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排序方式: 共有342条查询结果,搜索用时 15 毫秒
1.
Prepulse inhibition (PPI) refers to a reduction in the startle response to a strong sensory stimulus when this stimulus is preceded by a weaker stimulus--the prepulse. PPI reflects a nonlearned sensorimotor gating mechanism and also shows a robust gender difference, with women exhibiting lower PPI than men. The present study examined the eyeblink startle responses to acoustic stimuli of 59 healthy heterosexual and homosexual men and women. Homosexual women showed significantly masculinized PPI compared with heterosexual women, whereas no difference was observed in PPI between homosexual and heterosexual men. These data provide the first evidence for within-gender differences in basic sensorimotor gating mechanisms and implicate the known neural substrates of PPI in human sexual orientation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
X. J. Wu W. Wallace M.D. M. D. Raizenne A. K. Koul 《Metallurgical and Materials Transactions A》1994,25(3):575-588
A series of fatigue-crack growth rate (FCGR) tests was carried out on 8090 Al-Li plate to examine the effects of specimen
orientation on fatigue-crack growth. The directionality of fatigue fracture behavior is found to be related to the strong
{110}〈112〉 texture in this alloy. Based on a previously developed transgranular FCGR model using restricted slip reversibility
(RSR) concepts, [1] a mechanistic model is developed for transgranular fatigue-crack growth in highly textured materials.
The model takes the form of the Paris relationship with a power law exponent of 3, and the material texture is shown to strongly
influence the proportional factor. The effect of texture on FCGR is related through a geometric factor cos2
ϕ, where ϕ defines the angle between the load axis and the normal of the favorable slip plane. The effect of specimen orientation
on FCGR in 8090 Al-Li alloy is shown to be related to a combination of its anisotropic mechanical properties and the variation
of angleϕ with specimen orientation. The model further predicts that fatigue-crack growth rates will be slower in many textured materials
than texturefree materials becauseϕ > 0 and cos2
ϕ < 1. 相似文献
3.
The paper describes the synthesis of N-2/4-toluyl methacrylatoethyl carbamates using 2/4-toluyl isocyanate and 2-hydroxyethyl methacrylate. Homopolymerisation and copolymerisation of these novel monomers with methyl methacrylate was carried out using benzoyl peroxide as an initiator and tetrahydrofuran as solvent. Photopolymerisation of N-4-toluyl methacrylatoethyl carbamate could be carried out without the use of photosensitiser. Structural characterisation of copolymers was done using 1H-NMR. Thermal stability of copolymers was evaluated in a nitrogen atmosphere by dynamic thermogravimetry. 相似文献
4.
Veena Misra Xiaoli Xu Brian E. Hornung Richard T. Kuehn Donald S. Miles John R. Hauser Jimmie J. Wortman 《Journal of Electronic Materials》1996,25(3):527-535
In the present study, we have performed electrical characterization of oxides deposited via rapid thermal chemical vapor deposition using SiH4 and N2O. We have investigated the effect of temperature, pressure, and SiH4 to N2O ratio on the electrical and material properties of as-deposited films. We have found that as-deposited oxides deposited at low temperatures, low pressures, and with a low silane to nitrous oxide ratio of ~0.5% give good material and electrical properties. The as-deposited films are stoichiometric in nature and have high deposition rates. As-deposited films had very low Dit values, high breakdown fields, and excellent subthreshold swing. The leakage currents and metal oxide semiconductor field effect transistor current drive, although lower than thermal oxides, were found to be quite acceptable. We have also investigated the thickness dependence of the films and found that as the film thickness is reduced below 50Å, the reliability improves for all oxides including the silicon-rich deposited oxides. 相似文献
5.
6.
Assessment of service induced microstructural damage and its rejuvenation in turbine blades 总被引:1,自引:0,他引:1
Correlations between service induced microstructural degradation and creep properties in investment cast IN738LC turbine blades
are discussed. Microstructural degradation in the form of γ’ coarsen-ing, MC carbide degeneration, formation of continuous
networks of grain boundary M23C6 carbides, and the disappearance of serrated grain boundaries are considered in some detail. Their influence on primary (t
p
,ε
p
), secondary (t
s
, ε
s
,ε
m
) and tertiary (tt, εt) creep behavior is analyzed through rela-tionships of the form:
相似文献
7.
Natural, cyanoethylated, and formaldehyde-crosslinked cotton cellulose has been grafted with methyl, ethyl, and n-butyl acrylate and methyl methacrylate monomers. Various physical properties such as density, moisture regain, birefringence, and mechanical properties were studied. The results indicate that the density and moisture regain of the grafted fibers are less than those of natural cotton. The birefringence of grafted fibers is also less than that of natural cotton. The variation in birefringence with percent graft-on depends on the monomer. Parameters such as orientation factor, helix angle, and refractive power of fibers were calculated from the birefringence data and the results discussed. It was observed that due to grafting of both natural and crosslinked cotton, there is a decrease in tensile strength, increase in elongation at break, and decrease in the initial modulus. Attempts are made to understand these changes in the properties of cotton in terms of the changes occurring in the fine structure of the fiber. 相似文献
8.
The two-dimensional problem of expanding ring load in a modified couple stress theory of thermoelastic diffusion with heat sources in time and frequency domains is investigated. The mathematical formulation prepared for thermoelastic diffusion solids with one and two relaxation times using Laplace and Hankel transforms. The displacements, stress components, temperature change, and chemical potential are obtained in a transformed domain. Numerical computation is performed for these quantities and the resulting quantities are shown graphically for the time and frequency domains. Comparisons are made with the results predicted by the two theories and different values of time and frequency. Particular cases of interest are also deduced. 相似文献
9.
Many developing world cities have seen the emergence of informal markets where private tanker truck operators transport water extracted from peri-urban wells to urban consumers. This study adopted a systems-modelling approach to analyzing the informal tanker market in India. The results indicate that the demand for tanker supply was caused by lack of groundwater availability in private wells as well as unreliable piped supply. The study shows that two groundwater factors are relevant: depth to water and aquifer productivity. Together, these could explain the difference in spatial, temporal and consumer-specific variations in tanker dependence. 相似文献
10.
Halari Rozmin; Hines Melissa; Kumari Veena; Mehrotra Ravi; Wheeler Mike; Ng Virginia; Sharma Tonmoy 《Canadian Metallurgical Quarterly》2005,119(1):104
Sexually dimorphic cognitive performance in men (n=42) and women (n=42) was related to testosterone, estradiol, progesterone, luteinizing hormone, follicle-stimulating hormone, and sex hormone binding globulin, measured in 10-ml blood samples collected between 0900 and 1030 and, among women, during the follicular phase of the menstrual cycle. Significant sex differences favored men on spatial tasks (Mental Rotation and Judgment of Line Orientation) and on an inhibition task and favored women on a verbal task (category fluency). However, there were no significant relationships between any of the hormones and cognitive performance, suggesting that there are few, if any, consistent, substantial relationships between endogenous, nonfluctuating levels of gonadal hormones or gonadotropins and these cognitive abilities in men or women. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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