全文获取类型
收费全文 | 5930篇 |
免费 | 173篇 |
国内免费 | 3篇 |
出版年
2019年 | 54篇 |
2018年 | 110篇 |
2017年 | 87篇 |
2016年 | 83篇 |
2015年 | 65篇 |
2014年 | 74篇 |
2013年 | 449篇 |
2012年 | 171篇 |
2011年 | 160篇 |
2010年 | 82篇 |
2009年 | 98篇 |
2008年 | 136篇 |
2007年 | 152篇 |
2006年 | 131篇 |
2005年 | 127篇 |
2004年 | 123篇 |
2003年 | 103篇 |
2002年 | 117篇 |
2001年 | 214篇 |
2000年 | 205篇 |
1999年 | 142篇 |
1998年 | 56篇 |
1996年 | 59篇 |
1993年 | 54篇 |
1992年 | 118篇 |
1991年 | 120篇 |
1990年 | 117篇 |
1989年 | 99篇 |
1988年 | 89篇 |
1987年 | 97篇 |
1986年 | 108篇 |
1985年 | 105篇 |
1984年 | 95篇 |
1983年 | 82篇 |
1981年 | 53篇 |
1979年 | 95篇 |
1978年 | 70篇 |
1977年 | 62篇 |
1976年 | 54篇 |
1975年 | 67篇 |
1974年 | 92篇 |
1973年 | 100篇 |
1972年 | 72篇 |
1971年 | 69篇 |
1970年 | 80篇 |
1969年 | 75篇 |
1968年 | 106篇 |
1967年 | 82篇 |
1966年 | 93篇 |
1958年 | 62篇 |
排序方式: 共有6106条查询结果,搜索用时 15 毫秒
241.
Theoretical and technical considerations of measuring puff and inhalation volumes during cigarette smoking are reviewed. Measures of smoking behavior using a flowmeter and inductance plethysmography are described and demonstrated with seven subjects smoking over a 3-to 4-h period. Puff volume and duration, inhaled volume and duration, interpuff and intercigarette interval, and number of puffs varied for each individual over the session. The ratio of puff volume to inhaled volume changed with successive cigarettes. Smokers adjust the concentration of smoke by blending air with the smoke. Thus, to completely characterize smoking behavior, the volume of smoke and air inhaled into the lungs must be measured directly. 相似文献
242.
An Apple II/FIRST system has been developed to control classical conditioning experiments, collect analog data, and extract dependent variable measures of conditioning from uniphasic (Scandrett & Gormezano, 1980) and multiphasic (Johnson, 1981) response signals. The present paper details the development of an electrical brain stimulation system as a peripheral device to the Apple II/FIRST system. In addition, data are presented that document the capabilities of the EBS system to concurrently stimulate up to eight animals while values along the dimension of each of four stimulation parameters are manipulated by a program written in FIRST. In our judgment, the EBS system has a number of advantages over currently available commercial stimulators, including cost, number of sites that can be independently stimulated, and availability of complete software control. 相似文献
243.
The purpose of the present investigation was to evaluate the role of vicarious experience in the acquisition of pain termination and work avoidance. Fifty-six experimental subjects were randomly assigned to view a film of a model who either terminated exposure to a pain stimulus and work task after 10 sec (high-avoidant) or 70 sec (low-avoidant). Following the film presentation, subjects were exposed to the pain stimulus and work task. Half of the subjects were randomly chosen to perform the task with a low-intensity pain stimulus (LP) and the other half performed the task while exposed to a high-intensity pain stimulus (HP). The results indicated that subjects in the high-avoidant model conditions (HA) did significantly less work and tolerated the pain stimulus for significantly fewer seconds compared to the low-avoidant model groups (LA). Subjects in the LP groups tolerated the pain stimulus significantly longer and did significantly more work compared to subjects in the HP groups. No significant interaction was observed. The results provide support for the hypothesis that behavioral reactions to pain can be acquired by vicarious experience. Implications for future research are discussed. 相似文献
244.
R W Proctor M B Nunn I Pallos 《Journal of experimental psychology. Human perception and performance》1983,9(2):278-287
Several studies of metacontrast masking in the 1960s apparently showed that the latency of simple detection responses was uninfluenced by the phenomenal dimming of the target induced by the mask. More recent studies using more suitable methodologies have clearly shown that such is not the case for situations in which the masking is a monotonically decreasing function of stimulus onset asynchrony. Experiment 1 investigated this issue for the situation in which masking is a U-shaped function of stimulus onset asynchrony. Contrary to the results obtained in monotonic masking situations, simple detection responses were not slowed by the masking. Experiment 2 demonstrated that although detection responses are not slowed in the U-shaped masking situation, spatial-choice judgments are. Experiments 3 and 4 indicated that this masking effect on spatial-choice reaction time is lost relatively rapidly with practice. However, changing the stimulus-response assignments reinstates the effect. The experiments suggest that for the situation in which U-shaped masking functions are obtained, responses that require attention (spatial-choice judgments early in practice or after stimulus-response relationships have been switched) are influenced by the metacontrast-induced phenomenal dimming, whereas responses that are automatic (i.e., detection responses; practiced spatial-choice judgments with consistent stimulus-response mappings) are not. 相似文献
245.
An experiment is reported designed to test the hypothesis that female rats might discriminate between males that differed in the quantity of odor deposited by scent marking. Male odor donors were selected by prior screening for high or low rates of scent marking in an open arena. Females were then tested to determine whether they showed any preference for males that marked at a high rate. It was found that female rats did discriminate, but that they preferred to remain near males selected for low rates of scent marking. 相似文献
246.
Preprogramming vs. on-line control in simple movement sequences 总被引:1,自引:0,他引:1
In the present experiment the acceleration traces produced during a repetitive arm extension/flexion movement were measured in addition to the RT required to initiate such a movement. The speed at which this task was completed as well as the number of extension/flexion segments were varied to allow for either preprogramming or on-line control. Evidence from the acceleration traces and the RT data suggested that the movements completed as quickly as possible were preprogrammed; whereas, those completed more slowly were controlled on-line. Furthermore, the topologies of the power spectral density functions from the acceleration traces of each type of movement displayed characteristics typical of these forms of control. 相似文献
247.
A modified form of Nathanson and Becker's (1983) Health Belief Model Questionnaire and other measures designed to assess cognitive processing were administered to low-income black adolescent female clients of an inner-city comprehensive health care clinic. The purpose of the study was to explore determinants of sexual activity and contraceptive use. Subjects were classified as not sexually active (n = 50), sexually active/noncontracepting (n = 20), or sexually active/contracepting (n = 72). Not sexually active subjects tended to be younger, more career motivated, to have a father at home, to be more influenced by family values, and to have more conservative attitudes regarding adolescent sexuality than did sexually active subjects. Sexually active/noncontracepting subjects tended to report fewer benefits and more barriers to the use of contraception. Level of cognitive processing did not differ among the three groups, but was at a lower-than-expected level for age. Finally, inconsistent contraceptive use was common to both sexually active groups. 相似文献
248.
A I Leshner 《The American psychologist》1991,46(9):977-979
As an essential contributor to the scientific understanding of mental health and illness, psychology continues to be the leading discipline receiving National Institute of Mental Health (NIMH) research support. Future behavioral science research initiatives at NIMH are likely to emphasize cognitive science, behavioral genetics, behavioral patterns and physiological systems, and personality, motivation, emotion, and interpersonal processes. Although prognostication is particularly risky in times of transition such as the present, advocacy efforts focused on mental-illness-related research are most likely to help the NIMH and the field if they avoid polarization and factionalization by providing equal encouragement for studies of biological aspects, of behavioral aspects, and of their interaction. 相似文献
249.
A decade of research and services for homeless mentally ill persons. Where do we stand? 总被引:4,自引:0,他引:4
Over the past decade, researchers have documented the range of needs and devised new methods for increasing our understanding of the homeless severely mentally ill population. Clinicians have developed an appreciation of the difficulty and complexity of effectively treating this population, and policymakers have become increasingly aware of the barriers to developing services and housing. In this article, the progress-to-date in research, the evolution of new service approaches, and the development of federal, state, and local policies to meet the needs of homeless mentally ill individuals are assessed. The many challenges that remain are also considered. 相似文献
250.
I A Friedman 《Adolescence》1991,26(104):967-976
This study explored the concerns of Israeli adolescents, who grow up in a socially, politically, and economically highly stressed environment. Ninth- and eleventh-grade students (N = 1,645) completed a questionnaire in which they indicated three important problems they had recently experienced. Content analysis identified six major categories of concerns (listed in descending order of occurrence): studies and career, social "I," personal "I," existential issues, army or national service, and health and drugs. Younger adolescents were found to be more concerned with problems involving studies and career and with issues pertaining to the social "I"; older adolescents were more concerned with existential issues and army or national service. Boys were more concerned with existential issues, army or national service, studies and career, and the social "I." Girls were more concerned with issues pertaining to the personal "I." Three major sources of advice were identified: friends, parents, and brothers/sisters. 相似文献