全文获取类型
收费全文 | 118761篇 |
免费 | 7170篇 |
国内免费 | 1580篇 |
专业分类
耳鼻咽喉 | 1578篇 |
儿科学 | 2977篇 |
妇产科学 | 4109篇 |
基础医学 | 18323篇 |
口腔科学 | 3614篇 |
临床医学 | 9285篇 |
内科学 | 21633篇 |
皮肤病学 | 2440篇 |
神经病学 | 8013篇 |
特种医学 | 4029篇 |
外国民族医学 | 3篇 |
外科学 | 16759篇 |
综合类 | 5216篇 |
一般理论 | 34篇 |
预防医学 | 8689篇 |
眼科学 | 2842篇 |
药学 | 10208篇 |
中国医学 | 821篇 |
肿瘤学 | 6938篇 |
出版年
2021年 | 993篇 |
2019年 | 1052篇 |
2018年 | 1617篇 |
2017年 | 1174篇 |
2016年 | 1206篇 |
2015年 | 1449篇 |
2014年 | 1891篇 |
2013年 | 2450篇 |
2012年 | 3561篇 |
2011年 | 3810篇 |
2010年 | 2292篇 |
2009年 | 2050篇 |
2008年 | 3390篇 |
2007年 | 3619篇 |
2006年 | 3602篇 |
2005年 | 3166篇 |
2004年 | 2977篇 |
2003年 | 2773篇 |
2002年 | 2627篇 |
2001年 | 6734篇 |
2000年 | 6922篇 |
1999年 | 5697篇 |
1998年 | 1830篇 |
1997年 | 1377篇 |
1996年 | 935篇 |
1995年 | 862篇 |
1992年 | 3728篇 |
1991年 | 3808篇 |
1990年 | 3549篇 |
1989年 | 3553篇 |
1988年 | 3428篇 |
1987年 | 3277篇 |
1986年 | 3090篇 |
1985年 | 2967篇 |
1984年 | 2048篇 |
1983年 | 1792篇 |
1982年 | 985篇 |
1979年 | 1909篇 |
1978年 | 1184篇 |
1977年 | 986篇 |
1976年 | 918篇 |
1975年 | 1191篇 |
1974年 | 1358篇 |
1973年 | 1413篇 |
1972年 | 1357篇 |
1971年 | 1247篇 |
1970年 | 1137篇 |
1969年 | 1121篇 |
1968年 | 1024篇 |
1967年 | 897篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
61.
Measurements of the fetal eyeball and its pattern of growth 总被引:1,自引:0,他引:1
62.
63.
64.
Computed tomographic (CT) scans of the brain in a child with Smith-Lemli-Opitz syndrome revealed enlargement of the ventricular system, hypoplasia of the cerebellum, and abnormal thickening of the gray matter, consistent with pachygyria. These findings have been previously noted in autopsies performed on patients with this disorder. We conclude that CT scanning is a valuable tool in the evaluation of children suspected of having the Smith-Lemli-Opitz syndrome. 相似文献
65.
本文介绍香港九龙海底铁路建设中高气压作业与减压病发病情况。该工程有11条坑道,共计259 448个高压工作日,减压288 140人次,发生减压病1 534例。根据不同的工作压力,以暴露次数、高压工作日数及暴露4小时以上次数3种方法分别计算减压病发病率。结果表明:各种方法计算出的发病率都有随工作压力增高而上升的趋势,说明现用的减压表对不同的工作压力达不到同样的预防效果。本文还对3大主要工种和14个小工种的减压病作了分析。 相似文献
66.
Normal seminal vesicles were studied histologically in 80, and by Feulgen’s cytophotometric method in 10 autopsied cases (males,
44–82 years of age). In every case large, hyperchromatic nuclei were found. By cytophotometry euploid polyploid atypia was
also shown in every case, which is characteristic of benign hormonal dysplasia. 相似文献
67.
G E Davies A V Thompson Z Niewola G E Burrows E L Teasdale D J Bird D A Phillips 《Occupational and environmental medicine》1983,40(4):442-449
Twenty four volunteers who had been allergic to laboratory animals for some years were examined by means of a questionnaire paying particular attention to symptoms associated with rats and by serological and skin tests with extracts of rat urine (retrospective study). Nasal and eye symptoms were reported by 21 and 16 individuals respectively: 13 had asthma. Positive skin tests and high levels of specific IgE antibody to rat urine extract were found in 17 of the more severely affected individuals and this group included 12 of those with asthma. Latent periods of work with animals before symptoms appeared varied from 0.5 to 12 years. Also 148 individuals were studied during their first year of work with animals (prospective study). Symptoms developing during the year were reported by 15%, asthma by 2%. IgE antibody levels to rat urine were raised in 40% of affected and 6% of the unaffected individuals but there was no significant correlation between symptoms and either antibody levels or positive skin tests. Allergic symptoms developing during the first year of postemployment were, on the whole, much milder than those seen in the retrospective study. A tentative conclusion is that most individuals who become allergic to laboratory animals develop the condition in a mild form during their first year of employment but it appears probable that atopic individuals, although having an equal chance of developing allergy as compared with non-atopic individuals, may eventually progress to a more severe form of the disease. 相似文献
68.
S Amartur Z P Liang F Boada E M Haacke 《Journal of magnetic resonance imaging : JMRI》1991,1(6):721-724
The authors present an improvement to a sigma-filter extrapolation method for the reconstruction of magnetic resonance (MR) images from symmetric discrete Fourier data. By making use of the phase information in the image data, the proposed method can overcome the data inconsistency problem of the original method for handling MR image data with large phase variations, such as those obtained in gradient-echo pulse sequences. Reconstruction results show that its performance is comparable with that of the modified complex sigma-filter method proposed previously to handle the inconsistency problem. However, the new approach has the advantage of reducing computation time by a factor of two with use of a sigma filter applied to real instead of complex images. It is expected that this method will be more practical for use in clinical MR imaging systems. 相似文献
69.
K Mahmood M N Chowdhury E A Ayoola I A Mofleh R S Rashed F Z Faleh 《Tropical gastroenterology》1991,12(4):188-191
Seventy seven antral biopsies were collected from patients attending endoscopy clinic at King Khalid University Hospital, Riyadh, Saudi Arabia during a period of six months between December 1988 to May 1989. Of these 69 (89.6%) showed chronic gastritis as well as Helicobacter-like organisms (HLOs) in the biopsy specimens while 63 (81.8%) of biopsies grew Helicobacter pylori on culture. These findings indicate a good correlation between the histological diagnosis of chronic gastritis and isolation of H. pylori on culture. 相似文献
70.
Rats exposed on their first postnatal day to 100% nitrogen for 25 min developed hyperactivity and lower performance in passive avoidance task during development. Administration of MK-801 (0.5 mg/kg i.p.) 1 h before anoxia or (0.25 and 0.5 mg/kg) 1 h after completely reversed this behavioral impairment. Senescent rats (24-26 months) exposed to hypoxia (92% N2 + 8% O2) for 5 h failed in their performance in C.A.R., 30 days later. Pretreatment with MK-801 (1 mg/kg i.p.) completely reversed this impairment. These data suggest that activation of endogenous NMDA receptors produces different behavioral consequences in neonatal and senescent rats and that MK-801 administration close to exposure of animals to anoxia or hypoxia can prevent such damage, thus preventing behavioral impairments in postnatal as well as in senescent rats. 相似文献