首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   24484篇
  免费   68篇
  24552篇
  2022年   26篇
  2021年   26篇
  2020年   67篇
  2019年   55篇
  2018年   3542篇
  2017年   2890篇
  2016年   2375篇
  2015年   255篇
  2014年   187篇
  2013年   617篇
  2012年   716篇
  2011年   2539篇
  2010年   2591篇
  2009年   1592篇
  2008年   1850篇
  2007年   2318篇
  2006年   210篇
  2005年   324篇
  2004年   318篇
  2003年   244篇
  2002年   192篇
  2001年   97篇
  2000年   118篇
  1999年   73篇
  1998年   89篇
  1997年   80篇
  1996年   63篇
  1995年   51篇
  1994年   73篇
  1993年   52篇
  1992年   43篇
  1991年   38篇
  1990年   39篇
  1989年   36篇
  1988年   40篇
  1987年   47篇
  1986年   34篇
  1985年   50篇
  1984年   42篇
  1983年   35篇
  1982年   56篇
  1981年   42篇
  1980年   37篇
  1979年   34篇
  1978年   45篇
  1977年   48篇
  1976年   50篇
  1975年   41篇
  1974年   34篇
  1973年   27篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
In Experiment 1, rats were given a 1-pellet reward for 48 preshift trials. During a subsequent 20-trial postshift phase, one group was shifted to a 12-pellet reward on Trial 1, a second was shifted on Trial 11, and a third was given 1 more pellet each trial and then 12 pellets for the last 10 trials. The speeds of all three groups increased to a level above that of a control group given a 12-pellet food reward throughout training (positive contrast). In experiment 2, rats were shifted from 1 to 12 pellets either gradually or abruptly following either abbreviated training (9 trials) or extended training (20 trials). One group of control subjects received 12 pellets throughout training. The results revealed a positive contrast effect for gradually shifted subjects following extended training but not following abbreviated training. The abrupt shift procedure produced positive contrast following abbreviated training but only a marginal effect following extended training. These results indicate that, contingent upon the amount of preshift training, either gradual or abrupt reward increases may produce positive contrast.  相似文献   
82.
An attempt was made to reproduce and extend previously reported data suggesting the operation of sex-related bias in clinicians' attributions of parental involvement in children's psychopathologies. More and less sex-role traditional male and female family-oriented practitioners were shown contrived profiles in which a boy or girl was described as masculine or feminine role-deficient, and apportioned maternal versus paternal blame, treatment focus, adjunctive therapy need, and likelihood of sabotage. As in the previous study, mothers were implicated slightly more than fathers and also were viewed as requiring relatively greater therapeutic attention by female than by male clinicians. However, several earlier findings were not replicated. Overall, the results offer only marginal support for the notion of sex-related practitioner bias.  相似文献   
83.
School counsellors are often presented with information about pupils from a third party - a parent, another pupil, a member of the canteen staff a social worker, or a member of the teaching staff - with the expectation that the counsellor is in a position to take 'necessary' or 'appropriate' action. One particular case is used to illustrate some of the difficulties involved in acting upon third-party information.  相似文献   
84.
85.
86.
The effects of altering the contingency between the conditioned stimulus (CS) and the unconditioned stimulus (US) on the acquisition of autoshaped responding was investigated by changing the frequency of unsignaled USs during the intertrial interval. The addition of the unsignaled USs had an effect on acquisition speed comparable with that of massing trials. The effects of these manipulations can be understood in terms of their effect on the amount of information (number of bits) that the average CS conveys to the subject about the timing of the next US. The number of reinforced CSs prior to acquisition is inversely related to the information content of the CS.  相似文献   
87.
This study examined emotional labor processes from a within-person, episodic framework. The authors hypothesized that the influence of negative emotions on affective delivery would be lessened by regulation strategies for supervisor perceptions but not self-perceptions. In addition, difficulty maintaining display rules was hypothesized to mediate the relation between negative emotions and self-perceptions of affective delivery. Finally, the influence of surface acting strategies on these processes as well as correlations with individual differences was investigated. Hypotheses were tested using ecological momentary assessment of a sample of cheerleading instructors. Results suggest that surface actors can regulate emotions effectively on an episode-to-episode basis but find the episode more difficult. In addition, surface actors exhibit more general tendencies to devalue themselves and experience fewer positive emotions.  相似文献   
88.
The major aim of this study was to examine the longitudinal association between adolescent smoking involvement and self-reported psychological and physical outcomes in young adulthood. Participants included 333 African Americans and 329 Puerto Ricans who were surveyed in 1990 in their New York City schools and interviewed in 1995 and 2000-2001, primarily in their homes. The psychological outcomes included ego integration, symptoms of depression, anxiety, and interpersonal difficulty. The physical health measures included a general health rating, number of illnesses, and symptoms of ill health. Also, three scales measured problems due to alcohol, marijuana, and other illicit drug use. Smoking involvement varied by age, sex, and ethnicity but not by socioeconomic status nor by late adolescent parental status. Analysis showed that the relationships between adolescent smoking involvement and psychological and physical health problems in young adulthood remained significant even with control on demographic factors, earlier levels of the outcome variables, and marijuana use. The relationships between smoking behavior and problems with alcohol, marijuana and other illicit drug use were particularly strong. Thus, adolescent smoking seems to have a wide range of clinical implications for young adulthood.  相似文献   
89.
Nonhuman animals, like humans, appear sensitive to the structure of the elements of sequences, perhaps even when the structure relates nonadjacent elements. In the present study, we examined the contribution of chunking, rule learning, and item memory when rats learned serial patterns composed of two interleaved subpatterns. In one group, the first interleaved subpattern was a formally simple sequence, whereas in two other groups the first subpattern was formally more complex, containing 2 or 4 violation elements, respectively. In all groups, the second interleaved subpattern encountered was formally simple. Evidence from the study suggests that rats chunked their interleaved patterns into component subpatterns, that is, they cognitively sorted pattern elements to form chunks based on nonadjacent structural relationships that can be characterized as rules. They also learned interitem associations via traditional discrimination learning to use adjacent elements as compound or configural cues for later events in the sequence. Thus, the evidence suggests that rats used chunking, rule learning, and interitem association learning concurrently to master these complex patterns.  相似文献   
90.
Our reduced ability to correctly report two sequentially presented targets is seen in the robust effect known as the attentional blink (AB; Raymond, Shapiro, & Arnell, 1992). One recent report (Olivers & Nieuwenhuis, 2005) strikingly reveals the AB to be virtually abolished when non-task-demanding music occurs in the background. The authors suggest that a diffuse attentional state is the mediating factor. Here, we seek to broaden the finding’s generality by determining if task-irrelevant visual motion and flicker also attenuate the AB. In our experiments, the AB task was presented together with a background field of moving dots that could moveaway from ortoward the central AB task, or flicker. In the control condition, the dots remained static. The AB was attenuated—though to different degrees—in all experimental conditions, but not in the static condition. Our findings add to the generality of the previous conclusions, and we emphasize an account based on the overallocation of attention.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号