全文获取类型
收费全文 | 2476251篇 |
免费 | 183738篇 |
国内免费 | 5542篇 |
专业分类
耳鼻咽喉 | 35097篇 |
儿科学 | 78714篇 |
妇产科学 | 71621篇 |
基础医学 | 348016篇 |
口腔科学 | 71087篇 |
临床医学 | 216292篇 |
内科学 | 487838篇 |
皮肤病学 | 57236篇 |
神经病学 | 201228篇 |
特种医学 | 96190篇 |
外国民族医学 | 879篇 |
外科学 | 376701篇 |
综合类 | 57724篇 |
现状与发展 | 8篇 |
一般理论 | 865篇 |
预防医学 | 184641篇 |
眼科学 | 57826篇 |
药学 | 180310篇 |
5篇 | |
中国医学 | 5443篇 |
肿瘤学 | 137810篇 |
出版年
2018年 | 25341篇 |
2017年 | 19675篇 |
2016年 | 22020篇 |
2015年 | 24785篇 |
2014年 | 35092篇 |
2013年 | 52860篇 |
2012年 | 70566篇 |
2011年 | 74708篇 |
2010年 | 44229篇 |
2009年 | 42588篇 |
2008年 | 70247篇 |
2007年 | 75290篇 |
2006年 | 76301篇 |
2005年 | 74023篇 |
2004年 | 71153篇 |
2003年 | 68350篇 |
2002年 | 66810篇 |
2001年 | 119247篇 |
2000年 | 122321篇 |
1999年 | 102686篇 |
1998年 | 28487篇 |
1997年 | 25862篇 |
1996年 | 25404篇 |
1995年 | 24091篇 |
1994年 | 22199篇 |
1993年 | 20722篇 |
1992年 | 78695篇 |
1991年 | 75632篇 |
1990年 | 73444篇 |
1989年 | 70905篇 |
1988年 | 65657篇 |
1987年 | 64271篇 |
1986年 | 61124篇 |
1985年 | 58010篇 |
1984年 | 43993篇 |
1983年 | 37220篇 |
1982年 | 22590篇 |
1981年 | 20367篇 |
1979年 | 40555篇 |
1978年 | 28822篇 |
1977年 | 24611篇 |
1976年 | 22578篇 |
1975年 | 24674篇 |
1974年 | 29318篇 |
1973年 | 28547篇 |
1972年 | 27061篇 |
1971年 | 24918篇 |
1970年 | 23769篇 |
1969年 | 22547篇 |
1968年 | 21270篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Patterns of care: an analysis of the quality of nutritional care routinely provided to elderly hospitalized veterans 总被引:2,自引:0,他引:2
D H Sullivan M S Moriarty R Chernoff D A Lipschitz 《JPEN. Journal of parenteral and enteral nutrition》1989,13(3):249-254
To assess the adequacy of the nutritional care provided, a prospective noninterventional study was carried out on 250 randomly selected patients aged 65 and over who were admitted to a Veterans Administration Hospital. Of this group, 97 patients (39%) were found to be at high risk of having clinically significant protein-energy malnutrition. In 43 cases (17%), an assessment of the patient's nutritional status was not possible because the available data were inadequate. No patient had a diagnosis of malnutrition recorded on the problem list. Only 13 percent of the high-risk patients received some form of nutrition support therapy; 10 (10%) received oral supplements, and four (4%) were started on enteral feedings. Patients who received enteral feedings experienced a high rate of complications resulting from use of the feeding tubes. Over all, none of the high risk study patients received optimal nutrition support therapy. These findings indicate that elderly patients hospitalized in the Veterans Administration hospital in this study are usually not screened appropriately for protein-energy malnutrition, the diagnosis is frequently missed or ignored, and nutrition support therapy is underutilized and often ineffectually managed. 相似文献
992.
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
993.
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
994.
The present study was undertaken to define the response of plasma beta-endorphin immunoreactivity (ir-BE) to exercise of increasing intensity. Nineteen healthy males performed continuous exercise for 32 min on a cycle ergometer, comprised of 8-min bouts at %VO2max approximating 25, 50, and 75% of maximal exercise. Venous blood samples were collected before exercise (T = -20 and 0 min), during exercise (T = 8, 16, 24, and 32 min), and in recovery (T = +15, +30 min). Ir-BE in plasma was measured by radioimmunoassay using Immuno Nuclear assay kits. Plasma ir-BE level (pg X ml-1) was not altered from pre-exercise (18.3 +/- 1.3) after 8 min of exercise at 25 and 50% VO2max intensity; however, ir-BE rose significantly after 8 min of 75% VO2max work intensity (27.1 +/- 2.4) and was further elevated at maximal exercise (74.1 +/- 8.6). Ir-BE level remained elevated 15 min (60.9 +/- 8.1) and 30 min (35.2 +/- 5.2) post-exercise. The response pattern was further characterized by a significant (P less than 0.05) inter-individual variation, both at rest and during exercise; also, regression analysis indicated the ir-Be levels attained at maximal exercise were inversely related to the relative VO2max (ml X kg-1 X min-1) of the subject (predicted ir-BE = 248.2 - 3.39 VO2max; r = -0.397, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
995.
Evidence for a defect in urinary concentrating ability in primary aldosteronism and its reversal by adrenal surgery 总被引:1,自引:0,他引:1
Of 15 patients with primary aldosteronism, 7 had idiopathic adrenal hyperplasia (IHA) and 8 had aldosterone-producing adenoma (APA). In order to determine any renal problems involved in the treatment, the renal clearance of these patients was analyzed and the results compared with those obtained from 12 patients with essential hypertension. With water diuresis or under antidiuresis status, levels of urine volume, Cosm and CH2O in patients with APA were greater (p less than 0.05-p less than 0.001) than those of patients with essential hypertension, while the fractional tubular sodium delivery of the former patients was lower than that of the latter patients (p less than 0.001 or less than 0.05). A similar tendency was observed in clearance studies in patients with IHA, although to a lesser extent. Adrenal surgery for patients with APA normalized these values, but administration of trilostane (3 beta-hydrosteroid dehydrogenase inhibitor) to patients with IHA failed to improve these values. These results indicate that impaired urinary concentrating ability as well as reduced urinary diluting capability is a common feature of primary aldosteronism. Such impaired renal function was improved only in patients with APA after adrenal surgery. 相似文献
996.
A case of testicular cancer in 2 brothers is reported and a review of the literature about testicular malignancies and etiologic factors in closely related family members is given. The familial incidence of testicular tumor is found to be 3% in twins and 0.6-2.1% in less closely related men. Tumors were of the same histology in 70-77% of the twins, whereas in brothers and in other degrees of relationship tumors of different histology mostly occur. Following the diagnosis of the tumor in the first man, the average interval to presentation of the tumor in the relative was 3.7 years in twins, 7.7 years in nontwin brothers and 13.5 years for less closely related men. The need for a thorough checkup of other family members is advised. 相似文献
997.
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
998.
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
999.
1000.