全文获取类型
收费全文 | 1408966篇 |
免费 | 115734篇 |
国内免费 | 3330篇 |
专业分类
耳鼻咽喉 | 18362篇 |
儿科学 | 46581篇 |
妇产科学 | 41055篇 |
基础医学 | 200821篇 |
口腔科学 | 37690篇 |
临床医学 | 126060篇 |
内科学 | 284476篇 |
皮肤病学 | 33371篇 |
神经病学 | 116887篇 |
特种医学 | 53852篇 |
外国民族医学 | 464篇 |
外科学 | 210606篇 |
综合类 | 32774篇 |
现状与发展 | 3篇 |
一般理论 | 488篇 |
预防医学 | 110023篇 |
眼科学 | 31490篇 |
药学 | 98527篇 |
1篇 | |
中国医学 | 3354篇 |
肿瘤学 | 81145篇 |
出版年
2021年 | 10866篇 |
2019年 | 11675篇 |
2018年 | 16586篇 |
2017年 | 12674篇 |
2016年 | 14264篇 |
2015年 | 16010篇 |
2014年 | 22567篇 |
2013年 | 33402篇 |
2012年 | 45400篇 |
2011年 | 47936篇 |
2010年 | 28160篇 |
2009年 | 27056篇 |
2008年 | 44343篇 |
2007年 | 46849篇 |
2006年 | 47404篇 |
2005年 | 45867篇 |
2004年 | 43759篇 |
2003年 | 41703篇 |
2002年 | 40207篇 |
2001年 | 73025篇 |
2000年 | 74557篇 |
1999年 | 61586篇 |
1998年 | 16997篇 |
1997年 | 15436篇 |
1996年 | 15588篇 |
1995年 | 14793篇 |
1994年 | 13400篇 |
1993年 | 12586篇 |
1992年 | 45854篇 |
1991年 | 43488篇 |
1990年 | 41495篇 |
1989年 | 39558篇 |
1988年 | 36187篇 |
1987年 | 35366篇 |
1986年 | 32869篇 |
1985年 | 31281篇 |
1984年 | 23829篇 |
1983年 | 20024篇 |
1982年 | 12209篇 |
1981年 | 10779篇 |
1979年 | 20704篇 |
1978年 | 14578篇 |
1977年 | 12087篇 |
1976年 | 11366篇 |
1975年 | 11622篇 |
1974年 | 13994篇 |
1973年 | 13539篇 |
1972年 | 12635篇 |
1971年 | 11475篇 |
1970年 | 10911篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
871.
872.
873.
M C Plewa 《Emergency Medicine Clinics of North America》1991,9(4):827-852
Plain abdominal radiographs are rarely diagnostic when the patient presents with acute abdominal pain. Emergency physicians, therefore, should be aware of the appropriate indications and limitations of abdominal films in this setting and should be skilled in their interpretation to exclude the rare cases of pneumoperitoneum, pneumobilia, hepatic-portovenous gas, small and large bowel obstruction, toxic megacolon, volvulus and intramural gas. 相似文献
874.
875.
A study was conducted to evaluate the efficacy of family history factors as screening criteria for childhood hypercholesterolemia. When they were seen for routine care at one of eight office practices, 1005 prepubertal children underwent random serum cholesterol determinations. Parental and grandparental histories of cardiovascular risk factors and atherosclerotic complications prior to 55 years of age were also obtained. Of the initial group, 274 children had total cholesterol levels greater than or equal to 175 mg/dL, and 175 of these children returned for retesting after an overnight fast. A total of 88 children were found to have low-density lipoprotein-cholesterol (LDL-C) values greater than or equal to 90th percentile for age and sex. Maternal and paternal histories of hypercholesterolemia were significantly associated with elevated LDL-C (odds ratio = 7.3 and 2.9, respectively), but had extremely low sensitivities (0.09, 0.15) despite modest positive predictive values (0.42, 0.22). Grandparental histories of sudden death, peripheral vascular disease, and gout were associated with elevated LDL-C, but sensitivities and positive predictive values for all of these factors were less than 0.22. Family history factors most commonly recommended as criteria for cholesterol screening in children did not identify half of all the children with elevated LDL-C and did not selectively identify the most severely affected children. Adding information concerning the presence of childhood obesity did not result in appreciable improvement in LDL-C detection beyond that achieved by family history factors alone. It was concluded that if thorough identification of young children with elevated LDL-C is desired, inclusive population screening rather than a family history-based strategy would be the most effective approach. 相似文献
876.
C A González G López-Abente M Errezola A Escolar E Riboli I Izarzugaza M Nebot 《International journal of epidemiology》1989,18(3):569-577
A case-control study on bladder cancer was carried out in four regions of Spain. The study included 497 cases (438 males and 59 females), 583 hospital controls and 530 population controls matched by sex, age and residence. The present paper reports the results of the analyses on occupational history. Among men, an increased risk of bladder cancer was found for textile workers (OR = 1.97, 95% CL 1.2-3.3), mechanics and maintenance workers (OR = 1.86, 95% CL 1.2-2.8), workers in the printing industry (OR = 2.06, 95% CL 1.0-4.3) and for managers (OR = 2.03, 95% CL 1.2-3.5). The risk was highest among those first employed in the textile industry before the age of 25 and prior to 1960. Among mechanics the risk was highest for those who started after the age of 25 and later than 1960. The OR for smokers who had also been employed in one of the high risk occupations was 7.82 (95% CL 4.4-14.0) which is compatible with a multiplicative effect of joint exposure to tobacco and occupational hazards. 相似文献
877.
The intrathecal humoral immune response was analyzed in 83 patients with MS and 35 patients with acute CNS infections. CSF free kappa chains and CSF free lambda chains were quantified by radioimmunoassay; CSF IgG and albumin were measured by electroimmunodiffusion. The MS patients were characterized by higher levels of free kappa chains; free kappa:free lambda chain ratio; free kappa chain:albumin ratio; and IgG:albumin ratio. There were no differences in the level of free lambda chains or absolute concentration of IgG. A significant correlation was observed between free kappa chains and total IgG in MS and between free lambda chains and total IgG in infections, suggesting that the immune response was predominantly IgG-kappa in MS and IgG-lambda in infections. 相似文献
878.
Irradiation of a cytosolic fraction from vascular smooth muscle in the presence of [3H]felodipine resulted in the labelling of a protein with an apparent molecular weight of 62 kDa. The labelling was seen on UV-irradiation at 360 nm, but not at 254, 278 or at wavelengths above 410 nm. The photolabelling was enhanced in the absence of oxygen. In cytosolic fractions prepared from porcine liver, cardiac and skeletal muscle no photoaffinity labelling of proteins between 90 and 45 kDa could be demonstrated. The results suggest that felodipine is a photoaffinity ligand and that felodipine binds to a soluble protein present in vascular smooth muscle but not in the other tissues tested. 相似文献
879.
Concomitants of excess coronary deaths--major risk factor and lifestyle findings from 10,359 men and women in the Scottish Heart Health Study 总被引:9,自引:0,他引:9
The Scottish Heart Health Study is a study of lifestyle and coronary heart disease risk factors in 10,359 men and women aged 40-59 years, in 22 districts of Scotland. The study was conducted during 1984-86, when Scotland had the highest national coronary heart disease mortality reported by the World Health Organisation. A self-completed questionnaire, complemented by a 40 minute visit to a survey clinic, staffed by nurses, enabled the classical major risk factors and some more newly described ones to be measured. The study emphasised quality control and representativeness, and incorporated a World Health Organisation protocol for measurement of key items to allow comparisons in place and time, and therefore also to provide a definitive baseline against which interventions can be assessed. This paper describes the overall findings. Current cigarette smokers constitute 39% of men and 38% of women, higher levels than those reported in England but lower than previous Scottish reports. Mean blood pressure levels were 134/84 mmHg for men and 131/81 mmHg in women, lower than in British studies of the 1960s and 1970s. Mean body mass index levels, 26.1 Kg/m2 in men and 25.7 Kg/m2 in women, were not high by international standards. However, mean serum cholesterol levels were 6.4 mmol/l in men and 6.6 mmol/l in women--as high as those in previous British studies and high by international standards. Levels of high density lipoprotein cholesterol, non-fasting triglycerides and fibrinogen are also reported. Physical activity both at work and in leisure time was low.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
880.