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   28744篇
  免费   304篇
  国内免费   5篇
  2020年   101篇
  2019年   112篇
  2018年   3592篇
  2017年   2939篇
  2016年   2401篇
  2015年   330篇
  2014年   217篇
  2013年   940篇
  2012年   843篇
  2011年   2646篇
  2010年   2666篇
  2009年   1684篇
  2008年   1984篇
  2007年   2465篇
  2006年   335篇
  2005年   499篇
  2004年   427篇
  2003年   430篇
  2002年   349篇
  2001年   162篇
  2000年   176篇
  1999年   173篇
  1998年   142篇
  1997年   140篇
  1996年   134篇
  1995年   141篇
  1994年   109篇
  1993年   126篇
  1992年   112篇
  1991年   101篇
  1990年   94篇
  1989年   91篇
  1988年   100篇
  1987年   107篇
  1986年   92篇
  1985年   106篇
  1984年   130篇
  1983年   127篇
  1982年   121篇
  1981年   113篇
  1980年   119篇
  1979年   125篇
  1978年   123篇
  1977年   121篇
  1976年   133篇
  1975年   100篇
  1974年   107篇
  1973年   107篇
  1972年   69篇
  1971年   56篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
831.
To examine the association of 1) race/ethnicity and 2) numeracy with awareness of DTC genetic tests. Secondary analysis of 6,754 Hispanic, black, and white adult respondents to the National Cancer Institute’s 2007 Health Information National Trends Survey (HINTS). Logistic regression was used to examine sociodemographic predictors of DTC genetic tests awareness including race/ethnicity, income, education, and gender. Next, two numeracy variables were added to the model. After controlling for sociodemographic variables, black respondents were significantly less likely to have heard of DTC genetic tests compared to white respondents (OR = 0.79; CI: 0.65–0.97). When numeracy variables were added to the model, the effect of black race was no longer significant (OR = 0.84; CI: 0.69–1.04). Hispanic respondents did not significantly differ from white respondents in awareness of DTC genetic tests. Other significant correlates of DTC genetic tests awareness in the full model included education, income, age, and numeracy variables including degree to which people use medical statistics and numbers to make health decisions, and preference for words or numbers when discussing “the chance of something happening.” Although black respondents were generally less aware of DTC genetic tests than white respondents, this relationship appears to be partially mediated by numeracy.  相似文献   
832.
Technological advances and information-seeking consumers have pushed forward the movement of direct-to-consumer (DTC) genetic testing. Just like with other types of testing, there are potential risks, benefits and limitations. A major limitation of DTC testing is the incomplete view it provides regarding lifetime risk for common, complex diseases, since most tests only analyze 1–2 single nucleotide polymorphisms (SNPs) and do not include evaluation of medical or family histories, which is necessary to risk assessment. Further, it is not currently well-established whether personal genomic testing results will lead toward improved health behaviors, adverse psychological effects or potential overuse of the health care system. To display these and other issues, we present an in-depth case study of an individual who ordered DTC genetic testing and subsequently sought genetic counseling. This case presents a unique learning experience for the field of genomic counseling, as the patient did not fit the typical assumptions regarding ‘early adopters’ of DTC testing. It also allowed the genetics health care providers involved in the case to identify gaps in current genetic counseling practice that need to be filled and approaches to employ for successful delivery of genomic counseling. Based on our experience, we developed practical recommendations for genomic counseling, which include novel approaches to case preparation, use of electronic tools during the counseling session, and focusing on education as the major component of the genomic counseling session, in order to provide patients with the knowledge necessary to independently interpret and understand large amounts of genomic testing information provided to them.  相似文献   
833.
We investigated the relationship between conformative peer bullying and issues of peer conformity among adolescents. This relationship is examined through the establishment of a mediated moderation model for conformative peer bullying using structural equation modeling in a sample of 391 second-year middle school students in Seoul, South Korea. We found that peer pressure and resistance to peer influence interact with one another to affect antisocial conformity, which then affects conformative peer bullying, thereby establishing its mediated moderation effect. The results suggest that conformative peer bullying that encourages and assists active bullies is affected by antisocial conformity; moreover, an individual’s capacity to resist peer influence plays a protective role against peer conformity, and this must be acknowledged as a significant influence in conformative peer bullying among adolescents.  相似文献   
834.
Few programs exist for after school care designed to support children with Autism Spectrum Disorder (ASD). Not only do parents often depend on after school care, but also children with ASD are likely to benefit from opportunities to generalize skills in an authentic setting and interact with typically developing peers. This lack of support occurs at a time during which there is increasing research and community awareness regarding the need for high quality after school programs to support typically developing children. This study investigates reported experiences with and needs for after school care by parents of children with ASD. Survey results (N = 54) revealed that the majority of parents surveyed desired after school programs within their child’s school but are often denied access to such services or received low quality care for their child in after school programs. Recommendations are provided for future research and program development.  相似文献   
835.
In the aftermath of several school shooting incidents in recent years, students’ perceptions of unsafe schools has been a major concern for parents, teachers, school officials, school practitioners, and policy-makers. Using Bronfenbrenner’s ecological systems framework, we examined the micro-, meso-, and exosystem level factors associated with perceptions of unsafe school environments in a nationally representative sample of 10- to 15-year-old youth in the United States. We found that for the socio-demographic characteristics, students who were older, male, and poor had increased risks of perceiving higher levels of unsafe school environments. Within the microsystem of the family, our results indicate that parent-youth discussions of school activities/events decreased the risk of students perceiving unsafe schools. All of the school environment variables—ease of making friends, teachers’ involvement, observed weapon carrying, and school rule enforcement—were related in the expected direction to students’ perceiving their schools as unsafe. At the mesosystem level, findings from our study demonstrate that variables measuring parental school involvement were unrelated to perceptions of school safety. Finally, at the exosystem level, we found that students’ perceptions of residing in a safer neighborhood and residence in a non-central city metropolitan area, compared with a central city, decreased the odds of perceiving school environments as unsafe. School policy and practice implications are discussed.  相似文献   
836.
Research suggests a link between parental divorce and negative child outcomes; however, the presence of parental depression may confound this relationship. Studies exploring the simultaneous effects of depression and parents’ divorce on the adjustment of their children are scarce and rarely have a longitudinal design. This is the first three-generation study of the relative effects of depression and divorce on offspring psychopathology, based on data from a 25-year longitudinal study with families at high and low risk for depression. One hundred seventy-eight grandchildren (mean age?=?13.9?years) of depressed and nondepressed parents and grandparents were evaluated by raters blind to their parents’ and grandparents’ clinical status. We found that in both low and high-risk children, divorce had a limited impact on child adjustment over and above familial risk for depression. Divorce had a significant effect on child outcomes only among high-risk grandchildren with a depressed grandparent and non-depressed parents, with this group showing a threefold risk for anxiety disorders. Results support previous findings suggesting that familial risk for depression largely overshadows the effect of parental divorce on child psychopathology. Possible reasons for the lack of association between divorce and child psychopathology among low-risk offspring are discussed.  相似文献   
837.
In the present study, introductory-level German students read a simplified story and learned the meanings of new German words by reading English translations in marginal glosses versus trying to infer (i.e., guess) their translations. Students who inferred translations were given feedback in English or in German, or no feedback at all. Although immediate retention of new vocabulary was better for students who used marginal glosses, students who inferred word meanings and then received English feedback forgot fewer translations over time. Plausible but inaccurate inferences (i.e., those that made sense in the context) were more likely to be corrected by students who received English feedback as compared with German feedback, providing support for the beneficial effects of mediating information. Implausible inaccurate inferences, however, were more likely to be corrected on the delayed vocabulary test by students who received German feedback as compared with English feedback, possibly because of the additional contextual support provided by German feedback.  相似文献   
838.
A positive relationship between prior knowledge and item memory is a consistent finding in the literature. In the present study, we sought to determine whether this relationship extends to episodic details that are present at the time of encoding, namely source memory. Using a novel experimental design, we were able to show both between- and within-subjects effects of prior knowledge on source memory. Specifically, the results revealed that the degree of prior knowledge positively predicted memory for source specifying contextual details. In addition, by including two conditions in which attention was divided either at encoding or retrieval, we were able to show that prior knowledge influences memory by affecting encoding processes. Overall, the data suggest that a priori knowledge within a specific domain allows attentional resources to be allocated toward the encoding of contextual details.  相似文献   
839.
The type of experience involved with an object category has been regarded as one important factor in shaping of the human object recognition system. Laboratory training studies have shown that different kinds of learning experience with the same set of novel objects resulted in different perceptual and neural changes. Whether this applies to natural real-world objects remains to be seen. We compared two groups of observers who had different learning experiences with faces, using holistic processing as a dependent measure. We found that, while ordinary observers had extensive individuation experience with faces and displayed typical holistic face processing, art students who had acquired additional experience in drawing faces, and thus in attending to parts of a face, showed less holistic processing than did ordinary observers. These results converge with laboratory training studies on the role of type of experience in the development of different perceptual markers for different object categories. It is thus insufficient to categorize expertise simply in terms of object domains (e.g., expertise with faces). Instead, perceptual expertise should be classified in terms of the underlying process or task demand.  相似文献   
840.
People can learn word–referent pairs over a short series of individually ambiguous situations containing multiple words and referents (Yu & Smith, 2007, Cognition 106: 1558–1568). Cross-situational statistical learning relies on the repeated co-occurrence of words with their intended referents, but simple co-occurrence counts cannot explain the findings. Mutual exclusivity (ME: an assumption of one-to-one mappings) can reduce ambiguity by leveraging prior experience to restrict the number of word–referent pairings considered but can also block learning of non-one-to-one mappings. The present study first trained learners on one-to-one mappings with varying numbers of repetitions. In late training, a new set of word–referent pairs were introduced alongside pretrained pairs; each pretrained pair consistently appeared with a new pair. Results indicate that (1) learners quickly infer new pairs in late training on the basis of their knowledge of pretrained pairs, exhibiting ME; and (2) learners also adaptively relax the ME bias and learn two-to-two mappings involving both pretrained and new words and objects. We present an associative model that accounts for both results using competing familiarity and uncertainty biases.  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