全文获取类型
收费全文 | 71092篇 |
免费 | 5027篇 |
国内免费 | 152篇 |
专业分类
耳鼻咽喉 | 497篇 |
儿科学 | 2703篇 |
妇产科学 | 2475篇 |
基础医学 | 8858篇 |
口腔科学 | 909篇 |
临床医学 | 11615篇 |
内科学 | 12818篇 |
皮肤病学 | 1027篇 |
神经病学 | 7063篇 |
特种医学 | 1188篇 |
外国民族医学 | 33篇 |
外科学 | 6091篇 |
综合类 | 827篇 |
一般理论 | 125篇 |
预防医学 | 9917篇 |
眼科学 | 924篇 |
药学 | 4236篇 |
1篇 | |
中国医学 | 117篇 |
肿瘤学 | 4847篇 |
出版年
2023年 | 504篇 |
2022年 | 665篇 |
2021年 | 1439篇 |
2020年 | 993篇 |
2019年 | 1602篇 |
2018年 | 1801篇 |
2017年 | 1293篇 |
2016年 | 1426篇 |
2015年 | 1562篇 |
2014年 | 2187篇 |
2013年 | 3478篇 |
2012年 | 4974篇 |
2011年 | 5270篇 |
2010年 | 2814篇 |
2009年 | 2655篇 |
2008年 | 4543篇 |
2007年 | 5140篇 |
2006年 | 4991篇 |
2005年 | 4789篇 |
2004年 | 4652篇 |
2003年 | 4354篇 |
2002年 | 4091篇 |
2001年 | 550篇 |
2000年 | 391篇 |
1999年 | 546篇 |
1998年 | 871篇 |
1997年 | 701篇 |
1996年 | 585篇 |
1995年 | 499篇 |
1994年 | 474篇 |
1993年 | 487篇 |
1992年 | 339篇 |
1991年 | 302篇 |
1990年 | 282篇 |
1989年 | 238篇 |
1988年 | 231篇 |
1987年 | 238篇 |
1986年 | 200篇 |
1985年 | 230篇 |
1984年 | 262篇 |
1983年 | 279篇 |
1982年 | 338篇 |
1981年 | 311篇 |
1980年 | 262篇 |
1979年 | 178篇 |
1978年 | 152篇 |
1977年 | 170篇 |
1976年 | 154篇 |
1975年 | 127篇 |
1973年 | 128篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
81.
82.
83.
Can Electrocardiographic Criteria Predict Adverse Cardiac Events and Positive Cardiac Markers? 总被引:5,自引:0,他引:5
Andra L. Blomkalns MD Christopher J. Lindsell PhD Abhinav Chandra MD Mary E. Osterlund MD W. Brian Gibler MD Charles V. Pollack MS MD Brian R. Tiffany MD PhD Judd E. Hollander MD James W. Hoekstra MD 《Academic emergency medicine》2003,10(3):205-210
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
84.
85.
Anthony J Ireland Helen Knight Martyn Sherriff 《American journal of orthodontics and dentofacial orthopedics》2003,124(3):323-326
Self-etching primers have recently been introduced to simplify the orthodontic bonding process. The aim of this study was to compare the effectiveness of such a product with conventional 2-stage etching and priming with 37% o-phosphoric acid and a conventional unfilled primer. Twenty consecutive patients having orthodontic bonds placed were selected to participate in this cross-mouth control study. Diagonally opposite quadrants were randomly allocated to either the self-etching primer group or the conventional etching and priming group. A total of 364 teeth were bonded with a light-cured diacrylate adhesive; bond failures were then monitored over 6 months. There were 20 bond failures (10.99%) in the self-etching primer group and 9 bond failures (4.95%) in the conventional etch and priming group over this period. The results were analyzed with the McNemar test and 95% confidence interval. The difference between the failure proportions was -0.06 with an associated 95% confidence interval of -0.121 to 0.001. This study produced weak evidence to suggest that bond failures with a self-etching primer will be higher than those with conventional etching and priming. This increased likelihood of bond failure must be weighed against the time advantage of the self-etching primer when used at the initial bonding appointment. 相似文献
86.
Martina Ballmaier Elizabeth R Sowell Paul M Thompson Anand Kumar Katherine L Narr Helen Lavretsky Suzanne E Welcome Heather DeLuca Arthur W Toga 《Neuropsychopharmacology》2004,55(4):382-389
BACKGROUND: In elderly depression, volumetric brain imaging findings suggest abnormalities of the frontal lobe, particularly the orbitofrontal cortex, and the hippocampus. No studies to date have mapped cortical abnormalities over the entire brain surface in major depression. Here, we conducted detailed spatial analyses of brain size and gray matter within the cortical mantle in elderly patients with major depression. METHODS: High-resolution, three-dimensional, structural magnetic resonance imaging data and cortical pattern matching methods were used in 24 depressed elderly patients and 19 group-matched controls to measure local brain size and proportions of gray matter at thousands of homologous cortical surface locations. RESULTS: Prominent brain size reductions were observed in the depressed subjects in the orbitofrontal cortex bilaterally. Cortical gray matter measurements revealed significant gray matter increases in the orbitofrontal cortex, adjacent to focal trend level significant decreases of gray matter in the same region. Depressed patients also exhibited significant gray matter increases in parietal cortices, as well as the left temporal cortex. CONCLUSIONS: Complex cortical changes may contribute to the brain size reduction of the orbitofrontal cortex and to the gray matter abnormalities detected in orbitofrontal cortex and temporoparietal cortices, thereby providing a potentially new window into the pathophysiology of elderly depression. 相似文献
87.
88.
89.
90.