全文获取类型
收费全文 | 21820篇 |
免费 | 99篇 |
国内免费 | 2篇 |
专业分类
21921篇 |
出版年
2023年 | 26篇 |
2022年 | 15篇 |
2021年 | 46篇 |
2020年 | 56篇 |
2019年 | 57篇 |
2018年 | 3525篇 |
2017年 | 2870篇 |
2016年 | 2297篇 |
2015年 | 224篇 |
2014年 | 124篇 |
2013年 | 262篇 |
2012年 | 625篇 |
2011年 | 2438篇 |
2010年 | 2558篇 |
2009年 | 1510篇 |
2008年 | 1756篇 |
2007年 | 2218篇 |
2006年 | 84篇 |
2005年 | 260篇 |
2004年 | 194篇 |
2003年 | 147篇 |
2002年 | 97篇 |
2001年 | 50篇 |
2000年 | 76篇 |
1999年 | 32篇 |
1998年 | 42篇 |
1997年 | 27篇 |
1996年 | 24篇 |
1995年 | 14篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 16篇 |
1991年 | 14篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1982年 | 11篇 |
1981年 | 13篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1976年 | 15篇 |
1974年 | 8篇 |
1973年 | 6篇 |
1971年 | 5篇 |
1968年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
103.
Christopher Coenen 《Nanoethics》2018,12(3):177-180
104.
This study describes a method of modeling human trunk and whole body backward bending and suggests a possible neural control strategy. The hypothesis was that the control system can be modeled as a linear feedback system, in which the torque acting at a given joint is a function of the state variables (angular positions and angular velocities). The linear system enabled representation of the feedback system by a gain matrix. The matrix was computed from the kinematics recorded by a movement analysis system and from the joint torques calculated by inverse dynamics. To validate the control model, a comparison was made between the angular kinematics yielded by the model and the experimental data. Moreover, for all subjects, the same relationships between feedback coefficients were found although gain values were different. The study showed that the feedback system is an appropriate model of the strategy from performing an accurate controlled trunk or whole body backward bending in the sagittal plane. 相似文献
105.
Logvinenko AD 《Perception》2002,31(2):201-207
Many researchers believe the human visual system classifies luminance edges into those produced by reflectance edges or those produced by illumination edges, yet this classification process is not completely understood. One suggestion is that heuristics are used for edge classification. For example. specific contrast relationships at the luminance edge ('codirectional contrast invariance' and 'transversal luminance-ratio preserving') may distinguish an illumination edge from a reflectance edge on the one hand, and from a translucent edge on the other. Distinct from luminance junctions, these features are global characteristics of the luminance pattern that make distinguishing between different types of edge easier with more highly articulated scenes. I demonstrate that apparent translucency, nonreversing X-junctions, and single-reversing X-junctions are insufficient on their own to produce the lightness illusion of Adelson's well-known tile pattern. While tolerating violations of the codirectional contrast invariance and transversal-luminance-ratio presersving without reversing the sign of contrast, the visual system is quite sensitive to such contrast reversal at the luminance edge. I account for this by suggesting that humans process lightness in terms of an ordinal, rather than interval, (or ratio) scale. 相似文献
106.
In the first part of this paper we review evidence suggesting that there exists a mechanism that selects input on the basis of its similarity to the required action. This response-based input selection differs from the more established space- and object-based input selection in that it is not constrained by the structure of the input. Our evidence suggests that the two-choice Stroop effect is caused by this response-based selection mechanism. By contrast, it is known that the flanker effect is determined by the space- and object- based selection mechanisms. We explore whether the conflict resolution of the Stroop and flanker tasks is different as well by embedding these two tasks in a PRP (Psychological Refractory Period) paradigm. We show that the Stroop and the PRP effects are additive whereas the flanker and the PRP effects are underadditive, suggesting that the processes in charge of the conflict resolution in the Stroop and the flanker tasks are indeed different. We discuss possible reasons for this difference, and discuss possible ways in which the response-based mechanism can be implemented in information processing models. 相似文献
107.
Hofer SM Christensen H Mackinnon AJ Korten AE Jorm AF Henderson AS Easteal S 《Psychology and aging》2002,17(2):194-208
The influence of a genetic risk factor, apolipoprotein E (apoE) epsilon4 variant, was assessed in older adults aged 70 to 94 on 3 occasions over 7 years. The results of latent growth curve analyses are reported for individuals genotyped for apoE at the 2nd measurement occasion (n = 601) and for a subsample of individuals without probable or definite dementia during the 1st or 2nd occasion (n = 434). ApoE-epsilon4 status was a significant predictor of level and change in memory performance and change in speed performance in the full sample, and of initial level and change in memory performance in the nondemented subsample. These results support previous findings that apoE-epsilon4 is associated with accelerated memory deterioration in individuals without clinical dementia. 相似文献
108.
King BE Alexander GM 《Journal of comparative psychology (Washington, D.C. : 1983)》2000,114(2):193-199
The relationship between sexual behavior and pain sensitivity was assessed in 27 heterosexual men and 20 heterosexual women. Sexual behavior measures included sexual motivation and ratings of subjective sexual arousal to and enjoyment of an auditory stimulus. Pain sensitivity measures were pain threshold and pain tolerance in a cold pressor task. Participants were tested after exposure to a neutral or a sexual audio stimulus. Exposure to the sexual stimulus increased pain sensitivity in women but not in men. However, sexual behavior measures were correlated with pain threshold for both men and women. Specifically, higher pain thresholds were associated with weaker sexual motivation, lower enjoyment potential for sexual interaction, and increased inhibition during intercourse. These results are consistent with findings in laboratory animals, suggesting that differences in sexual behavior may reflect differences in responsiveness to a variety of stimuli. 相似文献
109.
Robert E. Lee Kathleen Burns Jager Jason B. Whiting Catherine T. Kwantes 《Contemporary Family Therapy》2000,22(1):81-90
Confirmatory factor analysis and regression analyses of the Beavers Interactional Scales did not appear to support the model offered by its developers, namely, several specified family attributes contributing respectively to two global factors of Family Competence and Family Style. Moreover, regression analysis indicated that only three of 12 items predicted raters' assessments of Global Family Health, and one of seven items predicted Global Family Style. Individuals interested in the family dynamic centripetal/centrifugal might best think of that as a unitary entity and rate it accordingly. 相似文献
110.
Deane-Peter Baker 《International Journal for Philosophy of Religion》2005,57(2):77-103
Alvin Plantingas Warranted Christian Belief is without questionone of the central texts of the Reformed epistemology movement. Critiques of Plantingas defence have been both multiple and varied. As varied as these responses are, however, it is my contention that many of them amount to the same thing. It is the purpose of this paper to offer an overview of the main lines of attack that have been directed as Plantingas project, and thereafter to show how many, if not most, of these objections can be understood as versions or aspects of the same criticism, what I call the Inadequacy Thesis. 相似文献