全文获取类型
收费全文 | 67120篇 |
免费 | 1136篇 |
国内免费 | 3篇 |
专业分类
68259篇 |
出版年
2020年 | 770篇 |
2019年 | 937篇 |
2018年 | 1260篇 |
2017年 | 1286篇 |
2016年 | 1394篇 |
2015年 | 1004篇 |
2014年 | 1220篇 |
2013年 | 5810篇 |
2012年 | 2235篇 |
2011年 | 2259篇 |
2010年 | 1408篇 |
2009年 | 1419篇 |
2008年 | 1985篇 |
2007年 | 1978篇 |
2006年 | 1834篇 |
2005年 | 1540篇 |
2004年 | 1565篇 |
2003年 | 1515篇 |
2002年 | 1452篇 |
2001年 | 2071篇 |
2000年 | 1971篇 |
1999年 | 1488篇 |
1998年 | 776篇 |
1997年 | 678篇 |
1996年 | 745篇 |
1995年 | 682篇 |
1994年 | 677篇 |
1993年 | 635篇 |
1992年 | 1232篇 |
1991年 | 1141篇 |
1990年 | 1098篇 |
1989年 | 1068篇 |
1988年 | 1036篇 |
1987年 | 977篇 |
1986年 | 965篇 |
1985年 | 1027篇 |
1984年 | 856篇 |
1983年 | 757篇 |
1982年 | 632篇 |
1981年 | 605篇 |
1979年 | 869篇 |
1978年 | 712篇 |
1977年 | 609篇 |
1976年 | 597篇 |
1975年 | 730篇 |
1974年 | 812篇 |
1973年 | 826篇 |
1972年 | 700篇 |
1971年 | 630篇 |
1968年 | 679篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
The responses toward denatonium saccharide and quinine by three rodent species differ from those exhibited by humans. This study measured the relative aversiveness of these two compounds in grasshopper mice (Onychomys leucogaster) to determine if this species responded similarly to or differently from these other rodents. In a choice test, the mice clearly preferred quinine over denatonium saccharide at concentrations of 1/10,000 and 1/50,000, but only marginally preferred quinine at a concentration of 1/1000. When denatonium or quinine was paired with toxicosis, both suppressed drinking at concentrations from 1/10,000 to 1/50,000, but only denatonium suppressed drinking at 1/100,000. Neither compound suppressed drinking at 1 part in million. Grasshopper mice perceived denatonium saccharide as more aversive than quinine in both experiments. Such a response resembled the behavior of humans more than that of the other three rodents previously tested. 相似文献
172.
This study compared normal developing children, aged 34 to 51 mo., on comprehension and production of relative dimensional adjectives using object manipulations in a close elicitation procedure and on Piagetian operational tests of conservation of continuous quantity, length, reversibility and seriation. Analysis indicated a significant difference on the expressive language performance of the transitional and the concrete operational children over the preoperational children, but no significant differences occurred between the first two groups. Children who performed better on seriation were significantly better on expressive language performance. Children classified as operational for length performed better on all language measures than those classified as nonoperational. Reversibility and conservation of a continuous quantity did not differentiate children. 相似文献
173.
This study examined job bias associated with business students' role-playing as sales managers who assigned trainees to sales territories. Personal characteristics of being extremely overweight and being a heavy smoker were studied. Research participants were given a personnel record (training record) of a sales trainee and asked to make a sales territory assignment decision; three vacant territories were also described. The participants were told to assign the trainee to one of the territories or to indicate a preference to not have the recruit assigned to any territory within the role-playing manager's region. Analysis indicates that a sales recruit described as extremely overweight was less likely to be assigned to an important or desirable sales territory and more likely to be assigned to an undesirable territory or not selected at all for an assignment within a sales region. Those described as heavy smokers were similarly treated but to a lesser degree. Overweight saleswomen were discriminated against more than overweight salesmen. 相似文献
174.
The technique of Free Visual Imagery Sequences was used with 32 outpatients, M age of 33.9, to determine the differences between Visual Imagery Reactors and Nonreactors as defined in previous studies. Reactors showed significantly more responses associated with Affect/Conflict material, frequently including bizarre and distorted images. The Affect/Conflict responses occurred earlier and had longer duration spans in Reactors. Neutral content was more prevalent in Nonreactors. An interpretive approach involving a regulatory processing system is proposed. Free Visual Imagery Sequences appears to be a simple and efficient clinical technique which can contribute data useful in determining the extent to which imagery techniques could be employed in certain forms of psychotherapy. 相似文献
175.
The naturalistic fallacy occurs when a person reads a report of scientific research and concludes that the moral implication of the research was included in the article when, in fact, it was not. For example, the fallacy is committed when a study contains the conclusion that TV advertising increases preference for sugar-based foods, but the reader later believes that the study concluded that TV advertising should be controlled. Previous research indicates that the commission of the fallacy was strong when memory for social research was tested. The present study showed that the commission of the fallacy was stronger when the research which was read involved children as subjects compared to adult subjects. Increased empathy for the subjects of a research article strengthens commission of the fallacy. 相似文献
176.
M Verkuyten 《Psychological reports》1989,65(2):577-578
A nationwide sample of 2710 Dutch adolescents and 518 ethnic minority adolescents living in the Netherlands was used to examine ethnic and sex differences in happiness. Analyses of variance were conducted with ethnic background, sex, and length of residence in the Netherlands, as variables. Socioeconomic status was included in the analyses as a covariate. Adolescents from ethnic minority backgrounds, as compared to the Dutch, had significantly lower scores on a generalized estimates of life satisfaction and on a measure of hedonic effect. Both differences, however, explained only a very small amount of variance. Girls (from all ethnic groups including the Dutch) had lower scores than boys on both measures. There was no significant effect for length of residence on either measure. 相似文献
177.
Trace mineral analysis of human hair was utilized to determine whether violent and nonviolent criminals could be differentiated on the basis of concentrations of levels of major and trace minerals. 40 violent and 40 nonviolent inmates from a prison population were selected for study. 27 mineral levels were analyzed and a discriminant function analysis correctly classified 86% of the violent and 78% of the nonviolent inmates. The results lent support to the hypothesis that significantly different levels of trace minerals could be found between the two groups. 相似文献
178.
H-reflex amplitudes were studied during the acquisition of a motor skill involving coordinated isometric plantarflexion at the ankle joints as subjects learned to trace a triangular pattern on an oscilloscope screen by controlling plantarflexion torque applied against load cells. Torque feedback was presented on a subject oscilloscope with the right foot controlling a vertical cursor and the left foot a horizontal cursor. Eleven subjects reached criterion performance. H-reflexes were recorded from the right soleus and timed to the initiation of soleus muscle activity to plantarflex the foot. Average time to complete one trial decreased from 9 sec. in the prelearning block to 4 sec. postlearning. No single learning strategy was evident as subjects varied widely in their levels of H-reflex amplitude, but during postlearning, H-reflex amplitude became consistent within subjects as tracing performance became faster and accurate. 相似文献
179.
Do response time advantage and interference reflect the order of processing of global- and local-level information? 总被引:1,自引:0,他引:1
Navon's (1977) global precedence hypothesis was based primarily on the joint occurrence of two effects: a response time (RT) advantage for identifying global targets, and interference by global distractors on responding to local targets. Although the hypothesis has been questioned on the basis of experiments in which it has been shown that a local RT advantage and local interference can occur, it is still frequently assumed that these two effects are a valid measure of the order in which local and global levels of structure are processed. In the present experiment, this assumption was examined. Subjects identified target letters that occurred randomly at the global or local level in a divided-attention task. The visual angle subtended by the stimulus pattern was varied, a manipulation known to affect the relative speed of response to local- or global-level information. Local targets were identified faster than global targets at the larger visual angles, but there was no difference in RT at the smallest visual angle. Despite this change in RT advantage, the interference effect did not change as a function of the visual angle of the stimulus pattern. Moreover, global distractors interfered with responding to local targets but local targets had no effect on responding to global targets, which is exactly the opposite of the finding one would expect if RT advantage and interference reflected order of processing. These findings are not consistent with the assumption that RT advantage and interference reflect order of processing in a simple way. 相似文献
180.
We reported earlier that occlusion of the central retina and stationary edges have highly interactive effects on the gain of optokinetic nystagmus (OKN; Murasugi, Howard, & Ohmi, 1986). In this study, we explored this effect in more detail. A central occluding band of variable height, flanked by vertical bars, was superimposed onto an array of dots moving at 30 degrees per second. The height of the occluding band required to abolish OKN increased with the separation of the vertical bars. For bars 3.5 degrees apart, OKN was abolished in most subjects when a band only 6' high ran between them. For bars 75 degrees apart, a band at least 20 degrees in height was required to abolish the response. The effects of the stationary figure depended to some extent on the subject's attention, but only at intermediate values of bar separation. Both low- and high-level mechanisms are proposed to account for the results. 相似文献