全文获取类型
收费全文 | 2026篇 |
免费 | 169篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 87篇 |
妇产科学 | 31篇 |
基础医学 | 263篇 |
口腔科学 | 21篇 |
临床医学 | 240篇 |
内科学 | 298篇 |
皮肤病学 | 13篇 |
神经病学 | 434篇 |
特种医学 | 32篇 |
外科学 | 157篇 |
综合类 | 35篇 |
一般理论 | 1篇 |
预防医学 | 86篇 |
眼科学 | 26篇 |
药学 | 113篇 |
1篇 | |
中国医学 | 4篇 |
肿瘤学 | 351篇 |
出版年
2023年 | 16篇 |
2022年 | 23篇 |
2021年 | 52篇 |
2020年 | 44篇 |
2019年 | 46篇 |
2018年 | 52篇 |
2017年 | 36篇 |
2016年 | 44篇 |
2015年 | 48篇 |
2014年 | 47篇 |
2013年 | 76篇 |
2012年 | 106篇 |
2011年 | 96篇 |
2010年 | 72篇 |
2009年 | 62篇 |
2008年 | 115篇 |
2007年 | 131篇 |
2006年 | 111篇 |
2005年 | 106篇 |
2004年 | 96篇 |
2003年 | 80篇 |
2002年 | 82篇 |
2001年 | 25篇 |
2000年 | 31篇 |
1999年 | 49篇 |
1998年 | 27篇 |
1997年 | 20篇 |
1996年 | 15篇 |
1995年 | 19篇 |
1994年 | 12篇 |
1993年 | 14篇 |
1992年 | 51篇 |
1991年 | 53篇 |
1990年 | 41篇 |
1989年 | 32篇 |
1988年 | 26篇 |
1987年 | 30篇 |
1986年 | 17篇 |
1985年 | 15篇 |
1984年 | 19篇 |
1982年 | 25篇 |
1981年 | 14篇 |
1980年 | 12篇 |
1979年 | 18篇 |
1978年 | 9篇 |
1974年 | 7篇 |
1973年 | 9篇 |
1972年 | 11篇 |
1971年 | 8篇 |
1970年 | 10篇 |
排序方式: 共有2201条查询结果,搜索用时 15 毫秒
1.
2.
P Riekkinen M Riekkinen H Lahtinen J Sirvi? A Valjakka P Riekkinen 《Brain research bulletin》1991,27(5):587-594
The present study examines whether tetrahydroaminoacridine (THA) can improve the deterioration in passive avoidance (PA) retention performance induced by medial septal (MS) and fimbria-fornix (FF) lesions in young rats or by aging. Retention of young MS-lesioned rats was improved by pretraining injection of THA at 3 mg/kg, but not by THA at 1 mg/kg or by either of the posttraining doses of THA (1 and 3 mg/kg). Pretraining injections of THA at 1 or 3 mg/kg had no effect on the PA retention performance of FF-lesioned rats. Age-induced PA failure was alleviated by pretraining administration of THA at 1 and 3 mg/kg. Posttraining injections of THA (1 or 3 mg/kg) had no effect on PA retention performance of aged rats. These results demonstrate that 1) THA may improve hippocampal cholinergic denervation-induced functional deficits and 2) some of the age-related PA deficits may be due to a cholinergic deficit and can be reversed with THA. 相似文献
3.
Anke Sambeth Minna Huotilainen Elena Kushnerenko Vineta Fellman Elina Pihko 《Clinical neurophysiology》2006,117(3):496-503
OBJECTIVE: We investigated whether newborns respond differently to novel and deviant sounds during quiet sleep. METHODS: Twelve healthy neonates were presented with a three-stimulus oddball paradigm, consisting of frequent standard (76%), infrequent deviant (12%), and infrequent novel stimuli (12%). The standards and deviants were counterbalanced between the newborns and consisted of 500 and 750 Hz tones with two upper harmonics. The novel stimuli contained animal, human, and mechanical sounds. All stimuli had a duration of 300 ms and the stimulus onset asynchrony was 1s. Evoked magnetic responses during quiet sleep were recorded and averaged offline. RESULTS: Two deflections peaking at 345 and 615 ms after stimulus onset were observed in the evoked responses of most of the newborns. The first deflection was larger to novel and deviant stimuli than to the standard and, furthermore, larger to novel than to deviant stimuli. The second deflection was larger to novel and deviant stimuli than to standards, but did not differ between the novels and deviants. CONCLUSIONS: The two deflections found in the present study reflect different mechanisms of auditory change detection and discriminative processes. SIGNIFICANCE: The early brain indicators of novelty detection may be crucial in assessing the normal and abnormal cortical function in newborns. Further, studying evoked magnetic fields to complex auditory stimulation in healthy newborns is needed for studying the newborns at-risk for cognitive or language problems. 相似文献
4.
Jouni Sirvi Hannele Lahtinen Paavo Riekkinen Jr. Paavo J. Riekkinen 《Experimental neurology》1994,125(2)
The present experiment studied whether a dysfunction of the noradrenergic neurons is related to spatial learning impairment by investigating the levels of noradrenaline in the brain and periphery as well as the acquisition of water maze task in saline-pretreated young rats, in noradrenergic neurotoxin (DSP-4)-pretreated young rats and in saline-pretreated aged rats. Aged rats, which had an increased escape latency onto the hidden platform, revealed a decreased noradrenaline content in the heart, but not in the hippocampus, striatum, or hypothalamus, whereas DSP-4-pretreated rats had decreased noradrenaline content in the brain; the acquisition of water maze task was not impaired. These results suggest that the peripheral noradrenergic system can show age-related changes different from those in the central noradrenergic system, and they failed to provide support for the hypothesis that decreased activity of the central noradrenergic nerves is related to impairment in the acquisition of the water maze task. 相似文献
5.
Production and secretion of neuroendocrine peptides by small cell lung cancer (SCLC) has been detected in the past years. Most recently the role of bombesin as an autocrine/paracrine growth modifier has been demonstrated. We used the soft agarose clonogenic assay to evaluate the influence of other neuroendocrine peptides on the in vitro proliferation of SCLC cell lines. Neuroendocrine peptides tested were adrenocorticotropic hormone, arginine vasopressin, calcitonin, glucagon, kassinin, neurotensin, physalaemin, somatostatin, and substance P. Experiments were carried out in serum-free and serum-supplemented media with and without serum-free incubation periods. Our results indicated that the amphibian undecapeptide physalaemin inhibits the clonal and mass culture growth of SCLC cell lines at picomolar concentrations. All other neuroendocrine peptides failed to influence SCLC growth in the test systems used. These results suggest a growth regulating effect of physalaemin and a potential new form of neuroendocrine peptide therapy for SCLC. 相似文献
6.
Neill Booth Antti Jula Pasi Aronen Minna Kaila Timo Klaukka Katriina Kukkonen-Harjula Antti Reunanen Pekka Rissanen Harri Sintonen Marjukka Mäkelä 《BMC health services research》2007,7(1):172
Background
Hypertension is one of the major causes of disease burden affecting the Finnish population. Over the last decade, evidence-based care has emerged to complement other approaches to antihypertensive care, often without health economic assessment of its costs and effects. This study looks at the extent to which changes proposed by the 2002 Finnish evidence-based Current Care Guidelines concerning the prevention, diagnosis, and treatment of hypertension (the ACCG scenario) can be considered cost-effective when compared to modelled prior clinical practice (the PCP scenario). 相似文献7.
Paavo Riekkinen Jr. Jouni Sirvi Pekka Jkl Maria Mazurkiewicz Antti Valjakka Minna Riekkinen Paavo Riekkinen 《Brain research bulletin》1991,27(2):287-289
Quisqualic acid NBM lesions had no effect on water maze performance, but slightly impaired passive avoidance acquisition. GammavinylGABA treatment alone had no effect on the passive avoidance and water maze performance, but aggravated acquisition deficit in rats subjected to NBM lesioning. However, gammavinylGABA-treated NBM-lesioned rats reached control level of performance. 相似文献
8.
P. Riekkinen Jr. P. Jkl J. Sirvi E. Koivisto R. Miettinen P. Riekkinen 《Brain research bulletin》1991,26(4):633-637
The effectiveness of THA (an anticholinesterae) on scopolamine (0.4 mg/kg) and nucleus basalis (NB) lesion-induced change in neocortical spectral electroencephalography (EEG) were investigated. Scopolamine increased the amplitudes of all the spectral components in waking-immobility. In the movement-related EEG spectral values, only the alpha power was increased. THA 7.5 mg/kg, but not THA 3 mg/kg, could reverse scopolamine-induced amplitude change. NB lesioning increased delta and theta amplitudes, but decreased beta amplitude. Delta amplitude was increased during movement recordings in NB-lesioned rats. THA 7.5 mg/kg and pilocarpine 10 mg/kg, but not THA 3 mg/kg, could partially reverse the increase of delta and theta amplitudes induced by NB lesions. However, the beta power decrease could not be restored with cholinomimetics. This study demonstrates that quantitative EEG activity analysis may reflect the THA-induced restoration of the function of the cholinergic nucleus basalis. 相似文献
9.
Toivo Halonen† Asla Pitkanen Esa Koivisto Juhani Partanen‡ Paavo J. Riekkinen 《Epilepsia》1992,33(1):122-127
Vigabatrin (gamma-vinyl GABA; GVG) is a new antiepileptic drug (AED) that increases the level of the inhibitory transmitter, gamma-aminobutyric acid (GABA) in the brain. We evaluated the effect of GVG on the EEG of normal rats. GVG was administered intraperitoneally (i.p.) at a dose of 100 mg/kg once a day for 12 days. EEG was recorded at baseline, on the fourth day, at the end of the 12-day GVG period and 10 days after discontinuation of GVG. GVG increased the amplitude of delta (1-4 Hz) and theta (4-8 Hz) frequency bands and resulted in slowing of the peak frequency (Fp) and mean frequency (Fm) in both the frontal and occipital cortex, especially during waking-immobility. EEG changes normalized within 10 days after the last GVG injections. The results suggest that a relationship may exist between the EEG changes and increase in GABA levels with GVG. 相似文献
10.
Paavo Riekkinen Jr. Minna Riekkinen Antti Valjakka Paavo Riekkinen Jouni Sirvio
《Brain research》1992,570(1-2):293-299
The present study examines the effects of noradrenergic lesions (either DSP-4 i.p. or 6-hydroxydopamine (6-OHDA) into the dorsal noradrenergic bundle on biochemical (noradrenaline (NA), dopamine (DA), serotonin (5-HT) and choline acetyltransferase (ChAT) activity) and cortical EEG (quantitative EEG (qEEG) and high-voltage spindle (HVS) activity in young and aged rats. Near complete 6-OHDA NA lesions, but not partial DSP-4 NA lesions, increased HVS activity in young rats. DSP-4 and 6-OHDA lesions produced no significant changes in the 5-HT or DA levels or in the ChAT activity in young rats. In some of the aged rats, DSP-4 produced similar biochemical and HVS effects, as it induced in young rats. In the remainder of the aged rats, NA levels were greatly and 5-HT levels slightly decreased. DA levels and ChAT activity were unaltered in either set of aged rats. HVS activity was increased only in that group of aged rats with the greatly lowered NA content. These results suggest that: (1) some of the aged rats are more sensitive to DSP-4 treatment than young adult rats; and (2) NA depletions have to be complete to produce an increase in HVS activity in young and aged rats. 相似文献