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   50507篇
  免费   6241篇
  国内免费   959篇
耳鼻咽喉   333篇
儿科学   1451篇
妇产科学   1083篇
基础医学   3133篇
口腔科学   1646篇
临床医学   6362篇
内科学   10127篇
皮肤病学   507篇
神经病学   3391篇
特种医学   1113篇
外国民族医学   1篇
外科学   4833篇
综合类   5107篇
现状与发展   9篇
一般理论   9篇
预防医学   9277篇
眼科学   682篇
药学   4234篇
  53篇
中国医学   613篇
肿瘤学   3743篇
  2024年   134篇
  2023年   1219篇
  2022年   1767篇
  2021年   3082篇
  2020年   2877篇
  2019年   2603篇
  2018年   2570篇
  2017年   2437篇
  2016年   2453篇
  2015年   2255篇
  2014年   3900篇
  2013年   4677篇
  2012年   2940篇
  2011年   3146篇
  2010年   2385篇
  2009年   2329篇
  2008年   2304篇
  2007年   2096篇
  2006年   1851篇
  2005年   1625篇
  2004年   1306篇
  2003年   1093篇
  2002年   924篇
  2001年   844篇
  2000年   638篇
  1999年   532篇
  1998年   491篇
  1997年   421篇
  1996年   326篇
  1995年   302篇
  1994年   256篇
  1993年   266篇
  1992年   218篇
  1991年   181篇
  1990年   146篇
  1989年   145篇
  1988年   132篇
  1987年   109篇
  1986年   96篇
  1985年   126篇
  1984年   100篇
  1983年   54篇
  1982年   83篇
  1981年   58篇
  1980年   49篇
  1979年   45篇
  1978年   25篇
  1977年   23篇
  1976年   15篇
  1974年   12篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
121.
122.
OBJECTIVES: To determine electrocardiogram (ECG) predictors of positive cardiac markers and short-term adverse cardiac events in an undifferentiated chest pain population presenting to emergency departments (EDs). The authors hypothesized that specific ECG findings, other than those previously identified in higher-risk populations, would be predictive of cardiac outcomes and positive cardiac markers. METHODS: This study used data from a prospectively collected, retrospectively analyzed Internet-based data registry of undifferentiated chest pain patients (i*trACS). Logistic regression modeling was performed to determine the ECG findings that were predictive of 1) positive cardiac markers and 2) short-term adverse cardiac events. RESULTS: ST-segment elevation (STE), ST-segment depression (STD), pathological Q-waves (PQW), and T-wave inversion were associated with increased odds of percutaneous coronary intervention or catheterization, myocardial infarction, or coronary artery bypass grafting. The odds of creatine kinase-MB (CK-MB) measuring positive were increased if STE, STD, or PQW were present [odds ratio (OR) 2.495, 2.582, and 1.295, respectively]. A right bundle branch block tended to decrease the odds of CK-MB measuring positive (OR 0.658). A similar pattern of results was observed for troponin I (OR 3.608 for STE, 3.72 for STD, 1.538 for PQW). Troponin T showed an increased odds of measuring positive if any of STE, STD, left bundle branch block, or T-wave inversion were evident (OR 2.313, 2.816, 1.80, and 1.449, respectively). CONCLUSIONS: Initial ECG criteria can be used to predict short-term cardiac outcomes and positive cardiac markers. These findings can be important aids in the risk-stratification and aggressive treatment regimens of chest pain patients presenting to EDs.  相似文献   
123.
To determine the prevalence of excessive daytime sleepiness (EDS) and that of dozing and sudden onset of sleep episodes (SOS) while driving in ambulatory patients with Parkinson's disease (PD) in France, a national sample of private and public neurologists was asked to recruit the first 10 consecutive nondemented PD patients. Each patient completed a questionnaire including the Epworth Sleepiness Scale (ESS) and the likelihood of dozing off and experiencing SOS episodes behind the wheel. Clinical and demographic data were collected. One thousand six hundred and twenty‐five patients with PD were included in the survey. Twenty‐nine percent of the patients suffered from EDS (ESS score ≥10) but only 0.8% declared a high chance of dozing while driving and 0.5% reported totally unpredictable SOS episodes while driving. Risk factors for EDS were male gender, reduced activity of daily living, and a high daily levodopa equivalent dosage. Risk factors for SOS episodes while driving were an ESS score ≥10, male gender, and low Hoehn and Yahr staging. EDS is common in ambulatory patients with PD and is a major risk factor for dozing and for SOS episodes behind the wheel in patients who drive. © 2007 Movement Disorder Society  相似文献   
124.
125.
Risk of death from acute pancreatitis   总被引:5,自引:0,他引:5  
Summary Conclusions The analysis of all the data available in 192 patients at 24 h from admission shows that only serum glucose above 250 mg/dL (13.88 mmol/L) and serum creatinine above 2 mg/dL (176.8 μmol/L) are prognostic factors of death (P<0.0001). When, however, pathological chest X-rays are also considered in a subset of 149 patients, these and serum creatinine are prognostic factors of death with odds ratios of 2.9 (95% CL 1.3–6.3) and 9.4 (95% CL 2.2–40.7), respectively (P<0.0001). Background In patients suffering from acute pancreatitis, neither Ranson scores nor Glasgow criteria evaluation at 24 h yield a sufficiently reliable prognosis of the risk of death from the first acute attack. Methods After excluding posttraumatic, postsurgical, and post-ERCP acute pancreatitis, we selected 192 consecutive patients admitted in the first instance to our center for a first attack, distinguishing between patients who died and patients who survived. We used Cox's model to analyze the prognostic weight of variables available within 24 h of admission (sex, age, alcohol intake, smoking habits, 17 biochemical tests, body mass index, chest X-rays, body temperature, and shock status). Results Seventeen (8.8%) patients died; mortality showed a decreasing trend over the period of years considered and was correlated, among other things, with necrotizing type of pancreatitis, idiopathic etiology, and shock status on admission.  相似文献   
126.
Localized pleural plaques and lung cancer.   总被引:1,自引:0,他引:1  
In a mass chest radiography survey conducted in 1971 for 7,986 residents of three Finnish communities, 604 subjects (7.6%) with pleural plaques but not other asbestos-related radiographic signs were identified. The same number of referents, each individually matched to each plaque carrier on sex, birth year, and community, was selected from among persons in the same source population with no pleural plaques. The two groups were followed for investigation of incidence of lung cancer during 1972-1989. Twenty-eight of those with plaques and 25 referents contracted lung cancer (crude conditional RR = 1.1; CL95 = 0.7, 1.9). The application of the proportional hazards model, with adjustment for sex, age, and residence, resulted in a hazard ratio of 1.1 (CL = 0.6, 1.8). The risk ratio estimate may be biased; hence, the result is inconclusive in regard to the predictive assessment of lung cancer risk among carriers of pleural plaques.  相似文献   
127.
 To monitor the lead hazards in industries and to investigate the prevalence of elevated blood lead levels (BLLs) in lead-exposed workers, a lead surveillance system (PRESS-BLLs) has been established and operated in Taiwan, Republic of China, since July 1993. A cohort of lead-exposed workers who received a periodic annual health examination at 55 accredited hospital laboratories was constructed. A total of 9807 separate BLL measurements were reported to the system in 1994. The mean BLL was 15.8 μg/dl in male workers and 11.6 μg/dl in female workers. The mean BLL of lead-exposed workers was significantly (P<0.05, z-test) higher than that of the general Taiwanese population (8.6 μg/dl for males and 6.7 μg/dl for females). In addition, the BLLs of 983 (10.0%) workers exceeded the regulatory action level (40 μg/dl for males; 30 μg/dl for females). The workplaces and homes of 57% of the workers with elevated BLLs were thoroughly investigated to determine the sources of lead contamination. These actions identified the causes of elevated BLLs and set up strategies to reduce workers’ lead exposure. The establishment of this occupational lead surveillance system represents a method for monitoring of lead hazards from occupational and environmental settings to prevent lead poisoning. The information acquired from the system can help in the setting up of a priority of prevention and the development of control measures. It is also useful for further monitoring of changes in the BLLs of the lead-exposed-worker cohort. The Health Department of Taiwan can use this information to evaluate the effectiveness of current industrial hygiene practice. Subjects with elevated BLLs have been medically treated and placed on long-term follow-up for sequelae. Received: 2 September 1996/Accepted: 29 November 1996  相似文献   
128.
本文对20岁以上22830人按HBsAg状况和肝损害表现分队列进行随访,平均追踪6.8年,在肝癌高发区和低发区均以HBsAg携带者并有重度肝损害者(肝大+肝功能异常)的肝癌死亡率和相对危险性最高,相对危险性分别为37.3和22.5倍。以无肝大和肝功能异常的非携带者最低,肝癌的发生和肝损害的程度呈平行关系。HBsAg携带者发生肝癌死亡的相对危险性高于非携带者7倍,并发现HBsAg携带并有重度肝损害的肝癌死亡的平均年龄显著提前。认为肝癌高发区人群中HBV的持续感染和肝损害的广泛存在是导致肝癌高发和早发的重要因素。  相似文献   
129.
Abstract From August to October 1991, the periodontal status of 1001 Yemenis representing the age groups 12-14, 15-19, 20-24 and 35-44 years was recorded and evaluated with preference to the CPITN, the calculus index and clinical attachment levels. The impact of chewing khat, the leaves of a cultivated, alkaloid shrub, and of using the traditional miswak chewing stick for oral hygiene purposes were investigated. The results show that 6.9% of the juvenile probands (15-19 years) had healthy periodontal tissue (CPITN 0). whereas bleeding on probing and calculus (CPITN 1+2) were registered in 86.2%. In the 35-44 year age group. 1.7% were periodontally healthy, whereas 84.5% displayed plaque retention or shallow pocketing (CPITN 2-3) and 12.5% deep pocketing (CPITN 4). The treatment needs in all age groups are confined primarily to calculus removal and instruction in oral hygiene. The clinical attachment level and the calculus index revealed age-related attachment loss and calculus formation, primarily among male probands. The higher khat consumption among the male population is reflected in its detrimental effect on the periodontal tissue, especially among younger probands. Oral hygiene aids have also an influence on periodontal status, with a toothbrush proving more efficient than the miswak. WHO efforts directed towards prophylactic programs need to be intensified but can be staffed by dental hygienists.  相似文献   
130.
X射线照射量(治疗水平)标准装置的研究和建立   总被引:3,自引:0,他引:3       下载免费PDF全文
X射线照射量(治疗水平)标准装置是由标准剂量仪,X射线照射源,测量车、定位系统及其辅助设备组成,本文作者主要介绍标准装置各个部分的构成及技术参数,该标准装置于1991年通过国家技术监督局认证,尔后,正式开展放射仪表的检定和校准工作。  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