全文获取类型
收费全文 | 29430篇 |
免费 | 2619篇 |
国内免费 | 52篇 |
专业分类
耳鼻咽喉 | 245篇 |
儿科学 | 1079篇 |
妇产科学 | 821篇 |
基础医学 | 4124篇 |
口腔科学 | 635篇 |
临床医学 | 3715篇 |
内科学 | 5389篇 |
皮肤病学 | 424篇 |
神经病学 | 3183篇 |
特种医学 | 595篇 |
外科学 | 2822篇 |
综合类 | 433篇 |
一般理论 | 56篇 |
预防医学 | 3995篇 |
眼科学 | 655篇 |
药学 | 2008篇 |
中国医学 | 38篇 |
肿瘤学 | 1884篇 |
出版年
2023年 | 242篇 |
2022年 | 274篇 |
2021年 | 576篇 |
2020年 | 422篇 |
2019年 | 655篇 |
2018年 | 722篇 |
2017年 | 560篇 |
2016年 | 566篇 |
2015年 | 648篇 |
2014年 | 936篇 |
2013年 | 1378篇 |
2012年 | 1933篇 |
2011年 | 2012篇 |
2010年 | 1096篇 |
2009年 | 1044篇 |
2008年 | 1695篇 |
2007年 | 1870篇 |
2006年 | 1841篇 |
2005年 | 1796篇 |
2004年 | 1727篇 |
2003年 | 1615篇 |
2002年 | 1532篇 |
2001年 | 390篇 |
2000年 | 400篇 |
1999年 | 343篇 |
1998年 | 344篇 |
1997年 | 312篇 |
1996年 | 235篇 |
1995年 | 239篇 |
1994年 | 178篇 |
1993年 | 195篇 |
1992年 | 229篇 |
1991年 | 230篇 |
1990年 | 212篇 |
1989年 | 201篇 |
1988年 | 178篇 |
1987年 | 175篇 |
1986年 | 180篇 |
1985年 | 182篇 |
1984年 | 168篇 |
1983年 | 170篇 |
1982年 | 152篇 |
1981年 | 159篇 |
1980年 | 145篇 |
1979年 | 127篇 |
1978年 | 120篇 |
1976年 | 109篇 |
1975年 | 101篇 |
1974年 | 107篇 |
1973年 | 127篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
The mechanism of action of systemitically administered(±)-MDMA (3, 4-methylenedioxymethamphetamine) on spontaneously active neurons in the medial prefrontal cortex (mPFc) of chloral hydrate anesthetized rats was examined using standard single unit extracellular recording techniques. Intravenously administered MDMA dose-dependently decreased the firing rates of the majority of mPFc neurons in control rats. In contrast, in rats that were pretreated withp-chlorophenylalanine (PCPA), which depletes the brain serotonin (5-hydroxytryptamine, 5-HT) content by inhibiting tryptophan hydroxylase, the rate-limiting enzyme in the synthesis of 5-HT, MDMA was largely ineffective in inhibiting the firing of mPFc cells. In PCPA-treated animals, the administration of 5-hydroxytryptophan (5-HTP), which presumably restored the brain 5-HT content, but notl-DOPA, reinstated MDMA's inhibitory action in PCPA-treated rats. In rats that were pretreated withα-methyl-p-tyrosine (AMPT), which depletes the brain dopamine (DA) content by inhibiting tyrosine hydroxylase, the rate-limiting enzyme in the synthesis of DA, MDMA inhibited the firing of all of the mPFc cells. MDMA's effect on mPFc neurons was reversed by 5-HT receptor antagonists such as granisetron and metergoline. These results strongly suggest that MDMA exerts its action on mPFc cells indirectly by releasing endogenous 5-HT. 相似文献
32.
Antibiotic prophylaxis and secondary haemorrhage following transurethral resection of the prostate: a prospective trial 总被引:2,自引:0,他引:2
One hundred and sixty-two patients were studied in a random double-blind controlled trial of co-trimoxazole to prevent secondary haemorrhage following transurethral resection of the prostate (TURP). There was a significant correlation between the incidence of post-operative urinary infection and secondary haemorrhage (P less than 0.05) but no difference between the incidence of bleeding in the treatment and placebo groups. Although infection may play a role in the development of secondary haemorrhage, co-trimoxazole for 10 days does not decrease the incidence of this complication. 相似文献
33.
34.
35.
Minor Psychiatric Morbidity, Its Prevalence and Outcome in a Cohort of Civil Servants A Seven-year Follow-up Study 总被引:1,自引:0,他引:1
Jenkins R.; Harvey S.; Butler T.; Lloyd Thomas R. 《Occupational medicine (Oxford, England)》1996,46(3):209-215
During the years 1979–1986, a cohort of direct entrantexecutive officers in the Civil Service were followed up toexamine the prevalence and outcome of minor psychiatric morbidityin an occupational setting. All studies using epidemiologicalstandardized research methods agree, that prevalence rates arehigh in occupational settings. As in primary care settings,half of the illness episodes followed a chronic course, whichemphasizes the need for early detection and prompt managementof these conditions, and for evaluative studies of interventionstrategies. 相似文献
36.
Paul Corcoran Michael J. Kelleher Helen S. Keeley Sinéad Byrne Ursula Burke Eileen Williamson 《Archives of Suicide Research》1997,3(1):65-74
This paper presents a statistical model constructed using logisticregression to identify those at high-risk of repeating parasuicide. Thesubjects in the study are Cork city residents who exhibited parasuicidalbehaviour between 1 January and 30 June 1995. Repetition of the behaviourwithin six months of the index episode distinguishes repeaters fromnon-repeaters. The model was designed so that it could be used bynon-clinicians and hence does not require information relating topsychiatric diagnosis or use of psychiatric services. The proportion ofsubjects correctly classified remained stable across a range of cut-pointprobabilities (mean = 86%, range: 83.9–87.5%). Using acut-point of 0.2, 96% of repeaters and 81% of non-repeaters were correctly classified. Using 0.45 led to the correct identification of81% of repeaters and 90% of non-repeaters. If these highlevels of sensitivity and specificity are maintained in validation tests onfuture cohorts in Cork city then the model could form the basis of anintervention programme designed to prevent the repetition of parasuicide. 相似文献
37.
Alan T. Villavicencio MD Lloyd A. Hey MD Dhavalkumar Patel MD PhD Peter Bressler MD 《The Journal of allergy and clinical immunology》1997,100(6):853-854
J Allergy Clin Immunol 1997;100:853-4. 相似文献
38.
Jeffrey A. Gray Stephen N. Mitchell Michael H. Joseph Grigory A. Grigoryan Sharon Dawe Helen Hodges 《Drug development research》1994,31(1):3-17
Data are reviewed, largely from experiments in the authors'laboratory, that suggest three modes of action of systemic nicotine in producing three different types of effect upon behavior and cognitive function. (1) Preexposure of a stimulus without consequence makes it harder subsequently to form associations to that stimulus, a form of selective attention known as latent inhibition. Latent inhibition is blocked by nicotine, an effect that is apparently mediated by a nicotine-induced increase in dopamine release in the nucleus accumbens. (2) A single dose of nicotine proactively increases the partial reinforcement extinction effect measured several weeks later: that is, resistance to extinction is decreased by nicotine in animals that have been trained on a continuous reinforcement schedule, and increased in animals trained on a partial reinforcement schedule. This effect appears to be due to increased synthesis of tyrosine hydroxylase in the cell bodies of noradrenergic neurons in the locus coeruleus, followed by axonal transport to the hippocampus and increased synthesis and release of noradrenaline in that structure. (3) Nicotine improves vigilance in animals with cognitive deficits due to destruction of the forebrain cholinergic projection system, either as a consequence of excitotoxic lesions of the nuclei of origin of this system or after prolonged alcohol consumption; and also in human subjects with Alzheimer's disease (in which this system undergoes degeneration). This effect is most likely due to an action at denervated cholinergic synapses in the hippocampus and neocortex. © 1994 Wiley-Liss, Inc. 相似文献
39.
Alma Au Agnes S Chan Helen Chiu 《Journal of the International Neuropsychological Society》2003,9(3):363-375
Many recent findings in Western countries suggest that episodic recall is the most sensitive discriminator between patients with mild Alzheimer disease (AD) and the normal elderly, while semantic memory tends best to differentiate between moderate and severe AD patients. The present study is the first to examine in detail the episodic memory of Chinese AD patients in Hong Kong with a locally developed list learning test, comparing procedures that do or do not encourage the use of semantic organization. The performance of 28 AD patients was compared to that of 30 normal controls. AD patients did significantly worse in terms of acquisition and retention and also benefited significantly less from external organization cues. In the discriminant function analysis, the rate of forgetting in the random condition and the total retention score in the blocked condition were found to be the best predictors for differentiating between AD patients and controls. On the other hand, in the differentiation between mild and moderate AD, semantic clustering in the blocked condition was found to be the best predictor. Results of the present study were discussed in the light of the previous findings reported in the Western countries and the neuropathological changes of AD patients. 相似文献
40.