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31.
Three studies examined children's understanding of the role that looking behavior plays in revealing another's desired goal. In each study, participants were asked which of 2 objects a protagonist wanted to obtain. Four-year-olds did not infer that an object examined via prolonged looking was more likely to be the protagonist's goal than an object that was either glanced at or inadvertently touched. Instead, they were accurate only when the protagonist looked at one of two potential goals. In contrast, the majority of 6-year-olds (and adults in Experiment 1) consistently regarded prolonged looking as the more important cue of the protagonist's goal. These age differences suggest that development is characterized by an increasing appreciation that goal is revealed by comparative differences in the quality of perceptual connectedness to objects in the world. One explanation for these age differences is that preschoolers are limited in their understanding of the difference between perceiving with full attention and without it.  相似文献   
32.
33.
Nutrient Cycling in Agroecosystems - Reducing agriculturally derived diffuse contaminant losses (via non-point sources) from land to water has proven difficult for decades. Owing to the diversity...  相似文献   
34.
The advanced TALSPEAK process is a selective solvent extraction that utilizes 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) to separate lanthanide elements from trivalent actinides, which are held back in the aqueous phase by N-hydroxylethyl-N,N’,N’-ethylenediamine triacetic acid (HEDTA) buffered by citric acid. Gamma irradiation of an experiment containing Eu(III) and Am(III) as representative lanthanide and actinide elements resulted in higher distribution ratios of both and separation factors which decreased in an exponential fashion with increasing dose. Analysis of the reagents showed that the HEDTA concentration also decreased in an exponential fashion, strongly suggesting that degradation was correlated with loss of separation selectivity. In contrast, the concentration of citrate was unaffected, and while the concentration of HEH[EHP] did decrease, its dose-dependent kinetic profile indicated that it was not limiting partitioning. A second set of experiments were conducted using a citrate concentration that was 7.5 X higher, with the expectation that citrate would protect the HEDTA by scavenging radiolytically formed OH radicals. HEDTA degradation was significantly mitigated at higher gamma doses, but the Eu-Am separation was worse than in the low citrate experiments, presumably because at the high citrate concentrations, the Eu-citrate complexes formed in abundances competitive with the Am complexes, and are more effectively held back in the aqueous phase.  相似文献   
35.
The formation and reduction of passive layers on copper in weakly alkaline solutions saturated with N2 and O2 were studied. Voltammetric and ellipsometric techniques were employed to examine the structural characteristics of the layers formed in the –0.32 to 0.75 V vs RHE potential region. Optical measurements at open circuit potentials (Eoc) were also made to simulate operational conditions. The passive layer consists of a duplex structure: an outer hydrated copper oxide film and an inner dehydrated film. This inner layer is composed of Cu2O with a surface excess of Cu(ii) ions. The growth rate of the oxide layers at controlled potentials is higher in O2 saturated solution. The corrosion resistance of copper depends on the presence of O2 in the electrolyte, on the stirring rate and on the Eoc value.  相似文献   
36.
刘赞群  邓德华  Geert De Schutter  刘运华 《硅酸盐学报》2012,40(5):631-632,633,634,635,636,637
运用环境扫描电镜、能谱仪和X射线衍射等微观分析手段研究了稳定环境中,半浸泡混凝土试件在硫酸钠和硫酸镁溶液中的劣化破坏特征,以及混凝土碳化对"混凝土硫酸盐结晶破坏"的影响。结果表明:粗骨料界面过渡区生成的大量钙矾石和石膏等晶体是引起混凝土试件劣化的原因;在碳化混凝土内发现了硫酸钠结晶破坏现象。  相似文献   
37.
介绍了在合成氨改扩建工程中,选择氨合成塔时应着重考虑的工艺参数和结构设计,并在实际工作中得到验证。  相似文献   
38.
The polarized wave electromagnetic shielding (EM SE) of nanocomposites containing 10 vol% of carbon nanomodifiers in a semicrystalline matrix is reported. Heat‐treated carbon nanofibers, Pyrograf® III PR‐19 heat treatment (HT) and multiwalled carbon nanotubes (MWNT) HT were dispersed in a linear low‐density polyethylene matrix to produce flow‐induced orientation of the nanomodifiers in the spun microfilaments. Consequently, the electrical conductivity of the resulting nanocomposites exhibited anisotropic behavior due to the nanomodifier orientation. The in‐plane conductivity in the longitudinal direction (PR‐19 HT comp.: ~0.02 S/m; MWNT HT comp.: ~3 S/m) was at least an order of magnitude higher than that along the transverse direction. As measured with a rectangular waveguide (WR510, 1.45–2.2 GHz), the PR‐19 HT‐ and MWNT HT‐oriented nanocomposites (1‐mm thick) displayed EM SE values of 0.7 dB and 3.0 dB, respectively, when the nanomodifiers were transversely oriented with the polarized electric field. In contrast, when the orientation of the nanomodifiers was parallel with the field, EM SE values of 3.2 and 9.0 dB were obtained, respectively. The higher EM SE values are consistent with high conductivities observed in the direction of preferred orientation of the modifiers. POLYM. ENG. SCI., 55:299–307, 2015. © 2014 Society of Plastics Engineers  相似文献   
39.
ABSTRACT

A numerical solution of the diffusion equation to describe solute transport inside ellipsoids, assuming a constant difiusion coefficient and a corrective boundary condition, is presented. The difiusion equation in a prolate spheroidal coordinate system was used for a hidimensional case. The finite volume method was employed to discretize the basic equation, utilizing a uniform grid size. The equation was solved irteratively using the Gauss-Seidel method. The effect of Biot number and the aspect ratio of the body on diffusion rate and concentration during the process is presented. Plots are presented for Biot numbers from 0.05 to infinity and aspect ratios of 1.1, 2.0 and 5.0. To investigate the effect of the aspect ratio, different results changing the aspect ratio for Bi= 1.0 are shown. The results show that the model is consistent and it may be used to solve other cases such as those that include cylinder and sphere geometry, and/ or those with variable diffusion coefficients with small modifications.  相似文献   
40.
Grapevine moth Lobesia botrana is the economically most important insect of grapevine Vitis vinifera in Europe. Flower buds, flowers, and green berries of Chardonnay grapevine are known to attract L. botrana for oviposition. The volatile compounds collected from these phenological stages were studied by gas chromatography—mass spectrometry, and the antennal response of L. botrana females to these headspace collections was recorded by gas chromatography—electroantennography. The compounds found in all phenological stages, which consistently elicited a strong antennal response, were pentadecane, nonanal, and -farnesene. In a wind tunnel, gravid L. botrana females flew upwind to green grapes, as well as to headspace collections from these berries released by a piezoelectric sprayer release device. However, no females landed at the source of headspace volatiles, possibly due to inappropriate concentrations or biased ratios of compounds in the headspace extracts.  相似文献   
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