全文获取类型
收费全文 | 23570篇 |
免费 | 331篇 |
国内免费 | 14篇 |
专业分类
教育 | 16782篇 |
科学研究 | 1921篇 |
各国文化 | 250篇 |
体育 | 2303篇 |
综合类 | 7篇 |
文化理论 | 212篇 |
信息传播 | 2440篇 |
出版年
2021年 | 239篇 |
2020年 | 361篇 |
2019年 | 543篇 |
2018年 | 732篇 |
2017年 | 667篇 |
2016年 | 667篇 |
2015年 | 403篇 |
2014年 | 535篇 |
2013年 | 4268篇 |
2012年 | 485篇 |
2011年 | 541篇 |
2010年 | 405篇 |
2009年 | 439篇 |
2008年 | 477篇 |
2007年 | 444篇 |
2006年 | 416篇 |
2005年 | 362篇 |
2004年 | 396篇 |
2003年 | 308篇 |
2002年 | 326篇 |
2001年 | 459篇 |
2000年 | 508篇 |
1999年 | 435篇 |
1998年 | 256篇 |
1997年 | 249篇 |
1996年 | 306篇 |
1995年 | 244篇 |
1994年 | 258篇 |
1993年 | 220篇 |
1992年 | 351篇 |
1991年 | 368篇 |
1990年 | 340篇 |
1989年 | 364篇 |
1988年 | 337篇 |
1987年 | 326篇 |
1986年 | 325篇 |
1985年 | 371篇 |
1984年 | 292篇 |
1983年 | 304篇 |
1982年 | 240篇 |
1981年 | 246篇 |
1980年 | 259篇 |
1979年 | 350篇 |
1978年 | 258篇 |
1977年 | 238篇 |
1976年 | 199篇 |
1975年 | 181篇 |
1974年 | 182篇 |
1973年 | 176篇 |
1971年 | 174篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
In an attempt to clarify the chronological relationship between identity and equivalence conservation, normal preschool-aged children (experiment 1) were exposed to brief videotape demonstrations of a model conserving identity and equivalence, identity only, equivalence only, or neither. Subsequent performances indicate that identity was easier to accelerate than equivalence, and training in both identity and equivalence appeared to be most effective in accelerating conservation. Trainable mentally retarded (TMR) children were then exposed to either the identity-equivalence-conserving or control model (experiment 2). This population, which some have argued remains at a preoperational level of functioning, was more likely to conserve identity than equivalence. In addition, conservation in the training group increased following training, though these gains were not maintained over a 3-week retention interval. 相似文献
172.
93 first graders (mean age 6.5 years) were given a pretest and posttest on half of the items from the Children's Embedded Figures Test. Half of the children were randomly assigned to a training condition and received a brief training procedure on visual-spatial disembedding prior to the administration of the posttest. Children in the control condition received no training. The performance of girls improved significantly more from pretest to posttest than the performance of boys. Boys and girls showed similar beneficial effects of training in addition to the benefit of direct practice. The tendency that was observed for boys to perform higher than girls on the pretest, p less than .10, was not evident on the posttest. Scores on the pretest predicted scores on a different measure of visual-spatial ability only for children in the control group. The results are interpreted in terms of current theories of sex differences in visual-spatial perception. 相似文献
173.
First-grade males performed a 30-min visual vigilance task under 5 conditions of auditory background stimulation. The 5 conditions consisted of (1) continuous conversation, in which subjects listened to a tape of conversation spliced so that there were no intervals of silence lasting longer than 3 sec; (2) continuous reverse, in which subjects heard the continuous conversation tape played in reverse; (3) intermittent conversation, in which subjects heard alternating segments of conversation and silence; (4) intermittent reverse, in which subjects heard alternating segments of reverse conversation and silence; and (5) silence control. Compared with silence or continuous stimulation, intermittent stimulation produced better detection regardless of whether or not it was meaningful. High achievers made more correct detections than low achievers, but only in the second and third time periods. Few subjects made errors of commission. 相似文献
174.
The effects of salience on 4- and 6-year-old children's ability to classify multiplicatively was investigated. A rank-ordered salience hierachy consisting of 3 dimensions was first assessed for each S. Several weeks later half the Ss of each age group were presented with a series of 9 3 times 3 matrix problems consisting of values from 2 dimensions ranked high in salience. The remaining half received identically structured matrices consisting of values from 1 highly salient dimension and of others from a dimension ranked low in salience. The goal in each problem was to select that compound stimulus from a set of alternatives that appropriately filled an empty cell in the matrix. Prior to the matrix problems, half the Ss in each matrix condition received sensitization training designed to increase the salience of the relevant dimensions in the matrix problems. The results showed that the pre-assessed salience of the relevant dimensions affected matrix solution in that more accurate performance was associated with those problems with both relevant dimensions relatively high in salience than those with one high and one low. Although the older Ss solved more problems, the evidence for coordination in the younger Ss was clear. No effects of sensitization training were found. 相似文献
175.
The behavior of narcotics-addicted and nonaddicted newborns on the first 2 days of life was assessed with the Brazelton Neonatal Behavioral Assessment Scale. In addition to classic signs of narcotics abstinence, addicted infants were less able to be maintained in an alert state and less able to orient to auditory and visual stimuli. These deficits were especially pronounced at 48 hours of age. Addicted infants were as capable of self-quieting and responding to soothing intervention as normal neonates, although they were substantially more irritable. These characteristics and addicted infants' greater resistance to cuddling are discussed in terms of their potential impact on early infant-care-giver interaction. 相似文献
176.
177.
178.
179.
William N. Anderson Richard J. Duffin George E. Trapp 《Journal of The Franklin Institute》1974,298(1):9-27
A mathematical theory is developed for an imagined device termed a “junctor”. A junctor could be used to interconnect two n-terminal networks giving rise to another n-terminal network. Actually a junctor is itself a simple network with three banks of n-terminals internally connected in some fashion by perfectly conducting wires. Adjacency matrices are formulated to analyze various junctors and their current flows. The main problem treated concerns conditions which would ensure that the junctor operation is associative. 相似文献
180.
The functional integral representation for the space-time Hopf characteristic functional associated with boundary-free incompressible fluid turbulence is evaluated accurately to order R-2, where R is the dimensionless Reynolds number in the theory. This work extends the results obtained previously for C-dominant turbulence to the regime of experimentally accessible large Reynolds numbers. We obtain a characteristic functional of non-Gaussian form as an asymptotically exact solution to the theory for large values of R. Two-point and three-point velocity correlation tensors of physical interest are derived from the characteristic functional. 相似文献