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   42416篇
  免费   5529篇
  国内免费   801篇
耳鼻咽喉   154篇
儿科学   1313篇
妇产科学   1009篇
基础医学   2541篇
口腔科学   1189篇
临床医学   5344篇
内科学   9383篇
皮肤病学   429篇
神经病学   2936篇
特种医学   776篇
外国民族医学   1篇
外科学   4263篇
综合类   3986篇
现状与发展   8篇
一般理论   9篇
预防医学   7724篇
眼科学   628篇
药学   3167篇
  26篇
中国医学   323篇
肿瘤学   3537篇
  2024年   103篇
  2023年   1100篇
  2022年   1361篇
  2021年   2690篇
  2020年   2520篇
  2019年   2319篇
  2018年   2297篇
  2017年   2131篇
  2016年   2141篇
  2015年   1951篇
  2014年   3329篇
  2013年   4106篇
  2012年   2429篇
  2011年   2610篇
  2010年   1972篇
  2009年   1924篇
  2008年   1952篇
  2007年   1747篇
  2006年   1568篇
  2005年   1372篇
  2004年   1109篇
  2003年   915篇
  2002年   794篇
  2001年   719篇
  2000年   538篇
  1999年   435篇
  1998年   391篇
  1997年   328篇
  1996年   253篇
  1995年   245篇
  1994年   199篇
  1993年   212篇
  1992年   160篇
  1991年   133篇
  1990年   103篇
  1989年   98篇
  1988年   86篇
  1987年   66篇
  1986年   55篇
  1985年   75篇
  1984年   57篇
  1983年   24篇
  1982年   39篇
  1981年   26篇
  1980年   23篇
  1979年   14篇
  1978年   6篇
  1977年   9篇
  1976年   4篇
  1974年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
围生期窒息发生率和死亡率近10年变迁及相关因素   总被引:2,自引:1,他引:1  
目的 分析近10年来围生期窒息发生率和死亡率的变迁,探讨围生期窒息相关因素及开展新法复苏对围生期窒息发生率和死亡率的影响。方法对近10年郑州大学第三附属医院分娩的所有活产新生儿的病历资料进行回顾性分析,计算窒息的发生率、死亡率、病死率,观察上述指标的逐年变化趋势及季节变化的情况,并探讨性别、双/多胎、出生体质量、胎龄分娩方式对这些指标的影响。结果轻度窒息发生率在开展新法复苏后明显下降,并稳定在1.5%左右,而重度窒息的发生率和病死率均无明显变化。窒息儿的发生率以4月份最高,但死亡率和病死率以7月份最高。窒息的发生还与性别、双/多胎、出生体质量、早产以及阴道助产有关。结论围生期窒息的发生与性别、双/多胎、出生体质量、胎龄密切相关;新法复苏能显著降低轻度窒息的发生率,对重度窒息的发生率和窒息病死率无明显影响;窒息儿的死亡率和病死率与季节有关。  相似文献   
102.
Alzheimer's disease (AD) is a neurodegenerative disorder with mixed cognitive and behavioural clinical manifestations. The possession of apolipoprotein-E (ApoE) epsilon4 allelic variant is one of the most important risk factors for developing late-onset AD (LOAD). In this study we analysed the relationship between the entire range of behavioural symptoms, cognitive deficit, and sociodemographic characteristics and ApoE epsilon4 allele possession with multivariate logistic regression models in LOAD patients. Patients included (n = 171) were consecutively admitted in a memory clinic for the first diagnostic visit. Levels of behaviour and cognition within the last month were assessed by the Neuropsychiatric Inventory and Mini Mental State Examination. Presence of clinically significant psychosis, delusions and hallucinations at the early stage of the illness, from the onset to the first visit, was measured with diagnostic criteria. ApoE epsilon4 allele possession was associated with increased levels of delusions within the last month from the first visit (OR 1.23; 95% CI 1.01-1.50; P < 0.05) and with the presence of categorical delusions at the early stage until the first visit (OR 3.11; 95% CI 1.21-8.01; P < 0.02). In this study, which considers the entire range of behavioural expressions in LOAD patients at the early stage of the illness, the relationship between behaviour and ApoE epsilon4 allele is confirmed for delusions only.  相似文献   
103.
104.
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   
105.
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   
106.
107.
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   
108.
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   
109.
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   
110.
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