全文获取类型
收费全文 | 73201篇 |
免费 | 3026篇 |
国内免费 | 30篇 |
出版年
2020年 | 823篇 |
2019年 | 985篇 |
2018年 | 1417篇 |
2017年 | 1465篇 |
2016年 | 1531篇 |
2015年 | 1107篇 |
2014年 | 1310篇 |
2013年 | 6266篇 |
2012年 | 2405篇 |
2011年 | 2424篇 |
2010年 | 1462篇 |
2009年 | 1478篇 |
2008年 | 2061篇 |
2007年 | 2090篇 |
2006年 | 1872篇 |
2005年 | 1588篇 |
2004年 | 1619篇 |
2003年 | 1554篇 |
2002年 | 1509篇 |
2001年 | 2446篇 |
2000年 | 2285篇 |
1999年 | 1717篇 |
1998年 | 792篇 |
1997年 | 694篇 |
1996年 | 784篇 |
1995年 | 701篇 |
1994年 | 682篇 |
1993年 | 670篇 |
1992年 | 1429篇 |
1991年 | 1335篇 |
1990年 | 1331篇 |
1989年 | 1264篇 |
1988年 | 1252篇 |
1987年 | 1147篇 |
1986年 | 1173篇 |
1985年 | 1198篇 |
1984年 | 990篇 |
1983年 | 852篇 |
1979年 | 1040篇 |
1978年 | 774篇 |
1975年 | 840篇 |
1974年 | 989篇 |
1973年 | 1011篇 |
1972年 | 847篇 |
1971年 | 795篇 |
1970年 | 731篇 |
1969年 | 690篇 |
1968年 | 900篇 |
1967年 | 794篇 |
1966年 | 737篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
This project studied the effects of weather variables and size of the population on minor and major violence rates within six prisons in the Kingston, Ontario, Canada area from January, 1980 through December, 1983. While weather variables have been studied in relation to mood changes within the general population, this study was the first to analyze the impact of weather variables on rates of violence within the prison setting using forward inclusion multiple regression. Analysis showed that population size consistently appeared positively correlated with assaults on other inmates among the male medium-security prisoners during the summer months. In the summer months, temperature tended to be positively related to some minor kinds of offenses, but in the winter months the relationship was negative. Humidity, rain, sunshine hours, snow, and snow on the ground were not consistently related to incidences of minor and major violence. Indices of geomagnetic disturbances had statistically significant inverse relationships with attempted suicide/self-inflicted injury rates among the male prisoners during the summer months. Over 12 months, wind was generally negatively correlated with incidences of major and minor violence among the male inmates. For 6-mo. periods, wind was generally positively correlated with violence rates during the winter months and negatively correlated during the summer months among the male inmates. The findings relating weather variables to violence rates in the women's prison were consistently in opposition to those found for male prisoners during the 4-yr. period. 相似文献
992.
C M Whissell 《Perceptual and motor skills》1985,61(1):3-12
Evidence relating to the hypothesis on facial feedback which ties the experience of discrete emotions to feedback from innately patterned facial expressions is discussed. Strong evidence is deduced for a more general form of the hypothesis, but the requirements of necessity and sufficiency representing the strictest form are only satisfied within narrow limits of experimental manipulations which are not common to all investigations. Evidence is deemed to support a relationship between facial expression and emotion, but facial expression is regarded as one of many systems and cannot be assigned an exclusive role (either as first system or as necessary system). 相似文献
993.
994.
995.
Psychometric studies on the specificity of psychological performance disorders of epileptic patients
H Herzer G Rabending R Altenstein M Grimmberger 《Psychiatrie, Neurologie, und medizinische Psychologie》1985,37(1):1-10
Using a psychological test battery for registration of psychic/psychomotoric speed and flexibility/perseveration we examined 78 epileptic patients with different forms of epilepsy and the same number of brain healthy control persons, parallelised in sex, age, education, profession and intelligence. The registrated data were varianz-, correlation- and factoranalised. We found a deceleration of psychic/psychomotoric speed as a primary basic disorder in epileptics. Decreases of flexibility independent of speed were not ascertainable. 相似文献
996.
997.
998.
Rats were given backward pairings of a tone (CS) and shock (US) and were then tested for response to the CS in a lick suppression test. Animals given a cuing or reminder treatment prior to the test exhibited enhanced suppression in the presence of the tone relative to a variety of control conditions. The cue-induced suppression enhancement did not appear to result from sensitization or short-term motivational changes nor did it seem to depend on second-order conditioning of the test context. The effect appeared more robust as the number of backward conditioning trials preceding the cue increased. The results were discussed in terms of current explanations of backward conditioning effects. 相似文献
999.
White KG Pipe ME McLean AP Redman S 《Journal of the experimental analysis of behavior》1985,44(2):207-215
Distributions of reinforcers between two components of multiple variable-interval schedules were varied over a number of conditions. Sensitivity to reinforcement, measured by the exponent of the power function relating ratios of responses in the two components to ratios of reinforcers obtained in the components, did not differ between conditions with 15-s or 60-s component durations. The failure to demonstrate the “short-component effect,” where sensitivity is high for short components, was consistent with reanalysis of previous data. With 60-s components, sensitivity to reinforcement decreased systematically with time since component alternation, and was higher in the first 15-s subinterval of the 60-s component than for the component whose total duration was 15 s. Varying component duration and sampling behavior at different times since component transition may not be equivalent ways of examining the effects of average temporal distance between components. 相似文献
1000.
Two experiments examined pigeons' response rates during short trials signaled by stimuli closely spaced along a wavelength continuum. In Experiment 1 separate halves of the continuum were correlated with different reinforcement schedules. In Experiment 2, the middle stimulus was accompanied by a lower probability of reinforcement than were the remaining wavelengths. Both procedures resulted in dimensional contrast “shoulders,” seen as relatively enhanced or depressed response rates in the presence of stimuli between the extreme of the continuum and the border separating the positive and negative stimuli. Sequential analyses addressed possible contributions of the following interactions: (a) local contrast, seen when rate during a given schedule depends on the schedule in the just-preceding trial; (b) modification of local contrast by the similarity of the signaling stimuli (P. Blough, 1983); and (c) schedule-independent rate contrast, seen when rate in a given trial depends on the rate controlled by the stimulus that accompanied the just-preceding trial (Malone & Rowe, 1981). Dimensional contrast functions were similar when isolated according to the schedule, to the similarity of the signaling stimulus, and to the response rate of the just-preceding trial. The interactions noted above do not appear to make important contributions to this effect. 相似文献