全文获取类型
收费全文 | 83093篇 |
免费 | 8194篇 |
国内免费 | 160篇 |
专业分类
耳鼻咽喉 | 1185篇 |
儿科学 | 2528篇 |
妇产科学 | 1789篇 |
基础医学 | 11852篇 |
口腔科学 | 2010篇 |
临床医学 | 10202篇 |
内科学 | 14650篇 |
皮肤病学 | 1295篇 |
神经病学 | 6734篇 |
特种医学 | 2889篇 |
外国民族医学 | 10篇 |
外科学 | 11421篇 |
综合类 | 1689篇 |
一般理论 | 67篇 |
预防医学 | 9487篇 |
眼科学 | 1852篇 |
药学 | 6761篇 |
1篇 | |
中国医学 | 77篇 |
肿瘤学 | 4948篇 |
出版年
2021年 | 1114篇 |
2020年 | 738篇 |
2019年 | 1120篇 |
2018年 | 1398篇 |
2017年 | 1007篇 |
2016年 | 1096篇 |
2015年 | 1247篇 |
2014年 | 1646篇 |
2013年 | 2580篇 |
2012年 | 3472篇 |
2011年 | 3744篇 |
2010年 | 1989篇 |
2009年 | 1911篇 |
2008年 | 3232篇 |
2007年 | 3546篇 |
2006年 | 3418篇 |
2005年 | 3478篇 |
2004年 | 3255篇 |
2003年 | 3024篇 |
2002年 | 2960篇 |
2001年 | 2720篇 |
2000年 | 2829篇 |
1999年 | 2516篇 |
1998年 | 1092篇 |
1997年 | 904篇 |
1996年 | 894篇 |
1995年 | 805篇 |
1994年 | 832篇 |
1993年 | 751篇 |
1992年 | 2096篇 |
1991年 | 2023篇 |
1990年 | 1897篇 |
1989年 | 1867篇 |
1988年 | 1780篇 |
1987年 | 1788篇 |
1986年 | 1694篇 |
1985年 | 1675篇 |
1984年 | 1392篇 |
1983年 | 1265篇 |
1982年 | 840篇 |
1981年 | 722篇 |
1979年 | 1214篇 |
1978年 | 873篇 |
1977年 | 762篇 |
1976年 | 719篇 |
1975年 | 715篇 |
1974年 | 859篇 |
1973年 | 752篇 |
1972年 | 733篇 |
1971年 | 640篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
R J Smith 《The British journal of ophthalmology》1989,73(7):481-482
12.
Alpha-adrenoreceptor reagents. 4. Resolution of some potent selective prejunctional alpha 2-adrenoreceptor antagonists 总被引:1,自引:0,他引:1
A P Welbourn C B Chapleo A C Lane P L Myers A G Roach C F Smith M R Stillings I F Tulloch 《Journal of medicinal chemistry》1986,29(10):2000-2003
The resolution of three 2-substituted derivatives of idazoxan is described. The enantiomers show large separations in activity in a variety of in vitro and in vivo tests, and the active isomers are all potent and selective antagonists at the alpha 2-adrenoreceptor. The significance of these results in relation to those published on the enantiomers of idazoxan and to those on optically active alpha 2-adrenoreceptor agonists is discussed. 相似文献
13.
A Messineo R M Filler B Bahoric C Smith A Bahoric 《Journal of pediatric surgery》1991,26(11):1296-1300
A major problem in tracheal transplantation is the restoration of an adequate vascular supply to the transplanted trachea. In 12 piglets, a segment (6 rings) of thoracic trachea was removed and the excised segment was then sutured back in place. In 9 animals (group A), a vascularized omental flap was wrapped around the autotransplanted trachea. In the other 3 pigs (group B), the omentum was not used. Eight of 9 group A pigs were killed, 1 or 2 months later, having had no signs of airway obstruction; the 9th pig was killed after 14 days because of airway obstruction. The 3 pigs in group B were killed after 11 to 13 days because of progressive respiratory obstruction. In the 8 asymptomatic pigs in group A, the omental flap was viable and tracheal growth was normal with no differences in diameter between normal and autotransplanted trachea. Histologically intact cartilage was lined with respiratory epithelium. In the one group A pig who was killed early, the omental flap was necrotic. In this pig and in the 3 group B animals, extensive tracheal necrosis and nonviable cartilage were observed. These findings indicate that in the pig, a 6-ring segment of trachea can be transplanted with vascularization provided by an omental flap. 相似文献
14.
Complete Freund's adjuvant (CFA) administered before sensitization dampened the normal and cyclophosphamide-enhanced response of high and moderate IgE responder phenotype mice (CAF1 and C57B1/6J, respectively). CFA-induced suppression of IgE biosynthesis was effective in reducing anaphylactic histamine release from approximately 2,900 ng histamine per milliliter to background levels (less than 100 ng/ml). CFA-induced ascites fluid was able to reduce the cyclophosphamide-enhanced IgE response of low-responder phenotype SJL mice from 1:320 to less than 1:5 as determined by passive cutaneous anaphylaxis. Muramyl dipeptide, a mycobacterial cell wall component capable of eliciting effects similar to those seen with CFA, was shown to induce suppression of IgE production if incorporated in incomplete Freund's adjuvant. Muramyl dipeptide administered in saline was ineffective, while incomplete Freund's adjuvant alone had some immunoregulatory properties. Ongoing IgE responses were less susceptible to regulation. CFA administered to sensitized C57B1/6J mice was ineffective in inducing IgE suppression when animals were challenged with antigen. 相似文献
15.
Horner's syndrome or oculosympathetic paralysis is not an uncommon finding in patients with head and neck neoplasms. While in most cases the syndrome is easily established at the bedside, it can be confirmed and topographically defined as a central, preganglionic, or postganglionic lesion through sequential pharmacologic testing. The importance of such localization lies in differentiating neoplasia vs. a benign condition as the cause of the syndrome. Such variants as congenital Horner's, an alternating Horner's, and a pseudo-Horner's syndrome are discussed in regard to their differential features. 相似文献
16.
17.
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
18.
Adenocarcinoma of the lower esophagus. A disease primarily of white men with Barrett's esophagus 总被引:3,自引:0,他引:3
E L Rogers S F Goldkind O A Iseri M Bustin L Goldkind S R Hamilton R L Smith 《Journal of clinical gastroenterology》1986,8(6):613-618
Sex and racial predilection, social history, and histology were analyzed in a biopsy-proven adenocarcinoma of the lower esophagus/esophagogastric junction collected over a 5-year period in two teaching institutions with different patient populations. Adenocarcinoma occurred in 11% of patients with biopsy-proven esophageal cancer. The disease occurred only in males at one center, and in a 7:1 ratio of males to females at the other center. Clear racial predilection was seen, since 12 of 13 patients with adenocarcinoma of the esophagus were white, whereas less than 20% of patients with squamous carcinoma of the esophagus were white. The finding of Barrett's epithelium in eight of the 13 cases strongly supports the theory that in white males, Barrett's epithelium is a precursor lesion of adenocarcinoma of the esophagus/esophagogastric junction. 相似文献
19.
20.
S. Ahmed A. L. Sparnon J. P. Savage H. A. Boucaut A. J. Smith 《ANZ journal of surgery》1986,56(9):675-680
One hundred and one children over 1 year of age have had surgery for pelviureteric obstruction over an 11 year period. The common clinical features were abdominal pain, urinary infection or haematuria, but number presented as an incidental finding. Less commonly, the patients presented with an abdominal mass or with hypertension. The diagnosis was usually made on intravenous pyelography (IVP) but in the latter part of the series, renal nuclide scan (RNS) and ultrasonography (US) were preferred. Ninety–three patients had unilateral pyeloplasty, three had bilateral pyeloplasty and five had nephrectomy or heminephrectomy. Whereas initially nephrostomy drainage was used in the majority of patients after pyeloplasty, trend away from nephrostomy evolved in the latter part of the series. With experience, the incidence of postoperative complications was also reduced and there was reduction in the period of hospitalization. Clinical results were consistently satisfactory. Postoperative assessment after pyeloplasty was made by IVP and/or RNS and also US. A review of these investigations showed that RNS provided more factual information of the result when compared with the IVP. 相似文献