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   3589篇
  免费   135篇
  2022年   18篇
  2021年   20篇
  2020年   44篇
  2019年   58篇
  2018年   85篇
  2017年   80篇
  2016年   95篇
  2015年   85篇
  2014年   85篇
  2013年   367篇
  2012年   161篇
  2011年   154篇
  2010年   128篇
  2009年   111篇
  2008年   157篇
  2007年   184篇
  2006年   148篇
  2005年   121篇
  2004年   120篇
  2003年   136篇
  2002年   142篇
  2001年   70篇
  2000年   52篇
  1999年   72篇
  1998年   63篇
  1997年   54篇
  1996年   60篇
  1995年   40篇
  1994年   44篇
  1993年   43篇
  1992年   54篇
  1991年   43篇
  1990年   50篇
  1989年   35篇
  1988年   30篇
  1987年   32篇
  1986年   36篇
  1985年   39篇
  1984年   50篇
  1983年   36篇
  1982年   50篇
  1981年   39篇
  1980年   34篇
  1979年   32篇
  1978年   21篇
  1977年   30篇
  1976年   26篇
  1975年   14篇
  1974年   18篇
  1973年   14篇
排序方式: 共有3724条查询结果,搜索用时 140 毫秒
161.
Electrical stimulation of the region of the lateral hypothalamus produced a consistent form of quiet-biting attack behavior in cats. In one series of experiments, cats, implanted with electrodes from which attack had been elicited, were anesthetized and then were injected with a bolus of 14C-2-deoxyglucose at the same time as electrical stimulation was delivered through the attack electrodes. Brains prepared for X-ray autoradiography revealed that lateral hypothalamic stimulation activated the classical medial forebrain bundle pathway supplying the septal region, diagonal band, lateral preoptic area, and ventral tegmental region. Stimulation of quiet-attack sites in perifornical hypothalamus resulted in the activation of a much more extensive projection system which included the central and lateral tegmental fields of the midbrain and pons, and central gray region, as well as the structures described above. In a second series of experiments, 3H-leucine was placed into the region of the electrode tip from which attack was elicited in order to identify more precisely the pathways arising from that site. In general, tritiated amino acid radioautography replicated the 14C-2-deoxyglucose findings. In addition, the amino acid radioautographic data revealed the presence of extensive projections from perifornical hypothalamus to such pontine structures as the nucleus locus coeruleus, motor nucleus of NV , and the lateral pontine tegmental field. The functional connections between the lateral hypothalamic “attack region” and lateral preoptic zone were also confirmed by electrophysiological methods.  相似文献   
162.
Subjects had their initial frames of reference concerning a decision problem (Asian Disease problem; Tversky & Kahneman, 1981, Science,211, 453–458) manipulated in order to compose four-person groups containing members with different frames of reference. Three different group compositions (number of members with "gain-oriented" vs "loss-oriented" frames) were used: three gain-oriented and one loss oriented (3–1), two gain-oriented and two loss-oriented (2–2), and one gain-oriented and three loss-oriented (1–3). Results indicated a postgroup discussion choice shift toward the risk alternative in the 2–2 and the 1–3 composition conditions. However, changes in members′ frames of reference were unrelated to preference changes. Group composition also affected group decision processes. Implications for future theory and research in small group decision-making are discussed.  相似文献   
163.
164.
Infants are uniquely vulnerable to maternal depression's noxious effects, but few longitudinal studies have tried to identify discrete postnatal trajectories of maternal depressive symptoms (MDS) beginning in infancy. This study extends evidence of heterogeneous change in postnatal MDS by examining their cross-contextual antecedents in infancy and their consequences for children's early behavior problems and language skills in late toddlerhood. A community sample of mother–child dyads (N = 235, 72% Caucasian) was assessed when children were 7, 15, and 33 months old. Mothers reported their socioeconomic status (SES), social support, marital relationship quality, family dysfunction, parenting stress, and infants’ functional regulatory problems at 7 months postpartum, and children's internalizing and externalizing symptoms at 33 months. Children completed a receptive vocabulary assessment at 33 months in the lab. Latent class growth analysis identified three postnatal MDS trajectory classes that fit the data best: low-decreasing, moderate, and increasing. Psychosocial measures at seven months postpartum primarily predicted membership to these postnatal trajectory classes, which subsequently differed in children's internalizing, externalizing, and receptive vocabulary in late toddlerhood, controlling for family SES and functional regulatory problems in infancy. We discuss salient antecedents and consequences of postnatal depression for mothers and their offspring.  相似文献   
165.
A mother's propensity to refer to internal states during mother–child interactions is important for her child's developing social understanding. However, adolescent mothers are less likely to reference internal states when interacting with their children. We investigated whether young mothers’ references to internal states are promoted by the Family Nurse Partnership (FNP) intervention, an intensive home-visiting programme designed to support adolescent mothers in England. We also investigated family, maternal, and child factors associated with young mothers’ references to inner states during interactions with their children. Adolescent mothers (= 483, aged ≤ 19 years when recruited in pregnancy) and their children participated in an observational substudy of a randomized controlled trial investigating the impact of FNP compared to usual care. Mother–child dyads were video-recorded during free play, and mothers’ speech was coded for use of internal state language (references to cognitions, desires, emotions, intentions, preferences, physiology, and perception). We found no differences in mothers’ use of internal state language between the FNP and usual care groups. A sample-wide investigation identified that other features of mothers’ language and relationship status with the child's father were associated with internal state language use. Findings are discussed with reference to targeted interventions and implications for future research.  相似文献   
166.
167.
This longitudinal study examined adolescent girls' perception of control over sexually transmitted disease (STD) acquisition. Participants were asked questions regarding their perception of their STD locus of control (internal control; control by parents, partners, peers, and health care providers; and chance) at two waves of data collection. Of the 116 participants (mean age = 17 years), 82% were African-American and 18% were Caucasian. Responses to the measure of locus of control were significantly correlated across a 6-month interval. The responses regarding internal control, control by partner, and chance were not related to the acquisition of an STD in the next 6 months. Further, they were not influenced by an STD in the preceding 6 months. These results indicate that responses to a locus of control measure were stable over a 6-month period, and internal, partner, and chance locus of control perceptions seem to be neither determined by STD experience nor directly related to future STD acquisition. However, understanding an individual's locus of control may be helpful in providing appropriate counseling. Future research could examine how adolescent girls form their perceptions of control over STD acquisition.  相似文献   
168.
Processing speed was assessed at 5, 7, and 12 months in full-term and preterm infants (birth-weight < 1,750 g). Speed was gauged directly in a new task by presenting infants with a series of paired faces, one that remained the same across trials and one that changed; trials continued until infants showed a consistent novelty preference. At all ages, preterms required about 20% more trials and 30% more time than full-terms to reach criterion. Among preterms, slower processing was associated with greater medical risk (e.g., respiratory distress syndrome). Developmental trajectories for speed (and attention) were similar for both groups. Thus, the deficits in processing speed previously found for preterms in childhood are already present in the 1st year of life.  相似文献   
169.
All languages rely to some extent on word order to signal relational information. Why? We address this question by exploring communicative and cognitive factors that could lead to a reliance on word order. In Study 1, adults were asked to describe scenes to another using their hands and not their mouths. The question was whether this home-made "language" would contain gesture sentences with consistent order. In addition, we asked whether reliance on order would be influenced by three communicative factors (whether the communication partner is permitted to give feedback; whether the information to be communicated is present in the context that recipient and gesturer share; whether the gesturer assumes the role of gesture receiver as well as gesture producer). We found that, not only was consistent ordering of semantic elements robust across the range of communication situations, but the same non-English order appeared in all contexts. Study 2 explored whether this non-English order is found only when a person attempts to share information with another. Adults were asked to reconstruct scenes in a non-communicative context using pictures drawn on transparencies. The adults picked up the pictures for their reconstructions in a consistent order, and that order was the same non-English order found in Study 1. Finding consistent ordering patterns in a non-communicative context suggests that word order is not driven solely by the demands of communicating information to another, but may reflect a more general property of human thought.  相似文献   
170.
A within-scale meta-analysis was performed on 310 samples of children (ages 8-16; N = 61,424) responding to the Children's Depression Inventory (CDI). Girls' depression scores stayed steady from ages 8 to 11 and then increased between ages 12 and 16. Boys' CDI scores were stable from ages 8 to 16 except for a high CDI score at age 12. Girls' scores were slightly lower than boys' during childhood, but girls scored higher beginning at age 13. There were no socioeconomic status effects and no differences between White and Black samples. However, Hispanic samples scored significantly higher on the CDI. Analyses for birth cohort showed a slight decrease in boys' CDI scores over time and no change for girls. Longitudinal studies demonstrated a marked testing effect.  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