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   8463篇
  免费   412篇
  国内免费   246篇
  2024年   14篇
  2023年   136篇
  2022年   65篇
  2021年   142篇
  2020年   227篇
  2019年   259篇
  2018年   203篇
  2017年   239篇
  2016年   214篇
  2015年   196篇
  2014年   205篇
  2013年   658篇
  2012年   139篇
  2011年   190篇
  2010年   146篇
  2009年   216篇
  2008年   244篇
  2007年   204篇
  2006年   212篇
  2005年   175篇
  2004年   152篇
  2003年   151篇
  2002年   136篇
  2001年   85篇
  2000年   70篇
  1999年   48篇
  1998年   55篇
  1997年   21篇
  1996年   44篇
  1995年   37篇
  1994年   30篇
  1993年   19篇
  1992年   19篇
  1990年   6篇
  1989年   11篇
  1988年   7篇
  1987年   7篇
  1985年   345篇
  1984年   411篇
  1983年   301篇
  1982年   317篇
  1981年   350篇
  1980年   364篇
  1979年   343篇
  1978年   371篇
  1977年   293篇
  1976年   267篇
  1975年   259篇
  1974年   275篇
  1973年   237篇
排序方式: 共有9121条查询结果,搜索用时 15 毫秒
141.
The influence of contextual stimuli on the conditioning and performance of responding to a discrete stimulus was examined in the US preexposure paradigm using both context shift manipulations and a measure of context conditioning. Four groups of rats received both repeated exposure to an electric shock US in one context (Context 1), and repeated nonshocked exposure to a second context (Context 2). Two additional groups of rats received exposure to these contexts, but never received shock presentations. Rats exposed to shock learned to escape from the stimuli of Context 1, but did not escape from the stimuli provided by Context 2. Rats not exposed to shock failed to escape from either context. All rats then received a single CER conditioning session in which four pairings of a 3-min noise CS and shock US were presented. Half the rats received those CS-US pairings in the excitatory Context 1, while the remaining rats received those pairings in the neutral Context 2. Finally, half the rats in each of the CER conditioning treatments received extinction test trials of the noise CS in Context 1, while the remaining rats received those test trials in Context 2. Thus, this design factorially manipulated the presence of excitatory or neutral contextual stimuli during both conditioning and testing of a discrete CS. In comparison with the two groups of rats never preexposed to shock alone, attenuation in acquisition of conditioned suppression observed during test trials occurred only when CER conditioning had been administered in the excitatory Context 1, and this effect was manifested when testing occurred in either the excitatory Context 1 or the neutral Context 2. These results support the model of R. A. Rescorla and A. R. Wagner (1972) (in A. H. Black & W. F. Prokasy (Eds.) Classical Conditioning II, pp. 64–99, New York: Appleton-Century-Crofts) which asserts that contextual stimuli and sicrete CSs compete for limited associative strength supportable by a given US.  相似文献   
142.
In two experiments, we assessed the ability of a feedback stimulus during helplessness training to reduce the performance deficits common to inescapable shock. In each experiment, four groups of rats were exposed to either escapable shock (E), inescapable shock with a feedback stimulus following shock termination (Y-FS), inescapable shock with no feedback stimulus (Y-NFS), or no shock (N). The feedback stimulus eliminated the interference effects of inescapable shock when tested with an FR-3 lever press escape task (Experiment 1) or on an FR-1 task with a 3-s delay between the response and shock termination (Experiment 2). These results suggest that stress-induced biochemical changes may mediate the interference effects seen in inescapably shocked rats.  相似文献   
143.
In two experiments, fear was conditioned to the situational cues in one compartment of a hurdle-jumping apparatus and was then extinguished. Subsequently, either one shock (Experiment 1) or three or nine shocks (Experiment 2) were given in a situation distinctively different from that in which conditioning and extinction had taken place. Although some associative strength between the situational cues and fear was shown to have remained after extinction, in neither experiment did the postextinction-shock treatment increase the fear elicited by these cues: Escape-from-fear performance was no better in the shocked groups than in control groups given no additional shock. Thus, the nonassociative hypothesis which postulates that inflating the value of the representation of the UCS with shock-alone presentations can reinstate the extinguished fear of a stimulus was not supported. Rather, the results showed that, after extinction, an increase in fear of a simulus depended on further conditioning to that stimulus. The data also indicated that the nonvisual components of the situational cues predominated over the visual component.  相似文献   
144.
To evaluate a contingency interpretation of conditioned inhibition (CI), rats were given “explicity unpaired” training in which the locus and duration of a CS within the inter-US (shock) interval were systematically manipulated for different groups. Summation and retardation tests in Experiment 1 indicated that stronger CI resulted from both a backward and a trace CS than from a midlocus CS of equal or greater duration. Complementing these findings, the same tests in Experiment 2 showed that, by comparison with novel-stimulus controls, CI developed to a trace CS but not to a mid-locus CS, nor to a trace CS that was accompanied by an immediate signal for the US. These findings argue against a contingency interpretation of CI and favor a contiguity interpretation stressing the short-term rehearsal of stimulus events. Such rehearsal of the US allows a backward CS, but not a mid-locus CS with an extended US-CS interval, to be discriminated as a signal for nonreinforcement, and thus to develop as a conditioned inhibitor. Similarly, excitatory conditioning to the memory trace of a CS allows the nominal trace CS to develop as a signal for nonreinforcement, and thus as a conditioned inhibitor, but not when its memory trace is overshadowed by another CS that immediately precedes the US. In short, the development of CI is facilitated when excitation is mediated by the memorial processing of either the US or a discrete CS for the US rather than by contextual cues.  相似文献   
145.
146.
147.
148.
American Indian/Alaska Native (AI/AN) communities are disproportionally impacted by the opioid overdose epidemic. There remains a dearth of research evaluating methods for effectively implementing treatments for opioid use disorder (OUD) within these communities. We describe proceedings from a 2-day Collaborative Board (CB) meeting tasked with developing an implementation intervention for AI/AN clinical programs to improve the delivery of medications to treat OUD (MOUD). The CB was comprised of Elders, cultural leaders, providers, individuals with lived experience with OUD, and researchers from over 25 communities, organizations, and academic institutions. Conversations were audio-recorded, transcribed, and coded by two academic researchers with interpretation oversight provided by the CB. These proceedings provided a foundation for ongoing CB work and a frame for developing the program-level implementation intervention using a strength-based and holistic model of OUD recovery and wellbeing. Topics of discussion posed to the CB included engagement and recovery strategies, integration of extended family traditions, and addressing stigma and building trust with providers and clients. Integration of traditional healing practices, ceremonies, and other cultural practices was recommended. The importance of centering AI/AN culture and involving family were highlighted as priorities for the intervention.  相似文献   
149.
Research demonstrates that contingent and appropriate maternal responsiveness to infant requests and bids for attention leads to better language outcomes. Research also indicates that infants who are less distracted by irrelevant competing stimulation and attend efficiently to audiovisual social events (e.g., faces and voices) show better language outcomes. However, few studies have assessed relations between maternal responsiveness, infant attention to faces and voices, and distractibility, and how together these factors lead to early language outcomes. A newly developed audiovisual protocol, the Multisensory Attention Assessment Protocol (MAAP; Bahrick et al., 2018), allows researchers to examine individual differences in attention to faces and voices and distractibility, and to assess relations with other variables. At 12 months, infants (n = 79) in an ongoing longitudinal study participated in the MAAP to assess intersensory matching of synchronous faces and voices and attention to an irrelevant competing visual distractor event. They also were observed in a brief play interaction to assess infant bids for attention and maternal responsiveness (accept, redirect, or ignore). At 18 months, receptive and expressive language were assessed using the Mullen Scales of Early Learning. Several noteworthy findings emerged: 1) mothers were generally responsive, accepting 74% and redirecting 14% of infant bids, 2) infants who had a greater number of their bids redirected by mothers, and who had better intersensory matching of synchronous faces and voices, showed less attention to the distractor, and 3) infants who showed less attention to the distractor had better receptive language. Findings demonstrate that maternal redirecting of infant attention by mothers who are generally responsive may promote better infant attentional control (lower distractibility) which in turn predicts better receptive language in toddlers.  相似文献   
150.
Research shows that parents have a strong influence on the party preferences of their children. Yet little is known about how such preferences are transmitted in multiparty systems with weak party identification and high electoral volatility. We propose a model of intergenerational transmission that includes both direct effects of parents' party preferences on those of their children, as well as indirect effects through left–right and issue positions. We test this model with original survey data of Dutch adolescents (14–20 years old) and their parents (N = 751 adolescent-parent pairs). We find two paths through which parents exert influence on the party preferences of their adolescent children. On the first path, parental party preferences function as a direct predictor of adolescent party preferences. On the second path, adolescent left–right and issue positions function as a mediator between parental left–right and issue positions and adolescent party preferences, with the effect of left–right positions being stronger than that of issue positions. The frequency with which adolescents discuss political topics with their parents moderates these effects.  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