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   234693篇
  免费   20717篇
  国内免费   7722篇
耳鼻咽喉   1339篇
儿科学   5678篇
妇产科学   1937篇
基础医学   28677篇
口腔科学   4152篇
临床医学   27258篇
内科学   35943篇
皮肤病学   1930篇
神经病学   12431篇
特种医学   6277篇
外国民族医学   32篇
外科学   20963篇
综合类   38161篇
现状与发展   28篇
一般理论   25篇
预防医学   13707篇
眼科学   12194篇
药学   23183篇
  91篇
中国医学   11573篇
肿瘤学   17553篇
  2024年   244篇
  2023年   3404篇
  2022年   4587篇
  2021年   8983篇
  2020年   8517篇
  2019年   7980篇
  2018年   7755篇
  2017年   7806篇
  2016年   8199篇
  2015年   8132篇
  2014年   13064篇
  2013年   14720篇
  2012年   12202篇
  2011年   13716篇
  2010年   11684篇
  2009年   11261篇
  2008年   11365篇
  2007年   12548篇
  2006年   11620篇
  2005年   11226篇
  2004年   9881篇
  2003年   8887篇
  2002年   6378篇
  2001年   6083篇
  2000年   5005篇
  1999年   4445篇
  1998年   3244篇
  1997年   2935篇
  1996年   2856篇
  1995年   2925篇
  1994年   2571篇
  1993年   2268篇
  1992年   1984篇
  1991年   1702篇
  1990年   1418篇
  1989年   1371篇
  1988年   1269篇
  1987年   991篇
  1986年   837篇
  1985年   1133篇
  1984年   1006篇
  1983年   656篇
  1982年   794篇
  1981年   719篇
  1980年   563篇
  1979年   461篇
  1978年   390篇
  1977年   293篇
  1976年   305篇
  1975年   189篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
BackgroundIschemia reperfusion (I/R) play an imperative role in the expansion of cardiovascular disease. Sinomenine (SM) has been exhibited to possess antioxidant, anticancer, anti-inflammatory, antiviral and anticarcinogenic properties. The aim of the study was scrutinized the cardioprotective effect of SM against I/R injury in rat.MethodsRat were randomly divided into normal control (NC), I/R control and I/R + SM (5, 10 and 20 mg/kg), respectively. Ventricular arrhythmias, body weight and heart weight were estimated. Antioxidant, inflammatory cytokines, inflammatory mediators and plasmin system indicator were accessed.ResultsPre-treated SM group rats exhibited the reduction in the duration and incidence of ventricular fibrillation, ventricular ectopic beat (VEB) and ventricular tachycardia along with suppression of arrhythmia score during the ischemia (30 and 120 min). SM treated rats significantly (P < 0.001) altered the level of antioxidant parameters. SM treatment significantly (P < 0.001) repressed the level of creatine kinase MB (CK-MB), creatine kinase (CK) and troponin I (Tnl). SM treated rats significantly (P < 0.001) repressed the tissue factor (TF), thromboxane B2 (TXB2), plasminogen activator inhibitor 1 (PAI-1) and plasma fibrinogen (Fbg) and inflammatory cytokines and inflammatory mediators.ConclusionOur result clearly indicated that SM plays anti-arrhythmia effect in I/R injury in the rats via alteration of oxidative stress and inflammatory reaction.  相似文献   
2.
A priori subcell limiting approach is developed for high-order flux reconstruction/correction procedure via reconstruction (FR/CPR) methods on two-dimensional unstructured quadrilateral meshes. Firstly, a modified indicator based on modal energy coefficients is proposed to detect troubled cells, where discontinuities exist. Then, troubled cells are decomposed into nonuniform subcells and each subcell has one solution point. A second-order finite difference shock-capturing scheme based on nonuniform nonlinear weighted (NNW) interpolation is constructed to perform the calculation on troubled cells while smooth cells are calculated by the CPR method. Numerical investigations show that the proposed subcell limiting strategy on unstructured quadrilateral meshes is robust in shock-capturing.  相似文献   
3.
Barrett's esophagus (BE) is the precursor to esophageal adenocarcinoma (EAC). Progression to cancer typically occurs in a stepwise fashion through worsening dysplasia and ultimately, invasive neoplasia. Established EAC with deep involvement of the esophageal wall and/or metastatic disease is invariably associated with poor long-term survival rates. This guides the rationale of surveillance of Barrett’s in an attempt to treat lesions at an earlier, and potentially curative stage. The last two decades have seen a paradigm shift in management of Barrett’s with rapid expansion in the role of endoscopic eradication therapy (EET) for management of dysplastic and early neoplastic BE, and there have been substantial changes to international consensus guidelines for management of early BE based on evolving evidence. This review aims to assist the physician in the therapeutic decision-making process with patients by comprehensive review and summary of literature surrounding natural history of Barrett’s by histological stage, and the effectiveness of interventions in attenuating the risk posed by its natural history. Key findings were as follows. Non-dysplastic Barrett’s is associated with extremely low risk of progression, and interventions cannot be justified. The annual risk of cancer progression in low grade dysplasia is between 1%-3%; EET can be offered though evidence for its benefit remains confined to highly select settings. High-grade dysplasia progresses to cancer in 5%-10% per year; EET is similarly effective to and less morbid than surgery and should be routinely performed for this indication. Risk of nodal metastases in intramucosal cancer is 2%-4%, which is comparable to operative mortality rate, so EET is usually preferred. Submucosal cancer is associated with nodal metastases in 14%-41% hence surgery remains standard of care, except for select situations.  相似文献   
4.
5.
BackgroundTherapeutic plasma exchange (TPE) is an extracorporeal treatment that can be used in adult and pediatric patients with acute demyelinating syndromes of the central nervous system. In this study, the efficacy and safety of TPE was evaluated in 10 pediatric patients who underwent TPE that were unresponsive to corticosteroid treatment.MethodsRecords of 10 pediatric patients who underwent TPE in our pediatric intensive care unit (PICU) between May 2017 and June 2020 were used. Expanded Disability Status Scale (EDSS), Gait Scale (GS), and Visual Outcome Scale (VOS) were applied to the patients before and after TPE.ResultsOf the 10 patients who underwent TPE, five were diagnosed with multiple sclerosis (MS), three with transverse myelitis (TM), and two with acute disseminated encephalomyelitis (ADEM). The median age of the patients was 13.3 years (IQR 8-15), and the median day from symptom onset to onset of TPE was 12.5 days (IQR 7-28). A total of 104 TPE sessions were performed successfully. While no complications were encountered in three patients during the sessions, the most common complication was hypofibrinogenemia. The decrease in EDSS and GS scores was found to be consistent with the clinical response of the patients. There was no statistically significant decrease in the VOS.ConclusionsWith this study, we can say that TPE is a feasible, effective, and safe treatment modality in children with acute demyelinating syndromes of the central nervous system.  相似文献   
6.
BackgroundCentrally located pancreatic lesions are often treated with extended pancreaticoduodenectomy or distal pancreatectomy resulting in loss of healthy parenchyma and a high risk of diabetes and exocrine insufficiency. Robotic central pancreatectomy (RCP) is a parenchyma sparring alternative that has been shown safe and feasible [[1], [2]].MethodsIn this article, we describe our operative technique and the perioperative outcomes of a series of RCP for low-grade or benign pancreatic tumors.ResultsSix patients (5 female and 1 man) with a median age of 51.5 (44–68) years underwent a RCP for 2 serous cystadenomas, 2 mucinous cystic tumors, 1 neuroendocrine tumor, and 1 autoimmune pancreatitis. There were no conversions, intraoperative complications, or perioperative transfusions. Median operative time and was 240 (230–291) minutes and median blood loss was 100 (100–400) ml. The median hospital stay was 8 (5–27) days. There were no mortalities, reoperations, or readmissions. One patient developed a grade B pancreatic fistula which was successfully managed conservatively. All resections had free margins and the median tumor size was 2.5 (1.5–3.5) cm. After a mean follow-up of 46 months, no patients presented new-onset diabetes or exocrine insufficiency.ConclusionsRCP represents the least invasive option for both the patient and the pancreatic parenchyma. With a standardized technique, RCP results in low postoperative morbidity and excellent long-term pancreatic function. Although our results are excellent, POPF still represents the main complication of central pancreatectomy with an incidence ranging from 0 to 80% depending on multiple factors such as the surgeon, technique, and pancreatic texture.  相似文献   
7.
Continuous utero-placental circulation, and patent umbilical blood vessels ensure an uninterrupted transfer of oxygen and nutrients to the fetus as well as clearance of metabolic waste products. The onset of labour characterized by progressive and strong uterine contractions poses a threat to fetal oxygenation as a result of collapsing the spiral arterioles traversing the myometrium to supply the placental bed, and repetitive compression of the blood vessels within the umbilical cord. Human fetuses are equipped with compensatory mechanisms to cope with transient interruptions of blood supply during labour. The ability to compensate may be blunted in cases of poor fetal reserves, increased metabolic demand (macrosomia or maternal fever), and due to non-hypoxic pathways (e.g. chorioamniontis or fetal hypovolumia-hypotension syndrome). Intrapartum fetal surveillance involves prompt recognition of the features that signal the onset of fetal decompensation on the cardiotocograph (CTG) to ensure a timely intervention to avoid hypoxic-ischaemic encephalopathy (HIE) or perinatal deaths. This article summarises a ‘physiological approach’ to the interpretation of the CTG which, in places, conflicts with other current UK guidance.  相似文献   
8.
9.
10.

Background

Hyperglycaemia is common in patients with acute brain injury admitted to an intensive care unit (ICU). Many studies have found associations between development of hyperglycaemia and increased mortality in hospitalised patients. However, the optimal target for blood glucose control is unknown. We want to conduct a systematic review with meta-analysis and trial sequential analysis to explore the beneficial and harmful effects of restrictive versus liberal glucose control on patient outcomes in adults with severe acute brain injury.

Methods

We will systematically search medical databases including CENTRAL, Embase, MEDLINE and trial registries. We will search the following websites for ongoing or unpublished trials: http://www.controlled-trials.com/ , http://www.clinicaltrials.gov/ , www.eudraCT.com , http://centerwatch.com/ , The Cochrane Library's CENTRAL, PubMed, EMBASE, Science Citation Index Expanded and CINAHL. Two authors will independently review and select trials and extract data. We will include randomised trials comparing levels of glucose control in our analyses and observational studies will be included to address potential harms. The primary outcomes are defined as all-cause mortality, functional outcome and health-related quality of life. Secondary outcomes include serious adverse events including hypoglycaemia, length of ICU stay and duration of mechanical ventilation, and explorative outcomes including intracranial pressure and infection. Trial Sequential Analysis will be used to investigate the risk of type I error due to repetitive testing and to further explore imprecision. Quality of trials will be evaluated using the Cochrane Risk of Bias tool, and quality of evidence will be assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach.

Discussion

The results of the systematic review will be disseminated through peer-reviewed publication. With the review, we hope to inform future randomised clinical trials and improve 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