全文获取类型
收费全文 | 141篇 |
免费 | 6篇 |
专业分类
147篇 |
出版年
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 2篇 |
2013年 | 27篇 |
2012年 | 11篇 |
2011年 | 12篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 12篇 |
2007年 | 6篇 |
2006年 | 9篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有147条查询结果,搜索用时 0 毫秒
21.
We report on the effect of cooling rate on the size-dependent atomic ordering of CoPt nanoparticles using aberration corrected high-resolution transmission electron microscopy. It was found that cooling rate plays a crucial role in promoting atomic ordering during the cooling process after annealing. Nanoparticles of ≈3?nm in diameter show the A1-disordered phase after annealing at 873?K for 1?h followed by rapid cooling (110?K/min), while the L10-ordered phase is obtained when the cooling rate is slow (1.5?K/min). The disordered phase is also obtained by rapid cooling after annealing at 973?K for 1?h. These results unambiguously indicate that the order–disorder transformation temperature is reduced to a temperature at least lower than 873?K for CoPt nanoparticles smaller than 3?nm in diameter. The slow cooling process promotes the atomic ordering, which resulted in an enhancement of magnetic coercivity as high as 2200?Oe. This study demonstrates that hard magnetic properties of the CoPt nanoparticles can be improved by controlling the cooling rate after heat treatments. 相似文献
22.
It is interesting to investigate the formation of He bubbles in amorphous alloys because point defects do not exist in amorphous materials. In the present study, the microstructural evolution of amorphous Fe79B16Si5 alloy, either irradiated with 5?keV He+ ions or implanted with 150?eV He+ ions without causing displacement damage, and then annealed at a high temperature, was investigated using transmission electron microscopy (TEM). Vacancy-type defects were formed in the amorphous alloy after irradiation with 5?keV He+ ions, and He bubbles formed during annealing the irradiated samples at high temperature. On the other hand, for samples implanted with 150?eV He+ ions, although He atoms are also trapped in the free volume, no He bubbles were observed during annealing the samples even up to 873?K. In conclusion, the formation of He bubbles is related to the formation and migration of vacancy-type defects even in amorphous alloys. 相似文献
23.
24.
A.Mieko Watanabe-Muraoka Tomotsugu Kawasaki Shin'ichi Sato 《Journal of Vocational Behavior》1998,52(3):300-311
This paper introduces some findings about the vocational behavior of the late adult Japanese who are in a process of transition. The first part of the paper emphasizes the need for research on Japanese vocational behavior in late adulthood from a developmental–contextual frame of reference. In the second part, discussion is focused on circumstances of late adult workers in Japan who have been affected most by the current socioeconomic changes and who have been caught in the middle of changes in employment management systems and policies. A brief summary of the findings from two ongoing research projects which emphasize the need for psychological–interventional assistance in order for retiring persons to maintain their well-being in a period of personal and social transition is presented. 相似文献
25.
Koichi Shimono Sachio Nakamizo Michiaki Kondo 《The Japanese psychological research》2000,42(2):91-101
We examined oculomotor responses to binocular disparities of one stereo‐normal and three stereo‐anomalous observers, who were identified through a stereoscopic depth‐discrimination task, in two experimental conditions. In the pulse disparity condition, crossed and uncrossed disparities (1–6°) were briefly presented (for .25–2.0 s). In the ramp disparity condition, disparities were varied continuously with constant velocities (.7–2.0°/s) and with an amplitude of 10°. The stereo‐normal observer showed vergence responses to both pulse and ramp disparities. The three stereo‐anomalous observers showed a marked reduction or absence of vergence responses to pulse disparities but showed vergence responses to ramp disparities. The results suggest the existence of separate sub‐systems mediating disparity vergence eye movements. 相似文献
26.
In this study, Knauff and Johnson‐Laird's (2002) visual impedance hypothesis (i.e., mental representations with irrelevant visual detail can impede reasoning) is applied to the domain of external representations and diagrammatic reasoning. We show that the use of real objects and augmented real (AR) objects can control human interpretation and reasoning about conditionals. As participants made inferences (e.g., an invalid one from "if P then Q" to "P"), they also moved objects corresponding to premises. Participants who moved real objects made more invalid inferences than those who moved AR objects and those who did not manipulate objects (there was no significant difference between the last two groups). Our results showed that real objects impeded conditional reasoning, but AR objects did not. These findings are explained by the fact that real objects may over‐specify a single state that exists, while AR objects suggest multiple possibilities. 相似文献
27.
This study applied volumetric analysis and voxel-based morphometry (VBM) of brain magnetic resonance (MR) images to assess whether correlations exist between global and regional gray/white matter volume and the cognitive functions of semantic memory and short-term memory, which are relatively well preserved with aging, using MR image data from 109 community-dwelling healthy elderly individuals. We used the Information and Digit Span subtests of the Wechsler Adult Intelligent Scale-Revised as measures of semantic memory and short-term memory, respectively. We found significant positive correlations between the gray matter ratio, the percentage of gray matter volume in the intracranial volume, and performance on the Digit Span subtest, and between the regional gray matter volumes of the bilateral anterior temporal lobes and performance on the Information subtest. No significant correlations between performance on the cognitive tests and white matter volume were found. Our results suggest that individual variability in specific cognitive functions that are relatively well preserved with aging is accounted for by the variability of gray matter volume in healthy elderly subjects. 相似文献
28.
29.
Sato Kentaro 《Studia Logica》2008,88(2):295-324
We study filters in residuated structures that are associated with congruence relations (which we call -filters), and develop a semantical theory for general substructural logics based on the notion of primeness for those filters.
We first generalize Stone’s sheaf representation theorem to general substructural logics and then define the primeness of
-filters as being “points” (or stalkers) of the space, the spectrum, on which the representing sheaf is defined. Prime FL-filters
will turn out to coincide with truth sets under various well known semantics for certain substructural logics. We also investigate
which structural rules are needed to interpret each connective in terms of prime -filters in the same way as in Kripke or Routley-Meyer semantics. We may consider that the set of the structural rules that
each connective needs in this sense reflects the difficulty of giving the meaning of the connective. A surprising discovery
is that connectives , ⅋ of linear logic are linearly ordered in terms of the difficulty in this sense.
Presented by Wojciech Buszkowski 相似文献
30.
Toshihisa Sato Motoyuki Akamatsu 《Transportation Research Part F: Traffic Psychology and Behaviour》2008,11(4):242-258
This paper focuses on modeling and predicting the influence of a vehicle’s velocity and the relative position between a driver’s vehicle and a vehicle to the front or rear on the onset of driver preparations for making a right turn at an intersection. Repeated experiments were carried out on a public road to measure driver preparations, including releasing the accelerator pedal, moving the right foot to cover the brake pedal, and activating the turn signal, as well as to record vehicle velocity and the relative distances to the leading and following vehicles. Structural equation modeling was applied to estimate these relationships quantitatively. Two separate latent variables accounting for the interaction between the driver’s vehicle and leading or following vehicles, and the onset point where driving behavior changes from straight mode to preparation mode before a right turn, were introduced in the specification of the structural equation model. The model estimates and testing indicate that the proposed structural equation model represents well the relationship hypothesized by observational analysis: that the vehicle velocity and the traffic conditions surrounding the driver’s vehicle strongly influence the driver’s deceleration and more weakly influenced turn signal activation. The proposed structural equation model contributes to the prediction of the onset locations of covering the brake pedal and activating the turn signal based on the vehicle velocity and the relative distances to the front and rear vehicles when the accelerator pedal is released. The prediction accuracy is high compared with predictions in which the vehicle velocity and the headway or rear distances are not taken into account or predictions using a single regression model with one independent variable, namely driving speed. Finally, a possible new addition to in-vehicle navigation systems that detects unusual driver behavior by predicting the driver’s preparatory maneuvers is discussed. 相似文献