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   7973篇
  免费   677篇
  国内免费   13篇
耳鼻咽喉   62篇
儿科学   376篇
妇产科学   195篇
基础医学   1094篇
口腔科学   33篇
临床医学   969篇
内科学   1498篇
皮肤病学   156篇
神经病学   890篇
特种医学   114篇
外科学   917篇
综合类   62篇
一般理论   12篇
预防医学   1225篇
眼科学   57篇
药学   517篇
中国医学   6篇
肿瘤学   480篇
  2024年   24篇
  2023年   170篇
  2022年   227篇
  2021年   504篇
  2020年   307篇
  2019年   462篇
  2018年   476篇
  2017年   345篇
  2016年   325篇
  2015年   306篇
  2014年   456篇
  2013年   506篇
  2012年   812篇
  2011年   763篇
  2010年   321篇
  2009年   248篇
  2008年   503篇
  2007年   412篇
  2006年   353篇
  2005年   316篇
  2004年   268篇
  2003年   214篇
  2002年   197篇
  2001年   16篇
  2000年   5篇
  1999年   15篇
  1998年   25篇
  1997年   16篇
  1996年   14篇
  1995年   9篇
  1994年   9篇
  1993年   4篇
  1992年   4篇
  1991年   2篇
  1990年   4篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   4篇
  1984年   1篇
  1983年   3篇
  1981年   4篇
  1980年   1篇
  1978年   2篇
  1976年   1篇
  1975年   1篇
  1974年   2篇
  1972年   1篇
  1961年   1篇
  1949年   1篇
排序方式: 共有8663条查询结果,搜索用时 31 毫秒
31.
A number of studies have demonstrated that adolescent rodents are more sensitive to the rewarding effects of nicotine compared to adults. To help determine the potential brain circuitry involved, we investigated the effect of acute nicotine administration (0.4 or 0.8 mg/kg, s.c.) on the expression of c-fos mRNA in the brains of adolescent (P35) and adult (P67-70) male Wistar rats using in situ hybridization. Nicotine administration increased c-fos mRNA expression in several brain regions, including the central amygdala, locus coeruleus, nucleus accumbens core, paraventricular nucleus of the hypothalamus and lateral septum of adolescent and adult rats. Nicotine increased c-fos mRNA expression more robustly in the bed nucleus of the stria terminalis, nucleus accumbens shell and ventral tegmental area in adolescent rats. The current results suggest that nicotine may have greater activational effects in brain regions associated with reward in adolescent rats and may help to explain the differences between adolescents and adults in behavioral responses to nicotine.  相似文献   
32.
Current HIV/AIDS statistics show that women account for almost 60% of HIV infections in Sub-Saharan Africa. HIV prevention tools such as male and female condoms, abstinence and monogamy are not always feasible options for women due to various socio-economic and cultural factors. Microbicides are products designed to be inserted in the vagina or rectum prior to sex to prevent HIV acquisition.  相似文献   
33.
34.
Leukodystrophies are a heterogeneous group of heritable disorders characterized by abnormal brain white matter signal on magnetic resonance imaging (MRI) and primary involvement of the cellular components of myelin. Previous estimates suggest the incidence of leukodystrophies as a whole to be 1 in 7,000 individuals, however the frequency of specific diagnoses relative to others has not been described. Next generation sequencing approaches offer the opportunity to redefine our understanding of the relative frequency of different leukodystrophies. We assessed the relative frequency of all 30 leukodystrophies (associated with 55 genes) in more than 49,000 exomes. We identified a relatively high frequency of disorders previously thought of as very rare, including Aicardi Goutières Syndrome, TUBB4A‐related leukodystrophy, Peroxisomal biogenesis disorders, POLR3‐related Leukodystrophy, Vanishing White Matter, and Pelizaeus‐Merzbacher Disease. Despite the relative frequency of these conditions, carrier‐screening laboratories regularly test only 20 of the 55 leukodystrophy‐related genes, and do not test at all, or test only one or a few, genes for some of the higher frequency disorders. Relative frequency of leukodystrophies previously considered very rare suggests these disorders may benefit from expanded carrier screening.  相似文献   
35.
36.
Various forms of private investment are considered necessary for the sustainability of biobanks, yet pose significant challenges to public trust. To manage this tension, it is vital to identify the concerns of relevant stakeholders to ensure effective and acceptable policy and practice. This research examines the aspects of commercialisation that are of most concern to the Australian public (n = 800) and patients who had donated their tissue to two large disease specific (cancer) public biobanks (n = 564). Overall, we found a commercialisation effect (higher support for public relative to private) in relation to funding, research location and access to stored biospecimens. The effect was strongest for research locations and access compared to funding. A latent class analysis revealed the pattern of concern differed, with the majority (34.1%) opposing all aspects of commercialisation, a minority supporting all (15.7%), one quarter (26.8%) opposing some (sharing and selling tissue) but not others (research locations and funding), and a group who were unsure about most aspects but opposed selling tissue (23.5%). Patient donors were found to be more accepting of and unsure about most aspects of commercialisation. Members of the (general) public who were motivated to participate in biobanking were more likely to oppose some aspects while supporting others, while those who indicated they would not donate to a biobank were more likely to oppose all aspects of commercialisation. The results suggest that approaches to policy, engagement and awareness raising need to be tailored for different publics and patient groups to increase participation.Subject terms: Genetics research, Ethics  相似文献   
37.

Background

Dupilumab blocks the shared receptor component for interleukin (IL)-4/IL-13, key drivers of type 2 inflammation. In phase 2b (NCT01854047) and phase 3 LIBERTY ASTHMA QUEST (NCT02414854), add-on dupilumab 200/300 mg every 2 weeks (q2w) reduced severe exacerbations, improved prebronchodilator (pre-BD) forced expiratory volume in 1 second (FEV1) and quality of life measures, and it was generally well tolerated in patients with uncontrolled, persistent (phase 2b), or moderate-to-severe (phase 3) asthma.

Methods

In patients on high-dose inhaled corticosteroids (ICS) with type 2-high asthma (subgroups including baseline blood eosinophils ≥150/300 cells/µL and/or fractional exhaled nitric oxide [FeNO] ≥25 ppb), annualized severe exacerbation rates over the treatment period, changes from baseline in pre-BD FEV1 and asthma control (5-item asthma control questionnaire [ACQ-5]) were analyzed.

Results

In high-dose ICS type 2-high subgroups, dupilumab 200/300 mg q2w vs placebo in the phase 2b (24 weeks) and phase 3 (52 weeks) studies significantly reduced severe exacerbations by 55%-69%/57%-60% (all P<.05) and 53%-69%/48%-66% (all < .001), respectively, except in patients with ≥ 300 eosinophils/µL in phase 2b study (24%/50% (= .52/0.15). Across subgroups, pre-BD FEV1 improved by 0.18-0.22 L/0.19-0.24 L (all < .05) and 0.23-0.36 L/0.15-0.25 L (all < .01) and ACQ-5 scores were reduced by 0.46-0.55/0.47-0.85 (all < .05) and 0.38-0.50/0.24-0.30 (all < .05), respectively, except dupilumab 200 mg q2w in phase 2b in patients with FeNO ≥ 25 ppb (0.41; = .09). Dupilumab was also effective in patients taking medium-dose ICS.

Conclusion

Dupilumab significantly reduced severe exacerbations and improved lung function and asthma control in patients with type 2-high asthma on high-dose ICS at baseline.
  相似文献   
38.
OBJECTIVES: To examine whether wasting during pregnancy, as measured by weight loss and low weight gain, is associated with increased mother-to-child transmission (MTCT) of HIV-1. METHODS: This was a cohort study in Dar es Salaam, Tanzania, among 957 HIV-1-infected pregnant women. Weight was measured at the first prenatal visit and every month thereafter until delivery. Weight loss was defined as a weekly rate of weight gain 0 and /=167 g/wk, weight loss during pregnancy was related to higher risk of intrauterine MTCT (adjusted relative risk [RR] = 2.32, 95% CI = 1.23-4.36, P = 0.009), HIV positive at birth or fetal death (RR = 2.13, 95% CI = 1.40-3.24, P = 0.0004), and HIV positive at birth or early neonatal death (RR = 1.96, 95% CI = 1.26-3.07, P = 0.003). The rate of weight gain during the 3rd trimester was inversely related to the risk of intrapartum/early breast-feeding transmission (adjusted P value, test for trend = 0.05). CONCLUSIONS: Weight loss during pregnancy increases the risk of early MTCT. Identifying causes of wasting during pregnancy may provide clues for new strategies to prevent MTCT.  相似文献   
39.
Child & Youth Care Forum - In the United States, 68% of children do not get the recommended nine hours of sleep, which can lead to many negative health outcomes (e.g., mental health)....  相似文献   
40.
Background: The coronavirus disease 2019 (COVID-19) pandemic has increased the already high levels of stress that higher education students experience. Stress influences health behaviors, including those related to dietary behaviors, alcohol, and sleep; yet the effects of stress can be mitigated by resilience. To date, past research studying the connections between dietary behaviors, alcohol misuse, sleep, and resilience commonly investigated singular relationships between two of the constructs. The aim of the current study was to explore the relationships between these constructs in a more holistic manner using mediation and moderation analyses. Methods: Higher education students from China, Ireland, Malaysia, South Korea, Taiwan, the Netherlands, and the United States were enrolled in a cross-sectional study from April to May 2020, which was during the beginning of the COVID-19 pandemic for most participants. An online survey, using validated tools, was distributed to assess perceived stress, dietary behaviors, alcohol misuse, sleep quality and duration, and resilience. Results: 2254 students completed the study. Results indicated that sleep quality mediated the relationship between perceived stress and dietary behaviors as well as the relationship between perceived stress and alcohol misuse. Further, increased resilience reduced the strength of the relationship between perceived stress and dietary behaviors but not alcohol misuse. Conclusion: Based on these results, higher education students are likely to benefit from sleep education and resilience training, especially during stressful events.  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