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961.
Zhang Ning Zhang Bin Pang Yong Yang Hong-Sheng Zong Lu Duan Yong-Xin Zhang Jian-Ming 《高分子科学》2022,40(4):373-383
Chinese Journal of Polymer Science - Macromolecule nanocrystal network and strong interfacial interaction are always beneficial to enhance the mechanical property of polymer-based nanocomposites.... 相似文献
962.
963.
Min Lu Saad Sadiq Daniel J. Feaster Hemant Ishwaran 《Journal of computational and graphical statistics》2018,27(1):209-219
Estimation of individual treatment effect in observational data is complicated due to the challenges of confounding and selection bias. A useful inferential framework to address this is the counterfactual (potential outcomes) model, which takes the hypothetical stance of asking what if an individual had received both treatments. Making use of random forests (RF) within the counterfactual framework we estimate individual treatment effects by directly modeling the response. We find that accurate estimation of individual treatment effects is possible even in complex heterogenous settings but that the type of RF approach plays an important role in accuracy. Methods designed to be adaptive to confounding, when used in parallel with out-of-sample estimation, do best. One method found to be especially promising is counterfactual synthetic forests. We illustrate this new methodology by applying it to a large comparative effectiveness trial, Project Aware, to explore the role drug use plays in sexual risk. The analysis reveals important connections between risky behavior, drug usage, and sexual risk. Supplementary material for this article is available online. 相似文献
964.
Microstructural evolution and grain refinement mechanism in AZ31 magnesium alloy subjected to sliding friction treatment were investigated by means of transmission electron microscopy. The process of grain refinement was found to involve the following stages: (I) coarse grains were divided into fine twin plates through mechanical twinning; then the twin plates were transformed to lamellae with the accumulation of residual dislocations at the twin boundaries; (II) the lamellae were separated into subgrains with increasing grain boundary misorientation and evolution of high angle boundaries into random boundaries by continuous dynamic recrystallisation (cDRX); (III) the formation of nanograins. The mechanisms for the final stage, the formation of nanograins, can be classified into three types: (i) cDRX; (ii) discontinuous dynamic recrystallisation (dDRX); (iii) a combined mechanism of prior shear-band and subsequent dDRX. Stored strain energy plays an important role in determining deformation mechanisms during plastic deformation. 相似文献
965.
966.
The dinuclear zinc complexes as high performance catalysts were used to catalyze phospha-Michael reaction of exocyclic α,β-unsaturated benzocyclic ketones under mild conditions, and the desired products possessing 1-indanones or 1-tetralones skeleton were obtained with excellent enantioselectivities of up to 99%/99% ee and yields of up to 99%. The absolute stereochemistry of the major products catalyzed by (R,R)-L1 was determined to be the (R,R)-configuration by X-ray crystallographic analysis of 3d. A positive nonlinear effect was observed and the possible mechanism was proposed. 相似文献
967.
968.
Xingwen Lu Lingmin Zeng Kaimin Shih 《Journal of Physics and Chemistry of Solids》2012,73(9):1191-1195
A new ternary intermetallic compound, Nd2Cu0.8Ge3, was synthesized and its crystal structure was determined by Rietveld refinement of X-ray powder diffraction data. The Nd2Cu0.8Ge3 compound crystallizes in space group I41/amd (No. 141), with a tetragonal a-ThSi2 structure type, and a=0.41783(2) nm, c=1.43689(9) nm, Z=2 and Dcalc=7.466 g/cm3. Using the high temperature powder X-ray diffraction (HTXRD) technique, the lattice thermal expansion behavior of the compound was investigated in the temperature range of 298–648 K, and the result shows that its unit-cell parameters increased anisotropically when temperature increased. The magnetic susceptibility measured in the temperature range of 5–300 K indicated antiferromagnetic order of Nd2Cu0.8Ge3 at low temperatures, and the magnetic susceptibility can be well described over the range of 50–300 K using Curie–Weiss law. The calculated effective magnetic moment (μeff) is 3.53 μB and dominated by the contribution of the Nd3+ ions. 相似文献
969.
970.
Rosário Monteiro Gil Faria Manuela Meireles Luísa Correia‐Sá Diana Teixeira Ana Faria Conceição Calhau Valentina F. Domingues Cristina Delerue‐Matos 《Biomedical chromatography : BMC》2012,26(12):1494-1501
Scientific evidence has shown an association between organochlorine compounds (OCC) exposure and human health hazards. Concerning this, OCC detection in human adipose samples has to be considered a public health priority. This study evaluated the efficacy of various solid‐phase extraction (SPE) and cleanup methods for OCC determination in human adipose tissue. Octadecylsilyl endcapped (C18‐E), benzenesulfonic acid modified silica cation exchanger (SA), poly(styrene‐divinylbenzene (EN) and EN/RP18 SPE sorbents were evaluated. The relative sample cleanup provided by these SPE columns was evaluated using gas chromatography with electron capture detection (GC–ECD). The C18‐E columns with strong homogenization were found to provide the most effective cleanup, removing the greatest amount of interfering substance, and simultaneously ensuring good analyte recoveries higher than 70%. Recoveries > 70% with standard deviations (SD) < 15% were obtained for all compounds under the selected conditions. Method detection limits were in the 0.003–0.009 mg/kg range. The positive samples were confirmed by gas chromatography coupled with tandem mass spectrometry (GC‐MS/MS). The highest percentage found of the OCC in real samples corresponded to HCB, o,p′‐DDT and methoxychlor, which were detected in 80 and 95% of samples analyzed respectively. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献