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   5221篇
  免费   2322篇
  国内免费   257篇
  2024年   8篇
  2023年   58篇
  2022年   51篇
  2021年   210篇
  2020年   257篇
  2019年   676篇
  2018年   549篇
  2017年   699篇
  2016年   630篇
  2015年   553篇
  2014年   473篇
  2013年   773篇
  2012年   329篇
  2011年   323篇
  2010年   244篇
  2009年   219篇
  2008年   177篇
  2007年   222篇
  2006年   203篇
  2005年   186篇
  2004年   150篇
  2003年   130篇
  2002年   135篇
  2001年   120篇
  2000年   99篇
  1999年   66篇
  1998年   33篇
  1997年   34篇
  1996年   33篇
  1995年   14篇
  1994年   24篇
  1993年   16篇
  1992年   19篇
  1991年   9篇
  1990年   9篇
  1989年   6篇
  1988年   6篇
  1987年   7篇
  1986年   5篇
  1985年   6篇
  1984年   10篇
  1983年   8篇
  1982年   4篇
  1981年   4篇
  1979年   4篇
  1978年   2篇
  1977年   5篇
  1976年   2篇
排序方式: 共有7800条查询结果,搜索用时 15 毫秒
161.
Family-Based Therapy for Adolescent Drug Abuse: Knowns and Unknowns   总被引:1,自引:0,他引:1  
Family-based therapy is one of the most thoroughly studied treatments for adolescent drug abuse. Considerable empirical support exists for the efficacy of family-based therapy in curtailing adolescent drug use and cooccurring behavior problems. This article extends knowledge of the effects of family-based therapy for adolescent drug abuse by reviewing 16 controlled trials and 4 therapy process studies from a treatment development perspective. We articulate knowns and unknowns regarding the outcomes of treatment as well as the components, processes, mechanisms, moderators, and boundaries of effective family-based therapy for adolescent drug abuse. The review highlights areas of progress and future research needs within the specialty of family-based therapy for adolescent drug abuse.  相似文献   
162.
This article describes a systematic program of research that focuses on Brief Strategic Family Therapy (BSFT) and the adaptations that were developed based on BSFT principles. The culture-specific origins of BSFT are reviewed, as well as its broader applications to the field of family therapy. Research is reviewed demonstrating that BSFT is a promising family-based approach to treating Hispanic youth behavior problems and drug abuse. Treatment innovations are described that address the combination of intergenerational and cultural differences that occur among youths and their Hispanic parents. Programmatic work is described that challenges basic principles of family therapy by expanding BSFT to a One Person modality and a strategic engagement procedure. Both of these novel approaches are intended to add tools to therapists' repertoire in working with difficult-to-engage families. A preview discussion of results is presented from a randomized clinical trial that is an application of an ecosystemic prevention version of BSFT. The implications of the work of the Center for Family Studies are discussed in the context of the broader service system. Ultimately, this article articulates a way of thinking about adolescent problem behavior, its social interactional determinants, and a range of theoretically consistent family-centered strategies that attempt to change social ecological processes that impact adolescent developmental trajectories.  相似文献   
163.
Brief multiple-stimulus-without-replacement (MSWO) preference assessments were conducted with 3 adolescent boys with emotional-behavioral disorders in the context of their public school educational program. The reinforcing effects of stimuli identified as high, medium, and low preference were then evaluated using an alternating treatments design in which, following an initial baseline, stimuli were delivered contingent on on-task behavior. High-preference stimuli produced the highest percentages of on-task behavior for all 3 participants.  相似文献   
164.
Key pecking by 3 pigeons was maintained by a multiple fixed-ratio 10, fixed-ratio 30, fixed-ratio 90 schedule of food presentation. Components differed with respect to amount of reinforcement, such that the unit price was 10 responses per 1-s access to food. Acute administration of morphine, l-methadone, and cocaine dose-dependently decreased overall response rates in each of the components. When a rate decreasing dose of morphine was administered daily, tolerance, as measured by an increase in the dose that reduced response rates to 50% of control (i.e., the ED50 value), developed in each of the components; however, the degree of tolerance was smallest in the fixed-ratio 90 component (i.e., the ED50 value increased the least). When the l-methadone dose-effect curve was redetermined during the chronic morphine phase, the degree of cross-tolerance conferred to l-methadone was similar across components, suggesting that behavioral variables may not influence the degree of cross-tolerance between opioids. During the chronic phase, the cocaine dose-effect curve shifted to the right for 2 pigeons and to the left for 1 pigeon, which is consistent with predictions based on the lack of pharmacological similarity between morphine and cocaine. When the morphine, l-methadone, and cocaine dose-effect curves were redetermined after chronic morphine administration ended, the morphine and l-methadone ED50s replicated those obtained prior to chronic morphine administration. The morphine data suggest that the fixed-ratio value (i.e., the absolute output) determines the degree of tolerance and not the unit price.  相似文献   
165.
To examine the effects on concurrent performance of independent manipulations of response-unit duration and number, 6 hens were exposed to concurrent second-order schedules of reinforcement. Each first-order operant unit required completion of a fixed-ratio schedule within the time specified by a fixed-interval schedule, with one further response completing the fixed-interval schedule. The fixed-ratio and fixed-interval requirements comprising the first-order operant units were systematically and independently varied under three pairs of concurrent variable-interval schedules to produce differences in the first-order response and duration requirements (response and duration differentials). These manipulations produced consistent changes in response, time, and operant-unit biases. A 1:4 response differential biased the time and operant-unit measures towards the smaller fixed ratio, but to a degree less than the imposed response differential. The response-based biases favored the larger fixed ratio. Duration differentials of 4:1 and 8:1 biased the response and operant-unit measures towards the shorter fixed interval, again less than the imposed duration differential, but the time biases remained close to zero. Both sorts of differentials acted to bias operant-unit completions more systematically than the other measures, but undermatching to the differentials occurred. The undermatching appears to have arisen from a pattern of fix and sample (in which visits to the less preferred alternative involved only a single completed operant unit) under combinations of unequal operant-unit requirements and reinforcer rates. The response and time bias measures appeared to arise as by-products of the changes in operant-unit completions.  相似文献   
166.
Neural correlates of a default response in a delayed go/no-go task   总被引:3,自引:0,他引:3  
Working memory, the ability to temporarily retain task-relevant information across a delay, is frequently investigated using delayed matching-to-sample (DMTS) or delayed Go/No-Go tasks (DGNG). In DMTS tasks, sample cues instruct the animal which type of response has to be executed at the end of a delay. Typically, performance decreases with increasing delay duration, indicating that working memory fades across a delay. However, no such performance decrease has been found when the sample cues exist of present vs. absent stimuli, suggesting that pigeons do not rely on working memory, but seem to respond by default in those trials. We trained 3 pigeons in a DGNG task and found a similar default response pattern: The diverging slopes of the retention functions on correct Go and No-Go trials suggested that pigeons by default omitted their response following No-Go stimuli, but actively retained task-relevant information across the delay for successful responses on Go trials. We conducted single-cell recordings in the avian nidopallium caudolaterale, a structure comparable to the mammalian prefrontal cortex. On Go trials, many neurons displayed sustained elevated activity during the delay preceding the response, replicating previous findings and suggesting that task-relevant information was neurally represented and maintained across the delay. However, the same units did not show enhanced delay activity preceding correct response suppressions in No-Go trials. This activation-inactivation pattern presumably constitutes a neural correlate of the default response strategy observed in the DGNG task.  相似文献   
167.
Recent progress in mouse genetics has led to an increased interest in developing procedures for assessing mouse behavior, but relatively few of the behavioral procedures developed involve positively reinforced operant behavior. When operant methods are used, nose poking, not lever pressing, is the target response. In the current study differential acquisition of milk-reinforced lever pressing was observed in five inbred strains (C57BL/6J, DBA/2J, 129X1/SvJ, C3H/HeJ, and BALB/cJ) and one outbred stock (CD-1) of mice. Regardless of whether one or two levers (an "operative" and "inoperative" lever) were in the operant chamber, a concomitant variable-time fixed-ratio schedule of milk reinforcement established lever pressing in the majority of mice within two 120-min sessions. Substantial differences in lever pressing were observed across mice and between procedures. Adding an inoperative lever retarded acquisition in C57BL/6J, DBA/2J, 129X1/SvJ, and C3H/HeJ mice, but not in CD-1 and BALB/cJ mice. Locomotor activity was positively correlated with number of lever presses in both procedures. Analyses of durations of the subcomponents (e.g., time to move from hopper to lever) of operant behavior revealed further differences among the six types of mice. Together, the data suggest that appetitively reinforced lever pressing can be acquired rapidly in mice and that a combination of procedural, behavioral, and genetic variables contributes to this acquisition.  相似文献   
168.
Experiment 1 investigated the controlling properties of variability contingencies on choice between repeated and variable responding. Pigeons were exposed to concurrent-chains schedules with two alternatives. In the REPEAT alternative, reinforcers in the terminal link depended on a single sequence of four responses. In the VARY alternative, a response sequence in the terminal link was reinforced only if it differed from the n previous sequences (lag criterion). The REPEAT contingency generated low, constant levels of sequence variation whereas the VARY contingency produced levels of sequence variation that increased with the lag criterion. Preference for the REPEAT alternative tended to increase directly with the degree of variation required for reinforcement. Experiment 2 examined the potential confounding effects in Experiment 1 of immediacy of reinforcement by yoking the interreinforcer intervals in the REPEAT alternative to those in the VARY alternative. Again, preference for REPEAT was a function of the lag criterion. Choice between varying and repeating behavior is discussed with respect to obtained behavioral variability, probability of reinforcement, delay of reinforcement, and switching within a sequence.  相似文献   
169.
Differing task and motivational characteristics of the competitive setting (viz., task-involving/ego-involving climates, cooperative/individual, and win/loss competitive outcome) were explored in relation to need satisfaction and subjective well-being (SWB). Participants, one-on-one or in pairs, were required to participate in a physical co-ordination task. Results revealed participants exposed to a task-involving condition and those who worked in cooperation to report higher levels of need satisfaction and SWB. Conversely, individuals exposed to ego-involving conditions and those who competed individually experienced higher levels of negative affect. Winning resulted in higher levels of need satisfaction and SWB, whereas losing led to higher levels of negative affect. Losing individually in an ego-involving condition led to the highest levels of negative affect responses and attenuated levels of reported need satisfaction and SWB. Via structural equation modeling, a model of motivational processes grounded in self-determination theory was supported in which elements of the competitive situation that facilitated need satisfaction led to increments in reported indices of SWB.  相似文献   
170.
The study examines a recurrent interactional pattern in genetic counseling. It describes clinical geneticists' responses in situations in which clients have presented information from other sources that is potentially discrepant with information given by the doctor. The data consists of 12 video-recorded sessions of genetic counseling in Finland, and the method is conversation analysis. There are two primary ways the doctors respond: either they accept the client's information as such, but show that it is not discrepant with the doctor's information, or they reject the client's information. In the latter case they mitigate the ‘wrongness’ of the client's information. The clinical geneticists seem to be working with a dilemma: they need to find a balance between ensuring correct understanding of the information and showing respect for the expertise of others. A particularly complex case is also analyzed and reflected on.  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