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   114201篇
  免费   10019篇
  国内免费   4102篇
耳鼻咽喉   979篇
儿科学   3194篇
妇产科学   1512篇
基础医学   15643篇
口腔科学   2189篇
临床医学   9505篇
内科学   23553篇
皮肤病学   1804篇
神经病学   5676篇
特种医学   3114篇
外国民族医学   17篇
外科学   10647篇
综合类   14933篇
现状与发展   13篇
预防医学   8046篇
眼科学   1140篇
药学   14299篇
  43篇
中国医学   5109篇
肿瘤学   6906篇
  2024年   398篇
  2023年   2423篇
  2022年   4791篇
  2021年   5582篇
  2020年   4841篇
  2019年   4890篇
  2018年   5028篇
  2017年   4553篇
  2016年   4073篇
  2015年   4456篇
  2014年   7175篇
  2013年   7832篇
  2012年   6696篇
  2011年   7691篇
  2010年   6215篇
  2009年   6073篇
  2008年   5761篇
  2007年   5522篇
  2006年   4687篇
  2005年   4012篇
  2004年   3403篇
  2003年   2809篇
  2002年   2198篇
  2001年   1881篇
  2000年   1558篇
  1999年   1406篇
  1998年   1272篇
  1997年   1152篇
  1996年   1001篇
  1995年   1005篇
  1994年   891篇
  1993年   712篇
  1992年   624篇
  1991年   555篇
  1990年   494篇
  1989年   412篇
  1988年   328篇
  1987年   325篇
  1986年   315篇
  1985年   476篇
  1984年   534篇
  1983年   328篇
  1982年   391篇
  1981年   317篇
  1980年   270篇
  1979年   195篇
  1978年   166篇
  1977年   150篇
  1976年   167篇
  1975年   104篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
目的总结近年来股骨转子间骨折在稳定性重建方面的概念演化与研究进展。方法查阅国内外相关文献并结合自身经验,从股骨转子间骨折的解剖特点、稳定型骨折与不稳定型骨折分类、稳定性复位与不稳定性复位、术中加压初始稳定与术后滑动二次稳定、内固定术后稳定性评估、早期下地站立负重等方面进行总结分析。结果股骨转子间骨折发生于股骨颈干骺端转换区,具有天然的内翻不稳定倾向。骨折复位质量是影响后续内固定物安放的最重要前提因素。判断骨折复位质量有对线和对位两方面,对线采用 Garden 指数;在对位方面,随着皮质对位理念(正性、中性、负性)的提出,特别强调前内侧皮质的相互砥住支撑(解剖、正性),是获得骨折稳定性复位的关键,而不再强调后内侧小转子骨块的作用。术后影像学的稳定性评分为早期下地站立负重提供了量化指标。但术中的前内侧皮质支撑复位,在术后头颈骨块滑动获得二次稳定的过程中,仍有皮质对位丢失现象,需研究其危险因素和防范措施。结论股骨转子间骨折在取得良好对线的基础上,只要获得了前内侧皮质的相互砥住和支撑,并用内固定器械维持住,就获得了术后稳定性。术后稳定性评分优良者,可以安全地早期下地负重、站立行走活动。  相似文献   
22.
Academic output is just one aspect of a successful career as a plastic surgeon. However, for those with a strong interest in academia, the academic output of a department will likely be a key factor when deciding how to rank jobs. The aim of this study was to quantify and rank the academic output of plastic surgery units across the UK and Ireland. The Institute for Scientific Information (ISI) Web of Science Bibliometric analysis tool was used to collate cumulative (1950–2016), 10 year (2006–2016) and 3 years (2013–2015) research output data for plastic surgery units in the UK and Ireland. Sixty-six plastic surgery units were identified. Departments were ranked for each time period according to the number of papers produced, number of citations (Nc) and h-index (a measure of the impact of scientific output). The top 3 departments for number of papers in the last 10 years were The Royal Free Hospital, London (226) Broomfield Hospital, Chelmsford (218), and Morriston Hospital and Swansea (188). The top 3 for h-number were The Royal Free Hospital (21) Wythenshawe Hospital, Manchester (18) and Morriston Hospital (17). Academic output varies across plastic surgery units in the UK and Ireland. A number of departments have consistently maintained high academic outputs across the years and will be of interest to surgeons hoping to pursue a career in academia.  相似文献   
23.
Although an inverse relationship between body mass index (BMI) and baroreflex sensitivity (BRS) was found, the effect of waist circumference (WC) on BRS is still inconclusive. The contradictory results of previous studies may be related to the heterogeneity and relatively small sample size of the subjects examined. The aim of this population-based study was to investigate whether the influence of increased WC is more detrimental to BRS than BMI. A total of 760 community dwellers were recruited and they were classified into Q1 (n = 189), Q2 (n = 183), Q3 (n = 192) and Q4 (n = 196) groups, based on WC quartiles. Spontaneous BRS was determined by spectral α coefficient method. Valsalva ratio was the longest RR interval after release of Valsalva maneuver divided by the shortest RR interval during maneuver. Cardiac autonomic function was calculated by power spectrum of heart rate in low and high frequency (LF, 0.04–0.15 Hz; HF, 0.15–0.40 Hz), and LF/HF ratio in supine position for five minutes. There were significant differences in spontaneous BRS and Valsalva ratio among different WC groups. In multivariate analysis, obesity was inversely associated with spontaneous BRS and Valsalva ratio. However, these inverse relationships became insignificant after further adjustment for WC quartiles. In contrast, Q4 vs. Q1, Q3 vs. Q1 and Q2 vs. Q1 of WC were inversely related to spontaneous BRS. Q4 vs. Q1 and Q3 vs. Q1 of WC were negatively associated with the Valsalva ratio. In conclusion, increased and even high-normal WC had a stronger adverse effect on BRS than BMI, independent of cardio-metabolic risk factors.  相似文献   
24.
25.
ABSTRACT

In clinical trials, selection of appropriate study endpoints is critical for an accurate and reliable evaluation of safety and effectiveness of a test treatment under investigation. In practice, however, there are usually multiple endpoints available for measurement of disease status and/or therapeutic effect of the test treatment under study. For example, in cancer clinical trials, overall survival, response rate, and/or time to disease progression are usually considered as primary clinical endpoints for evaluation of safety and effectiveness of the test treatment under investigation. Once the study endpoints have been selected, sample size required for achieving a desired power is then determined. It, however, should be noted that different study endpoints may result in different sample sizes. In practice, it is usually not clear which study endpoint can best inform the disease status and measure the treatment effect. Moreover, different study endpoints may not translate one another although they may be highly correlated one another. In this article, we intend to develop an innovative endpoint namely therapeutic index based on a utility function to combine and utilize information collected from all study endpoints. Statistical properties and performances of the proposed therapeutic index are evaluated theoretically. A numerical example concerning a cancer clinical trial is given to illustrate the use of the proposed therapeutic index.  相似文献   
26.
27.

Background

Resistin is an immunometabolic mediator that is elevated in several inflammatory disorders. A ligand for Toll-like receptor 4, resistin modulates the recruitment and activation of myeloid cells, notably neutrophils. Neutrophils are major drivers of cystic fibrosis (CF) lung disease, in part due to the release of human neutrophil elastase- and myeloperoxidase-rich primary granules, leading to tissue damage. Here we assessed the relationship of resistin to CF lung disease.

Methods

Resistin levels were measured in plasma and sputum from three retrospective CF cohorts spanning a wide range of disease. We also assessed the ability of neutrophils to secrete resistin upon activation in vitro. Finally, we constructed a multivariate model assessing the relationship between resistin levels and lung function.

Results

Plasma resistin levels were only marginally higher in CF than in healthy control subjects. By contrast, sputum resistin levels were very high in CF, reaching 50–100 fold higher levels than in plasma. Among CF patients, higher plasma resistin levels were associated with allergic bronchopulmonary aspergillosis, and higher sputum resistin levels were associated with CF-related diabetes. Mechanistically, in vitro release of neutrophil primary granules was concomitant with resistin secretion. Overall, sputum resistin levels were negatively correlated with CF lung function, independently of other variables (age, sex, and genotype).

Conclusions

Our data establish relationships between resistin levels in the plasma and sputum of CF patients that correlate with disease status, and identify resistin as a novel mechanistic link between neutrophilic inflammation and lung disease in CF.  相似文献   
28.
29.
ResearchGate is a world wide web for scientists and researchers to share papers, ask and answer questions, and find collaborators. As one of the more than 15 million members, the author uploads research output and reads and responds to some of the questions raised, which are related to type 2 diabetes. In that way, he noticed a serious gap of knowledge of this disease among medical professionals over recent decades. The main aim of the current study is to remedy this situation through providing a comprehensive review on recent developments in biochemistry and molecular biology, which can be helpful for the scientific understanding of the molecular nature of type 2 diabetes. To fill up the shortcomings in the curricula of medical education, and to familiarize the medical community with a new concept of the onset of type 2 diabetes, items are discussed like: Insulin resistance, glucose effectiveness, insulin sensitivity, cell membranes, membrane flexibility, unsaturation index (UI; number of carbon-carbon double bonds per 100 acyl chains of membrane phospholipids), slow-down principle, effects of temperature acclimation on phospholipid membrane composition, free fatty acids, energy transport, onset of type 2 diabetes, metformin, and exercise. Based on the reviewed data, a new model is presented with proposed steps in the development of type 2 diabetes, a disease arising as a result of a hypothetical hereditary anomaly, which causes hyperthermia in and around the mitochondria. Hyperthermia is counterbalanced by the slow-down principle, which lowers the amount of carbon-carbon double bonds of membrane phospholipid acyl chains. The accompanying reduction in the UI lowers membrane flexibility, promotes a redistribution of the lateral pressure in cell membranes, and thereby reduces the glucose transporter protein pore diameter of the transmembrane glucose transport channel of all Class I GLUT proteins. These events will set up a reduction in transmembrane glucose transport. So, a new blood glucose regulation system, effective in type 2 diabetes and its prediabetic phase, is based on variations in the acyl composition of phospholipids and operates independent of changes in insulin and glucose concentration. UI assessment is currently arising as a promising analytical technology for a membrane flexibility analysis. An increase in mitochondrial heat production plays a pivotal role in the existence of this regulation system.  相似文献   
30.
PurposeTo explore the safety and effectiveness of bronchial artery (BA) embolization (BAE) in children with pulmonary hemorrhage.Materials and MethodsBetween February 2016 and February 2019, 41 patients (median age, 4 y; interquartile range, 2.3-8 y; median weight, 17.6 kg; interquartile range, 12.3–23.6 kg) underwent BAE. The indication of BAE included massive hemoptysis in 10 patients (24.4%), recurrent hemoptysis in 18 patients (43.9%), and refractory anemia in 13 patients (31.7%). The main etiology of pulmonary hemorrhage included pulmonary hemosiderosis (58.5%), congenital heart disease (17.1%), and infection (14.6%). A retrospective review was conducted of clinical outcomes of BAE.ResultsThere were 44 embolization sessions, with a total of 137 embolized vessels. Pulmonary hemorrhage was caused by BAs in 30 cases, nonbronchial systemic arteries plus BAs in 10, and nonbronchial systemic arteries in 1. Embolic particles were used in 30 cases (24 polyvinyl alcohol [PVA] and 6 microsphere), coils in 9 cases, and particles plus coils in 5 cases (4 PVA and 1 microsphere). Technical success (ability to embolize abnormal vessel) was achieved in 97.6% of patients (40 of 41), and clinical success (complete or partial resolution of hemoptysis within 30 days of embolization) was achieved in 90.2% (37 of 41). There was 1 procedure-related complication (2.4%) of cerebral infarction and 1 death from multiple-organ dysfunction (2.4%). Bleeding-free survival rates at 6, 12, 24, and 36 months were 92.5%, 83.9%, 83.9%, and 70.8%, respectively.ConclusionsBAE is a safe and effective procedure in children with pulmonary hemorrhage.  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