全文获取类型
收费全文 | 18470篇 |
免费 | 918篇 |
国内免费 | 15篇 |
专业分类
19403篇 |
出版年
2021年 | 158篇 |
2020年 | 275篇 |
2019年 | 282篇 |
2018年 | 425篇 |
2017年 | 424篇 |
2016年 | 444篇 |
2015年 | 345篇 |
2014年 | 365篇 |
2013年 | 1563篇 |
2012年 | 647篇 |
2011年 | 741篇 |
2010年 | 438篇 |
2009年 | 407篇 |
2008年 | 565篇 |
2007年 | 523篇 |
2006年 | 458篇 |
2005年 | 376篇 |
2004年 | 375篇 |
2003年 | 372篇 |
2002年 | 377篇 |
2001年 | 733篇 |
2000年 | 728篇 |
1999年 | 480篇 |
1998年 | 197篇 |
1997年 | 182篇 |
1996年 | 151篇 |
1995年 | 145篇 |
1993年 | 146篇 |
1992年 | 361篇 |
1991年 | 332篇 |
1990年 | 350篇 |
1989年 | 338篇 |
1988年 | 323篇 |
1987年 | 294篇 |
1986年 | 313篇 |
1985年 | 309篇 |
1984年 | 241篇 |
1983年 | 205篇 |
1979年 | 196篇 |
1978年 | 165篇 |
1975年 | 193篇 |
1974年 | 243篇 |
1973年 | 202篇 |
1972年 | 204篇 |
1971年 | 170篇 |
1970年 | 149篇 |
1969年 | 198篇 |
1968年 | 202篇 |
1967年 | 162篇 |
1966年 | 182篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
41.
Knowledge and beliefs regarding the consequences of cigarette smoking and their relationships to smoking status in a biracial sample 总被引:3,自引:0,他引:3
R C Klesges G Somes R W Pascale L M Klesges M Murphy K Brown E Williams 《Health psychology》1988,7(5):387-401
The purpose of this investigation was to evaluate carefully smoking-related knowledge and beliefs and their relationships to smoking status in a large, heterogeneous sample of smokers and nonsmokers in two settings: (a) a large, biracial southern city and (b) a small midwestern community. Participants were 611 (198 male, 413 female) adult respondents to a random-dialing telephone survey in Fargo, North Dakota (n = 200), and Memphis, Tennessee (n = 411). Each participant was given the Smoking Attitudes Survey, which assesses generalized health beliefs as well as health-related problems associated with smoking. Participants' knowledge of smoking-associated diseases (e.g., lung cancer) and of diseases not associated with smoking (e.g., kidney stones) was assessed. Stepwise regression analysis of composite knowledge scores revealed four independent predictors of the health consequences of smoking: education, race, smoking status, and income. Smokers, compared to nonsmokers, reported less knowledge related to the health consequences of smoking, were more likely to be male, were less concerned with the health consequences of smoking, and were more concerned about the health consequences of cholesterol. The best predictor of smokers who had never attempted cessation was their greater concern over weight control when compared to smokers with a history of smoking cessation attempts. The results are discussed in terms of smoking prevention and intervention efforts. 相似文献
42.
In two experiments, key-peck responding of pigeons was compared under variable-interval schedules that arranged immediate reinforcement and ones that arranged unsignaled delays of reinforcement. Responses during the nominal unsignaled delay periods had no effect on the reinforcer presentations. In Experiment 1, the unsignaled delays were studied using variable-interval schedules as baselines. Relative to the immediate reinforcement condition, 0.5-s unsignaled delays decreased the duration of the reinforced interresponse times and increased the overall frequency of short (<0.5-s) interresponse times. Longer, 5.0-s unsignaled delays increased the duration of the reinforced interresponse times and decreased the overall frequency of the short interresponse times. In Experiment 2, similar effects to those of Experiment 1 were obtained when the 0.5-s unsignaled delays were imposed upon a baseline schedule that explicitly arranged reinforcement of short interresponse times and therefore already generated a large number of short interresponse times. The results support earlier suggestions that the unsignaled 0.5-s delays change the functional response unit from a single key peck to a multiple key-peck unit. These findings are discussed in terms of the mechanisms by which contingencies control response structure in the absence of specific structural requirements. 相似文献
43.
The effects of two alternative sources of food delivery on the key-peck responding of pigeons were examined. Pecking was maintained by a variable-interval 3-min schedule. In the presence of this schedule in different conditions, either a variable-time 3-min schedule delivering food independently of responding or an equivalent schedule that required a minimum 2-s pause between a key peck and food delivery (a differential-reinforcement-of-other-behavior schedule) was added. The differential-reinforcement-of-other-behavior schedule reduced response rates more than did the variable-time schedule in most instances. The delay between a key peck and the next reinforcer consistently was longer under the differential-reinforcement-of-other-behavior schedule than under the variable-time schedule. Response rates and median delay between responses and reinforcers were negatively correlated. These results contradict earlier conclusions about the behavioral effects of alternative reinforcement. They suggest that an interpretation in terms of response–reinforcer contiguity is consistent with the data. 相似文献
44.
K Friemert 《Psychiatrie, Neurologie, und medizinische Psychologie》1988,40(11):671-677
Basing on the author's experiences during his study stay at the Serbsky All-Union Research Institute for General and Forensic Psychiatry in Moscow a report is given about the theoretical foundations and the carrying-out of forensic-psychiatric expert-opinions in the field of penal as well as civil law in the U.S.S.R. Some peculiarities in comparison with the practice in the G.D.R. are taken in special account. 相似文献
45.
S Martin K Housley H Mccoy P Greenhouse F Stigger M A Kenney S Shoffner V Fu M Korslund F G Ercanli-Huffman 《Perceptual and motor skills》1988,67(3):879-884
The Rosenberg Self-esteem Scale was administered to 550 14- and 16-yr.-old (+/- 6 mo.) girls. Self-esteem scores were categorized by weight and weight by height. Scores on the Quetelet Index for obesity were correlated with self-esteem scores. Mean self-esteem of the low- and middle-weight by height group was significantly higher than the mean of the high-weight by height group. In analyzing weight alone, the self-esteem of the middle-weight group was significantly higher than the self-esteem of the high-weight group. The correlation of the obesity index and self-esteem indicated that as weight increased self-esteem decreased. 相似文献
46.
D K Simonton 《Psychological bulletin》1988,104(2):251-267
47.
48.
49.
50.
M H Kelly J K Bock 《Journal of experimental psychology. Human perception and performance》1988,14(3):389-403
The goals of this research were to determine whether speakers adjust the stress patterns of words within sentences to create an alternation between strong and weak beats and to explore whether this rhythmic alternation contributes to the characteristics stress differences between two major lexical categories of English. Two experiments suggested that speakers do alter lexical stress in accordance with rhythmic biases. When speakers produced disyllabic pseudowords in sentence contexts, they were more likely to place stress on the first syllable when the pseudoword was preceded by a weak stress and followed by a strong one than when the strong stress preceded and the weak followed. This occurred both when the pseudowords served as nouns and when they served as verbs. Text analyses further revealed that weakly stressed elements precede nouns more often than verbs, whereas such elements follow verbs more often than nouns. Thus, disyllabic nouns are more likely than disyllabic verbs to occupy contexts biased toward trochaic rhythm, a finding consistent with leftward dominant stress in disyllabic English nouns. The history of stress changes in English nouns and verbs also conforms with the view that rhythmic context may have contributed to the evolution of stress differences. Together, the findings suggest that the citation stress patterns of words may to some degree reflect adaptations of lexical knowledge to conditions of language performance. 相似文献