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   69228篇
  免费   5426篇
  国内免费   3777篇
耳鼻咽喉   315篇
儿科学   1312篇
妇产科学   437篇
基础医学   4717篇
口腔科学   617篇
临床医学   10383篇
内科学   6135篇
皮肤病学   270篇
神经病学   7330篇
特种医学   4429篇
外国民族医学   2篇
外科学   14042篇
综合类   13370篇
现状与发展   3篇
一般理论   1篇
预防医学   3660篇
眼科学   894篇
药学   6632篇
  43篇
中国医学   3234篇
肿瘤学   605篇
  2024年   189篇
  2023年   1128篇
  2022年   1933篇
  2021年   3072篇
  2020年   2792篇
  2019年   2239篇
  2018年   2278篇
  2017年   2578篇
  2016年   2708篇
  2015年   2565篇
  2014年   4622篇
  2013年   5513篇
  2012年   4411篇
  2011年   4811篇
  2010年   4066篇
  2009年   3824篇
  2008年   3758篇
  2007年   3730篇
  2006年   3487篇
  2005年   3027篇
  2004年   2397篇
  2003年   2137篇
  2002年   1777篇
  2001年   1559篇
  2000年   1289篇
  1999年   1053篇
  1998年   903篇
  1997年   810篇
  1996年   664篇
  1995年   555篇
  1994年   423篇
  1993年   338篇
  1992年   279篇
  1991年   206篇
  1990年   194篇
  1989年   170篇
  1988年   126篇
  1987年   119篇
  1986年   108篇
  1985年   136篇
  1984年   86篇
  1983年   54篇
  1982年   65篇
  1981年   64篇
  1980年   59篇
  1979年   32篇
  1978年   22篇
  1977年   19篇
  1976年   24篇
  1975年   11篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
31.
32.
ObjectiveTo analyze the incidence and characteristics of traumatic spinal cord injury (SCI) in geriatric population of Galicia (Spain), hospital management and functional prognosis.MethodsComparative retrospective study. Patients admitted with acute traumatic SCI during the time period between January 2010 and December 2016 were included. Two groups established: The elderly over and under 75 years of age, with the latter acting as a control group.ResultsThree hundred seventy-nine patients were studied (27.2% ≥75 years). The main etiology in the >75 years group were falls: 80.6%. There were 65.7% who presented incomplete spinal cord injuries with mean motor index (MI) of 44.9/100. Upon discharge, 90.8% were dependent. Hospital mortality was 34.9%. Those >75 years suffered from more cervical injuries (74.8 vs. 51.2%; p<0.001), longer delay in diagnosis (31.1 vs. 9.2%; p<0.001) and higher hospital mortality (34.9 vs. 3.2%; p<0.001). Fewer surgical interventions were performed, with a longer delay. Percentages for admission into ICU, mechanical ventilation and performing a tracheostomy proved to be similar. There were no significant differences found in the evolution according to the ASIA scale or the MI.Conclusions1) The frequency of traumatic SCI in the elderly in Galicia is high; 2) Neurological evolution is similar to younger patients but the level of dependence is higher; 3) The level of care provided is similar in both groups, except for the surgical indication, and 4) Hospital mortality is high.  相似文献   
33.
Objective: Report measured resting energy expenditure (REE) in wheelchair rugby athletes and evaluate agreement between REE and the prediction models of Chun, Cunningham, Harris-Benedict, Mifflin, Nightingale and Gorgey, and Owen.

Design: Cohort-based validation study.

Setting. Paralympic team training camp.

Participants: Fourteen internationally competitive athletes who play wheelchair rugby, 13 of whom had cervical spinal cord injuries (SCI).

Outcome Measures: A portable metabolic analyzer was used to measure REE following an overnight fast and dual-energy X-ray absorptiometry (DXA) was used to assess lean body mass for the prediction equations.

Results: REE in the current sample was 1735?±?257?kcal?×?day?1 ranging from 1324 to 2068?kcal?×?day?1 Bhambhani Y. Physiology of wheelchair racing in athletes with spinal cord injury. Sports Med 2002;32(1):2351.[Crossref], [PubMed], [Web of Science ®] [Google Scholar]. Bland–Altman analyses revealed negative mean bias but similar limits of agreement between measured REE and scores predicted by Chun, Cunningham, Mifflin, Nightingale and Gorgey, and Owen models in elite athletes who play wheelchair rugby.

Conclusion: Prediction models regressed on persons with and without SCI under-predicted REE of competitive wheelchair rugby athletes. This outcome may be explained by the higher REE/fat-free mass (FFM) ratio of current athletes compared to less active samples. Findings from the current study will help practitioners to determine nutrient intake needs on training days of varied intensity.  相似文献   
34.
冠状病毒(coronavirus,CoVs)感染主要累及肺部,但对心血管系统损伤作用也不容忽视。CoVs感染引起的心脏损伤并非罕见,其发生与病情的严重程度密切相关。本文首先从CoVs引起心血管损伤的证据入手,进一步探讨了CoVs对心肌的直接损伤,以及肾素血管紧张素(RAS)系统激活和细胞因子风暴与炎症反应对心血管损伤的可能作用机制。相关心血管损伤的可能机制包括,(1)病毒直接作用:CoVs在心肌细胞复制,损伤心肌;(2)RAS系统激活:感染CoVs后,心脏血管紧张素转化酶2(angiotensin-converting enzyme 2,ACE2)的表达下调,激活RAS系统,使得血管紧张素Ⅱ(AngiotensinⅡ,AngⅡ)收缩血管功能增强,Ang1-7保护心脏效应减弱;(3)诱发细胞因子风暴:循环细胞因子和全身炎症反应引起心脏损伤;(4)其他:包括低氧血症和儿茶酚胺心脏毒性。本文就相关内容作一综述,为后续的详尽机制和治疗策略研究提供思路。  相似文献   
35.
AimThe aim of this study was to develop a Turkish version of the Pressure Ulcer Knowledge Assessment Tool 2.0 (PUKAT 2.0) and determine its validity and reliability.Materials and MethodsThis was a cross-cultural adaptation and validation study. The study sample included a total of 451 participants (232 nurses and 219 nursing students). The validity of the Turkish version of the PUKAT 2.0 was evaluated with linguistic validity, content validity, item validity (item difficulty, discriminating index), and construct validity (known-groups technique) analyses. The reliability of the tool was evaluated by conducting a test–retest analysis.ResultsContent validity index (CVI) for the items (Item-CVI) ranged from 0.83 to 1.00 and the CVI for the scale (Scale-CVI) was 0.95. The difficulty index for 21 items ranged from 0.10 to 0.63. Four items were found to be too difficult. Item discriminating index values ranged from 0.00 to 0.61. The overall intraclass correlation coefficient (ICC) was found to be 0.80.ConclusionThe Turkish version of the Pressure Injury Knowledge Assessment Tool 2.0 (PIKAT 2.0-Tr) is supported by acceptable psychometric properties and can be used to evaluate the knowledge of nurses and nursing students in Turkey about the prevention of PI.  相似文献   
36.

Background

Current blunt cerebrovascular injury (BCVI) grading grossly differentiates injury characteristics such as luminal stenosis (LS) and aneurysmal disease. The effect of increasing degree of LS beyond the current BCVI grading scale on stroke formation is unknown.

Study Design

BCVI over a 3-year period were retrospectively reviewed. To investigate influence of LS beyond the BCVI grading scale within aneurysmal and non-aneurysmal BCVI, grade 2 BCVI were subdivided into BCVI with ≥ 25% and ≤ 50% LS and BCVI with > 50% and ≤ 99% LS. Grade 3 BCVI were subdivided into BCVI with pseudoaneurysm (PSA) without LS and BCVI with PSA and LS. We hypothesized increased LS beyond the current BCVI grade distinctions would be associated with higher rates of stroke formation.

Results

312 BCVI were included, of which 140 were carotid BCVI and 172 vertebral BCVI. Sixteen carotid BCVI underwent endovascular intervention (EI) and 19 suffered a stroke. In carotid BCVI stroke rates increased sequentially with BCVI grade except in grade 3. There was a stroke rate of 12% in grade 1 carotid BCVI, 18% in grade 2, 6% in grade 3, and 31% in grade 4. In subgroup analysis for grade 2 carotid BCVI, BCVI with > 50% and ≤ 99% LS had higher rates of stroke (22% vs. 15%, p?=?0.44) than BCVI with ≥ 25% and ≤ 50% LS. In subgroup analysis of grade 3 carotid BCVI, BCVI with PSA and LS had higher rates of stroke (9% vs. 4%, p?=?0.48) than BCVI with PSA without LS. Higher rates of EI in grade 2 carotid BCVI with > 50% and ≤ 99% LS (22% vs. 5%, p?=?0.14) and grade 3 carotid BCVI with PSA and LS (35% vs. 4%, p?=?0.01) were noted in subgroup analysis.

Conclusion

Higher percentage LS beyond the currently used BCVI grading scale has a non-significantly increased rate of stroke in both aneurysmal and non-aneurysmal BCVI. Grade 3 BCVI with PSA and LS seems to be a high-risk subgroup. Use of EI confounds modern measurement of stroke risk in higher LS BCVI.  相似文献   
37.
38.
PurposeType B aortic dissection is a rare but life-threatening disease. Thoracic endovascular aortic repair (TEVAR) was widely used for Type B aortic dissection patients in the last decade due to the lower mortality and morbidity compared with open chest surgical repair (OCSR). AKI in type B aortic dissection is a well-recognized complication and indicates poor short-term and long-term outcome. The objective of this concise review was to identify the risk factors and the impact of AKI on type B aortic dissection patients.Methods and resultsA literature search was performed using PubMed, Embase, MEDLINE, and Cochrane Library with the search terms ‘type B aortic dissection’ and ‘acute kidney injury’ (AKI), and all English-language literatures published in print or available online from inception through August 2020 were thoroughly reviewed. Studies that reported relative AKI risks and outcomes in type B aortic dissection patient were included. Major mechanisms of AKI in type B aortic dissection included renal hypoperfusion, inflammation response, and the use of contrast medium. Type B aortic dissection patients with AKI significantly had increased hospital stay duration, need of renal replacement therapy, and 30-d and 1-year mortality.ConclusionsAKI in type B aortic dissection is a well-recognized complication and associated with poor short-term and long-term outcome. Early identification of high-risk patients, early diagnosis of AKI, stabilization of the hemodynamic parameters, avoidance of nephrotoxic drugs, and optimization of the use of contrast agents are the major strategies for the reduction of AKI in type B aortic dissection patients.  相似文献   
39.
40.
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   
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