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   3522篇
  免费   203篇
  2023年   23篇
  2022年   53篇
  2021年   51篇
  2020年   105篇
  2019年   92篇
  2018年   172篇
  2017年   162篇
  2016年   186篇
  2015年   135篇
  2014年   168篇
  2013年   486篇
  2012年   195篇
  2011年   190篇
  2010年   100篇
  2009年   128篇
  2008年   161篇
  2007年   155篇
  2006年   124篇
  2005年   97篇
  2004年   102篇
  2003年   109篇
  2002年   71篇
  2001年   45篇
  2000年   79篇
  1999年   54篇
  1998年   28篇
  1997年   27篇
  1996年   29篇
  1995年   16篇
  1994年   20篇
  1993年   20篇
  1992年   21篇
  1991年   19篇
  1990年   15篇
  1989年   14篇
  1987年   11篇
  1984年   14篇
  1983年   10篇
  1982年   17篇
  1980年   11篇
  1979年   13篇
  1977年   11篇
  1975年   10篇
  1974年   9篇
  1972年   11篇
  1971年   13篇
  1970年   14篇
  1969年   8篇
  1967年   11篇
  1966年   8篇
排序方式: 共有3725条查询结果,搜索用时 15 毫秒
801.
Stress regulation during pregnancy is considered to be connected to the timing of labour initiation. Although increasing knowledge is emerging on the regulation of parturition, there is currently no way to predict the start of spontaneous labour in women. The main aim of this study was to assess pain threshold and the sympathetic nervous system response to cold pain in relation to the onset of labour in healthy pregnant women. Ninety-three pregnant women were recruited and assessed for skin conductance (SC) activity during a cold pressor test in gestational week 38. Pain threshold and cold endurance were also measured and the results were compared with data obtained from hospital records. Seventy-four women had a spontaneous labour onset and a valid SC measurement. SC activity during the cold pressor test decreased significantly with the number of days left to spontaneous parturition. This may indicate a gradual decrease in sympathetic autonomic nervous system reactivity even during the last weeks of pregnancy. Measuring SC activity during mild stress provocation is a rapid and non-invasive means to study variation in sympathetic reactivity during pregnancy, and may be useful in research on stress regulation in pregnancy and its relation to labour initiation.  相似文献   
802.
A suboptimal prenatal environment may induce permanent changes in cells, organs and physiology that alter social, emotional and cognitive functioning, and increase the risk of cardiometabolic and mental disorders in subsequent life ("developmental programming"). Although animal studies have provided a wealth of data on programming and its mechanisms, including on the role of stress and its glucocorticoid mediators, empirical evidence of these mechanisms in humans is still scanty. We review the existing human evidence on the effects of prenatal maternal stress, anxiety and depression, glucocorticoids and intake of liquorice (which inhibits the placental barrier to maternal glucocorticoids) on offspring developmental outcomes including, for instance, alterations in psychophysiological and neurocognitive functioning and mental health. This work lays the foundations for biomarker discovery and affords opportunities for prevention and interventions to ameliorate adverse outcomes in humans.  相似文献   
803.
We review studies that investigate negative social cognitions of socially anxious youth in relation to two specific domains: interpretation of ambiguous social situations and self-evaluation of social performance, including social skills and nervous behaviors. In this review, we address the question whether socially anxious youth’s negative perceptions are distortions of reality or reflect a kernel of truth as compared to other sources of information including independent adult observers and age peers. Studies key to this question are those that investigate not only the social perceptions themselves but also the social behavior of socially anxious youth. Hence the selection of studies for the review was based on this criterion. From the relevant literature it is, as yet, unclear whether the negative interpretations of ambiguous social situations shown by socially anxious youth are distorted or a reflection of reality. Socially anxious youth’s self-evaluations of social skills appear partly distorted and partly true, depending on the person judging the social skills. In contrast, self-evaluations of nervous behaviors appear distorted. The studies reviewed indicate that research would benefit from including a wider range of perceptions from persons relevant to the socially anxious youth’s daily social environment, not only parents and teachers but also their age peers.  相似文献   
804.
Research is subject to more stringent ethical requirements than most other human activities, and a procedure that is otherwise allowed may be forbidden in research. Hence, risk-taking is more restricted in scientific research than in most non-research contexts, and privacy is better protected in scientific questionnaires than in marketing surveys. Potential arguments for this difference are scrutinized. The case in its favour appears to be weak. A stronger case can be made in favour of a difference in the opposite direction: If perilous or otherwise problematic activities have to be performed it is usually better to perform them in a research context where they are properly evaluated so that guidance is obtained for the future. However, retreating from current ethical demands on research is not a desirable direction to go. Instead, research ethics can serve to inspire the introduction of more stringent ethical principles in other social sectors.  相似文献   
805.
The Mirror Neuron System hypothesis stating that observed actions are projected onto the observer’s own action system assigns an important role to development, because only actions mastered by the observer can be mirrored. The purpose of the present study was to investigate whether there is evidence of a functioning mirror neuron system (MNS) in 8-month-old infants. High-density EEG was used to assess the mu rhythm desynchronization in an action observation task where the infants observed a live model. To reduce noise, ICA decompositions were used. The results show a higher desynchronization of the mu rhythm when infants observed a goal-directed action than when they observed a spatially similar non-goal-directed movement. The localizations of the sources are in agreement with those proposed by the MNS hypothesis. This indicates that the MNS is functioning at this age.  相似文献   
806.
807.
Given a reasonable coherentist view of justification in ethics, applied ethics, as here conceived of, cannot only guide us, in our practical decisions, but also provide moral understanding through explanation of our moral obligations. Furthermore, applied ethics can contribute to the growth of knowledge in ethics as such. We put moral hypotheses to crucial test in individual cases. This claim is defended against the challenges from moral intuitionism and particularism.  相似文献   
808.
Die chronische bipolare Depression bei ?lteren Menschen ist eine klinische Herausforderung und erfordert unter Umst?nden, wie der vorliegende Fallbericht zeigt, Behandlungswege, die von Leitlinien nicht unbedingt abgedeckt werden.  相似文献   
809.
Studies of children's knowledge of the Earth have led to very different conclusions: some appear to show that children construct their own, non‐scientific ‘theories’ (mental models) of the flat, hollow or dual Earth. Others indicate that many young children have some understanding of the spherical (scientific) Earth, and that their knowledge lacks the coherence of mental models. The reasons for these contrasting views were tested by interviewing French children (N = 178) aged 5–11 years and varying the different methods used in previous research, namely the types of questions (open and forced‐choice), the form of representation (two‐dimensional pictures and three‐dimensional models), and the method of analysis (the mental model theorists' coding scheme and a statistical test for associations using MANOVA). Forced‐choice questions resulted in higher proportions of scientific answers than open questions, and children appeared to have naïve mental models of the Earth only when the mental model theorists' coding scheme was used. These findings support the view that children tend to have ‘fragments’ of scientific knowledge, and that naïve mental models of the Earth are methodological artifacts. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
810.
Although the majority of research focuses on the risks and disadvantages of online gaming, the present authors suggest that online games also represent new ways of satisfying basic human needs within the conditions of modern society. The aim of our present study was to reveal and operationalize the components of the motivational basis of online gaming. A total 3,818 persons (90.6% males; mean age 20.9 years, SD = 5.81) were recruited through websites providing online games. A combined method of exploratory and confirmatory factor analysis was applied. The results confirmed our preliminary model as we identified seven motivational factors (social, escape, competition, coping, skill development, fantasy, and recreation), which were used to develop the 27-item Motives for Online Gaming Questionnaire (MOGQ). The seven dimensions identified seem to cover the full range of possible motives for gaming, and the MOGQ proved to be an adequate measurement tool to assess these motives.  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