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   72114篇
  免费   2829篇
  国内免费   37篇
  2020年   744篇
  2019年   905篇
  2018年   1326篇
  2017年   1337篇
  2016年   1396篇
  2015年   956篇
  2014年   1178篇
  2013年   5969篇
  2012年   2113篇
  2011年   2298篇
  2010年   1402篇
  2009年   1397篇
  2008年   2125篇
  2007年   2054篇
  2006年   1855篇
  2005年   1653篇
  2004年   1618篇
  2003年   1511篇
  2002年   1572篇
  2001年   2222篇
  2000年   2119篇
  1999年   1655篇
  1998年   874篇
  1997年   787篇
  1996年   740篇
  1995年   733篇
  1993年   682篇
  1992年   1383篇
  1991年   1310篇
  1990年   1277篇
  1989年   1157篇
  1988年   1151篇
  1987年   1111篇
  1986年   1165篇
  1985年   1205篇
  1984年   977篇
  1983年   847篇
  1979年   987篇
  1978年   765篇
  1976年   693篇
  1975年   878篇
  1974年   986篇
  1973年   979篇
  1972年   839篇
  1971年   783篇
  1970年   724篇
  1969年   751篇
  1968年   913篇
  1967年   863篇
  1966年   820篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
851.
Pigeons keypecked on a two-key procedure in which their choice ratios during one time period determined the reinforcement rates assigned to each key during the next period (Vaughan, 1981). During each of four phases, which differed in the reinforcement rates they provided for different choice ratios, the duration of these periods was four minutes, duplicating one condition from Vaughan's study. During the other four phases, these periods lasted six seconds. When these periods were long, the results were similar to Vaughan's and appeared compatible with melioration theory. But when these periods were short, the data were consistent with molecular maximizing (see Silberberg & Ziriax, 1982) and were incompatible with melioration, molar maximizing, and matching. In a simulation, stat birds following a molecular-maximizing algorithm responded on the short- and long-period conditions of this experiment. When the time periods lasted four minutes, the results were similar to Vaughan's and to the results of the four-minute conditions of this study; when the time periods lasted six seconds, the choice data were similar to the data from real subjects for the six-second conditions. Thus, a molecular-maximizing response rule generated choice data comparable to those from the short- and long-period conditions of this experiment. These data show that, among extant accounts, choice on the Vaughan procedure is most compatible with molecular maximizing.  相似文献   
852.
The effects of electroconvulsive shock (ECS) on spatial memory first reported by Shavalia, Dodge, and Beatty (1981, Behavioral and Neural Biology, 31, 261-273) were systematically replicated in two experiments. Rats acquired concurrent spatial memories in two 8-arm radial mazes. Each rat was allowed four choices in Maze 1 and then, after 2 h, four choices in Maze 2. After 2 h each rat was tested for retention in Maze 1 and, after 2 more h, was tested for retention in Maze 2. A single ECS was administered immediately after the fourth choice in Maze 2. Retention (as measured by accuracy of Choices 5-8) was diminished for Maze 1 but not for Maze 2. In the second experiment, the delay between the retention tests was eliminated (thus holding the ECS-Choice 5 interval constant for the two mazes). Once again retention of Maze 1 was impaired and retention of Maze 2 was spared; that finding suggests that ECS does not proactively affect radial-arm maze performance. The results of a third experiment converge on the same conclusion; ECS failed to reduce levels of spontaneous alternation. Therefore, ECS appears to interfere retroactively with relatively old spatial memories and newly established memories appear to be immune to the amnestic effects of ECS. Implications and various explanations are considered.  相似文献   
853.
Training and Research in Counselling   总被引:1,自引:0,他引:1  
Formal counselling training in Britain began with the preparation of school counsellors in universities and relied largely upon American models. Early courses were highly didactic but over the last decade practical and experiential aspects have taken precedence. Basic counselling training has now been extended into the preparation of many workers, voluntary and professional. Counselling research also had academic origins, but has broadened to include many different work settings. Much of the published research has been in the form of surveys of counselling services, but some detailed studies of process are noted. There is a need for research to be increased, and the gap between research and practice shortened, if counselling is to demonstrate its relevance to contemporary needs.  相似文献   
854.
Michael W. Martin 《Sex roles》1985,13(11-12):597-605
The relative effects of equity, equality, and reward level upon assessments of marital satisfaction are investigated. In doing so, the impact of gender-role orientation upon the relationship between the predictor variables and marital satisfaction is specified. The data indicate that reward level is the major variable affecting assessments of satisfaction for both moderns and traditionals. Further, the effect of reward level is more pronounced for those with modern gender-role orientations. Contrary to expectation, the effects of the exchange-related variables, equity and equality, are minimal for both moderns and traditionals. These findings suggest that intimates, regardless of gender-role orientation, tend to avoid the “bookkeeping” involved in global equity and equality comparisons and instead accentuate individual reward levels. It appears, however, that moderns are significantly more demanding than traditionals in their emphasis upon reward levels.  相似文献   
855.
Some effects of color on naming and recognition of objects   总被引:1,自引:0,他引:1  
In this article, we investigated the role of color in the recognition and naming of everyday objects. In the first experiment we found that color pictures were named faster than black-and-white and that shape information did not facilitate color naming. Experiment 2 was carried out to determine at which stage of object processing the color facilitation occurred. We found that color had no effect on object recognition but did facilitate object naming, even when color was redundant for discrimination. This did not apply to naming abstract shapes. Experiment 3 replicated the findings of Experiment 2 using different objects and colors. The results showed that color could facilitate but not inhibit object naming and did not affect object recognition.  相似文献   
856.
Dobbins  Gregory H.  Stuart  Cecile  Pence  Earl C.  Sgro  Joseph A. 《Sex roles》1985,12(5-6):549-560
The present study examined the effects of the sex of the leader, the sex of the rater, and the temporal position of leader performance information on ratings of leader behavior. Male and female subjects listened to an audiotape of a male or female leader and then rated the leader's initiating structure and consideration behaviors. The position of the leader performance information was manipulated by describing the leader as successful before or after raters listened to the audiotape or not presenting raters with the performance information. Analyses indicated that the sex of the leader and/or sex of the rater biased ratings of initiating structure when the performance information was presented after the audiotape and when no leader performance information was presented. Consideration ratings were affected only by the position of the leader performance information. The results are interpreted within a cognitive/implicit sex theory framework. Implications for leadership research are also discussed.Portions of the data analyzed in this study were collected by the second author as part of a master's thesis directed by Joseph A. Sgro.  相似文献   
857.
This research examined the creative writing of 180 elementary school children for evidence of sex difference and sex-role perceptions. Stories were analyzed for frequency of male and female characters, attributes, and roles. Writers were equally divided by sex and into three age groups—grades 1–2, 3–4, and 5–6. Results suggest that the total number of characters, roles, and attributes was equivalent. However, the distribution of male and female characters, roles, and attributes differed with male and female writers. Female writers included significantly more female characters and assigned more attributes and roles to these characters. Nevertheless, in the stories of both male and female writers, there was a predominance of male characters and assignment of attributes and roles to male characters. The findings support the development and implementation of a nonsexist curriculum.  相似文献   
858.
The effects of dopaminergic depletion of the nucleus accumbens was tested in various behavioral tasks such as alternation, spatial discrimination, and reversal learning, and in an extinction paradigm in a T maze. Animals with lesions showed impairment of spontaneous alternation behavior, disturbances in the acquisition of spatial discrimination, and great difficulty in reversing previously learned habits. In the extinction phase, experimental animals are unable to adjust their behavior, and continue to choose the previously reinforced arm of the T maze. It is suggested that the nucleus accumbens plays an important role in the transition of motivation into action, and that dopamine has a facilitatory influence on the mediation of these processes.  相似文献   
859.
To test the generality, across modality and across species, of a bidirectional effect of photic stimulation in infant rats found in previous experiments, two experiments examined the effects on heart rate (HR) of onset and offset of auditory stimulation in rats and of photic stimulation in guinea pigs. Experiment 1 demonstrated a unidirectional, decelerative response in rats 17 and 21 days of age to the onset and offset of a 1-kHz tone, at both low (80 dB) and high (100 dB) intensity levels and at 14 days to the onset of the high-intensity tone. Experiment 2 demonstrated that infant guinea pigs, which unlike infant rats are precocial and not nocturnal, responded to the offset but not to the onset of light, and that this response was decelerative. These results indicated a lack of generality of the bidirectional HR effect, and were discussed in terms of the orienting/defensive reflex distinction.  相似文献   
860.
During 46 consecutive days the daily food intake and weight were recorded in 16 male Wistar rats. On Days 31-45 one mouse was presented each rat daily. Before any experience with mice (Days 0-27) the mousekiller rats, compared with the nonkiller rats, regulated their individual food intake more closely to their homeostatic equilibria, corrected for the linear trend. This result indicates a functional difference in food intake regulation between mousekiller rats and nonkiller rats prior to any experience with mice. However, no difference in the mean food intake was found between the mousekiller and the nonkiller rats.  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