全文获取类型
收费全文 | 16035篇 |
免费 | 982篇 |
国内免费 | 74篇 |
专业分类
耳鼻咽喉 | 95篇 |
儿科学 | 396篇 |
妇产科学 | 410篇 |
基础医学 | 2415篇 |
口腔科学 | 530篇 |
临床医学 | 1260篇 |
内科学 | 3850篇 |
皮肤病学 | 354篇 |
神经病学 | 1539篇 |
特种医学 | 366篇 |
外国民族医学 | 2篇 |
外科学 | 1565篇 |
综合类 | 60篇 |
一般理论 | 6篇 |
预防医学 | 1517篇 |
眼科学 | 365篇 |
药学 | 1211篇 |
中国医学 | 94篇 |
肿瘤学 | 1056篇 |
出版年
2023年 | 100篇 |
2022年 | 235篇 |
2021年 | 476篇 |
2020年 | 276篇 |
2019年 | 421篇 |
2018年 | 563篇 |
2017年 | 314篇 |
2016年 | 437篇 |
2015年 | 474篇 |
2014年 | 661篇 |
2013年 | 801篇 |
2012年 | 1265篇 |
2011年 | 1327篇 |
2010年 | 657篇 |
2009年 | 605篇 |
2008年 | 1025篇 |
2007年 | 1075篇 |
2006年 | 966篇 |
2005年 | 867篇 |
2004年 | 723篇 |
2003年 | 751篇 |
2002年 | 677篇 |
2001年 | 251篇 |
2000年 | 223篇 |
1999年 | 203篇 |
1998年 | 134篇 |
1997年 | 111篇 |
1996年 | 100篇 |
1995年 | 76篇 |
1994年 | 67篇 |
1993年 | 80篇 |
1992年 | 120篇 |
1991年 | 99篇 |
1990年 | 87篇 |
1989年 | 97篇 |
1988年 | 76篇 |
1987年 | 67篇 |
1986年 | 73篇 |
1985年 | 58篇 |
1984年 | 55篇 |
1983年 | 39篇 |
1982年 | 29篇 |
1981年 | 36篇 |
1980年 | 29篇 |
1979年 | 32篇 |
1978年 | 24篇 |
1976年 | 17篇 |
1975年 | 17篇 |
1974年 | 24篇 |
1966年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
61.
62.
63.
64.
A 72-year-old man presented with an apparent frontal syndrome. He also had bilateral trigeminal neuralgia, a pyramidal syndrome of all 4 limbs, balance disturbances, a horizontal nystagmus when looking to the left and a right velopalatine paralysis. CT scan with contrast showed a hyperdense rounded lesion in the left cerebello-pontine angle. Cerebral angiography showed this to be a large aneurysm of the end of the vertebral arteries. The patient died suddenly. Autopsy confirmed the site and presence of the aneurysm. Balance disturbances, the pyramidal syndrome and velopalatine paralysis could all be explained by brain stem compression and the bilateral nature of the trigeminal neuralgia by compression of the trigemino-thalamic tract. The apparent frontal syndrome, the authors suggest could have resulted from subacute raised intracranial pressure. 相似文献
65.
Antonella d’Arminio Monforte Paola Cinque Luca Vago Aleandro Rocca Antonella Castagna Cristina Gervasoni Maria Rosa Terreni Roberto Novati Andrea Gori Adriano Lazzarin Mauro Moroni 《Journal of neurology》1996,244(1):35-39
Twenty patients with AIDS who had intracranial lesions underwent both brain biopsy and cerebro-spinal fluid (CSF) examination
to compare histological diagnosis with the polymerase chain reaction (CSF-PCR) for the identification of infectious agents.
CSF-PCR was performed for herpes simplex virus, varicella zoster virus, cytomegalovirus (CMV), JC virus (JCV), Epstein-Barr
virus (EBV), Toxoplasma gondii and Mycobacterium tuberculosis. A definitive diagnosis was obtained by brain biopsy in 14 patients (2 with astrocytoma, 12 with brain infection). CSF-PCR
was positive for EBV DNA in 3 of 3 cases of primary cerebral lymphoma, positive for JCV DNA in 6 of 7 biopsy-proven (and one
autopsy-proven) cases of progressive multifocal leukoencephalopathy (PML). CSF-PCR was positive for CMV DNA in one biopsy-proven
and one autopsy-proven case of CMV encephalitis (the former also had PML) and positive for M. tuberculosis DNA in one case of tuberculous encephalitis. None of the five toxoplasmic encephalitis cases (one definite, four presumptive)
were T. gondii DNA positive. There was close correlation between histology and CSF-PCR for CMV encephalitis, PML and PCL. Antitoxoplasma
therapy affected the sensitivity of both histological and CSF-PCR methods.
Received: 8 November 1995 Received in revised form: 9 July 1996 Accepted: 19 July 1996 相似文献
66.
67.
Garcea Renato; Danio Lucia; Frassetto Serenella; Cozzolino Patrizia; Ruggiu Maria E.; Vannini Maria G.; Pascale Rosa; Lenzerini Luciano; Simile Maria M.; Puddu Marco; Feo Francesco 《Carcinogenesis》1988,9(6):931-938
The effect of dehydroepiandrosterone (DHEA) on the activityof NADPH-producing enzymes and the development of enzyme-alteredfoci has been investigated in the liver of female Wistar ratssubjected to an initiating treatment (a necrogenic dose of diethylnitrosaimine)followed, 15 days later, by a selection treatment [a 15-dayfeeding of a diet containing 0.03% 2-acetylamlnofluorene (2-AAF),with a partial hepatectomy at the midpoint of this feeding].At the end of the selection treatment all rat groups received,for 15 days, a basal diet containing, when indicated, 0.05%phenobarbital (PB) and/or 0.6% DHEA. The effect of DHEA on theactivity of NADPH producing enzymes was also studied in normalrats fed, for 15 days, a diet containing 0.6% DHEA and in theirpair-fed controls. DHEA caused a 4358% inhibition ofglucose-6-phosphate dehydrogenase (G6PD) and, respectively,338420% and 2124% increases in malic enzyme (ME)and isocitric dehydrogenase activities in all rat groups. Thiswas coupled with a great fall in the production of ribulose-5-phosphate,while no change in NADP+/NADPH ratio occurred. Hepatocytes,isolated from DHEA-treated rats, exhibited a very low activityof hexose monophosphate shunt (HMS), which was not stimulatedby methylene blue, an exogenous oxidizing agent that markedlystimulated HMS activity in control hepatocytes. DHEA causeda great fall in the percentage of liver occupied by -glutamyltranspeptidase(GGT)-positive foci, in the rats subjected to the initiation- selection treatments. PB enhanced the development of thesefoci, an effect which was completely overcome by DHEA. In addition,focal cells no longer expressed a G6PD activity higher thanthat of surrounding liver in DHEA-treated rats, but exhibiteda high histochemical reaction for ME. DHEA also caused a greatfall in labelling index of GGT-positive foci. Starting at theend of 2-AAF feeding, a mixture of ribonucleosides (RNs) ofadenine, cytosine, guanine and uracil and of deoxyribonucleosides(DRNs) of adenine, cytosine, guanine and thymine were injectedi.p. every 8 h for 12 days to the rats subjected to the initiation- selection treatments plus PB. Rats were killed 3 days afterthe end of RN and DRN treatments. These treatments completelyovercome the DHEA effect on the development of GGT-positivefoci and DNA synthesis by the focal cells, without affectingG6PD activity of both whole liver and putative preneoplasticfoci. Experiments with labeled nucleosides revealed that RNsand DRNs produced derivatives that were incorporated into liverDNA. These data indicate that liver of DHEA-treated rats produceenough NADPH for reduction of RNs to DRNs and growth. The antipromotingeffect of DHEA could depend on a relative deficiency of nudeosidesfor DNA synthesis, caused by a great fall in pentose phosphateproduction. 相似文献
68.
S Ricci M G Celani G Guercini P Rucireta R Vitali F La Rosa E Duca R Ferraguzzi M Paolotti D Seppoloni 《Stroke; a journal of cerebral circulation》1989,20(7):853-857
The SEPIVAC study (Italian initials for "epidemiologic study of incidence of acute cerebrovascular disease") is a community-based epidemiologic survey of incidence and outcome of cerebrovascular disease in the territory of the 6th Local Health Unit, Umbria, Italy, where 49,101 people live. All cases were registered with the study either by notification from general practitioners or by check of hospital admission within the study area and in the two hospitals of Perugia. Death certificates were looked at as well. Patients were registered with the study when the clinical picture fulfilled the definition of stroke and transient ischemic attack (TIA) adopted for this study. Patients were followed up at approximately 30 days and 6 months. During the first year of the study (September 1, 1986 to August 31, 1987), 189 cases were registered: 108 suffered a "first ever in a lifetime" stroke, 30 a recurrent stroke, and 51 a "first ever in a lifetime" transient ischemic attack. Sixty-one percent of patients (71% of first strokes) had a computed tomography scan. For our study, the crude annual incidence rate of first stroke was 2.2 per 1,000 (confidence intervals 1.81-2.66); the standardized rate to the European population was 1.36 (confidence intervals 1.06-1.74). At least 83% of first strokes were due to cerebral ischemia; in 26 cases a clinical diagnosis of lacunar ischemia was made. The 30-day case fatality rate was 21%; 25% of our patients had recovered completely or almost completely after 1 month. 相似文献
69.
Kaster MP Rosa AO Rosso MM Goulart EC Santos AR Rodrigues AL 《Neuroscience letters》2004,355(1-2):21-24
This study investigated the effect of adenosine in the forced swimming test (FST) and the tail suspension test (TST) in mice, and the contribution of adenosine A1 and A2A receptors to adenosine's antidepressant-like effect. The immobility time in the FST was reduced by adenosine given either by i.p. (5-10 mg/kg) or i.c.v. (0.01-10 microg/site) route. Adenosine (1-10 mg/kg, i.p.) also produced an antidepressant-like effect in the TST. No treatment affected locomotion in an open-field. The anti-immobility effect of adenosine (10 mg/kg, i.p.) in the FST was prevented by i.p. pretreatment of mice with caffeine (3 mg/kg), DPCPX (2 mg/kg) and ZM241385 (1 mg/kg). CHA (0.05 mg/kg, i.p.) and DPMA (1-5 mg/kg, i.p.) also produced an antidepressant-like effect in the FST. This is the first report of an antidepressant-like effect of adenosine in mice, apparently mediated through an interaction with A1 and A2A receptors. 相似文献
70.
Di Biase AM Pietrantoni A Tinari A Siciliano R Valenti P Antonini G Seganti L Superti F 《Journal of medical virology》2003,69(4):495-502
Lactoferrin, a member of the transferrin family of approximately 80 kDa, consists of a single polypeptide chain folded in two symmetric, globular lobes (N- and C-lobes), each able to bind one ferric ion. This glycoprotein, found in physiological fluids of mammals, plays an important role in immune regulation and in defense mechanisms against bacteria, fungi, parasites, and viruses. Although the antiviral activity of lactoferrin is one of the major biological functions of such protein, the mechanism of action is still under debate. We have investigated both the role of tryptic fragments of bovine lactoferrin and the mechanism of lactoferrin antiviral effect toward adenovirus infection in HEp-2 cells. The results obtained demonstrated that the anti-adenovirus activity of lactoferrin is mediated by the N-terminal half of the protein as the N-lobe was able to inhibit adenovirus infection, even if at lower extent than undigested lactoferrin, whereas C-lobe was ineffective. The results also showed that the anti-adenovirus action of lactoferrin and of its N-terminal peptide lactoferricin took place on virus attachment to cell membrane, mainly through competition for common glycosaminoglycan receptors. The data provide evidence that the anti-adenovirus activity of lactoferrin is mediated mainly by the cluster of positive charges at the N-terminus of whole molecule and that the N-terminal peptide lactoferricin alone is sufficient to prevent infection. 相似文献