全文获取类型
收费全文 | 602516篇 |
免费 | 38815篇 |
国内免费 | 1338篇 |
专业分类
耳鼻咽喉 | 7911篇 |
儿科学 | 19539篇 |
妇产科学 | 15675篇 |
基础医学 | 96829篇 |
口腔科学 | 16544篇 |
临床医学 | 51541篇 |
内科学 | 113000篇 |
皮肤病学 | 13999篇 |
神经病学 | 44311篇 |
特种医学 | 21901篇 |
外国民族医学 | 83篇 |
外科学 | 89558篇 |
综合类 | 10098篇 |
一般理论 | 165篇 |
预防医学 | 44096篇 |
眼科学 | 13537篇 |
药学 | 47829篇 |
3篇 | |
中国医学 | 1510篇 |
肿瘤学 | 34540篇 |
出版年
2019年 | 4924篇 |
2018年 | 6801篇 |
2017年 | 5069篇 |
2016年 | 5591篇 |
2015年 | 6245篇 |
2014年 | 8375篇 |
2013年 | 12951篇 |
2012年 | 17373篇 |
2011年 | 18957篇 |
2010年 | 11363篇 |
2009年 | 10447篇 |
2008年 | 17816篇 |
2007年 | 19024篇 |
2006年 | 19079篇 |
2005年 | 18289篇 |
2004年 | 18314篇 |
2003年 | 17508篇 |
2002年 | 17402篇 |
2001年 | 27396篇 |
2000年 | 28394篇 |
1999年 | 23275篇 |
1998年 | 6471篇 |
1997年 | 5527篇 |
1996年 | 5789篇 |
1995年 | 5361篇 |
1994年 | 4947篇 |
1992年 | 17368篇 |
1991年 | 17929篇 |
1990年 | 17797篇 |
1989年 | 17129篇 |
1988年 | 15805篇 |
1987年 | 15535篇 |
1986年 | 14707篇 |
1985年 | 13954篇 |
1984年 | 10346篇 |
1983年 | 8908篇 |
1982年 | 4989篇 |
1979年 | 9958篇 |
1978年 | 7252篇 |
1977年 | 6125篇 |
1976年 | 5925篇 |
1975年 | 6807篇 |
1974年 | 8104篇 |
1973年 | 7570篇 |
1972年 | 7360篇 |
1971年 | 7060篇 |
1970年 | 6503篇 |
1969年 | 6235篇 |
1968年 | 5879篇 |
1967年 | 5302篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
91.
The authors suggest additional criteria evidencing inflammations in the gallbladder and colloid stability of the bile: bile acid absorption and cholesterol sedimentation coefficients. Derivation of these coefficients is based on biochemical examination of the bile with measurements of bile acid, cholesterol, and bilirubin concentrations in both portions. The results of examinations of 99 subjects evidence the diagnostic value and specificity of the characteristics, and availability of this method for clinical practice. 相似文献
92.
Afterpotential characteristics and firing patterns in maturing rat hippocampal CA1 neurones in in vitro slices. 总被引:2,自引:0,他引:2
The postnatal evolution of depolarizing after-potentials (DAPs) and after-hyperpolarizations (AHPs) was studied in rat CA1 hippocampal neurones (5-68 days of age) using in vitro slices. Results were pooled into 4 age groups: P5-9, P10-16, P17-24 and P26-68. In P5-9 cells, DAPs were seen as passive signals, with a time constant similar to the time constant of the membrane. The evolution of the DAP was characterized by a decrease in amplitude, an increase in duration and a change in contour. In P10-16 and P17-24 cells, the DAPs often had a plateau or a hump-like shape which increased the probability of firing and the occurrence of spike doublets. The firing pattern and bursting behaviour of P10-16 CA1 neurones differed from the pattern typical of the adult. P5-9 and P10-16 cells had post-burst AHPs with a smaller amplitude and a more prolonged early phase than at late stages of development. 相似文献
93.
P Sacerdote F Rubboli L Locatelli I Ciciliato P Mantegazza A E Panerai 《Journal of neuroimmunology》1991,32(1):35-41
The concentrations of beta-endorphin and cholecystokinin were measured in fresh resting peripheral mononuclear cells obtained from rats and human subjects in basal conditions and after different pharmacological treatments. Both in the human and the rat, beta-endorphin concentrations in mononuclear cells, increased after treatment with serotoninergic agonists, decreased after dopaminergic or GABAergic drugs, while the respective antagonists exerted the opposite effect. In vitro, serotoninergic and GABAergic compounds confirmed their roles in the modulation of beta-endorphin in mononuclear cells. Cholecystokinin was never affected by the pharmacological treatments. 相似文献
94.
W I Schievink B Mokri V V Michels D G Piepgras 《Stroke; a journal of cerebral circulation》1991,22(11):1426-1430
BACKGROUND AND PURPOSE: The familial occurrence of intracranial aneurysms and cervical artery dissections has been described in different families and supports the hypothesis that a primary arteriopathy may play a role in the pathogenesis of these disorders. Although the basis for this arteriopathy is generally not believed to be similar among cases of intracranial aneurysms and cervical artery dissections, several similarities exist in the epidemiology of these disorders and a common underlying arterial abnormality may be suspected. SUMMARY OF REPORTS: The medical records of all 175 patients with spontaneous dissections of the cervical arteries who were seen at the Mayo Clinic between 1970 and 1989 were reviewed to identify families in which intracranial aneurysms and cervical dissections coexisted. Three families were identified in which intracranial aneurysms and cervical artery dissections were observed among siblings. These families are described in detail. CONCLUSIONS: The familial occurrence of intracranial aneurysms and cervical artery dissections within the same families provides support to the importance of a common underlying arteriopathy in the pathogenesis of both these disorders. The underlying vascular defect may, at least in some cases, be inherited. 相似文献
95.
We studied two patients which showed a paralysis of the oculomotor nerve on one side and isolated paralysis of the superior rectus on the other side. On the side of oculomotor nerve paralysis, midbrain infarct extending from the paramedian tegmentum to crus cerebri was demonstrated in one case who showed no recovery, and a small lacuna in midbrain tegmentum in another one who showed complete recovery. On the side of isolated paralysis of the superior rectus, no lesion was demonstrated by CT and MRI, and no clinical signs of the involvement of fiber tracts or nuclei were evident in both cases. A unilateral lesion of oculomotor nerve nucleus caused a paralysis of the contralateral superior rectus. 相似文献
96.
The involvement of excitatory amino acid (EAA) receptors in mediation of the toxic effects of cocaine was studied in male ICR mice. Cocaine HCl (90 mg/kg, IP) induced seizures in 95% and death within 24 h in 68% (n = 135) of the animals. There was a significant correlation (r = .54) between the time to onset of convulsions and the time to death in mice which died within 30 min of injection (n = 84). Pretreatment with selected EAA receptor antagonists 15 min prior to cocaine differentially blocked cocaine toxicity. Selective N-methyl-D-aspartic acid (NMDA) receptor antagonists (MK-801, dextrorphan, CPP) decreased both the incidence of seizures and mortality. A nonselective EAA antagonist, kynurenic acid, decreased lethality in doses which did not reduce convulsions. A similar action was observed following pretreatment with the selective kainic acid/AMPA receptor antagonist, GDEE. Antagonists at EAA receptors can provide significant protection against cocaine-induced toxicity. Moreover, the data provide evidence for the involvement of both NMDA and non-NMDA receptor subtypes in aspects of cocaine toxicity. 相似文献
97.
Oncologic screenings of the populations in the areas with increased incidence of esophageal cancer have revealed Barrett's ulcer in 1 percent of the examinees. Endoscopic and cytologic characteristics of this condition are presented. Precancer changes--severe dysplasia--are most frequent in male Kazakhs (14.1 percent) aged 50 to 59 (14.7 percent). Subjects with Barrett's ulcer developing severe dysplasia, as evidenced by cytograms, should be included in the group of subjects at risk for carcinoma of the lower third of the esophagus and cardia. 相似文献
98.
99.
100.
4-Aminopyridine affects synaptosomal protein phosphorylation in rat hippocampal slices 总被引:2,自引:0,他引:2
Rat brain hippocampal slices were incubated with or without the convulsant 4-aminopyridine (4-AP). From these slices a crude mitochondrial/synaptosomal membrane fraction was prepared and analyzed for endogenous protein phosphorylation. 4-AP (10(-5) M) stimulated the phosphorylation of a 50 kDa protein by 86%. The phosphorylation of this 50 kDa protein is Ca2+/calmodulin-dependent and we suggest that this protein is the lower molecular weight subunit of Ca2+/calmodulin-dependent protein kinase II (CaMK II). 相似文献