全文获取类型
收费全文 | 4483篇 |
免费 | 393篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 21篇 |
儿科学 | 159篇 |
妇产科学 | 182篇 |
基础医学 | 481篇 |
口腔科学 | 110篇 |
临床医学 | 410篇 |
内科学 | 776篇 |
皮肤病学 | 130篇 |
神经病学 | 507篇 |
特种医学 | 199篇 |
外科学 | 602篇 |
综合类 | 155篇 |
一般理论 | 1篇 |
预防医学 | 503篇 |
眼科学 | 45篇 |
药学 | 352篇 |
1篇 | |
中国医学 | 7篇 |
肿瘤学 | 248篇 |
出版年
2021年 | 55篇 |
2020年 | 43篇 |
2019年 | 63篇 |
2018年 | 98篇 |
2017年 | 59篇 |
2016年 | 48篇 |
2015年 | 76篇 |
2014年 | 97篇 |
2013年 | 162篇 |
2012年 | 224篇 |
2011年 | 220篇 |
2010年 | 150篇 |
2009年 | 145篇 |
2008年 | 211篇 |
2007年 | 238篇 |
2006年 | 234篇 |
2005年 | 214篇 |
2004年 | 241篇 |
2003年 | 204篇 |
2002年 | 201篇 |
2001年 | 86篇 |
2000年 | 91篇 |
1999年 | 75篇 |
1998年 | 64篇 |
1997年 | 82篇 |
1996年 | 63篇 |
1995年 | 71篇 |
1994年 | 56篇 |
1993年 | 29篇 |
1992年 | 66篇 |
1991年 | 69篇 |
1990年 | 64篇 |
1989年 | 56篇 |
1988年 | 71篇 |
1987年 | 52篇 |
1986年 | 59篇 |
1985年 | 42篇 |
1984年 | 44篇 |
1983年 | 48篇 |
1982年 | 40篇 |
1981年 | 49篇 |
1980年 | 40篇 |
1979年 | 40篇 |
1978年 | 43篇 |
1977年 | 35篇 |
1976年 | 32篇 |
1975年 | 30篇 |
1974年 | 40篇 |
1973年 | 28篇 |
1971年 | 33篇 |
排序方式: 共有4889条查询结果,搜索用时 812 毫秒
31.
Natural killer cell (NK) activity, which is important in the defense against tumors and viral infections, is reduced in women undergoing conjugal bereavement. The relationship between NK activity and plasma cortisol was investigated in three groups of subjects: women who were anticipating the death of their husbands, women whose husbands had recently died, and controls. Bereaved women showed reduced NK activity and increased plasma cortisol levels as compared to controls. Anticipatory bereaved women also showed significant reductions in NK activity, but had levels of plasma cortisol comparable to those of controls. The reduction of NK activity during anticipatory and actual bereavement cannot be explained solely on the basis of increased cortisol secretion. 相似文献
32.
The effects of withdrawal from continuous administration of cocaine on behavioral sensitivity to apomorphine and monoamine receptor density were examined in rats. Subdermal minipumps that delivered either saline or 20 mg/kg/day cocaine hydrochloride were implanted for 2 weeks. Apomorphine-induced stereotypy (0.5 mg/kg, SC) was examined in separate groups of rats either 4 hr or 7, 28, or 60 days after removal of the minipumps. Transient enhanced sensitivity to apomorphine-induced stereotypy occurred during the course of withdrawal. Animals withdrawn from cocaine for 4 hours did not differ from controls in their sensitivity to apomorphine, whereas animals withdrawn from cocaine for 7 days exhibited an increase in apomorphine-induced oral stereotypy relative to controls. However, the enhanced stereotypy response was no longer evident in animals withdrawn for 28–60 days. The animals were sacrificed after behavioral testing, and their brains were assayed for changes in monoamine receptor density in the frontal cortex, caudate-putamen, and nucleus accumbens. The density of 3H-SCH-23390-labeled D1 receptors was altered in all three regions examined in a time-dependent manner that paralleled the changes in behavioral sensitivity to apomorphine. There was a transient decrease in D1 receptor density that was evident by 7 days following withdrawal from continuous cocaine administration and was no longer evident 28 or 60 days posttreatment. There were no changes in 3H-spiroperidol-labeled D2 receptors, 125-pindolol-labeled β-adrenergic receptors, or 3H-ketanserin-labeled 5-HT2 receptors in any of the regions examined at both 4 hr and 7 days after termination of the cocaine infusion. These findings are discussed in terms of their relevance to developing pharmacologic treatments for withdrawal from cocaine. © 1994 Wiley-Liss, Inc. 相似文献
33.
Paul Steinbok Brendon Irvine D. Douglas Cochrane Beverly J. Irwin 《Child's nervous system》1992,8(2):92-96
The long-term functional outcome of 101 children born with meningomyelocele between 1971 and 1981 was assessed, by a combination of retrospective chart review and follow-up assessments. The children had been managed at birth using a process ofnonstandardized selection. Eighty-three of the 101 patients survived after a minimum follow-up of 8.6 years, for a mortality rate of 18%. Forty-four of 83 children (53%) were community ambulators, and this correlated well with the presence of intact quadriceps function. Forty-eight children (58%) attended normal school and were grade-appropriate. Sixty-two of 83 patients (75%) were socially continent of urine, and 71/83 (86%) were socially continent of stool. Hydrocephalus was present in 93 of the 101 children in the study, and 85 children were shunted. Half of the shunted children required a shunt revision in the first year of life, and thereafter the rate of revision decreased, so that after 2 years the risk of revision was approximately 10% per year. 相似文献
34.
35.
Protection against DSP-4-induced neurotoxicity by deprenyl is not related to its inhibition of MAO B 总被引:2,自引:0,他引:2
K T Finnegan J J Skratt I Irwin L E DeLanney J W Langston 《European journal of pharmacology》1990,184(1):119-126
Clinical studies suggest that deprenyl may retard the progression of Parkinson's disease, an effect that may be related to its monoamine oxidase (MAO) inhibiting properties. Deprenyl also protects against the neurodegenerative effects of the noradrenergic toxin DSP-4. In this study we investigated the role of MAO B inhibition in this protection. C57BL/6 mice were given DSP-4 (50 mg/kg i.p.) 1 h. 24 h or 4 days after the administration of deprenyl (10 mg/kg i.p.) or the selective MAO B inhibitor MDL 72974 (1.25 mg/kg), and then killed 1 week later for assay of hippocampal norepinephrine. The MAO B inhibiting effects of deprenyl or MDL 72974 were also determined after these same intervals of time. Deprenyl and MDL 72974 produced comparable degrees of enzyme inhibition 1 h (greater than 95%), 24 h (greater than 90%) or 4 days (greater than 70%) after their administration. Given 1 h before, deprenyl totally blocked the norepinephrine-depleting effects of DSP-4, but this protection declined sharply when 24 h or 4 days was allowed to elapse between deprenyl and DSP-4 administration. MDL 72974 failed to protect at any time point. In vitro, we detected no activity using DSP-4 as a substrate for MAO. These findings suggest that the ability of deprenyl to protect against DSP-4-induced neuronal degeneration may not depend on its MAO B inhibiting properties. 相似文献
36.
37.
38.
39.
Lysia S. Forno J. William Langston Louis E. DeLanney Ian Irwin George A. Ricaurte 《Annals of neurology》1986,20(4):449-455
Systemic administration of the recently discovered neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produces severe clinical parkinsonism and degeneration of the substantia nigra in humans and monkeys. In previous studies, no convincing structural damage to nerve cells outside the substantia nigra could be demonstrated in subhuman primates. Using a protracted MPTP regimen and older animals, we now report locus ceruleus lesions and eosinophilic inclusion bodies in squirrel monkeys. The inclusions were seen only in areas where Lewy bodies are found in human Parkinson's disease. No such abnormalities were seen in control animals. These findings suggest that similarities between the neuropathology of MPTP-induced parkinsonism in the monkey and human Parkinson's disease are greater than first thought and increase the usefulness of the MPTP monkey model for research in Parkinson's disease. 相似文献
40.