全文获取类型
收费全文 | 4043篇 |
免费 | 1048篇 |
国内免费 | 32篇 |
出版年
2019年 | 49篇 |
2018年 | 69篇 |
2017年 | 50篇 |
2016年 | 74篇 |
2015年 | 56篇 |
2014年 | 52篇 |
2013年 | 312篇 |
2012年 | 99篇 |
2011年 | 159篇 |
2010年 | 143篇 |
2009年 | 220篇 |
2008年 | 158篇 |
2007年 | 164篇 |
2006年 | 109篇 |
2005年 | 119篇 |
2004年 | 143篇 |
2003年 | 145篇 |
2002年 | 97篇 |
2001年 | 148篇 |
2000年 | 99篇 |
1999年 | 117篇 |
1998年 | 95篇 |
1997年 | 78篇 |
1996年 | 116篇 |
1995年 | 100篇 |
1994年 | 95篇 |
1993年 | 84篇 |
1992年 | 111篇 |
1991年 | 99篇 |
1990年 | 97篇 |
1989年 | 95篇 |
1988年 | 84篇 |
1987年 | 72篇 |
1986年 | 61篇 |
1985年 | 63篇 |
1984年 | 60篇 |
1982年 | 65篇 |
1981年 | 46篇 |
1980年 | 51篇 |
1974年 | 44篇 |
1973年 | 48篇 |
1972年 | 54篇 |
1971年 | 51篇 |
1968年 | 71篇 |
1967年 | 47篇 |
1966年 | 65篇 |
1964年 | 82篇 |
1963年 | 78篇 |
1962年 | 49篇 |
1961年 | 42篇 |
排序方式: 共有5123条查询结果,搜索用时 15 毫秒
191.
Professor Nelson Yuan-sheng Kiang 《Science and engineering ethics》1995,1(4):347-356
This paper provides examples drawn from the author’s experience that support the conclusion that errors and deceptions in archival science are often not easily or quickly corrected. The difficulty in correcting errors and deceptions needs wider recognition if it is to be overcome. In addition, the paper discusses how subtle abuses introduce errors into the archival literature. 相似文献
192.
In three experiments on apparent motion, subjects were to press a computer key as quickly as possible either when the apparently moving stimulus passed the midpoint of its trajectory or when it reached the endpoint. If motion is perceived as a trajectory through a series of spatial locations, and if this type of percept is the basis of deliberate responding (assumptions that can be considered Cartesian in origin), then reaction times should be faster to the midpoint than to the endpoint. In contrast to these assumptions, there was no difference between reaction times to these two points. Alternative accounts of the results are discussed. 相似文献
193.
Cris M. Sullivan Rebecca Campbell Holly Angelique Kimberly K. Eby William S. Davidson II 《American journal of community psychology》1994,22(1):101-122
Presented the 6-month follow-up findings of an experimental intervention designed to provide postshelter advocacy services
to women with abusive partners. The intervention involved randomly assigning half the research participants to receive the
free services of an advocate, 4 to 6 hours per week, for the first 10 weeks postshelter. One hundred forty-one battered women
were interviewed about their experiences immediately upon their exit from a domestic violence shelter: 95% of the sample were
interviewed 10 weeks thereafter (postintervention), and 93% were successfully tracked and interviewed 6 months later. At the
6-month follow-up, participants in both groups reported increased social support, increased quality of life, less depression,
less emotional attachment to their assailants, and an increased sense of personal power. Although women in both groups reported
some decrease in physical abuse over time, there were no statistically significant differences between those with and those
without advocates, and abuse continued to be a problem for many women. Those who were still involved with their assailants
continued to experience higher levels of abuse and had been more economically dependent upon the men prior to entering the
shelter. Women who had worked with advocates continued to report being more satisfied with their overall quality of life than
did the women in the control group.
The authors thank the Editor and anonymous reviewers for their helpful comments. Thanks also to all present and past staff
of the Community Advocacy Project, who helped in data collection and analyses. This work was supported by National Institute
of Mental Health Grant 1R01 MH 44849. 相似文献
194.
195.
Human d-amphetamine drug discrimination: methamphetamine and hydromorphone. 总被引:2,自引:0,他引:2 下载免费PDF全文
Standard measures of subjective and discriminative effects of drugs were compared in 5 human volunteers. Subjects responded on a second-order color-tracking procedure, where 30 mg of d-amphetamine served as a discriminative stimulus for one response and its absence as the discriminative stimulus for another response. Self-reported subjective effects were assessed concurrently using the single-dose questionnaire, subscales of the Addiction Research Center Inventory, and several analogue rating scales. On different days following discrimination acquisition, varying doses of d-amphetamine, methamphetamine, and hydromorphone were administered. In these test sessions, either response was reinforced. Methamphetamine and d-amphetamine occasioned dose-related increases in d-amphetamine appropriate responding; hydromorphone did not. Methamphetamine and d-amphetamine occasioned dose-related increases in reports of the drug received being most like "speed"; hydromorphone occasioned dose-related increases in reports of the drug received being most like "dope." All three drugs occasioned dose-related increases in reports of drug liking, and increases in the morphine-benzedrine group, amphetamine, and benzedrine group scales of the Addiction Research Center Inventory. This experiment demonstrated that although explicit discriminative control of behavior by a drug may covary with drug identification, it does not necessarily covary with other self-reported subjective effects. Thus, the complementary nature of the data provided by drug discrimination and standard subjective-effects measures provides quantitative and qualitative data useful in studying both relatively novel compounds and the behavioral biology of psychoactive drugs in general. 相似文献
196.
The advantages of presenting sensory data in terms of stimulus variables are stressed. Spectral sensitivity plots of local electroretinograms and ganglion cell discharges from the dark-adapted rabbit retina illustrate the utility of using this kind of procedure. Spectral data agreed with the literature demonstrating two cone and one rod process in this animal. The spectral sensitivities of both the local electroretinogram and ganglion cell spikes were closely similar. Data pertaining to pattern vision may also be subjected to the same type of analysis and described in terms of stimulus variables. 相似文献
197.
Changes in respiration associated with schedule-controlled behavior were determined in seated rhesus monkeys prepared with a pressure-displacement head plethysmograph for monitoring ventilation continuously during behavioral experiments. Subjects were trained to press a lever under fixed-ratio 40 and fixed-interval 300-s schedules of stimulus termination. Episodic increases in ventilation were closely associated with periods of responding under both schedules. Recurring episodes of increased ventilation occurred during fixed-ratio responding, and were separated by brief 10-s timeouts during which ventilation decreased. Under the fixed-interval schedule, both ventilation and response rate typically increased as the 300-s interval elapsed. The effects of cocaine, caffeine, and two adenosine agonists, 5'-N-ethylcarboxamidadenosine (NECA) and 2-(carboxyethylphenylamino)adenosine-5'-carboxamide (CGS 21680), on behavior and respiration were determined using a cumulative-dosing procedure. Drug-induced suppression of behavior eliminated the episodic increases in ventilation during the performance components of both schedules. Schedule-related increases in ventilation were compared to those produced by elevated levels of CO2 in inspired air. Exposure to 4% CO2 mixed in air increased ventilation in all subjects, and the combined effects of CO2 exposure and schedule-controlled responding on respiration appeared to be additive. The results suggest that behavioral activities may increase ventilation through increased metabolic demand and increased CO2 production. 相似文献
198.
M J Evans A Duvel M L Funk B Lehman J Sparrow N T Watson A Neuringer 《Journal of the experimental analysis of behavior》1994,62(1):149-156
An apparatus was developed to study social reinforcement in the rat. Four Long-Evans female rats were trained to press a lever via shaping, with the reinforcer being access to a castrated male rat. Responding under a fixed-ratio schedule and in extinction was also observed. Social access was found to be an effective reinforcer. When social reinforcement was compared with food reinforcement under similar conditions of deprivation and reinforcer duration, no significant differences were observed. 相似文献
199.
Choice responding by adult humans in a discrete-trial task was examined as a function of conditions that manipulated either the delay to point delivery or the delay between points and their exchange for money. In point-delay conditions, subjects chose between an "impulsive" alternative that provided a small amount of points immediately and a "self-control" alternative that provided a larger amount of points delayed by 15, 30, or 60 s. Points were exchanged for money immediately following the session. Subjects preferred the self-control alternative. In exchange-delay conditions, subjects chose between a small amount of points exchangeable for money immediately following the session and a larger amount of points exchangeable for money after 1 day, 3 weeks, or 6 weeks. A self-control preference observed for all subjects in the 1-day exchange-delay condition reversed to exclusive impulsive preference for 4 of the 6 subjects when choice conditions involved exchange delays of 3 or 6 weeks. These results show that human choice is sensitive to the manipulation of exchange delays and that impulsive preference can be obtained with exchange delays on the order of weeks. 相似文献
200.
Three rats, lever pressing for food delivered on a fixed-interval 128-s schedule, were presented with a 16-s opportunity to drink from a retractable water source. The temporal placement of the water probe within the reinforcement cycle was varied sequentially, in steps of 16 s. Although the lever-pressing pattern was modulated by the intercalated water probe, water consumption during the probe itself was a decreasing function of time from the following reinforcer. These results were interpreted as evidence against the notion that schedule-induced drinking is a "ubiquitous" phenomenon and are congruent with results from other "intruded stimulus" experiments. 相似文献