全文获取类型
收费全文 | 7631篇 |
免费 | 815篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 28篇 |
儿科学 | 309篇 |
妇产科学 | 176篇 |
基础医学 | 1153篇 |
口腔科学 | 92篇 |
临床医学 | 986篇 |
内科学 | 1509篇 |
皮肤病学 | 104篇 |
神经病学 | 597篇 |
特种医学 | 502篇 |
外科学 | 905篇 |
综合类 | 154篇 |
一般理论 | 10篇 |
预防医学 | 801篇 |
眼科学 | 168篇 |
药学 | 536篇 |
中国医学 | 2篇 |
肿瘤学 | 425篇 |
出版年
2021年 | 91篇 |
2020年 | 62篇 |
2019年 | 104篇 |
2018年 | 119篇 |
2017年 | 96篇 |
2016年 | 113篇 |
2015年 | 109篇 |
2014年 | 154篇 |
2013年 | 222篇 |
2012年 | 345篇 |
2011年 | 334篇 |
2010年 | 213篇 |
2009年 | 167篇 |
2008年 | 345篇 |
2007年 | 381篇 |
2006年 | 360篇 |
2005年 | 322篇 |
2004年 | 309篇 |
2003年 | 272篇 |
2002年 | 246篇 |
2001年 | 244篇 |
2000年 | 235篇 |
1999年 | 217篇 |
1998年 | 129篇 |
1997年 | 99篇 |
1996年 | 105篇 |
1995年 | 89篇 |
1994年 | 91篇 |
1993年 | 66篇 |
1992年 | 184篇 |
1991年 | 177篇 |
1990年 | 181篇 |
1989年 | 184篇 |
1988年 | 157篇 |
1987年 | 157篇 |
1986年 | 155篇 |
1985年 | 163篇 |
1984年 | 75篇 |
1983年 | 109篇 |
1982年 | 76篇 |
1981年 | 60篇 |
1980年 | 79篇 |
1979年 | 83篇 |
1978年 | 58篇 |
1977年 | 74篇 |
1976年 | 83篇 |
1975年 | 74篇 |
1974年 | 71篇 |
1973年 | 79篇 |
1972年 | 59篇 |
排序方式: 共有8457条查询结果,搜索用时 15 毫秒
21.
The aim of the present study was to determine whether patients with bronchiectasis and nontuberculous mycobacteria (NTM) have a higher prevalence of Aspergillus-related lung disease. A series of 30 consecutive patients with bronchiectasis and NTM (cases) were compared with 61 patients with bronchiectasis and no evidence of NTM (controls). Aspergillus serology and computerised tomography of the thorax were used to identify Aspergillus-related lung diseases, including aspergilloma, allergic bronchopulmonary aspergillosis and chronic necrotising pulmonary aspergillosis. The rate of positive Aspergillus serology was higher in cases with NTM disease compared with controls (10 out of 30 versus six out of 61). The radiological features of Aspergillus-related lung disease were also more common among patients with NTM disease than controls (six out of 30 versus none out of 61). This association between NTM disease and Aspergillus-related lung disease remained significant after adjustment for confounding effects of age and lung function (adjusted odds ratio 5.1, 95% confidence interval 1.5-17.0). Patients with bronchiectasis and nontuberculous mycobacterial disease have a higher prevalence of coexisting Aspergillus-related lung disease than patients with bronchiectasis and without nontuberculous mycobacteria. Identification of Aspergillus-related lung disease is important as prognosis amongst undetected cases is invariably poor. 相似文献
22.
Christopher D Wells Russell I Heigh Virender K Sharma Michael D Crowell Suryakanth R Gurudu Jonathan A Leighton Nora Mattek David E Fleischer 《BMC gastroenterology》2007,7(1):19
Background
Many factors impacting cecal intubation rates have been examined in detail; however, little information exists regarding the effect of the timing of the procedure. We sought to examine any difference in cecal intubation rates between morning and afternoon colonoscopies and identify factors contributing to a discrepancy. 相似文献23.
24.
A G Lawrence E T Houang E Hiscock M B Wells E Colli M Scatigna 《Current medical research and opinion》1990,12(2):114-120
An open, randomized comparative clinical trial was performed in 153 patients suffering from symptomatic vaginal candidiasis confirmed by mycological tests. Patients were allocated at random into two groups: the first group (consisting of 75 subjects) was treated with a single vaginal ovule of fenticonazole (600 mg) and the second group (consisting of 78 subjects) was treated with a single vaginal tablet of clotrimazole (500 mg). Therapeutic efficacy was assessed by microbiological and clinical criteria 7 days and 1 month (when possible) after the single dose treatment. At the first follow-up visit, complete disappearance of the signs and symptoms or a highly significant reduction of their intensity was observed in both treatment groups. No significant difference was evident between the two drugs. At 7 days, the mycological tests gave negative results in 92% of the patients in the fenticonazole group and in 88.5% of the patients in the clotrimazole group. The difference between the two treatment groups was again not statistically significant. The second follow-up visit was performed in 55 (73.3%) patients of the fenticonazole group and in 52 (66.7%) patients of the clotrimazole group. The results indicate that 83.6% of patients in the fenticonazole group and 69.2% of patients in the clotrimazole group were still disease free at the time of this visit. Both drugs were well tolerated. Mild, local and short lasting side-effects were reported in only 5 cases of the group treated with fenticonazole.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
25.
Immunohistochemical expression of carbonic anhydrase isoenzyme II (CAII) was demonstrated in a population of fibrous astrocytes in a young lamb and an adult sheep. Such cells were identified by co-expression of CAII and glial fibrillary acidic protein, nuclear morphology and their contribution of glial fibrillary acidic protein reactive processes to the glial limitans. Similar cells were not identified in neonatal lambs. As in man and mouse, CAII was also expressed in choroid plexus epithelium occurring in neonate, young and adult sheep brain. In contrast, however, to man and mouse, CAII was not expressed in sheep oligodendrocytes. 相似文献
26.
27.
N Bellamy W W Buchanan J M Esdaile A G Fam W F Kean J M Thompson G A Wells J Campbell 《The Journal of rheumatology》1991,18(11):1716-1722
Defining the minimum clinically important difference or delta to be detected in a clinical trial depends on a number of factors including the research hypothesis, patient characteristics, the nature of the intervention and the trial design. In 2 previous studies, we have developed standardized procedures for conducting outcome measurement based on current Food and Drug Administration and European League Against Rheumatism guidelines for clinical trials in ankylosing spondylitis, and thereafter, determined the standard deviation for these outcome measures. In the final component of this series of studies, we have employed a Delphi technique to establish estimates for delta, and calculated the sample size requirements under 2 different conditions of Type I and Type II error probabilities. 相似文献
28.
29.
J Wells Askew Todd D Miller David O Hodge Raymond J Gibbons 《Journal of the American College of Cardiology》2007,50(11):1080-1085
OBJECTIVES: We sought to determine if screening for coronary artery disease (CAD) with stress single-photon emission computed tomography (SPECT) is of value in patients with atrial fibrillation (AF) who do not have symptoms of chest pain or dyspnea. BACKGROUND: Although noninvasive stress testing is often done to screen for CAD in asymptomatic patients with AF and is considered to be appropriate in selected patients, its potential utility has not been demonstrated. METHODS: A retrospective study was conducted of 374 asymptomatic patients with AF referred for the detection of CAD. Mean follow-up was 5.7 +/- 3.8 years. The study group was compared with a control group of 374 asymptomatic age and gender-matched patients without AF. RESULTS: The mean summed stress score (SSS) was not significantly different between AF patients and control subjects (3.6 +/- 5.3 vs. 3.5 +/- 5.9; p = 0.35). Compared with controls, asymptomatic AF patients had similar rates of abnormal SPECT studies (51.6% vs. 48.4%; p = 0.38) and high-risk studies (14.4% vs. 14.4%; p = 1.0). The SSS was a significant predictor of outcome in both AF patients and control subjects. However, total mortality was significantly greater in AF patients (5-year overall mortality 27% vs. 18%, 10-year overall mortality 47% vs. 40%; p < 0.001), and this difference persisted (p = 0.01) after adjusting for multiple clinical variables and the SSS. CONCLUSIONS: Screening for CAD using stress SPECT in asymptomatic AF patients has a yield similar to age- and gender-matched control patients without AF. Although SSS predicts mortality in patients with and without AF, patients with AF have increased total mortality independent of the findings on stress SPECT. These results suggest that factors other than obstructive CAD are responsible for the increased mortality in AF. 相似文献
30.
J D Wells 《Journal of medical entomology》1991,28(3):471-473
Chrysomya megacephala (F.), an Old World calliphorid of considerable public health importance, was first discovered in Brazil in 1977 and is now widely distributed in Latin America. Reports that this species has become established in southern California, and the collection of a specimen in Texas, suggest that C. megacephala may be expanding its range rapidly in North America. The biology and worldwide spread of this pest are reviewed to alert entomologists and public health workers to this growing threat. 相似文献