首页 | 官方网站   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   46088篇
  免费   4140篇
  国内免费   83篇
医药卫生   50311篇
  2021年   657篇
  2020年   392篇
  2019年   623篇
  2018年   828篇
  2017年   599篇
  2016年   616篇
  2015年   718篇
  2014年   1116篇
  2013年   1605篇
  2012年   2285篇
  2011年   2337篇
  2010年   1321篇
  2009年   1154篇
  2008年   2018篇
  2007年   2235篇
  2006年   2159篇
  2005年   2240篇
  2004年   2036篇
  2003年   1957篇
  2002年   1785篇
  2001年   1312篇
  2000年   1328篇
  1999年   1186篇
  1998年   552篇
  1997年   456篇
  1996年   463篇
  1995年   404篇
  1994年   427篇
  1993年   383篇
  1992年   1047篇
  1991年   910篇
  1990年   851篇
  1989年   860篇
  1988年   785篇
  1987年   737篇
  1986年   721篇
  1985年   703篇
  1984年   566篇
  1983年   504篇
  1982年   388篇
  1981年   411篇
  1980年   335篇
  1979年   560篇
  1978年   467篇
  1977年   341篇
  1975年   345篇
  1974年   443篇
  1973年   402篇
  1972年   366篇
  1971年   326篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Abstract

Purpose

Financial hardship can be a major cause of distress among persons with cancer, resulting in chronic stress and impacting physical and emotional health. This paper provides an analysis of the lived experience of cancer patients’ financial hardship from diagnosis to post-treatment.  相似文献   
2.
3.
Major depressive disorder (MDD) has been the subject of many neuroimaging case–control classification studies. Although some studies report accuracies ≥80%, most have investigated relatively small samples of clinically‐ascertained, currently symptomatic cases, and did not attempt replication in larger samples. We here first aimed to replicate previously reported classification accuracies in a small, well‐phenotyped community‐based group of current MDD cases with clinical interview‐based diagnoses (from STratifying Resilience and Depression Longitudinally cohort, ‘STRADL’). We performed a set of exploratory predictive classification analyses with measures related to brain morphometry and white matter integrity. We applied three classifier types—SVM, penalised logistic regression or decision tree—either with or without optimisation, and with or without feature selection. We then determined whether similar accuracies could be replicated in a larger independent population‐based sample with self‐reported current depression (UK Biobank cohort). Additional analyses extended to lifetime MDD diagnoses—remitted MDD in STRADL, and lifetime‐experienced MDD in UK Biobank. The highest cross‐validation accuracy (75%) was achieved in the initial current MDD sample with a decision tree classifier and cortical surface area features. The most frequently selected decision tree split variables included surface areas of bilateral caudal anterior cingulate, left lingual gyrus, left superior frontal, right precentral and paracentral regions. High accuracy was not achieved in the larger samples with self‐reported current depression (53.73%), with remitted MDD (57.48%), or with lifetime‐experienced MDD (52.68–60.29%). Our results indicate that high predictive classification accuracies may not immediately translate to larger samples with broader criteria for depression, and may not be robust across different classification approaches.  相似文献   
4.
5.
6.
ABSTRACT

A qualitative grounded theory approach was used to analyze 34 narratives from young men about their experience of retaining, losing, or giving away their virginity, where 7 said they were virgins, 26 said they were non-virgins, and one did not mention his virginity status. We found that virginity is a multidimensional concept, with two distinct dimensions: the experiential and the developmental. The experiential dimension refers to young men's perception and understanding of their virginity in four overlapping areas: physical, spiritual, relational, and emotional. The developmental dimension refers to young men's perception of their underlying sexual identity growth processes and the gendered and sexual double standards that influence this understanding. Clinical implications of this study are useful in education and counseling. They seek to empower young men with information relating to the multidimensional nature of virginity experience, and minimize the negative effects on romantic relationships, sexual adjustment, and self-identity development. The findings are helpful in designing interventions for young men and women who are at high risk for sexually transmitted infections and can help them negotiate mutually safe and pleasurable experiences regarding their virginity.  相似文献   
7.
8.
9.
10.
ABSTRACT

Abortion is legal in South Africa, but negative abortion attitudes remain common and are poorly understood. We used nationally representative South African Social Attitudes Survey data to analyze abortion attitudes in the case of fetal anomaly and in the case of poverty from 2007 to 2016 (n = 20,711; ages = 16+). We measured correlations between abortion attitudes and these important predictors: religiosity, attitudes about premarital sex, attitudes about preferential hiring and promotion of women, and attitudes toward family gender roles. Abortion acceptability for poverty increased over time (b = 0.05, p < .001), but not for fetal anomaly (b = ?0.008, p = .284). Highly religious South Africans reported lower abortion acceptability in both cases (Odds Ratio (OR)anomaly = 0.85, p = .015; ORpoverty = 0.84, p = .02). Premarital sex acceptability strongly and positively predicted abortion acceptability (ORanomaly = 2.63, p < .001; ORpoverty = 2.46, p < .001). Attitudes about preferential hiring and promotion of women were not associated with abortion attitudes, but favorable attitudes about working mothers were positively associated with abortion acceptability for fetal anomaly ((ORanomaly = 1.09, p = .01; ORpoverty = 1.02, p = .641)). Results suggest negative abortion attitudes remain common in South Africa and are closely tied to religiosity, traditional ideologies about sexuality, and gender role expectations about motherhood.  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-23

京公网安备 11010802026262号