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   3990篇
  免费   362篇
  国内免费   12篇
耳鼻咽喉   88篇
儿科学   98篇
妇产科学   148篇
基础医学   598篇
口腔科学   75篇
临床医学   381篇
内科学   995篇
皮肤病学   41篇
神经病学   454篇
特种医学   86篇
外科学   511篇
综合类   39篇
一般理论   2篇
预防医学   239篇
眼科学   158篇
药学   245篇
中国医学   2篇
肿瘤学   204篇
  2019年   55篇
  2018年   49篇
  2017年   40篇
  2016年   49篇
  2015年   60篇
  2014年   61篇
  2013年   125篇
  2012年   142篇
  2011年   136篇
  2010年   85篇
  2009年   79篇
  2008年   114篇
  2007年   174篇
  2006年   152篇
  2005年   161篇
  2004年   160篇
  2003年   131篇
  2002年   131篇
  2001年   141篇
  2000年   136篇
  1999年   120篇
  1998年   45篇
  1997年   38篇
  1996年   31篇
  1995年   37篇
  1994年   35篇
  1992年   110篇
  1991年   114篇
  1990年   111篇
  1989年   100篇
  1988年   94篇
  1987年   78篇
  1986年   97篇
  1985年   100篇
  1984年   83篇
  1983年   79篇
  1982年   47篇
  1981年   48篇
  1980年   45篇
  1979年   93篇
  1978年   65篇
  1977年   54篇
  1976年   51篇
  1975年   39篇
  1974年   67篇
  1973年   54篇
  1972年   37篇
  1970年   30篇
  1967年   47篇
  1966年   30篇
排序方式: 共有4364条查询结果,搜索用时 31 毫秒
1.

Background

Patients undergoing cardiac surgery are at significant risk of developing postoperative acute kidney injury (AKI). Neutrophil–lymphocyte ratio (NLR) is a widely available inflammatory biomarker which may be of prognostic value in this setting.

Methods

We conducted a systematic review and meta-analysis of studies reporting associations between perioperative NLR with postoperative AKI. We searched Medline, Embase and the Cochrane Library, without language restriction, from inception to May 2022 for relevant studies. We meta-analysed the reported odds ratios (ORs) with 95% confidence intervals (CIs) for both elevated preoperative and postoperative NLR with risk of postoperative AKI and need for renal replacement therapy (RRT). We conducted a meta-regression to explore inter-study statistical heterogeneity.

Results

Twelve studies involving 10,724 participants undergoing cardiac surgery were included, with eight studies being deemed at high risk of bias using PROBAST modelling. We found statistically significant associations between elevated preoperative NLR and postoperative AKI (OR 1.45, 95% CI 1.18–1.77), as well as postoperative need for RRT (OR 2.37, 95% CI 1.50–3.72). Postoperative NLR measurements were not of prognostic significance.

Conclusions

Elevated preoperative NLR is a reliable inflammatory biomarker for predicting AKI following cardiac surgery.  相似文献   
2.
3.
4.
5.
In December 2019 a novel coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), started spreading from Wuhan city of Chinese Hubei province and rapidly became a global pandemic. Clinical symptoms of the disease range from paucisymptomatic disease to a much more severe disease. Typical symptoms of the initial phase include fever and cough, with possible progression to acute respiratory distress syndrome. Gastrointestinal manifestations such as diarrhoea, vomiting and abdominal pain are reported in a considerable number of affected individuals and may be due to the SARS-CoV-2 tropism for the peptidase angiotensin receptor 2. The intestinal homeostasis and microenvironment appear to play a major role in the pathogenesis of COVID-19 and in the enhancement of the systemic inflammatory responses. Long-term consequences of COVID-19 include respiratory disturbances and other disabling manifestations, such as fatigue and psychological impairment. To date, there is a paucity of data on the gastrointestinal sequelae of SARS-CoV-2 infection. Since COVID-19 can directly or indirectly affect the gut physiology in different ways, it is plausible that functional bowel diseases may occur after the recovery because of potential pathophysiological alterations (dysbiosis, disruption of the intestinal barrier, mucosal microinflammation, post-infectious states, immune dysregulation and psychological stress). In this review we speculate that COVID-19 can trigger irritable bowel syndrome and we discuss the potential mechanisms.  相似文献   
6.
7.
PURPOSE: The alveolar bone resorption that occurs around a 2-piece implant following abutment attachment is a well-documented observation. Several investigators propose that crestal bone loss is a response to the invasion of the biologic width by secondary bacterial colonization and micromovements at the implant-abutment interface. This study proposes the creation of a difference between the diameter of the implant platform and diameter of the abutment (implant platform modification), shifting the implant-abutment interface medially to minimize invasion of the biologic width. MATERIAL AND METHODS: We present a series of 30 control cases and 30 study cases using the platform-modification technique. Interproximal bone resorption on the medial and distal of each implant was assessed using digital radiography at 1, 4, and 6 months after abutment attachment. RESULTS: The mean value of bone resorption observed in the mesial measurement for the control group was 2.53 mm, whereas for those patients included in the study group, it was 0.76 mm. The mean value of bone resorption observed in the distal measurement for patients in the control group was 2.56 mm, whereas for those included in the study group, it was 0.77 mm. CONCLUSIONS: All patients in the study group had a significant reduction of bone loss in comparison to the control group (P < 0.0005).  相似文献   
8.
Interest has recently been directed towards the use of antiplaque mouthrinses. Most published material concerns the antimicrobial effects of these agents rather than their effects upon oral tissue. This study was conducted to evaluate the effect of a sanguinarine-containing mouthrinse called Viadent upon epithelial-like gingival cells. The cells were grown for 24 hours in supplemented Earle's medium, with and without different Viadent dilutions. Cell counts were made with a hematocytometer. It was found that 50% of the cells were inhibited at 1.2% Viadent. In similar studies, it was found that 70% ethanol and two pH buffers were less toxic than Viadent. Exposure of preformed cell monolayers to Viadent also showed significant inhibition. The relative toxicity of different antiplaque agents may be compared using such cells as a model system. In conclusion, it was observed that Viadent significantly affected gingival cell growth in vitro, that viable cell numbers were greatly reduced by short time exposure, and that the toxic effect of Viadent could only partially be accounted for by ethanol content and/or pH.  相似文献   
9.
The use of a barrier membrane, with or without osseous allograft, has been shown to establish regeneration of osseous tissue around dental implants. Following three episodes of persistent symptomatic failed apicoectomy and subsequent tooth extraction, an osseointegrated implant was placed in a wide fenestrated defect. Demineralized freeze-dried bone allograft was covered by an occlusive expanded polytetrafluorethylene membrane. The reentry procedure revealed complete bone fill that followed the texture of the augmentation material beyond the previous buccal bony envelope.  相似文献   
10.
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