全文获取类型
收费全文 | 477篇 |
免费 | 23篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 37篇 |
妇产科学 | 4篇 |
基础医学 | 35篇 |
口腔科学 | 10篇 |
临床医学 | 34篇 |
内科学 | 87篇 |
皮肤病学 | 9篇 |
神经病学 | 13篇 |
特种医学 | 90篇 |
外科学 | 40篇 |
综合类 | 62篇 |
预防医学 | 21篇 |
眼科学 | 11篇 |
药学 | 18篇 |
肿瘤学 | 30篇 |
出版年
2022年 | 8篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 16篇 |
2014年 | 4篇 |
2013年 | 7篇 |
2012年 | 13篇 |
2011年 | 14篇 |
2010年 | 23篇 |
2009年 | 15篇 |
2008年 | 13篇 |
2007年 | 15篇 |
2006年 | 16篇 |
2005年 | 23篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 18篇 |
2001年 | 14篇 |
2000年 | 11篇 |
1999年 | 14篇 |
1998年 | 31篇 |
1997年 | 24篇 |
1996年 | 21篇 |
1995年 | 15篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 1篇 |
1989年 | 16篇 |
1988年 | 11篇 |
1987年 | 15篇 |
1986年 | 11篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 8篇 |
1969年 | 1篇 |
排序方式: 共有504条查询结果,搜索用时 202 毫秒
91.
92.
93.
94.
95.
Mortality associated with acute watery diarrhea, dysentery and persistent diarrhea in rural North India 总被引:1,自引:0,他引:1
Mortality associated with diarrhea was investigated in a longitudinally followed cohort of children under six years of age in rural North India. During the follow-up, 1663 episodes of diarrhea and 23 diarrhea related deaths were recorded in 1467 children followed up for 20 months. The case fatality rate was 0.56% for acute watery diarrhea, 4.27% for dysentery and 11.94% for non-dysenteric persistent diarrhea. Most of the episodes lasted less than a week; 5.2% became persistent (duration > 14 days). The case fatality rate was similar in episodes of one and two weeks'duration (0.64% and 0.8%) and increased to 13.95% for persistent episodes. Of the total 86 persistent episodes, 22.1% were dysenteric; the case fatality rate for such dysenteric persistent episodes was 21.1% and for watery persistent diarrhea 11.4%. Diarrheal attack rates were similar among different nutritional groups, but diarrheal case fatality rates progressively increased with increasing severity of malnutrition, these were 24 times higher in children with severe malnutrition (7.48%) compared to those normally nourished (0.31%). With availability and use of oral rehydration therapy, dysentery and persistent diarrhea emerge as major causes of diarrhea related mortality, with underlying malnutrition as a key associated factor. 相似文献
96.
The role of feeding breast milk, unmodified bovine milk or adapted infant formula during acute diarrhoea in protecting against or causing persistence of the episodes was investigated in a population-based case control study in an urban area of north India. After adjustment for confounding variables, exclusive breast-feeding was associated with an odds ratio of 0.06 (95% CI 0.002-2.1), a 16.5 times lower odds in favour of developing persistence of an episode. Infants fed unmodified bovine milk in addition to breast milk had an odds of 2.5 times (95% CI 1.0-9.9) in favour of developing persistence of acute diarrhoea ( p = 0.04). In infants receiving unmodified bovine milk and no breast milk, this odds ratio was 11.1 (95% CI 1.0-228.8) ( p = 0.05). This study indicates that promoting exclusive breastfeeding may reduce the persistence of diarrhoea over and above its effect in decreasing the incidence of acute diarrhoea. In urban areas of the developing countries where working mothers often use milk supplementation beyond the age of three months, our findings suggest that use of adapted spray dried formula may be safer than unmodified bovine milk with respect to the risk of developing persistent diarrhoea. 相似文献
97.
Cancers of the oral cavity, pharynx, and esophagus are now suspected to have common etiologic factors and have been grouped together as “upper aerodigestive” cancers. Since this grouping is of relatively recent origin there have been no epidemiological studies on this group among Armed Forces personnel. 114 cases of upper aerodigestive cancers and an equal number of controls were studied. The largest number of cases were in the age group of 40–49 years with male preponderance. Lower level of education, smoking, quid chewing, and alcohol use were found to be the major risk factors for these cancers. A dose response relationship was observed for smoking, quid chewing and alcohol intake.KEY WORDS: Neoplasms, Smoking, Quid chewing, Alcohol 相似文献
98.
Femoral head avascular necrosis: correlation of MR imaging, radiographic staging, radionuclide imaging, and clinical findings 总被引:39,自引:0,他引:39
Mitchell DG; Rao VM; Dalinka MK; Spritzer CE; Alavi A; Steinberg ME; Fallon M; Kressel HY 《Radiology》1987,162(3):709-715
To better correlate the appearance of avascular necrosis (AVN) of the femoral head on magnetic resonance (MR) images with the stage of disease, MR images of 56 proved AVN lesions were compared with staging from corresponding radiographs (n = 56), Tc-99m scans (n = 41), and grade of symptoms (n = 28). Fractures complicating AVN were seen in 28 (50%) of 56 radiographs (radiographic stages III-V). With long repetition (TR) and echo delay (TE) times, a characteristic "double line sign" consisting of high signal intensity inside a low-intensity peripheral rim was seen in 45 lesions (80%). The central region within the rim was isointense with marrow fat on both short and long TR and TE images in 20 (71%) of 28 lesions uncomplicated by fracture (stages I-II) but in only four (14%) of 28 stage III-V lesions (P less than .001). Symptoms were least severe in lesions isointense with fat and most severe in lesions with low-signal central regions at short and long TRs and TEs. The peripheral double line sign on long TR/TE images may add specificity to the diagnosis of AVN by MR imaging. A chronologic pattern of central MR signal features is presented which may allow staging of AVN by MR imaging. 相似文献
99.
100.