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   161746篇
  免费   10340篇
  国内免费   1220篇
耳鼻咽喉   2262篇
儿科学   3029篇
妇产科学   3741篇
基础医学   24057篇
口腔科学   3353篇
临床医学   15258篇
内科学   30807篇
皮肤病学   4344篇
神经病学   12067篇
特种医学   8105篇
外科学   21912篇
综合类   2207篇
现状与发展   5篇
一般理论   81篇
预防医学   9771篇
眼科学   4308篇
药学   13702篇
中国医学   1624篇
肿瘤学   12673篇
  2023年   994篇
  2022年   2749篇
  2021年   4834篇
  2020年   2476篇
  2019年   3593篇
  2018年   4419篇
  2017年   3240篇
  2016年   4192篇
  2015年   5651篇
  2014年   6930篇
  2013年   8395篇
  2012年   12660篇
  2011年   12307篇
  2010年   7273篇
  2009年   6078篇
  2008年   9269篇
  2007年   9135篇
  2006年   8398篇
  2005年   7990篇
  2004年   7128篇
  2003年   6195篇
  2002年   5382篇
  2001年   4383篇
  2000年   4030篇
  1999年   3267篇
  1998年   1320篇
  1997年   993篇
  1996年   957篇
  1995年   872篇
  1994年   755篇
  1993年   643篇
  1992年   1572篇
  1991年   1571篇
  1990年   1354篇
  1989年   1237篇
  1988年   1157篇
  1987年   1033篇
  1986年   1010篇
  1985年   887篇
  1984年   646篇
  1983年   563篇
  1982年   399篇
  1981年   380篇
  1980年   338篇
  1979年   520篇
  1978年   409篇
  1977年   390篇
  1976年   343篇
  1974年   358篇
  1973年   327篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
BackgroundSocial media has become a ubiquitous part of daily life during the COVID-19 pandemic isolation. However, the role of social media use in depression and suicidal ideation of the general public remains unclear. Related empirical studies were limited and reported inconsistent findings. Little is known about the potential underlying mechanisms that may illustrate the relationship between social media use and depression and suicidal ideation during the COVID-19 pandemic.ObjectiveThis study tested the mediation effects of social loneliness and posttraumatic stress disorder (PTSD) symptoms on the relationship between social media use and depressive symptoms and suicidal ideation, as well as the moderation effect of age on the mediation models.MethodsWe administered a population-based random telephone survey in May and June 2020, when infection control measures were being vigorously implemented in Hong Kong. A total of 1070 adults (658 social media users and 412 nonusers) completed the survey. Structural equation modeling (SEM) and multigroup SEM were conducted to test the mediation and moderation effects.ResultsThe weighted prevalence of probable depression was 11.6%; 1.6% had suicidal ideation in the past 2 weeks. Both moderated mediation models of depressive symptoms (χ262=335.3; P<.05; comparative fit index [CFI]=0.94; nonnormed fit index [NNFI]=0.92; root mean square error of approximation [RMSEA]=0.06) and suicidal ideation (χ234=50.8; P<.05; CFI=0.99; NNFI=0.99; RMSEA=0.02) showed acceptable model fit. There was a significantly negative direct effect of social media use on depressive symptoms among older people (β=–.07; P=.04) but not among younger people (β=.04; P=.55). The indirect effect via PTSD symptoms was significantly positive among both younger people (β=.09; P=.02) and older people (β=.10; P=.01). The indirect effect via social loneliness was significant among older people (β=–.01; P=.04) but not among younger people (β=.01; P=.31). The direct effect of social media use on suicidal ideation was not statistically significant in either age group (P>.05). The indirect effects via PTSD symptoms were statistically significant among younger people (β=.02; P=.04) and older people (β=.03; P=.01). Social loneliness was not a significant mediator between social media use and suicidal ideation among either age group (P>.05).ConclusionsSocial media may be a “double-edged sword” for psychosocial well-being during the COVID-19 pandemic, and its roles vary across age groups. The mediators identified in this study can be addressed by psychological interventions to prevent severe mental health problems during and after the COVID-19 pandemic.  相似文献   
993.
Initial cases of coronavirus disease in Hong Kong were imported from mainland China. A dramatic increase in case numbers was seen in February 2020. Most case-patients had no recent travel history, suggesting the presence of transmission chains in the local community. We collected demographic, clinical, and epidemiologic data from 50 patients, who accounted for 53.8% of total reported case-patients as of February 28, 2020. We performed whole-genome sequencing to determine phylogenetic relationship and transmission dynamics of severe acute respiratory syndrome coronavirus 2 infections. By using phylogenetic analysis, we attributed the community outbreak to 2 lineages; 1 harbored a common mutation, Orf3a-G251V, and accounted for 88.0% of the cases in our study. The estimated time to the most recent common ancestor of local coronavirus disease outbreak was December 24, 2019, with an evolutionary rate of 3.04 × 10−3 substitutions/site/year. The reproduction number was 1.84, indicating ongoing community spread.  相似文献   
994.
PurposeTexting is used by many adolescents and has the potential to improve well-being, as youth can reach out for support immediately after experiencing a stressful situation. Many studies have examined whether texting is associated with well-being, but few have used experimental designs, preventing causal claims.MethodsIn this experimental study, 130 adolescents (Mage = 12.41) participated with a same-gender friend whom they texted regularly. Both adolescents completed a task that elicited stress and then engaged in one of the following randomly assigned activities: texting their friend, watching a video on a cellphone (passive-phone condition), or sitting quietly (no activity condition). Participants reported their mood and stress levels after the stress task and again after the activity. Heart rate variability was measured throughout.ResultsParticipants who texted their friend reported higher moods (b = ?.80, standard error [SE] = .24, p < .001, ηp2 = .09) and lower stress at the end of the study than those in the no activity condition (b = .51, SE = .25, p = .046, ηp2 = .04) and higher moods than adolescents in the passive-phone condition (b = ?.74, SE = .25, p = .004, ηp2 = .08). No differences were noted between the passive-phone and no activity conditions. There were no differences in heart rate variability between the three conditions. The effects of texting on mood, self-reported stress, and heart rate variability did not differ by gender.ConclusionsBoth boys and girls may benefit from texting a friend after experiencing a stressful event.  相似文献   
995.
A concerning development during the coronavirus disease pandemic has been multisystem inflammatory syndrome in children. Reports of this condition in East Asia have been limited. In South Korea, 3 cases were reported to the national surveillance system for multisystem inflammatory syndrome in children. All case-patients were hospitalized and survived with no major disease sequelae.  相似文献   
996.
997.
998.
International Urology and Nephrology - A systemic inflammation response index (SIRI) has been recently introduced as a tool for the assessment of the prognosis of several critical medical...  相似文献   
999.
International Urology and Nephrology - Late onset hypogonadism (LOH) is an age-dependent reduction of testosterone associated with alterations of metabolic profile, including glucose control,...  相似文献   
1000.
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