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   1033188篇
  免费   71623篇
  国内免费   1264篇
耳鼻咽喉   13275篇
儿科学   33161篇
妇产科学   28433篇
基础医学   153673篇
口腔科学   28088篇
临床医学   96287篇
内科学   201256篇
皮肤病学   22037篇
神经病学   82811篇
特种医学   37947篇
外国民族医学   216篇
外科学   144890篇
综合类   20996篇
现状与发展   3篇
一般理论   445篇
预防医学   85461篇
眼科学   23037篇
药学   75497篇
  32篇
中国医学   1643篇
肿瘤学   56887篇
  2019年   8537篇
  2018年   11124篇
  2017年   8452篇
  2016年   9352篇
  2015年   10639篇
  2014年   14771篇
  2013年   22476篇
  2012年   30723篇
  2011年   32633篇
  2010年   18903篇
  2009年   18029篇
  2008年   30803篇
  2007年   33111篇
  2006年   32633篇
  2005年   32142篇
  2004年   30531篇
  2003年   29305篇
  2002年   28289篇
  2001年   45213篇
  2000年   46192篇
  1999年   38942篇
  1998年   10888篇
  1997年   9961篇
  1996年   10318篇
  1995年   9647篇
  1994年   9015篇
  1993年   8413篇
  1992年   31029篇
  1991年   30531篇
  1990年   29503篇
  1989年   28480篇
  1988年   26463篇
  1987年   25892篇
  1986年   24664篇
  1985年   23284篇
  1984年   17638篇
  1983年   15428篇
  1982年   9225篇
  1979年   16967篇
  1978年   12354篇
  1977年   10339篇
  1976年   9606篇
  1975年   10301篇
  1974年   12591篇
  1973年   12409篇
  1972年   11787篇
  1971年   10941篇
  1970年   10309篇
  1969年   9706篇
  1968年   8994篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Hemolytic disease of fetus and newborn (HDFN) imposes great healthcare burden being associated with maternal alloimmunization against parental-inherited fetal red blood cell antigens causing fetal anemia or death. Noninvasive prenatal analysis (NIPT) provides safe fetal RHD genotyping for early identification of risk pregnancies and proper management guidance. We aimed to conduct systematic review and meta-analysis on NIPT's beneficial application, in conjunction with quantitative maternal alloantibody analysis, for early diagnosis of pregnancies at risk. Search for relevant articles was done in; PubMed/Medline, Scopus, and Ovid (January 2006April 2020), including only English-written articles reporting reference tests and accuracy data. Nineteen eligible studies were critically appraised. NIPT was estimated highly sensitive/specific for fetal RHD genotyping beyond 11-week gestation. Amplifications from ≥2 exons are optimum to increase accuracy. NIPT permits cost-effectiveness, precious resources sparing, and low emotional stress. Knowledge of parental ethnicity is important for correct NIPT result interpretations and quantitative screening. Cut-off titer ≥8-up-to-32 is relevant for anti-D alloantibodies, while, lower titer is for anti-K. Alloimmunization is influenced by maternal RHD status, gravida status, and history of adverse obstetrics. In conclusion, NIPT allows evidence-based provision of routine anti-D immunoprophylaxis and estimates potential fetal risks for guiding further interventions. Future large-scale studies investigating NIPT's non-RHD genotyping within different ethnic groups and in presence of clinically significant alloantibodies are needed.  相似文献   
13.
14.
ABSTRACT

This study focused on factors associated with antiretroviral therapy (ART) adherence and quality of life among transgenderwomen in Sao Paulo, Brazil, using univariable and adjusted analysis. Adherence was evaluated with a self-report tool and with HIV viral load (VL) measurement. PROQOL-HIV was used to assess quality of life. 106 TGW with median 41 years old were included; most were white (56%) and had >10 years of education (57%). Median time since HIV/AIDS diagnosis was 10 years. Overall, participants had high T CD4+ counts (median 659 cells/mm3) and most (75%) had undetectable HIV VL. 85% were considered adherent using self-report (95%CI 77-91), whereas 72% (95%CI 62-80) were considered adherent when self-report and undetectable HIV VL were analyzed jointly. Older age was associated with higher ART adherence; each year increase in age was associated with 5% higher odds of adherence (p?=?0.021). Quality of life ranged from good-excellent in 5 of 8 domains. Younger age, lower education, higher time since HIV diagnosis, comorbidities, illicit drugs use and depression were associated with lower PROQOL scores in specific domains in univariable analysis, while depression was also associated with lower total PROQOL score even after adjustment for age, comorbidities and time since HIV diagnosis (p?=?0.048).  相似文献   
15.
AimsSelf-expanding metal stents provide rapid improvement of dysphagia in oesophageal cancer but are associated with complications. The aim of the present study was to test the effectiveness of an alternative treatment of combining biodegradable stents with radiotherapy.Materials and methodsA Simon two-stage single-arm prospective phase II trial design was used to determine the efficacy of biodegradable stents plus radiotherapy in patients with dysphagia caused by oesophagus cancer who were unsuitable for radical treatment. Fourteen patients were recruited and data from 12 were included in the final analyses.ResultsFive of 12 patients met the primary end point: one stent-related patient death; four further interventions for dysphagia within 16 weeks of stenting (41.7%, 95% confidence interval 15.2–72.3%). The median time to a 10-point deterioration of quality of life was 2.7 weeks. Nine patients died within 52 weeks of registration. The median time to death from any cause was 15.0 weeks (95% confidence interval 9.6–not reached).ConclusionThe high re-intervention observed, which met the pre-defined early stopping criteria, meant that the suggested alternative treatment was not sufficiently effective to be considered for a larger scale trial design. Further work is needed to define the place of biodegradable stents in the management of malignant oesophageal strictures.  相似文献   
16.
17.
18.
19.
Nephrolithiasis is a common pathology encountered in the primary care and emergency department (ED) setting. In 2009 alone, there were over one million ED visits related to nephrolithiasis Higa et al. (2017) [1]. Emergent treatment options range from non-invasive pain control and patient education to lithotripsy and other invasive urologic procedures depending on stone location and related pathology. Urethral calculi are estimated to represent 0.3% of all urinary stone diseases Verit et al. (2006) [2]. There are very few case reports documenting distal urethral stone removal in the ED. Here we present a case of distal urethral stone impaction and the removal of this stone by ED providers, leading to expedited care and prevention of consultation and possible admission.  相似文献   
20.

Objective

To compare perioperative and long-term outcomes in patients undergoing hemiarch and aggressive arch replacement for acute type A aortic dissection (ATAAD).

Methods

From 1996 to 2017, we compared outcomes of hemiarch (n = 322) versus aggressive arch replacements (zones 2 and 3 arch replacement with implantation of 2-4 arch branches, n = 150) in ATAAD. Indications for aggressive arch were arch aneurysm >4 cm or intimal tear in the aortic arch that was not resectable by hemiarch replacement, or dissection of arch branches with malperfusion.

Results

Patients in the aggressive arch group were significantly younger (mean age: 57 vs 61 years old) and had significantly longer hypothermic circulatory arrest, cardiopulmonary bypass, and aortic crossclamp times. There were no significant differences in perioperative outcomes between hemiarch and aggressive arch groups, including 30-day mortality (5.3% vs 7.3%, P = .38) and postoperative stroke rate (7% vs 7%, P = .96). Over 15 years, Kaplan–Meier survival was similar between hemiarch and aggressive arch groups (log-rank P = .55, 10-year survival 70% vs 72%). Given death as a competing factor, incidence rates of reoperation over 15 years (2.1% vs 2.0% per year, P = 1) and 10-year cumulative incidence of reoperation (14% vs 12%, P = .89) for arch and distal aorta pathology were similar between the 2 groups.

Conclusions

Both hemiarch and aggressive arch replacement are appropriate approaches for select patients with ATAAD. Aggressive arch replacement should be considered for an arch aneurysm >4 cm or an intimal tear at the arch unable to be resected by hemiarch replacement, or dissection of the arch branches with malperfusion.  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