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   27248篇
  免费   2227篇
  国内免费   110篇
耳鼻咽喉   315篇
儿科学   908篇
妇产科学   742篇
基础医学   3838篇
口腔科学   552篇
临床医学   2594篇
内科学   5246篇
皮肤病学   364篇
神经病学   2442篇
特种医学   911篇
外科学   4028篇
综合类   763篇
现状与发展   1篇
一般理论   37篇
预防医学   1899篇
眼科学   864篇
药学   1766篇
中国医学   68篇
肿瘤学   2247篇
  2023年   146篇
  2022年   115篇
  2021年   534篇
  2020年   371篇
  2019年   542篇
  2018年   677篇
  2017年   401篇
  2016年   548篇
  2015年   646篇
  2014年   842篇
  2013年   1163篇
  2012年   1684篇
  2011年   1693篇
  2010年   1045篇
  2009年   984篇
  2008年   1562篇
  2007年   1620篇
  2006年   1488篇
  2005年   1520篇
  2004年   1481篇
  2003年   1357篇
  2002年   1167篇
  2001年   640篇
  2000年   599篇
  1999年   520篇
  1998年   247篇
  1997年   197篇
  1996年   194篇
  1995年   204篇
  1994年   167篇
  1993年   183篇
  1992年   349篇
  1991年   314篇
  1990年   328篇
  1989年   323篇
  1988年   274篇
  1987年   256篇
  1986年   256篇
  1985年   272篇
  1984年   207篇
  1983年   172篇
  1982年   174篇
  1981年   176篇
  1980年   145篇
  1979年   136篇
  1978年   107篇
  1977年   119篇
  1976年   129篇
  1975年   114篇
  1974年   133篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
1.
Evidence suggests that aspirin use reduces the occurrence of colorectal neoplasia. Few studies have investigated the association among Black Americans, who are disproportionately burdened by the disease. We assessed aspirin use in relation to colorectal adenoma among Black women. The Black Women's Health Study is a prospective cohort of self-identified Black American women established in 1995. Participants reported regular aspirin use on baseline and follow-up questionnaires. Beginning in 1999, participants reported undergoing a colonoscopy or sigmoidoscopy, the only procedures through which colorectal adenomas can be diagnosed. Multivariable logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI) for associations between aspirin use and colorectal adenoma among 34 397 women who reported at least 1 colonoscopy or sigmoidoscopy. From 1997 through 2018, 1913 women were diagnosed with an adenoma. Compared to nonaspirin users, regular users had 14% (OR = 0.86, 95% CI: 0.78-0.95) lower odds of adenoma. The odds of adenoma decreased with increasing duration of aspirin use (≥10 years: OR = 0.80, 95% CI: 0.66-0.96). Initiating aspirin at a younger age was associated with a reduced adenoma occurrence (age < 40 years at initiation: OR = 0.69, 95% CI: 0.55-0.86). Regular aspirin use was associated with a decreased odds of colorectal adenoma in our study of Black women. These findings support evidence demonstrating a chemopreventive impact of aspirin on colorectal neoplasia and suggest that aspirin may be a useful prevention strategy among US Black women.  相似文献   
2.
One in five children in the UK are affected by domestic violence and abuse. However, primary care clinicians (GPs and nurses) struggle to effectively identify and support children and young people living in homes where it is present. The IRIS+ (Enhanced Identification and Referral to Improve Safety) training and advocacy support intervention aimed to improve how clinicians respond to children and young people affected by domestic violence and abuse. IRIS+ training was delivered as part of a feasibility study to four general practices in an urban area in England (UK). Our mixed method design included interviews and questionnaires about the IRIS+ intervention with general practice patients, including children and young people as well as with clinicians and advocacy service providers. We collected the number of identifications and referrals by clinicians of children experiencing domestic violence and abuse through a retrospective search of medical and agency records 10 months after the intervention. Forty-nine children exposed to domestic violence and abuse were recorded in medical records. Thirty-five children were referred to a specialist domestic violence and abuse support service over a period of 10 months. Of these, 22 received direct or indirect support. The qualitative findings indicated that children benefitted from being referred by clinicians to the service. However, several barriers at the patient and professional level prevented children and young people from being identified and supported. Some of these barriers can be addressed through modifications to professional training and guidance, but others require systematic and structural changes to the way health and social care services work with children affected by domestic violence and abuse.  相似文献   
3.
4.
5.
6.
7.
Background:Airway pressure release ventilation (APRV) can be used for cadaveric donor lung recruitment. APRV elevates PaO2 in donor lungs; however, reported outcomes in recipients with APRV-managed donor lungs are limited. Methods:We retrospectively reviewed patients who underwent lung transplantation (LTx) from 2012 to 2013 and divided them into two groups based on mode of ventilation used during donor management and organ extraction (A: non-APRV; B: APRV). Kaplan-Meier method and multivariate Cox regression were used for analysis. Results:We found 126 LTx recipients (LTxRs); 9 were excluded for use of portable ventilation perfusion systems. Of the remaining 117 patients, 81 (69%) were in Group A; 36 (31%) were in Group B. Preoperative LTxR characteristics (age, sex, lung allocation score, end-stage lung disease type) were comparable between groups. Donors for Group B were older (P=0.03) and had higher body mass index (BMI) (P<0.001), higher incidence of death from chest trauma (P=0.008), longer ventilation duration after brain death (P<0.001), and higher pre-explant PaO2/FiO2 ratios (P<0.001). Post-LTx duration of mechanical ventilation, hospital stay, and median survival were similar in both groups. Risk of death was comparable between the two groups at the end of follow-up (HR =1.42; 95% CI: 0.57-3.56; P=0.45). Conclusions:APRV is a safe and effective pre-LTx donor lung management strategy. Short- and long-term survival outcomes were comparable in LTx recipients, irrespective of donor ventilation mode. APRV may help recruit lungs from older donors with higher BMI who die from chest trauma and have anticipated longer ventilation duration.  相似文献   
8.
IntroductionThe coronavirus disease 2019 (COVID-19) pandemic was expected to have a negative impact on organ donation. With the differences in health care systems and lockdown policies in various regions, the pandemic's effect on organ donation and transplant service may vary. Most of the deceased donor organ referrals in our hospital came from non–intensive care units (ICUs). The objective of this study is to report our experience and quantify the effects of the COVID-19 pandemic on deceased donor organ donation in our center.MethodsThis was a retrospective observational study comparing the deceased donor organ donation activity during the period January 23 to November 30, 2020 with the same period in 2018 in Queen Elizabeth Hospital, Hong Kong.ResultsThere was a 26.9% reduction in deceased donor organ donor referral in 2020 compared with 2018. No significant difference in the proportion of referrals from ICU or non-ICU areas between the 2 time periods was observed. The brain death confirmation rate was significantly higher in 2020 (40.8% vs 20.2%, P = .003). Nine patients had family consent for organ donation in 2020 (vs 7 patients in the same period in 2018). There were no significant differences in consent rate and number of recovered organs between the 2 periods.ConclusionsWith effective measures to limit the spread of COVID-19 in a community, it is possible to support the needs of both patients with COVID-19 and deceased donor organ donation services.  相似文献   
9.
10.

Background

There is a lack of studies addressing the occurrence of negative intraoperative findings (that is the absence of intussusception) after an unsuccessful hydrostatic reduction of an ileocolic intussusception. The aim of this study is to determine the incidence of negative intraoperative findings after unsuccessful hydrostatic reduction of ileocolic intussusception.

Methods

We conducted a multicentre retrospective study of all children aged 0–18?years treated for ileocolic intussusception from January 1, 2010 to December 31, 2015 in 9 Dutch hospitals. Primary outcome measure was the percentage of children without an intussusception during surgical exploration after unsuccessful hydrostatic reduction.

Results

In the study period 436 patients were diagnosed with an ileocolic intussusception. Of these, 408 patients underwent hydrostatic reduction of an ileocolic intussusception. 112 patients (27.5%) underwent surgery after an unsuccessful hydrostatic reduction. In 13 (11.6%) patients no intraoperative evidence of intussusception was found. Patients who underwent surgical intervention after unsuccessful hydrostatic reduction were significantly younger than patients who had a successful hydrostatic reduction; there was no gender difference.

Conclusion

A substantial number of children (11.6%) underwent a laparotomy after unsuccessful hydrostatic reduction in whom no intussusception was found intraoperatively. We suggest initiating laparoscopy instead of laparotomy when surgery is necessary.

Level of evidence

Level II.  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