全文获取类型
收费全文 | 2016789篇 |
免费 | 145283篇 |
国内免费 | 9767篇 |
专业分类
耳鼻咽喉 | 27347篇 |
儿科学 | 65172篇 |
妇产科学 | 55348篇 |
基础医学 | 286326篇 |
口腔科学 | 55607篇 |
临床医学 | 185975篇 |
内科学 | 381484篇 |
皮肤病学 | 44802篇 |
神经病学 | 153947篇 |
特种医学 | 78409篇 |
外国民族医学 | 539篇 |
外科学 | 300728篇 |
综合类 | 56817篇 |
现状与发展 | 24篇 |
一般理论 | 635篇 |
预防医学 | 148298篇 |
眼科学 | 47118篇 |
药学 | 156638篇 |
65篇 | |
中国医学 | 9122篇 |
肿瘤学 | 117438篇 |
出版年
2021年 | 18122篇 |
2019年 | 16984篇 |
2018年 | 23403篇 |
2017年 | 18438篇 |
2016年 | 20558篇 |
2015年 | 24167篇 |
2014年 | 32697篇 |
2013年 | 45565篇 |
2012年 | 62042篇 |
2011年 | 66155篇 |
2010年 | 39428篇 |
2009年 | 36174篇 |
2008年 | 59266篇 |
2007年 | 63094篇 |
2006年 | 63993篇 |
2005年 | 61754篇 |
2004年 | 58052篇 |
2003年 | 55488篇 |
2002年 | 53291篇 |
2001年 | 98646篇 |
2000年 | 101474篇 |
1999年 | 85315篇 |
1998年 | 23435篇 |
1997年 | 20871篇 |
1996年 | 20703篇 |
1995年 | 19600篇 |
1994年 | 17918篇 |
1993年 | 16581篇 |
1992年 | 65129篇 |
1991年 | 62948篇 |
1990年 | 62059篇 |
1989年 | 59743篇 |
1988年 | 54115篇 |
1987年 | 53496篇 |
1986年 | 50083篇 |
1985年 | 47722篇 |
1984年 | 35182篇 |
1983年 | 29666篇 |
1982年 | 17004篇 |
1979年 | 31868篇 |
1978年 | 22143篇 |
1977年 | 19387篇 |
1976年 | 17541篇 |
1975年 | 19097篇 |
1974年 | 22636篇 |
1973年 | 21904篇 |
1972年 | 20533篇 |
1971年 | 19195篇 |
1970年 | 17698篇 |
1969年 | 16860篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A family with two members (two generations) exhibiting Turner syndrome is described. Cytogenetic studies on these individuals showed the presence of multiple X chromosome changes. Evidence is presented to show that the maternally inherited X chromosome is the chromosome involved in the structural alterations observed. The effect of a tendency of the maternal X chromosome to break at specific sites on the development of the Turner phenotype and abnormal karyology is discussed. 相似文献
992.
G K Freeman 《The British journal of general practice》1989,39(321):145-147
The influence of receptionists on continuity of care in four group practices was examined. Twenty two receptionists were observed making 543 appointments and afterwards were interviewed about their personal priority for continuity of care. One of the practices ran a personal list system. It was found that the personal list practice attracted more requests for a specific doctor and time which were then more difficult to satisfy. Most receptionists thought it was important that patients should see the same doctor but their influence seemed to be small compared with that of the doctor as expressed in practice policies. Marked variation in demand for individual doctors was seen in two of the practices without a personal list system. 相似文献
993.
Studies were made on whether substance P-, leucine-enkephalin- and 5-hydroxytryptamine (serotonin)-like immunoreactive fibers exert a direct influence on the cremaster motoneurons of the male rat by immunocytochemistry combined with retrograde tracing at the light- and electron-microscopic levels. Horseradish peroxidase was used as a retrograde tracer. Two days after injection of horseradish peroxidase into the genitofemoral nerves, its accumulation in the cremaster motoneurons was demonstrated by the diaminobenzidine-nickel method. On immunocytochemical examination of the same sections immunoreactive end-products were detected by the peroxidase-antiperoxidase method. Two different kinds of reaction products were distinguishable at both the light- and electron-microscopical levels. The horseradish peroxidase-labeled cremaster motoneurons at the L1 and L2 levels of the spinal cord were surrounded by abundant immunoreactive terminals. Examination at the ultrastructural level showed that substance P-like immunoreactive terminals formed synaptic contacts almost exclusively with the proximal dendrites of these horseradish peroxidase-labeled cremaster motoneurons. On the other hand, in the leucine-enkephalin- and serotonin-like boutons, significant numbers of axosomatic contacts with horseradish peroxidase-labeled cells were seen although axodendritic contacts with horseradish peroxidase-labeled cells were predominant. Occasionally, leucine-enkephalin-like immunoreactive fibers with synapses on horseradish peroxidase-labeled neurons formed axoaxonic contacts with other leucine-enkephalin-like axonal terminals. Thus, substance P-, leucine-enkephalin- and serotonin-like fibers clearly regulate the function of cremaster motoneurons monosynaptically. The varied synaptic contacts of these fibers according to the neuroactive substances involved suggest different actions of these substances on the cremaster motoneurons. 相似文献
994.
995.
Lack of effect of aspartame or of L-phenylalanine on photically induced myoclonus in the baboon, Papio papio 总被引:1,自引:0,他引:1
The effects of large doses of L-phenylalanine and of aspartame on seizure susceptibility and severity have been assessed in baboons Papio papio from Senegal which show photosensitive epileptic responses similar to primary generalised epilepsy in man. L-Phenylalanine, 50, 150 or 450 mg/kg, or aspartame, 300 or 1000 mg/kg, were administered orally. Peak plasma L-phenylalanine concentrations of approximately 2000 mumoles/l occurred 1-4 h after the highest dose of L-phenylalanine or aspartame. The plasma L-phenylalanine to large neutral amino acid ratio increased approximately 30-fold at this time. Compared with water administration there were no changes in epileptic responses 1-5 h after either treatment. In this primate model of epilepsy acute increases in plasma phenylalanine concentration are neither pro- nor anticonvulsant. 相似文献
996.
Michael K. Gardner Elaine Clark Mary Ann C. Bowman Patrick J. Miller 《Alcoholism, clinical and experimental research》1989,13(4):508-511
This study investigated analogical reasoning abilities of alcoholics who had been abstinent from alcohol for at least 1 year. Their performance was compared to that of nonalcoholic controls matched as a group for education, age, and gender. Solution times and error rates were modeled using a regression model. Results showed a nonsignificant trend for alcoholics to be faster, but more error prone, than controls. The same componential model applied to both groups, and fit them equally well. Although differences have been found in analogical reasoning ability between controls and alcoholics immediately following detoxification, we find no evidence of differences after extended periods of sobriety. 相似文献
997.
B A Sommerville C G Scanes R Swaminathan A D Care S Harvey A Chadwick 《General and comparative endocrinology》1989,76(2):261-266
An experiment was carried out to investigate the effect of a range of estradiol (E2) doses (0.1-6.5 micrograms/g body wt/day) on vitamin D metabolism and the plasma levels of growth hormone (GH) and prolactin (PRL) in the growing chick. Doses of 0.5-0.7 microgram/g E2, which are insufficient to raise the plasma calcium level, did induce an increase in growth rate, an increase in 25-hydroxyvitamin D 1 alpha-hydroxylase (1-hydroxylase) and 24-hydroxylase activities, and an increase in plasma GH level. These parameters leveled off or fell over the dose range 1-2 micrograms/g E2 but there was evidence of a second peak in 1-hydroxylase activity at 6 micrograms/g E2. At this high dose rate, the plasma Ca level rose to 8 mM, as it does in the laying hen; 24-hydroxylase activity, growth rate, and plasma GH and plasma PRL levels all decreased. It was concluded that the dose response to estrogen in the growing chick is not linear and, in the case of 1-hydroxylase activity, may even be biphasic. 相似文献
998.
999.
Addison's disease is rarely caused by metastatic cancer. We report a unique case of hypoadrenalism owing to metastatic transitional cell carcinoma of the bladder. The relevant literature is reviewed. 相似文献
1000.