coherent process and is sensitive to the relative phases of the fundamental and second-harmonic pulses. Comparable THz signals have been observed from nitrogen and argon as well as from air. 相似文献
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Reallocation of input resources (RIR) is a process by which certain decision making units (DMUs) reallocate resources among themselves; a process that occurs frequently in many enterprises. In this paper, a new data envelopment analysis (DEA) approach is developed to select the best cooperative partner DMU. Context-dependent DEA is used to identify the different levels of best-practice frontiers. Two DEA-based models are established for two cooperative scenarios, namely, resources pooling only and best-practice sharing. A cooperative method is applied to determine how to reallocate the input resources, and Shapley value is used to estimate the revenue changes that the various DMUs should expect after RIR. Two different situations with different objectives are considered. One objective is to maximize total revenue for the partnership, while the other is to maximize the Shapley value. The proposed approaches are illustrated with two examples. 相似文献
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The concept of supported ionic liquid catalysis (silc) has successfully been applied to hydrogenation reactions, which significantly reduced the required amounts of ionic liquid phase and enabled the usage of fixed-bed technology; the resulting catalysts exhibited high activity and outstanding stability. 相似文献
57.
Cook MJ Nygård AM Wang Z Russell DA 《Chemical communications (Cambridge, England)》2002,(10):1056-1057
Photoswitching of 'on' and 'off' coordination sites in a self assembled monolayer containing the 4-(arylazo)pyridine chromophore has been achieved using the evanescent field and illustrated through coordination and photon induced release of zinc tetraphenylporphyrin. 相似文献
58.
Trypanothione reductase (TR) catalyzes the NAPDH-dependent reduction of the spermidine-glutathione conjugate trypanothione, an antioxidant found in Trypanosomatid parasites. TR plays an essential role in the parasite's defense against oxidative stress and has emerged as a prime target for drug development. Here we report the synthesis of several trypanothione analogues and their inhibitory effects on T. cruzi TR. All are competitive inhibitors with K(i) values ranging from 30 to 91 microM. 相似文献
59.
[formula: see text] An efficient site-specific cross-linking reaction between two carbohydrate residues present in two complementary DNA sequences is described. One oligodeoxynucleotide, 5'd(GGCTGA*CTGCG)3', carries an amino nucleophile tethered to the 2'-hydroxyl of an adenosine residue (A*). The target electrophile is an abasic site generated in the complementary sequence, 5'd(CGCAGDCAGCC)3' (D represents the deoxyribose). The cross-linking reaction was carried out by a reductive amination reaction in > 95% yield. 相似文献
60.
In this paper we extend the plane blow-up results of Grundy& McLaughlin (1997) to the three-dimensional Navier-Stokes equations.Using a solution structure originally due to Lin we first providenumerical evidence for the existence of blow-up solutions on- < x, z < , 0 y 1 with boundary conditions on y = 0and y = 1 involving derivatives of the velocity components.The formulation enables us to consider plane and radial flowas special cases. Various features of the computations are isolatedand are used to construct a formal asymptotic solution closeto blow-up. We show that the numerical and asymptotic analysesprovide a mutually consistent global picture which supportsthe conclusion that, for the family of problems we considerhere, blow-up in fact can take place in three dimensions butat an inverse linear rate rather than the faster inverse squareof the plane case. 相似文献