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   4985篇
  免费   383篇
  国内免费   60篇
耳鼻咽喉   40篇
儿科学   141篇
妇产科学   210篇
基础医学   634篇
口腔科学   74篇
临床医学   427篇
内科学   1297篇
皮肤病学   113篇
神经病学   612篇
特种医学   157篇
外科学   446篇
综合类   6篇
一般理论   3篇
预防医学   295篇
眼科学   54篇
药学   340篇
中国医学   9篇
肿瘤学   570篇
  2024年   18篇
  2023年   141篇
  2022年   284篇
  2021年   431篇
  2020年   250篇
  2019年   273篇
  2018年   320篇
  2017年   202篇
  2016年   232篇
  2015年   257篇
  2014年   263篇
  2013年   311篇
  2012年   412篇
  2011年   343篇
  2010年   187篇
  2009年   139篇
  2008年   231篇
  2007年   239篇
  2006年   199篇
  2005年   166篇
  2004年   143篇
  2003年   130篇
  2002年   98篇
  2001年   16篇
  2000年   6篇
  1999年   20篇
  1998年   24篇
  1997年   14篇
  1996年   11篇
  1995年   11篇
  1994年   12篇
  1993年   9篇
  1992年   2篇
  1991年   5篇
  1990年   3篇
  1989年   3篇
  1988年   5篇
  1987年   4篇
  1986年   3篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1981年   3篇
  1979年   3篇
排序方式: 共有5428条查询结果,搜索用时 15 毫秒
61.
62.
Low flow rate pumping of cell suspensions finds current applications in bioreactors for short‐term dynamic cell culture and adhesion assays. The aim of this study was to develop an atraumatic pump and hemodynamically adapted test circuit to allow operating periods of at least several hours. A computer‐controlled mini‐pump (MP) was constructed based on non‐occlusive local compression of an elastic tube with commercial bi‐leaflet valves directing the pulsatile flow into a compliant circuit. Cell damage and activation in the system were tested with whole blood in comparison with a set with a conventional peristaltic pump (PP). Activation of circulating THP‐1 monocytes was tested by measuring the expression of CD54 (ICAM‐1). Additionally, monocyte‐endothelial interactions were monitored using a parallel‐plate flow chamber with an artificial stenosis. The system required a priming volume of only 20 mL, delivering a peak pulsatile flow of up to 35 mL/min. After 8 h, blood hemolysis was significantly lower for MP with 11 ± 3 mg/dL compared with PP with 100 ± 16 mg/dL. CD142 (tissue factor) expression on blood monocytes was 50% lower for MP. With MP, THP‐1 cells could be pumped for extended periods (17 h), with no enhanced expression of CD54 permitting the long‐term co‐culture of THP‐1 with endothelial cells and the analysis of flow pattern effects on cell adhesion. A low‐damage assay setup was developed, which allows the pulsatile flow of THP‐1 cells and investigation of their interaction with other cells or surfaces for extended periods of time.  相似文献   
63.
64.
Graft rinse prior reperfusion in liver transplantation (LT) is believed to reduce the incidence of postreperfusion syndrome and improve clinical outcome. A MEDLINE search was performed to obtain a comprehensive review of the published literature dealing with graft rinse in LT. Moreover, all thirty‐four LT centers in the Eurotransplant (ET) region were invited to participate in an online survey to whether or not graft rinse is performed and whether further research in the field is needed. Seventeen reports have been found to investigate graft rinse protocols in 1894 LT recipients. Eighteen of the thirty centers that participated in the online survey performed graft rinse prior reperfusion in LT. The most commonly used rinse solution was albumin. Nineteen centers stated interest in participating in a multicenter RCT in the field. The published literature does not provide concluding appraisal of the benefit of graft rinse in LT. Graft rinse protocols are not standardized and are based on personal experience. Appropriately designed clinical trials addressing the topic are demanded. The online survey appears to be a helpful tool for the evaluation of clinical practice and future research topics in the transplant community.  相似文献   
65.
Impaired amyloid beta (Aβ) metabolism is currently considered central to understand the pathophysiology of Alzheimer's disease (AD). Measurements of cerebrospinal fluid Aβ levels remain the most useful marker for diagnostic purposes and to individuate people at risk for AD. Despite recent advances criticized the direct role in neurodegeneration of cortical neurons, Aβ is considered responsible for synaptopathy and impairment of neurotransmission and therefore remains the major trigger of AD and future pharmacological treatment remain Aβ oriented. However, experimental and clinical findings showed that Aβ peptides could have a wider range of action responsible for cell dysfunction and for appearance of clinico‐pathological entities different from AD. Such findings may induce misunderstanding of the real role played by Aβ in AD and therefore strengthen criticism on its centrality and need for CSF measurements. Aim of this review is to discuss the role of CSF Aβ levels in light of experimental, clinical pathologic, and electrophysiological results in AD and other pathological entities to put in a correct frame the value of Aβ changes.  相似文献   
66.

Background and study aims

Several studies have demonstrated the superiority of proton-pump inhibitors (PPIs) in resolving erosive gastro-oesophageal reflux disease (GORD). However, this first line of treatment can fail to control symptoms in around 30% of cases, especially in the presence of non-erosive GORD. In situations where the first line of treatment fails, there is a lack of concordance regarding the best strategy to apply. This study presents a systematic review of the trials which have tested second-line treatments after PPI failure.

Methods

The study was conducted according to the PRISMA statement. The systematic review included medical trials written in English which were published between 2000 and 2016 and were retrieved from PubMed and Scopus using the keywords ‘PPI-resistant gastro-oesophageal reflux’, ‘alginate AND gastro-oesophageal reflux’, ‘hyaluronic acid AND gastro-oesophageal reflux’, ‘prokinetics AND gastro-oesophageal reflux’, ‘sucralfate AND gastro-oesophageal reflux’ and ‘baclofen AND gastro-oesophageal reflux’.

Results

Ten randomised and non-randomised studies were included, which included 1515 patients of both sexes (mean age?=?49.19?years, age range?=?18–85, males?=?700; 46.2%).

Conclusions

A personalised choice of the best treatment for PPI-resistant GORD should be based on the results of an upper endoscopy and pH/MII monitoring. For patients in situations where the first line of treatment fails, we encourage the execution of trials for testing double doses of PPIs against alternative medicaments.  相似文献   
67.
68.
AIM: To investigate the role of laparoscopy in diagnosis and treatment of intra abdominal infections.METHODS: A systematic review of the literature was performed including studies where intra abdominal infections were treated laparoscopically.RESULTS: Early laparoscopic approaches have become the standard surgical technique for treating acute cholecystitis. The laparoscopic appendectomy has been demonstrated to be superior to open surgery in acute appendicitis. In the event of diverticulitis, laparoscopic resections have proven to be safe and effective procedures for experienced laparoscopic surgeons and may be performed without adversely affecting morbidity and mortality rates. However laparoscopic resection has not been accepted by the medical community as the primary treatment of choice. In high-risk patients, laparoscopic approach may be used for exploration or peritoneal lavage and drainage. The successful laparoscopic repair of perforated peptic ulcers for experienced surgeons, is demonstrated to be safe and effective. Regarding small bowel perforations, comparative studies contrasting open and laparoscopic surgeries have not yet been conducted. Successful laparoscopic resections addressing iatrogenic colonic perforation have been reported despite a lack of literature-based evidence supporting such procedures. In post-operative infections, laparoscopic approaches may be useful in preventing diagnostic delay and controlling the source.CONCLUSION: Laparoscopy has a good diagnostic accuracy and enables to better identify the causative pathology; laparoscopy may be recommended for the treatment of many intra-abdominal infections.  相似文献   
69.

Background

Growing evidence suggests that colorectal cancer (CRC) screening based on the fecal immunochemical test (FIT) reduces CRC incidence and surgical resection rates.

Aims

To compare trends in surgery for proximal and distal CRC among Italian regions at different stages of screening implementation.

Methods

From the National Hospital Discharge Database we selected hospitalizations with CRC resection of residents aged 50–74 years during 2002–2014, and computed surgery rates for the 8 most populous Italian regions with/without a screening program.

Results

In regions with screening, implemented around 2006–2007, the annual percent change (APC) of distal CRC resection was +1.7 (95% confidence interval ?1.0, 4.4) during 2002–2007 and ?9.1 (?10.6, ?7.7) during 2007–2014. No significant change was observed in regions without screening. The APC for proximal colon resection in regions with screening was +5.8 (2.5, 9.0) during 2002–2007 and ?4.1 (?5.8, ?2.4) during 2007–2014, while in regions without screening surgical rates increased through the whole study period. Compared to 2002, in 2014 distal CRC resection rates were greatly reduced in regions with screening, reaching values similar to proximal CRC resection.

Conclusion

Following the implementation of screening programs surgery rates steeply decreased, confirming the deep impact of FIT-based screening on the burden of CRC.  相似文献   
70.
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