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   31614篇
  免费   506篇
  国内免费   6篇
  32126篇
  2023年   67篇
  2022年   62篇
  2021年   122篇
  2020年   217篇
  2019年   252篇
  2018年   3710篇
  2017年   3034篇
  2016年   2533篇
  2015年   426篇
  2014年   400篇
  2013年   1364篇
  2012年   1100篇
  2011年   2845篇
  2010年   2838篇
  2009年   1825篇
  2008年   2201篇
  2007年   2632篇
  2006年   519篇
  2005年   630篇
  2004年   621篇
  2003年   526篇
  2002年   468篇
  2001年   205篇
  2000年   242篇
  1999年   198篇
  1998年   205篇
  1997年   173篇
  1996年   113篇
  1995年   146篇
  1994年   144篇
  1993年   131篇
  1992年   123篇
  1991年   111篇
  1990年   116篇
  1989年   106篇
  1988年   110篇
  1987年   107篇
  1986年   85篇
  1985年   101篇
  1984年   116篇
  1983年   97篇
  1982年   110篇
  1981年   115篇
  1980年   104篇
  1979年   102篇
  1978年   109篇
  1977年   89篇
  1976年   94篇
  1975年   64篇
  1974年   76篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The role of humans in the cognitive development of apes revisited   总被引:3,自引:3,他引:0  
  相似文献   
992.
We describe a new, open flow device for presenting taste stimuli to human subjects under controlled conditions of timing. The device delivers each stimulus as a mist to the participant’s tongue through one of 16 nozzles attached to a linear slide. Software controls the position of the slide, the duration of the stimulus, and the duration of the pre- and poststimulus water rinses and records the responses of the participant. Temporal characteristics of this system make it especially applicable to studies on the role of attention in taste perception.  相似文献   
993.
Justification for public funding of academic research is based on the linear model of technological advance first proposed by Francis Bacon. The model hypothesizes that government subsidized science generates new technology which creates new wealth. Mainstream economics supports Bacons model by arguing that academic research is a public good. The Bayh–Dole Act allows universities to privatize federally funded research and development (R&D) which is in direct conflict with the public good argument. Diminishing returns to university R&D, challenges to Bacons linear model and the labor exploitation of young scientists by research universities suggest that policy makers may want to reconsider the system for allocating federal R&D to universities and colleges.  相似文献   
994.
Many exciting findings have been reported in the 15 years since monkeys were first demonstrated to have the capacity to perform computerized tasks. The present data indicate that albino rats can also learn to respond to computer-generated stimuli by manipulating a joystick. Although the rat’s control of the cursor is not as skillful as has been reported for primate species, it is clearly better than chance and suggests the great potential for comparative investigation afforded by use of the computer test system.  相似文献   
995.
Defensive responses to a cat were observed in rats given excitotoxic lesions of the central nucleus of the amygdala (ACe), dorsolateral periaqueductal gray (dlPAG), ventral periaqueductal gray (vPAG), or sham lesions. Rats were placed adjacent to a compartment containing a cat. Sham-lesioned rats avoided the area nearest the cat and preferred the area furthest away from the cat. They also exhibited numerous defensive responses including, climbing, escape from the apparatus, and freezing. Rats with lesions of the ACe reacted like the sham lesioned rats by preferring the area of the apparatus furthest from the cat, however they climbed and escaped significantly less than sham lesioned rats. Avoidance of the area adjacent to the cat was attenuated in rats with lesions of the vPAG. Climbing along the walls of the apparatus was also attenuated in rats with lesions of the vPAG. Escapes from the apparatus were not significantly reduced by lesions of the vPAG and dlPAG. Thus, ACe lesions attenuated climbing and eliminated escapes, but did not impair locomotion of the rat away from the cat.  相似文献   
996.
The aim of the study was to examine the relationship between body esteem and body fat in British school children. Two hundred and seventy seven, 11–14-year-old children from central England took part in the study. Body esteem was measured using the Body Esteem Scale for children and percent body fat was determined by skin-fold measures. Results indicate that body esteem and adiposity were negatively related for the whole sample, for boys and girls and for White children, Black children and Asian children. Factorial ANOVA also indicated differences in body esteem according to gender and ethnicity. Boys and Black children had significantly higher body esteem than girls and Asian children respectively. Differences in body fat were also evident according to gender with boys being leaner than girls. No differences in body esteem or body fat were evident across school years.  相似文献   
997.
This research examined the role of working memory (WM) in probability judgment and hypothesis generation using a simulated task that involved estimating the likelihood that particular menu items would be ordered by customers at a dinner. Five main findings were observed. First, judgments of the likelihood of individual items were made relative to alternatives retrieved from long-term memory. Second, the number of alternatives retrieved was positively correlated with a measure of WM-capacity (the operation-span task). Third, participants' probability judgments were subadditive (summing to well over 100%). Fourth, the degree to which participants' judgments were subadditive was affected by the number and strength of the alternatives retrieved from long-term memory. Fifth, the degree to which participants were subadditive was negatively correlated with WM-capacity. The results suggest that individual differences in WM-capacity are fundamental to hypothesis generation and probability judgment.  相似文献   
998.
Symmetry properties have been shown to determine the perceived complexity of certain patterns. We used a paired-comparison method to obtain judgments of relative complexity for a family of two-dimensional regular patterns called band patterns. Although the complexity of these patterns is well predicted by their symmetry properties we were unable to explain an interaction observed between two of these properties for our experimental patterns. We discuss the implications of our results for two predominant approaches to the perceived complexity of patterns. Neither approach takes into account that the presence of grouping sometimes makes it difficult to perceive a relationship within the pattern that would--were it not for the grouping--simplify it. We conclude that grouping can mask simplicity and that this phenomenon is crucial to the understanding of perceived complexity.  相似文献   
999.
Cambodian refugees with posttraumatic stress disorder (PTSD) represent a cohort in severe need of treatment, but little information is available to guide treatment choices. We selected a sample of pharmacotherapy-refractory individuals to test the efficacy of combination treatment with sertraline and cognitive-behavior therapy (CBT) for treating PTSD. Participants in this pilot study were ten Khmer-speaking women who had been at a mean age of 22-26 years during the Pol Pot period (1975-1979). These patients were randomly assigned to either sertraline alone or combined treatment. We found that combined treatment offered additional benefit in the range of medium to large effect sizes for PTSD and associated symptoms. Our findings indicate that substantial gains can be achieved by adding CBT to pharmacotherapy for PTSD, and that a program of CBT emphasizing information, exposure, and cognitive-restructuring can be successfully modified for Khmer-speaking refugees.  相似文献   
1000.
The aims of this study were to investigate exposure-based treatments for cynophobia (dog phobia) and to test a newly developed hybrid imaginal exposure treatment that we have named active imaginal exposure. The treatment introduces an in vivo coping component to imaginal exposure whereby the patient physically performs coping responses to an imagined feared stimulus. Eighty-two participants meeting DSM-IV criteria for specific phobia (animal subtype) were randomly assigned to one of three 30-min. treatments: (a) active-imaginal exposure (AI), (b) imaginal exposure alone (IE), or (c) graduated in vivo exposure (IV). Participants completed a behavioral approach test at pre, post, and four-week follow-up. Significant pre- to posttreatment improvement was observed in all three treatment conditions. Response rates at posttreatment were 51.9, 62.1, and 73.1% for the IE, AI, and IV groups respectively. Likewise, effect sizes at posttreatment were 0.76, 1.41, and 1.55 for the IE, AI, and IV groups respectively. Although in the predicted direction, the between group differences were not significant. A similar pattern of results was observed at follow-up. Further, safety behavior utilization during treatment was associated with less improvement--particularly in the two imaginal treatment conditions. Exposure treatments of dog phobia appear feasible and effective in reducing phobic fear and avoidance associated with dog phobia. Furthermore, preliminary evidence suggests that our active-imaginal exposure treatment may be a viable alternative to in vivo exposure.  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