全文获取类型
收费全文 | 2640篇 |
免费 | 260篇 |
国内免费 | 721篇 |
专业分类
3621篇 |
出版年
2024年 | 10篇 |
2023年 | 29篇 |
2022年 | 55篇 |
2021年 | 91篇 |
2020年 | 105篇 |
2019年 | 80篇 |
2018年 | 102篇 |
2017年 | 117篇 |
2016年 | 77篇 |
2015年 | 83篇 |
2014年 | 73篇 |
2013年 | 231篇 |
2012年 | 166篇 |
2011年 | 220篇 |
2010年 | 188篇 |
2009年 | 192篇 |
2008年 | 208篇 |
2007年 | 295篇 |
2006年 | 278篇 |
2005年 | 244篇 |
2004年 | 160篇 |
2003年 | 120篇 |
2002年 | 72篇 |
2001年 | 57篇 |
2000年 | 43篇 |
1999年 | 63篇 |
1998年 | 34篇 |
1997年 | 32篇 |
1996年 | 26篇 |
1995年 | 27篇 |
1994年 | 18篇 |
1993年 | 22篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 3篇 |
排序方式: 共有3621条查询结果,搜索用时 15 毫秒
231.
From a longitudinal study, we have repeatedly measured data from multiple individuals at multiple occasions. For each individual, the relation between 2 variables can be measured by the Pearson’s correlation. The question is how to aggregate the multiple correlations and conduct statistical inference on the aggregated intra-individual correlation. Several methods are proposed to aggregate and test intra-individual correlations: (a) a meta-analysis method based on Fisher’s Z transformed correlations, (b) a meta-analysis method based on the Pearson’s correlations, and (c) a multilevel modeling method using data standardized within each individual. The performance of the methods after bias corrections was compared using simulations with considering factors including numbers of individuals, numbers of time points, population effect sizes, and their distribution forms (homogeneous vs heterogeneous). The results from the simulation studies show that estimation biases were found using the meta-analytic methods and suggestions on when and how to correct biases were provided based on the simulation results. Furthermore, the performance of the 3 methods after necessary bias corrections was found to be comparable and reasonably good, indicating that all 3 methods worked for aggregating and testing intra-individual correlations. An empirical daily diary data set was then used to illustrate the applications of the 3 methods. The assumptions, advantages and disadvantages, and possible extensions of the 3 methods were discussed. 相似文献
232.
Kevin Grimm Zhiyong Zhang Fumiaki Hamagami Michèle Mazzocco 《Multivariate behavioral research》2013,48(1):117-143
A general equadion is presented, covering all arbitrary values for the true population splits, for obtaining the true population phi, given observed cell frequencies for a selected sample, and true population splits. A nongeneral solution is also offered, based on the use of the G Index. Demonstrations with hypothetical data are given. 相似文献
233.
Miguel R. Ramos Jolanda Jetten Airong Zhang Constantina Badea Aarti Iyer Lijuan Cui Yuling Zhang 《European journal of social psychology》2013,43(1):72-83
Four studies investigated the conditions under which minority group members respond to group‐based discrimination with increased identification with their group. We propose that minorities' interaction goals should serve as a moderator: seeking distance from the majority might keep minority identification alive in the face of perceived discrimination. These predictions were tested correlationally in Study 1 among Chinese immigrants in Australia (sample 1a) and children of rural migrant workers in a Chinese city (sample 1b). In Studies 2 and 3, perceived discrimination was manipulated among Romanian immigrants in France and Polish immigrants in Scotland. In Study 4, both minority goals and perceived discrimination were manipulated among a sample of international students in Australia. Results showed that only for those who were inclined to seek distance from the majority, minority group identification increased when discrimination was high compared with low. Discussion focuses on the way that seeking distance might be an important strategy for coping with discrimination. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
234.
It is still unclear how attentional control influences stimulus processing. We investigated this issue in four Stroop task experiments utilizing a pretest–training–posttest design. Subjects were given extensive training on the Stroop task using typical incongruent Stroop trials. The rates of color naming and word reading, which reflect the efficiency of stimulus processing, were assessed in pretest and posttest. The difference in rates between posttests and pretests reflects the influence of attentional control, acquired during the training phase, on stimulus processing. In Experiment 1, members of color category were used in the training phase; in Experiment 2, members of color category were used, but not in the training phase; in Experiment 3, they were neither in the color category nor were they used in the training. The results consistently showed that the suppression of word reading and the enhancement of color naming were developed in the training phases and they were not due to general training of color-naming task without conflict but to color-naming training with Stroop conflict (Experiment 4). More importantly, both suppression and enhancement affected the members of color category regardless of whether they were trained or not. The present findings suggest that the influence of attentional control on stimulus processing is category specific. We discuss the implications of the present results in terms of existing research on the locus of attentional control in Stroop tasks. 相似文献
235.
Michael J. Hove John R. Iversen Allen Zhang Bruno H. Repp 《Psychological research》2013,77(4):388-398
Synchronization of finger taps with periodically flashing visual stimuli is known to be much more variable than synchronization with an auditory metronome. When one of these rhythms is the synchronization target and the other serves as a distracter at various temporal offsets, strong auditory dominance is observed. However, it has recently been shown that visuomotor synchronization improves substantially with moving stimuli such as a continuously bouncing ball. The present study pitted a bouncing ball against an auditory metronome in a target–distracter synchronization paradigm, with the participants being auditory experts (musicians) and visual experts (video gamers and ball players). Synchronization was still less variable with auditory than with visual target stimuli in both groups. For musicians, auditory stimuli tended to be more distracting than visual stimuli, whereas the opposite was the case for the visual experts. Overall, there was no main effect of distracter modality. Thus, a distracting spatiotemporal visual rhythm can be as effective as a distracting auditory rhythm in its capacity to perturb synchronous movement, but its effectiveness also depends on modality-specific expertise. 相似文献
236.
A process is described for the fabrication of opal-like thin films by controlling a solid–liquid interface moving at an inclined glass substrate. A special airflow is adopted to control solvent evaporation. SEM images and photographs show that the films, composed of polystyrene spheres, are coloured, flat, uniform, packed multilayers, and are well arrayed over a large scale. The ordered domains range in size from 10 to 15?µm. The spheres in suspension crystallized, caused by an intense interaction between the spheres on the boundary between the suspension and the substrate. A wide photonic band gap is observed in the normal-incidence transmission spectra of the films fabricated by this method. Cracks and defects in the films are examined and discussed. 相似文献
237.
Electropulsing usually promotes a metastable phase to evolve towards its equilibrium state. This work reports an alternative case, where electropulsing promotes the decomposition of the stable δ-phase in duplex stainless steel at high temperature. This decomposition enables both the γ-phase and the σ-phase in the steel to survive and hence to strengthen it at high temperature. The hardness of the quenched sample with electropulsing treatment is 49.4% higher than that without electropulsing treatment. A fundamental understanding of the observation is developed. 相似文献
238.
X. Zhang 《Philosophical Magazine Letters》2013,93(1):55-65
A continuum model is proposed to address the effects of deformation twinning on ductile versus brittle fracture behaviour of low strain-hardening fcc metals after exhaustion of work hardening. Instead of discrete twin nucleation, a number of partial dislocations ahead of the tip exhibit themselves as twins at the final stage of failure. The crack-tip plasticity is amended for deformation twinning and the constitutive form for the flow strength of arrays of twins of the same sign is expressed as a second gradient of microrotation for their coupling. The twins not only shield the crack tip but also inhibit further dislocation emission to form a dislocation-free zone (DFZ) in the immediate vicinity of the tip. The stress fields induced by deformation twinning lead to fracture branching under Mode I loading. The model is borrowed from the conceptual model presented by Beltz et al. [Acta Mater. 44 3943 (1996)], based on the equivalence of the stresses derived from twin-based crack-tip plasticity, macroscopic plasticity and elasticity on the DFZ boundary. The DFZ size and the crack-tip shielding ratio are obtained, as well as the branching angle. The branching angle is noteworthy for low strain-hardening metals. A strong dependence of the toughness on intrinsic surface energy and hardening index is examined. The toughness reduction due to crack-tip constraints and in the ductile-to-brittle transition (DBT) temperature region is revisited and found to be in agreement with experimental observations and available predictions. 相似文献
239.
One-dimensional silicon nanowires have been grown by thermal evaporation and their growth orientations determined by transmission electron microscopy studies. The nanowires, which are often highly curved in morphology and heavily twinned in microstructure, are crystallographically separated into several sections, each with a characteristic crystallographic orientation along the wire axis. Straight nanowires, or straight sections in a curved nanowire, are found to have non-unique crystallographic orientations when {111} twinning occurs. 相似文献
240.
The average velocities of screw dislocations in Ni 3 Al single crystals have been directly measured as a function of resolved shear stress (RSS) and orientation in the temperature domain of the flow stress anomaly using the etch-pit technique. The velocity was found to be extremely sensitive to the RSS in all cases. In contrast with ordinary metals, the screw dislocation velocities in Ni 3 Al show anomalous behaviour; under a constant RSS, the velocities decrease dramatically with increasing temperature. Furthermore, the velocities and the tension-compression asymmetry of the velocities depend on the orientation of applied stress. 相似文献