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   47961篇
  免费   4514篇
  国内免费   88篇
耳鼻咽喉   612篇
儿科学   1325篇
妇产科学   1320篇
基础医学   6929篇
口腔科学   1313篇
临床医学   5893篇
内科学   8388篇
皮肤病学   640篇
神经病学   3807篇
特种医学   2287篇
外国民族医学   1篇
外科学   6221篇
综合类   886篇
一般理论   23篇
预防医学   5289篇
眼科学   1099篇
药学   3559篇
  3篇
中国医学   56篇
肿瘤学   2912篇
  2021年   654篇
  2019年   646篇
  2018年   757篇
  2017年   628篇
  2016年   617篇
  2015年   726篇
  2014年   957篇
  2013年   1497篇
  2012年   2154篇
  2011年   2233篇
  2010年   1237篇
  2009年   1029篇
  2008年   1878篇
  2007年   2040篇
  2006年   2025篇
  2005年   2024篇
  2004年   1832篇
  2003年   1692篇
  2002年   1715篇
  2001年   1612篇
  2000年   1709篇
  1999年   1459篇
  1998年   698篇
  1997年   564篇
  1996年   555篇
  1995年   560篇
  1994年   463篇
  1993年   479篇
  1992年   1259篇
  1991年   1182篇
  1990年   1158篇
  1989年   1106篇
  1988年   1016篇
  1987年   1012篇
  1986年   925篇
  1985年   922篇
  1984年   717篇
  1983年   634篇
  1982年   452篇
  1981年   399篇
  1980年   412篇
  1979年   658篇
  1978年   532篇
  1977年   420篇
  1976年   409篇
  1975年   380篇
  1974年   451篇
  1973年   438篇
  1972年   450篇
  1971年   423篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Renal angiomyolipoma: 6 case reports and literature review   总被引:4,自引:0,他引:4  
We report 6 cases of renal angiomyolipomas and review the pertinent literature concerning this disease. One case involved the rare association of tuberous sclerosis and pregnancy. Another patient without tuberous sclerosis had renal cell carcinoma and later suffered a contralateral angiomyolipoma. The pathological conditions of renal angiomyolipomas with and without tuberous sclerosis are discussed. Since angiomyolipomas present with multiple clinical similarities to renal cell carcinoma, the primary task for the clinician is to differentiate this hamartoma from carcinoma. The distinguishing characteristics and the clinical management of renal angiomyolipomas are discussed.  相似文献   
102.
103.
104.
105.
Researchers usually employ orthogonal arrays or D-optimal designs with little or no attribute overlap in stated-choice surveys. The challenge is to balance statistical efficiency and respondent burden to minimize the overall error in the survey responses. This study examined whether simplifying the choice task, by using a design with more overlap, provides advantages over standard minimum-overlap methods. We administered two designs for eliciting HIV test preferences to split samples. Surveys were undertaken at four HIV testing locations in San Francisco, California. Personal characteristics had different effects on willingness to pay for the two treatments, and gains in statistical efficiency in the minimal-overlap version more than compensated for possible imprecision from increased measurement error.  相似文献   
106.
Traditionally, neuropsychological deficits due to Sickle Cell Disease (SCD) have been understudied in adults. We have begun to suspect, however, that symptomatic and asymptomatic Cerebrovascular Events (CVE) may account for an alarming number of deficits in this population. In the current brief review, we critically evaluated the pediatric and adult literatures on the neurocognitive effects of SCD. We highlighted the studies that have been published on this topic and posit that early detection of CVE via neurocognitive testing, neuropsychiatric evaluations, and neuroimaging may significantly reduce adult cognitive and functional morbidities.  相似文献   
107.
In a newly developed dual-source computed tomography system (DSCT) the relation of heart rate and image quality and the possible advantages of the system’s superior temporal resolution in the evaluation of left ventricular parameters as compared to results of cardiac magnetic resonance imaging (MRI) were assessed. Coronary CT angiography was performed using a DSCT (Somatom Defintion, Siemens Medical Solutions, Forchheim, Germany) in 21 patients (mean age 62±8; 15 male, 6 female). Image quality of the coronary arteries, the heart valves, and the left ventricular myocardium was assessed using a three-point grading scale. Ten of these patients also underwent cardiac MRI for the assessment of left ventricular function, using a SSFP (steady-state free precession) sequence. Left ventricular ejection fractions (LV-EF), the end-systolic volumes (ESV), and the end-diastolic volumes (EDV) were measured employing MRI and DSCT datasets. The image quality ratings for the coronary arteries at the optimal reconstruction interval were diagnostic even in patients with high heart rates (1.42±0.49). Analysis of global LV function using DSCT quantified from CTA datasets showed a good correlation with results of cardiac MRI [EF: r=0.75 (p=0.01); ESV: r=0.72 (p=0.19); EDV: r=0.71 (p=0.02)]. The dual-source CT system offers robust image quality of the coronary arteries, independent of the heart rate, and provides combined diagnostic imaging of coronary arteries, the heart valves, the myocardium, and the global left ventricular function.  相似文献   
108.
109.
BACKGROUND: Diagnosis of atopic dermatitis (AD) depends on clinical features because no definitive diagnostic test exists. Criteria proposed by Hanifin and Rajka (Acta Derm Venereol (Stockh) 1980; Suppl 92: 44-47) were acceptable for hospital-based studies but were found not to be suitable for field studies. A UK working party formulated clinical diagnostic criteria that could be used in both hospital and epidemiological settings. Validation studies of the criteria showed widely variable results, probably due to different clinical settings and ethnicity. AIM AND OBJECTIVE: This study was undertaken to validate Hanifin and Rajka's criteria and to assess the comparative efficacy of their criteria and the UK working party's diagnostic criteria in the diagnosis of AD in a hospital setting in North India. SUBJECTS AND METHODS: This study serially included 101 patients with AD and 48 controls of paediatric age group. The study period was from July 2003 to December 2004. RESULTS: Hanifin and Rajka's criteria (sensitivity 96%, specificity 93.75%, positive predictive value 97% (PPV) and negative predictive value (NPV) 91.84%) had a statistical advantage over the UK working party's diagnostic criteria (sensitivity 86%, specificity 95.83%, PPV 97.75% and NPV 76.67%), with a P-value < 0.005.  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