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   456086篇
  免费   29536篇
  国内免费   12452篇
耳鼻咽喉   4560篇
儿科学   12177篇
妇产科学   7537篇
基础医学   43852篇
口腔科学   8911篇
临床医学   51843篇
内科学   71118篇
皮肤病学   5945篇
神经病学   24849篇
特种医学   22028篇
外国民族医学   37篇
外科学   57449篇
综合类   52952篇
现状与发展   48篇
一般理论   8篇
预防医学   32952篇
眼科学   7359篇
药学   49302篇
  310篇
中国医学   17722篇
肿瘤学   27115篇
  2024年   1069篇
  2023年   5674篇
  2022年   15472篇
  2021年   19898篇
  2020年   14067篇
  2019年   18707篇
  2018年   13798篇
  2017年   13956篇
  2016年   15911篇
  2015年   18113篇
  2014年   28745篇
  2013年   29915篇
  2012年   30223篇
  2011年   29082篇
  2010年   23343篇
  2009年   23209篇
  2008年   23274篇
  2007年   24416篇
  2006年   21654篇
  2005年   16927篇
  2004年   11839篇
  2003年   10503篇
  2002年   8284篇
  2001年   7345篇
  2000年   6270篇
  1999年   5028篇
  1998年   4645篇
  1997年   4550篇
  1996年   4073篇
  1995年   3740篇
  1994年   3627篇
  1993年   2938篇
  1992年   2989篇
  1991年   2768篇
  1990年   2532篇
  1989年   2249篇
  1988年   2166篇
  1987年   1915篇
  1986年   1645篇
  1985年   2965篇
  1984年   2844篇
  1983年   2039篇
  1982年   2229篇
  1981年   2022篇
  1980年   1859篇
  1979年   1554篇
  1978年   1148篇
  1977年   1104篇
  1976年   989篇
  1975年   656篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The Latin American population has a double way of immigration, one toward the United States by proximity and another toward Spain by sociocultural affinity. This population increase is affecting organ donation and transplantation in receiving countries.

Objective

To analyze the brain death (BD) concept knowledge in the Dominican Republic immigrant population in Florida (United States) and Spain.

Method

Population under study: Population born in the Dominican Republic, resident in Florida (United States) and in Spain. Inclusion criteria: Population older than 15 years stratified by age and sex. Assessment instrument: Donation attitude questionnaire PCID-DTO-Ríos. Fieldwork: Random selection based on stratification. Immigration support association collaboration in Florida and Spain was needed to locate potential respondents. Completion was anonymous and self-administered, with verbal consent.

Results

A total of 123 respondents, 57 residents in Spain and 66 in Florida, have been included in the study. The 27% (n = 33) of the respondents knowledgeable of the BD concept consider it the death of an individual. Of the remainder, 52% (n = 64) do not know about it, and the remaining 21% (n = 26) believe it does not mean the death of a patient. No differences were observed regarding migration countries (P > .05). There was no association of the BD concept with other psychosocial factors analyzed or with the attitude toward organ donation.

Conclusions

Knowledge of the BD concept among the Dominican immigrant population is similar in Spain and Florida, and, unlike most studies, there is no objective association with the attitude toward organ donation.  相似文献   
42.

Background

Lung ultrasound can accelerate the diagnosis of life-threatening diseases in adults with respiratory symptoms.

Objective

Systematically review the accuracy of lung ultrasonography (LUS) for emergency diagnosis of pneumonia, acute heart failure, and exacerbation of chronic obstructive pulmonary disease (COPD)/asthma in adults.

Methods

PubMed, Embase, Scopus, Web of Science, and LILACS (Literatura Latino Americana e do Caribe em Ciências da Saúde; until 2016) were searched for prospective diagnostic accuracy studies. Rutter-Gatsonis hierarchical summary receiver operating characteristic method was used to measure the overall accuracy of LUS and Reitsma bivariate model to measure the accuracy of the different sonographic signs. This review was previously registered in PROSPERO (Centre for Reviews and Dissemination, University of York, York, UK; CRD42016048085).

Results

Twenty-five studies were included: 14 assessing pneumonia, 14 assessing acute heart failure, and four assessing exacerbations of COPD/asthma. The area under the summary receiver operating characteristic curve of LUS was 0.948 for pneumonia, 0.914 for acute heart failure, and 0.906 for exacerbations of COPD/asthma. In patients suspected to have pneumonia, consolidation had sensitivity of 0.82 (95% confidence interval [CI] 0.74–0.88) and specificity of 0.94 (95% CI 0.85–0.98) for this disease. In acutely dyspneic patients, modified diffuse interstitial syndrome had sensitivity of 0.90 (95% CI 0.87–0.93) and specificity of 0.93 (95% CI 0.91–0.95) for acute heart failure, whereas B-profile had sensitivity of 0.93 (95% CI 0.72–0.98) and specificity of 0.92 (95% CI 0.79–0.97) for this disease in patients with respiratory failure. In patients with acute dyspnea or respiratory failure, the A-profile without PLAPS (posterior-lateral alveolar pleural syndrome) had sensitivity of 0.78 (95% CI 0.67–0.86) and specificity of 0.94 (95% CI 0.89–0.97) for exacerbations of COPD/asthma.

Conclusion

Lung ultrasound is an accurate tool for the emergency diagnosis of pneumonia, acute heart failure, and exacerbations of COPD/asthma.  相似文献   
43.
Additive manufacturing is a rapidly emerging technology which is being successfully implemented in the various field of medicine as well as in orthopaedics, where it has applications in reducing cartilage defects and treatments of bones. The technology helps through systematic collection of information about the shape of the "defects" and precise fabrication of complex 3D constructs such as cartilage, heart valve, trachea, myocardial bone tissue and blood vessels. In this paper, a large number of the relevant research papers on the additive manufacturing and its application in medical specifically orthopaedics are identified through Scopus had been studied using Bibliometric analysis and application analysis is undertaken. The bibliometric analysis shows that there is an increasing trend in the research reports on additive manufacturing applications in the field of orthopaedics. Discussions are on using technological advancement like scanning techniques and various challenges of the orthopaedic being met by additive manufacturing technology. For patient-specific orthopaedic applications, these techniques incorporate clinical practice and use for effective planning. 3D printed models printed by this technology are accepted for orthopaedic surgery such as revision of lumbar discectomy, pelvic surgery and large scapular osteochondroma. The applications of additive manufacturing in orthopaedics will experience a rapid translation in future. An orthopaedic surgeon can convert need/idea into a reality by using computer-aided design (CAD) software, analysis software to facilitate the manufacturing. Thus, AM provides a comprehensive opportunity to manufacture orthopaedic implantable medical devices.  相似文献   
44.
ObjectiveMultiple treatment options for acetabular fractures in geriatric patients exist. However, no large-scale studies have reported the outcomes of acute total hip arthroplasty (THA) in this patient population. We systematically evaluated all available evidence to characterize clinical outcomes, complications, and revisions of acute THA for acetabular fractures in geriatric patients.MethodsMeta-analysis of 21 studies of 430 acetabular fractures with mean follow-up of 44 months (range, 17−97 months). Two independent researchers searched and evaluated the databases of Ovid, Embase, and United States National Library of Medicine using a Boolean search string up to December 2019. Population demographics and complications, including presence of heterotopic ossification (HO), dislocation, infection, revision rate, neurological deficits, and venous thromboembolic event (VTE), were recorded and analyzed.ResultsWeighted mean Harris Hip Score was 83.3 points, and 20% of the patients had reported complications. The most common complication was HO, with a rate of 19.5%. Brooker grade III and IV HO rates were lower at 6.8%. Hip dislocation occurred at a rate of 6.1%, 4.1% of patients developed VTE, deep infection occurred in 3.8%, and neurological complications occurred in 1.9%. Although the revision rate was described in most studies, we were unable to perform a survival analysis because the time to each revision was described in only a few studies. The revision rate was 4.3%.ConclusionsAcute THA is a viable option for treatment of acetabular fracture and can result in acceptable clinical outcomes and survivorship rates in older patients but with an associated complication rate of approximately 20%. Considering the limited treatment options, THA might be a viable alternative for appropriately selected patients.  相似文献   
45.
Quality of life (QoL) is an important consideration among asthma sufferers. The Pediatric Asthma Quality of Life Questionnaire (PAQLQ) is one of the most widely used instruments for measuring health-related QoL in children with asthma. The standardized version of PAQLQ contains 23 questions in three domains, i.e., activity limitation, symptoms and emotional function. The objective of this study was to validate the Thai-translated version of the PAQLQ. The study design consisted of a five-week single cohort study. Patients recorded symptoms, and peak expiratory flow rate (PEFR) each morning and evening during the first and fifth week of the study in asthma diary. At each clinic visit, a trained-interviewer administered the PAQLQ and performed spirometric measurements. Fifty-one children, ages between 7 and 17 yr participated in the study. Scores from the asthma diary were used to classify patients into stable vs. unstable groups. The construct validity of the questionnaire was confirmed in both cross-sectional and longitudinal studies by demonstrating correlations between various PAQLQ domains with clinical asthma parameters (asthma diary, beta-agonist use and PEFR). There was high internal consistency for scores of the three domains (Cronbach's alpha-coefficient = 0.83-0.95). For those with stable asthma, the reliability of PAQLQ was good for the rating scale (intra-class correlation coefficient--ICC = 0.84) and for total score (alpha = 0.97) indicating high reproducibility of the PAQLQ. The significant difference of changes QoL scores between stable and unstable groups was observed in all domains. We conclude that the Thai version of PAQLQ is valid and reliable for implementing in Thai children with asthma.  相似文献   
46.
Condensation of thiourea 1 with diethyl malonate 2 in the presence of sodium methoxide furnished 4,6‐dihydroxy‐2‐mercaptopyrimidine 3 . Compound 3 on methylation with diazomethane followed by oxidation with H5IO6/CrO3 in ethyl acetate gave 4,6‐dimethoxy‐2‐methylsulphonylpyrimidine 5 . Compound 5 on condensation with 2‐mercapto‐6‐chlorobenzoic acid in the presence of a phase transfer catalyst, tetrabutylammonium bromide and sodium carbonate gave the title compound – pyrithiobac‐sodium 6 with an overall yield of > 35% starting from thiourea. Following the above standardized procedure, using [14C]‐thiourea in lieu of thiourea, 14C labelled product 6 , was synthesized with an overall radiochemical yield > 30% (with respect to [14C]‐thiourea) for further evaluations of environmental fate of 6 , in soils and plants. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
47.
本文报告3例在疼痛诊疗过程中的误诊与误治,原发病分别为病灶未明确的颈椎癌转移、脊椎结核腰大肌间沟寒性脓肿与腰骶椎恶性肿瘤,分别被误诊为颈椎病、腰肌劳损与腰肌劳损,幸及时发现,纠正了错误的治疗。因此应强调从事疼痛业务必须有扎实的通科基础,严格的检查流程与认真的工作态度。  相似文献   
48.
49.
皮质发育障碍模型的建立及其致痫敏感性的研究   总被引:1,自引:0,他引:1  
目的:建立皮质发育障碍模型,探讨皮质发育障碍模型的敏感性。方法:在SD大鼠孕17d腹腔注入1,3-二氯乙烯-亚硝基脲(BCNU)制作皮质发育障碍模型;Nissl染色观察P60d仔鼠病理变化;选取P60d雄性仔鼠,腹腔注射氯化锂-毛果芸香碱,分别比较两组大鼠癫发生的潜伏期、持续状态时间和死亡率。结果:同龄仔鼠脑组织湿重实验组比对照组显著减轻(P<0.01);Nissl染色显示皮质变薄、皮质层次紊乱、海马区域异位细胞异常聚集;有皮质发育障碍的仔鼠注射氯化锂-毛果芸香碱后,癫发生的潜伏期显著缩短(P<0.01),癫持续状态时间延长(P<0.01),死亡率显著升高(P<0.05)。结论:BCNU致皮质发育障碍模型具有癫易感性。  相似文献   
50.
Abstract It is well established that thrombolytic therapy increases the risk of secondary intracerebral hemorrhage in ischemic stroke patients. However, the term “intracerebral hemorrhage” (ICH) covers a wide spectrum from tiny spots of blood to massive space-occupying hematoma. We will review the etiology and clinical consequences of secondary hemorrhage after thrombolysis in ischemic stroke patients and discuss the ability of magnetic resonance imaging (MRI) to predict this phenomenon. MRI is a highly sensitive tool for detection of hemorrhagic transformation after ischemic stroke. The definitions of a so-called symptomatic hemorrhage after ischemic infarction differ considerably and will also be described. Attributing a causal relationship of a clinical deterioration to a secondary hemorrhage is not easy and should be only addressed when it exceeds at least 30% of the infarct volume. In other patients, secondary hemorrhage might be regarded as side effect of reperfusion within the region with the most severe perfusion deficit. Cerebral microbleeds (CMBs) are a frequent finding in patients with leukoaraiosis and appear to be a general marker of various types of bleeding- prone small vessel disease and a predictor of recurrent vascular events. Current data do not support the hypothesis that the detection of CMBs is a useful diagnostic criterion for the exclusion of patients with CMBs from thrombolytic therapy. However, an increased risk for the rare patients with numerous CMBs can not be ruled out.   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