全文获取类型
收费全文 | 247640篇 |
免费 | 21956篇 |
国内免费 | 11224篇 |
专业分类
耳鼻咽喉 | 1514篇 |
儿科学 | 5952篇 |
妇产科学 | 3312篇 |
基础医学 | 46663篇 |
口腔科学 | 4828篇 |
临床医学 | 16925篇 |
内科学 | 41245篇 |
皮肤病学 | 3956篇 |
神经病学 | 19293篇 |
特种医学 | 4825篇 |
外国民族医学 | 81篇 |
外科学 | 16965篇 |
综合类 | 35088篇 |
现状与发展 | 50篇 |
一般理论 | 1篇 |
预防医学 | 11670篇 |
眼科学 | 3211篇 |
药学 | 29663篇 |
26篇 | |
中国医学 | 8081篇 |
肿瘤学 | 27471篇 |
出版年
2024年 | 622篇 |
2023年 | 3605篇 |
2022年 | 7420篇 |
2021年 | 9518篇 |
2020年 | 8076篇 |
2019年 | 9055篇 |
2018年 | 8522篇 |
2017年 | 8562篇 |
2016年 | 8667篇 |
2015年 | 10127篇 |
2014年 | 14266篇 |
2013年 | 16551篇 |
2012年 | 14783篇 |
2011年 | 17680篇 |
2010年 | 14960篇 |
2009年 | 14414篇 |
2008年 | 14075篇 |
2007年 | 13113篇 |
2006年 | 12076篇 |
2005年 | 10609篇 |
2004年 | 9371篇 |
2003年 | 8020篇 |
2002年 | 6480篇 |
2001年 | 5663篇 |
2000年 | 4735篇 |
1999年 | 4174篇 |
1998年 | 3600篇 |
1997年 | 3180篇 |
1996年 | 2596篇 |
1995年 | 2204篇 |
1994年 | 1847篇 |
1993年 | 1482篇 |
1992年 | 1205篇 |
1991年 | 1052篇 |
1990年 | 872篇 |
1989年 | 699篇 |
1988年 | 590篇 |
1987年 | 470篇 |
1986年 | 467篇 |
1985年 | 859篇 |
1984年 | 857篇 |
1983年 | 592篇 |
1982年 | 671篇 |
1981年 | 530篇 |
1980年 | 430篇 |
1979年 | 376篇 |
1978年 | 286篇 |
1977年 | 225篇 |
1976年 | 209篇 |
1975年 | 144篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Central nervous system (CNS) progenitor cells transiently proliferate in the embryonic neural tube and give rise to neurons and glial cells. A characteristic feature of the CNS progenitor cells is expression of the intermediate filament nestin and it was previously shown that the rat nestin second intron functions as an enhancer, directing gene expression to CNS progenitor cells. In this report we characterize the nestin enhancer in further detail. Cloning and sequence analysis of the rat and human nestin second introns revealed local domains of high sequence similarity in the 3' portion of the introns. Transgenic mice were generated with the most conserved 714 bp in the 3' portion of the intron, or with the complete, 1852 bp, human second intron, coupled to the reporter gene lacZ. The two constructs gave a very similar nestin-like expression pattern, indicating that the important control elements reside in the 714 bp element. Expression was observed starting in embryonic day (E)7.5 neural plate, and at E10.5 CNS progenitor cells throughout the neural tube expressed lacZ. At E12.5, lacZ expression was more restricted and confined to proliferating regions in the neural tube. An interesting difference, compared to the rat nestin second intron, was that the human intron at E10.5 mediated lacZ expression also in early migrating neural crest cells, which is a site of endogenous nestin expression. In conclusion, these data show that a relatively short, evolutionarily conserved region is sufficient to control gene expression in CNS progenitor cells, but that the same region differs between rodents and primates in its capacity to control expression in neural crest cells. 相似文献
82.
Demetrius M Maraganore Matthew J Farrer Timothy G Lesnick Mariza de Andrade James H Bower Dena Hernandez John A Hardy Walter A Rocca 《Movement disorders》2003,18(11):1233-1239
We conducted a case-control study of the alpha-synuclein-interacting protein gene (SNCAIP, also known as synphilin-1) and Parkinson's disease (PD). A total of 319 PD cases and 195 controls were genotyped for four SNCAIP variants, including a microsatellite repeat in intron 4 and three restriction fragment length polymorphisms (RFLP) proximal to the 5' terminal of exons 1, 4, and 6. None of the variants were found associated with PD overall. Global score statistics were not significant for four, three, and two loci haplotypes. All four loci were in linkage disequilibrium for cases, controls, or both groups combined (P < 0.0001). Recursive partitioning showed no interactions between variants of the SNCAIP gene and variants of the alpha-synuclein gene (SNCA) or the parkin (PARK2) gene. 相似文献
83.
选择南方热区某特种部队战士52人,分两组分别口服5mgVitB1和VitB2,收集4h尿液,用荧光法进行负荷试验。结果:VitB1组,所测29人中,15人缺乏,9人不足,2人正常,3人充裕;VitB2组,所测23人中,11人缺乏,12人不足,反映该部队全年约5%的发病是由于VitB1、VitB2缺乏不足所致。其原因为膳食摄入不够 相似文献
84.
85.
86.
R. Raininko I. Elovaara E. Poutiainen A. Virta L. Valanne M. Haltia J. Lhdevirta 《European journal of neurology》1997,4(2):143-151
The course of the organic brain disease caused by human immunodeficency virus (HIV-1) was evaluated in a follow-up study. The primary material included 200 consecutive HIV-1 infected persons. Sixty-one subjects, in whom other brain-affecting factors were excluded, consented to the follow-up. They underwent 278 radiologic examinations: computed tomography, magnetic resonance imaging, or a combination of both (mean 4.6 examinations/subject). Clinical neurologic status and, in 40 subjects, cognitive performance were repeatedly evaluated. Sixteen subjects were followed up until death and 11 of them were autopsied. Median follow-up time was 27 mo (range 2.5–66 mo). The most common radiologic finding was atrophy, found in 19 subjects at study entry and developing in 10 subjects during the study. Twenty-four subjects (39%) showed the development and/or progression of atrophy. Atrophic changes progressed most rapidly in acquired immunodeficiency syndrome (AIDS), but mild developing/progressive atrophy was found even in 33% of asymptomatic or neurologically intact subjects. Cognitive and radiologic worsening were simultaneous in 6/7 subjects with declining neuropsychologic test performance. Signal intensity changes including HIV-1 leukoencephalopathy appeared in AIDS patients with clear cognitive decline. 相似文献
87.
Philip J. Larsen David S. Jessop Hardial S. Chowdrey Stafford L. Lightman Jens D. Mikkelsen 《Journal of neuroendocrinology》1994,6(2):153-159
The complete sequence of the cDNA encoding the neuropeptide Y (NPY) Y1-receptor has recently been deduced from a rat brain library, and the presence of messenger ribonucleic acid (mRNA) encoding Y1-receptor protein has been demonstrated within the brain. Using quantitative in situ hybridization histochemistry, the content and distribution of Y1receptor and preproNPY mRNAs have been investigated in the hypothalamic arcuate nucleus of adrenalectomized rats receiving glucocorticoid replacement therapy for 12 days by means of either high doses of dexamethasone in their drinking water or by subcutaneous corticosterone pellets. Basal metabolic parameters such as weight gain or loss, blood glucose and plasma insulin were monitored: Dexamethasone treatment induced weight loss and a state of hyperinsulinemia with normoglycemia, while corticosterone treated animals displayed metabolic parameters identical to sham ADX animals. Within the arcuate nucleus of glucocorticoid treated animals, levels of Y1receptor and preproNPY mRNAs were increased. In contrast, adrenalectomy itself had no effect upon Y1-receptor mRNA levels or preproNPY mRNA levels in the arcuate nucleus. These studies demonstrate that glucocorticoids exert a stimulatory action on levels of Y1-receptor mRNA and preproNPY mRNA levels in the hypothalamic arcuate nucleus. This is the first evidence to suggest that the expression of a neuropeptide-receptor gene in the central nervous system may be directly sensitive to peripheral hormonal signals. 相似文献
88.
本文报告口服Sumatriptan 100mg对偏头痛急性发作119例次的治疗结果。治疗后4h内显效91例次(76.5%),好转16例次(13.4%),无效12例次(10.1%),总有效率为89.9%。对偏头痛伴随症状恶心、呕吐和畏光、畏声的缓解率分别为94.2%、96%和94.3%。 相似文献
89.
90.
Alan L Whone Sarah Von Spiczak Mark Edwards Enza-Maria Valente Alexander Hammers Kailash P Bhatia David J Brooks 《Movement disorders》2004,19(12):1498-1503
The opioid transmitters enkephalin and dynorphin are known to regulate pallidal output and consequently cortical excitability. Indeed, abnormal basal ganglia opioid transmission has been reported in several involuntary movement disorders, including levodopa-induced dyskinesias in Parkinson's disease (PD), tardive dyskinesias/dystonia, Huntington's disease, and Tourette's syndrome. Moreover, a previous 11C-diprenorphine PET study investigating levodopa-induced dyskinesias found reduced opioid receptor availability in PD with but not without dyskinesias. We wished to investigate if a similar alteration in basal ganglia opioid binding was present in DYT1 primary torsion dystonia (PTD). Regional cerebral 11C-diprenorphine binding was investigated in 7 manifesting carriers of the DYT1 gene and 15 age-matched normal controls using a region-of-interest (ROI) approach and statistical parametric mapping (SPM). No difference in regional mean 11C-diprenorphine binding was found between DYT1-PTD and controls, and no correlation between the severity of dystonia and opioid binding was seen. We conclude that aberrant opioid transmission is unlikely to be present in DYT1-PTD and altered opioid transmission is not a common mechanism underlying all disorders of involuntary movement. 相似文献