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   27058篇
  免费   1804篇
  国内免费   126篇
耳鼻咽喉   217篇
儿科学   847篇
妇产科学   620篇
基础医学   3548篇
口腔科学   446篇
临床医学   2395篇
内科学   6475篇
皮肤病学   640篇
神经病学   2755篇
特种医学   760篇
外科学   2833篇
综合类   263篇
一般理论   12篇
预防医学   2682篇
眼科学   495篇
药学   2029篇
中国医学   96篇
肿瘤学   1875篇
  2024年   33篇
  2023年   270篇
  2022年   580篇
  2021年   1089篇
  2020年   535篇
  2019年   857篇
  2018年   1066篇
  2017年   699篇
  2016年   732篇
  2015年   852篇
  2014年   1066篇
  2013年   1449篇
  2012年   2056篇
  2011年   2177篇
  2010年   1281篇
  2009年   1005篇
  2008年   1709篇
  2007年   1776篇
  2006年   1595篇
  2005年   1540篇
  2004年   1381篇
  2003年   1301篇
  2002年   1200篇
  2001年   346篇
  2000年   397篇
  1999年   327篇
  1998年   189篇
  1997年   140篇
  1996年   95篇
  1995年   86篇
  1994年   95篇
  1993年   67篇
  1992年   119篇
  1991年   95篇
  1990年   79篇
  1989年   74篇
  1988年   54篇
  1987年   48篇
  1986年   55篇
  1985年   43篇
  1984年   26篇
  1983年   26篇
  1982年   29篇
  1981年   33篇
  1979年   31篇
  1978年   31篇
  1977年   33篇
  1976年   30篇
  1974年   26篇
  1972年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
901.

Background

Postoperative pancreatic fistula (PPF) is the most frequent and serious complication after laparoscopic distal pancreatectomy (LDP). Our goal was to compare the performance, in terms of PPF prevention, and safety of a radiofrequency (RF)-assisted transection device versus a stapler device in a porcine LDP model.

Methods

Thirty-two animals were randomly divided into two groups to perform LDP using a RF-assisted device (RF group; n = 16) and stapler device (ST group; n = 16) and necropsied 4 weeks after surgery. The primary endpoint was the incidence of PPF. Secondary endpoints were surgery/transection time, intra/postoperative complications/deaths, postoperative plasmatic amylase and glucose concentration, peritoneal liquid amylase and interleukin 6 (IL-6) concentrations, weight variations, and histopathological changes.

Results

Two clinical and one biochemical PPF were observed in the ST and RF groups respectively. Peritoneal amylase concentration was significantly higher in the RF group 4 days after surgery, but this difference was no longer present at necropsy. Both groups presented a significant decrease in peritoneal IL-6 concentration during the postoperative follow-up, with no differences between the groups. RF group animals showed a higher postoperative weight gain. In the histopathological exam, all RF group animals showed a common pattern of central coagulative necrosis of the parenchymal surface, surrounded by a thick fibrosis, which sealed main and secondary pancreatic ducts and was not found in ST group.

Conclusions

The fibrosis caused by an RF-assisted device can be at least as safe and effective as stapler compression to achieve pancreatic parenchyma sealing in a porcine LDP model.  相似文献   
902.
903.
904.
905.
Infections by bacteria are a serious complication following orthopedic implant surgery, that can usually only be cured by removing the implant, since the biofilm mode of growth of infecting bacteria on an implant surface protects the organisms from the host immune system and antibiotic therapy. Over the past few decades, attempts have been made to prevent and cure orthopedic implant infections by incorporating antibiotics in polymethylmethacrylate bone cements, in primary and revision surgery. However, the clinical efficacy of antibiotic-releasing bone cements is not accepted by all and the long-term exposure to low doses from antibiotic-releasing bone cements in patients is strongly related to the emerging threat of antibiotic resistance in medicine today. In this article, we start by reviewing the mechanisms governing the formation of an infectious biofilm on orthopedic implant materials, the release mechanisms and properties of clinically-used, antibiotic-loaded bone cements. The clinical efficacy of antibiotic-loaded bone cements is evaluated analyzing separatedly the prophylactic and therapeutic uses of these products.  相似文献   
906.
ObjectiveTo determine whether there is an increased risk of hip fracture associated with the use of proton pump inhibitors in a Mediterranean area after adjusting for other potential risk factors.MethodsRetrospective multicenter case–control study carried out in 6 primary health care centers in Catalonia, Spain. Cases were patients aged 50 years and over with a fragility hip fracture registered between January 2007 and December 2010, matched with 2 controls by sex and age. Data collected: use of proton pump inhibitors (type, dosage) in the 5 years previous to the hip fracture, socio-demographic data, body mass index, alcohol and tobacco consumption as well as health conditions and drugs associated with an increase risk of fragility hip fracture.Results358 cases were matched with 698 controls. The mean age was 82 years old in both groups. Women represented 77.1% in the case group and 76.9% in the control group. Crude association between proton pump inhibitors and hip fracture was 1.44 (95% CI, 1.09–1.89) and adjusted OR was 1.24 (95% CI, 0.93–1.65). No association was found with the continuous or discontinuous use of proton pump inhibitors, OR 1.17 (95% CI, 0.77–1.79), and OR of 1.16 (95% CI, 0.85–1.60) respectively. No association was found when restricting the analysis by sex, OR of 1.19 (95% CI, 0.27–5.14) or by age, younger or older than 80 years, OR of 0.72 (95% CI, 0.24–2.15).ConclusionThe use of proton pump inhibitors was not associated with an increased risk of hip fracture after adjusting for other risk factors in a Mediterranean area. This result suggests the existence of protective environmental factors linked to this southern area of Europe that eventually could compensate for the potential harm produced by proton pump inhibitors.  相似文献   
907.
908.
909.
Background: Diffusion tensor imaging (DTI) is an emerging research technique that is used to map and characterise white matter tracts in the healthy and damaged brain.

Aims: The aim of this paper is to familiarise the readers with DTI while giving the tools to understand and evaluate recent developments in aphasia research that use DTI methodology.

Main Contribution: Principles of DTI technology as well as its main caveats are described. An overview of studies that used DTI to explore the language system and aphasia is given. Future directions and the potential contribution of DTI to the understanding of aphasia diagnosis and recovery are highlighted.

Conclusions: DTI is an emerging technology, increasingly being applied to further our understanding of aphasia and its recovery. So far it has contributed to our knowledge in four areas of research. In the area of brain anatomy it is used to redefine the borders between various parts of the cortex based on their structural connectivity, to acquire a more accurate map of the tracts connecting the various parts of the language system, and to measure hemispheric asymmetry. Future studies might be able to further our understanding of language anatomy and relate hemispheric asymmetry to recovery potential. Second, DTI can help in relating structure to function. So far many studies focused on repetition deficits and conduction aphasia. Future studies can explore the anatomy of other language deficits. Third, DTI has been used in the study of brain damage and recovery. Studies have documented the damage that occurs to white matter following stroke and other insults, and the spontaneous reorganisation that follows. In the future DTI might contribute to the debate about the role of the right hemisphere in recovery from aphasia. Lastly, in the area of aphasia rehabilitation there is great lack of data. The studies reviewed here have shown that rehabilitation potential is dependent on white matter integrity and that white matter changes can occur as a result of therapy. Future studies should further our understanding of the role of white matter integrity in recovery, therefore contributing to the question of why some patients show good recovery while others do not. Future studies should also try and map white matter changes that are associated with successful versus unsuccessful rehabilitation, and with different stages of recovery.  相似文献   
910.
The aim of this study was to characterize the interaction between 1-methyl-1,2,3,4-tetrahydroisoquinoline (1-MeTHIQ—an endogenous parkinsonism-preventing substance) and various antiepileptic drugs [AEDs: clonazepam (CZP), ethosuximide (ETS), gabapentin (GBP), levetiracetam (LEV), tiagabine (TGB) and vigabatrin (VGB)] in the mouse maximal electroshock (MES)-induced seizure model. Results indicate that 1-MeTHIQ in combination with CZP (at the fixed ratios of 50:1 and 25:1), ETS (1:10) and GBP (1:1, 1:2, 1:5 and 1:10) exerted supra-additive (synergistic) interactions in the mouse MES model. In contrast, 1-MeTHIQ in combination with CZP (200:1 and 100:1), ETS (1:1, 1:2 and 1:5), LEV and VGB (1:1, 1:2, 1:5 and 1:10), and TGB (200:1, 100:1, 50:1 and 25:1) produced additive interaction in the mouse MES model. Total brain AED concentrations were unaffected by 1-MeTHIQ, and inversely, CZP, ETS and GBP had no impact on total brain concentrations of 1-MeTHIQ, indicating pharmacodynamic nature of synergistic interactions between 1-MeTHIQ and the tested AEDs in the mouse MES model. In conclusion, the supra-additive interactions of 1-MeTHIQ with CZP (at the fixed ratios of 50:1 and 25:1), ETS (1:10) and GBP (1:1, 1:2, 1:5 and 1:10) in the mouse MES model appear to be particularly favorable combinations from a clinical viewpoint. The additive combinations of 1-MeTHIQ with CZP (100:1, 50:1), ETS (1:1, 1:2 and 1:5), LEV and VGB (1:1, 1:2, 1:5, and 1:10), and TGB (200:1, 100:1, 50:1 and 25:1) seem to be neutral and worthy of consideration in further clinical practice.  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