全文获取类型
收费全文 | 8684篇 |
免费 | 818篇 |
国内免费 | 432篇 |
出版年
2024年 | 33篇 |
2023年 | 189篇 |
2022年 | 151篇 |
2021年 | 162篇 |
2020年 | 414篇 |
2019年 | 423篇 |
2018年 | 391篇 |
2017年 | 418篇 |
2016年 | 383篇 |
2015年 | 271篇 |
2014年 | 341篇 |
2013年 | 1114篇 |
2012年 | 202篇 |
2011年 | 320篇 |
2010年 | 247篇 |
2009年 | 371篇 |
2008年 | 426篇 |
2007年 | 481篇 |
2006年 | 459篇 |
2005年 | 393篇 |
2004年 | 341篇 |
2003年 | 288篇 |
2002年 | 214篇 |
2001年 | 150篇 |
2000年 | 118篇 |
1999年 | 138篇 |
1998年 | 104篇 |
1997年 | 83篇 |
1996年 | 63篇 |
1995年 | 67篇 |
1994年 | 51篇 |
1993年 | 51篇 |
1992年 | 41篇 |
1991年 | 18篇 |
1990年 | 24篇 |
1989年 | 28篇 |
1988年 | 22篇 |
1985年 | 129篇 |
1984年 | 124篇 |
1983年 | 104篇 |
1982年 | 87篇 |
1981年 | 67篇 |
1980年 | 73篇 |
1979年 | 65篇 |
1978年 | 94篇 |
1977年 | 56篇 |
1976年 | 42篇 |
1975年 | 31篇 |
1974年 | 24篇 |
1973年 | 28篇 |
排序方式: 共有9934条查询结果,搜索用时 15 毫秒
861.
ABSTRACT Careers provision for young people in the UK is being re-formulated on the basis of a central role for career websites but this policy is based on unproven assumptions about their value. In this article we consider the use and impact of the two main career websites in Scotland on pupils' career management skills. We found that pupils at risk of not achieving positive post-school destinations were less likely to use the websites, as were minority ethnic pupils. Although similar in functions, the two websites differed in their effect: one had no impact while the other impacted on only one aspect of pupils' career management skills. Careers policy needs to be informed by more extensive research on career websites. 相似文献
862.
Being imitated has a wide range of pro‐social effects, but it is not clear how these effects are mediated. Naturalistic studies of the effects of being imitated have not established whether pro‐social outcomes are due to the similarity and/or the contingency between the movements performed by the actor and those of the imitator. Similarity is often assumed to be the active ingredient, but we hypothesized that contingency might also be important, as it produces positive affect in infants and can be detected by phylogenetically ancient mechanisms of associative learning. We manipulated similarity and contingency between performed and observed actions in a computerized task. Similarity had no positive effects; however, contingency resulted in greater enjoyment of the task, reported closeness to others, and helping behavior. These results suggest that the pro‐social effects of being imitated may rely on associative mechanisms. 相似文献
863.
双酚A (bisphenol, BPA)是一种广泛存在的环境内分泌干扰物,它可与雌激素受体结合干扰内源性雌激素对中枢神经系统的调控作用。本研究通过将10周龄小鼠灌胃染毒BPA (0.4、4、40 mg/kg/day)3个月,研究长期BPA暴露对成年小鼠记忆行为和突触可塑性的影响。开场行为测试结果表明, BPA (0.4、4、40 mg/kg/day)增加雄性的站立次数和理毛频率, BPA (4 mg/kg/day)却显著减少雌鼠的站立次数。水迷宫和被动回避行为模型检测显示, BPA主要损伤雄鼠的空间学习记忆和被动回避记忆。通过制备海马CA1区超薄切片后,电镜观测发现, BPA (0.4、40 mg/kg/day)暴露降低雄鼠海马CA1区突触数密度,缩短雄鼠突触前活性带长度,减小雄鼠突触后致密体(PSD)厚度,增加雄鼠突触间隙宽度。进一步用Western blot方法检测突触前、后的标志性蛋白Synapsin I和PSD95以及兴奋性氨基酸NMDA受体NR1亚基和AMPA受体GluR1亚基蛋白的表达,发现BPA暴露致雄鼠Synapsin I、PSD95、NR1蛋白表达水平下调。而BPA对雌鼠的记忆行为、突触形态、突触蛋白和受体蛋白均没有明显作用。以上结果提示长期B PA暴露性别特异性地影响成年小鼠的活动性和探究行为,损伤雄鼠的学习记忆,这些作用可能通过下调突触蛋白和NMDA受体的表达而负性影响突触结构可塑性,最终影响雄鼠的学习记忆功能。 相似文献
864.
Thomas F. Tracy 《Zygon》2013,48(2):454-465
When Darwin's theory of natural selection threatened to put Paley's Designer out of a job, one response was to reemploy God as the author of the evolutionary process itself. This idea requires an account of how God might be understood to act in biological history. I approach this question in two stages: first, by considering God's action as creator of the world as a whole, and second, by exploring the idea of particular divine action in the course of evolution. As creator ex nihilo God acts directly in every event as its sustaining ground. Because God structures the world as a lawful order of natural causes, God also acts indirectly by means of creatures. More controversially, God might act directly within the world to affect the course of events; this action need not take the form of a miraculous intervention, if the natural order includes the right sort of indeterministic chance. In each of these ways God's purposes can shape evolutionary processes. 相似文献
865.
Remembering persisting objects over occlusion is critical to representing a stable environment. Infants remember hidden objects at multiple locations and can update their representation of a hidden array when an object is added or subtracted. However, the factors influencing these updating abilities have received little systematic exploration. Here we examined the flexibility of infants’ ability to update object representations. We tested 11-month-olds in a looking-time task in which objects were added to or subtracted from two hidden arrays. Across five experiments, infants successfully updated their representations of hidden arrays when the updating occurred successively at one array before beginning at the other. But when updating required alternating between two arrays, infants failed. However, simply connecting the two arrays with a thin strip of foam-core led infants to succeed. Our results suggest that infants’ construal of an event strongly affects their ability to update memory representations of hidden objects. When construing an event as containing multiple updates to the same array, infants succeed, but when construing the event as requiring the revisiting and updating of previously attended arrays, infants fail. 相似文献
866.
Abstract The use of shock tactics to motivate people to learn more about AIDS and to take appropriate protective action characterised the approach adopted by the national health authorities in Australia during 1987. The rationale underlying this approach is critically examined, particularly in the light of results obtained from surveys of community concern and knowledge about AIDS in the state of South Australia before the campaign and after it had been in progress for some five months. Contrary to expectations no significant increases in either personal or social concern were found; in fact, among older respondents personal concern had decreased significantly. Levels of knowledge about AIDS, in general, remained unchanged, apart from an increase in acceptance of the safety of blood transfusions from a very low to a somewhat higher level. Among a minority of respondents (29%) who approved of the campaign and also believed they had been influenced by it, personal and social concern about AIDS, but not knowledge, was significantly greater than among others. The view that fear-inducing techniques can be used to bring about increases in knowledge about AIDS was not supported, although some positive effects on the social attitudes of respondents most affected by the campaign are suggested. 相似文献
867.
Joseph G. Jill Susanne B. Montgomery Carol-Ann Emmons Ronald C. Kessler David G. Ostrow Camille B. Wortman 《Psychology & health》2013,28(1):73-95
The magnitude and predictors of longitudinal behavioral change are reported in a cohort of homosexual men at risk for AIDS. Self-reports of sexual behavior were obtained at two points in time separated by an interval of approximately six months. These self-reports were used to construct both dichotomous and continuous measures of changes in behavior consistent with reduction in the transmission of the AIDS virus (HIV). Although there was considerable variability in behavior. mean changes were consistently in the desired direction. Avoidance of anonymous sexual partners, monogamy, and modification of receptive anal sex to reduce exposure to semen by condom use or withdrawal prior to ejaculation appeared to be especially important in this cohort. Both multiple linear regression and multiple logistic regression were used to examine the relationship between a model of health behavior and these outcomes. Variables examined included knowledge of AIDS. perceived risk of AIDS. the perceived efficacy of behavior in reducing AIDS risk, difficulties with sexual impulse control, belief in biomedical technology to provide a prevention or cure, social norms supportive of behavioral change, and gay network affiliation. Of all these factors, only the availability of supportive peer norms was consistently, significantly and positively related to multiple measures of outcome. Differences between these analyses and longitudinal analyses reported elsewhere are discussed. These results suggest the policies regarding HIV antibody testing should be developed cautiously. taking account of the failure of a sense of risk to predict subsequent behavioral change. They also emphasize the important role of gay organizations in developing social norms supportive of behavioral risk reduction. 相似文献
868.
869.
Abstract This paper reports on a study carried out to identify predictors of uptake of cervical screening among 142 women (59% response rate) in inner London. Two social cognition models were used: The Health Belief Model (HBM; Becker, 1974) and the Theory of Planned Behaviour (TPB; Ajzen, 1991) and in addition anticipated affect following non-attendance for screening was assessed. The TPB emerged as by far the superior model for predicting screening intentions, explaining 51% of the variance in comparison with only 4% explained by the HBM variables. However, neither model was able to predict a significant amount of variance in uptake of screening three months later. Possible reasons for the poor prediction of this type of behaviour are discussed. 相似文献
870.
Objective: Studying personal narratives can generate understanding of how people experience physical and mental illness. However, few studies have explored narratives of engagement in health positive behaviours, with none focusing on men specifically. Thus, we sought to examine men’s experiences of their efforts to engage in and maintain healthy behaviours, focusing on meditation as an example of such behaviour.Design: We recruited 30 male meditators, using principles of maximum variation sampling, and conducted two in-depth interviews with each, separated by a year. Main outcome measures: We sought to elicit men’s narratives of their experiences of trying to maintain a meditation practice.Results: We identified an overall theme of a ‘positive health trajectory,’ in particular, making ‘progress’ through meditation. Under this were six main accounts. Only two articulated a ‘positive’ message about progress: Climbing a hierarchy of practitioners, and progress catalysed in other areas of life. The other four reflected the difficulties around progress: Progress being undermined by illness; disappointment with progress; progress ‘forgotten’ (superseded by other concerns); and progress re-conceptualised due to other priorities.Conclusion: Men’s narratives reveal the way they experience and construct their engagement with meditation – as an example of health behaviour – in terms of progress. 相似文献