全文获取类型
收费全文 | 2822篇 |
免费 | 212篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 167篇 |
妇产科学 | 47篇 |
基础医学 | 244篇 |
口腔科学 | 131篇 |
临床医学 | 234篇 |
内科学 | 771篇 |
皮肤病学 | 69篇 |
神经病学 | 179篇 |
特种医学 | 337篇 |
外科学 | 233篇 |
综合类 | 38篇 |
一般理论 | 1篇 |
预防医学 | 185篇 |
眼科学 | 32篇 |
药学 | 256篇 |
1篇 | |
中国医学 | 9篇 |
肿瘤学 | 121篇 |
出版年
2023年 | 10篇 |
2022年 | 18篇 |
2021年 | 39篇 |
2020年 | 24篇 |
2019年 | 30篇 |
2018年 | 42篇 |
2017年 | 41篇 |
2016年 | 46篇 |
2015年 | 60篇 |
2014年 | 70篇 |
2013年 | 92篇 |
2012年 | 85篇 |
2011年 | 82篇 |
2010年 | 82篇 |
2009年 | 121篇 |
2008年 | 58篇 |
2007年 | 97篇 |
2006年 | 83篇 |
2005年 | 89篇 |
2004年 | 77篇 |
2003年 | 81篇 |
2002年 | 63篇 |
2001年 | 54篇 |
2000年 | 71篇 |
1999年 | 64篇 |
1998年 | 110篇 |
1997年 | 129篇 |
1996年 | 124篇 |
1995年 | 82篇 |
1994年 | 86篇 |
1993年 | 107篇 |
1992年 | 51篇 |
1991年 | 45篇 |
1990年 | 40篇 |
1989年 | 86篇 |
1988年 | 64篇 |
1987年 | 53篇 |
1986年 | 71篇 |
1985年 | 66篇 |
1984年 | 48篇 |
1983年 | 52篇 |
1982年 | 38篇 |
1981年 | 44篇 |
1980年 | 27篇 |
1979年 | 20篇 |
1978年 | 14篇 |
1977年 | 32篇 |
1976年 | 22篇 |
1974年 | 11篇 |
1973年 | 12篇 |
排序方式: 共有3062条查询结果,搜索用时 31 毫秒
71.
Ashraf Kamour David James David J. Lupton Gillian Cooper Micheal Eddleston Allister Vale 《Clinical toxicology (Philadelphia, Pa.)》2014,52(10):1025-1031
Objective. To characterise the patterns of presentation and clinical features of toxicity following reported recreational use of benzofuran compounds ((2-aminopropyl)-2,3-dihydrobenzofurans) in the UK, as reported to the National Poisons Information Service (NPIS), and to compare clinical features of toxicity with those after reported mephedrone use. Methods. NPIS patient-specific telephone enquiries and user sessions for TOXBASE®, the NPIS online information database, related to (2-aminopropyl)-2,3-dihydrobenzofurans and associated synonyms were reviewed from March 2009 to August 2013. These data were compared with those of mephedrone, the recreational substance most frequently reported to NPIS, collected over the same period. Results. There were 63 telephone enquiries concerning 66 patients and 806 TOXBASE® user sessions regarding benzofuran compounds during the period of study. The first telephone enquiry was made in July 2010 and the highest numbers of enquiries were received in August 2010 (33 calls, 112 TOXBASE® sessions). Patients were predominantly male (82%) with a median age of 29 years; 9 reported co-ingestion of other substances. Comparing the 57 patients who reported ingesting benzofuran compounds alone with 315 patients ingesting mephedrone alone, benzofurans were more often associated with stimulant features, including tachycardia, hypertension, mydriasis, palpitation, fever, increased sweating, and tremor, (72% vs. 38%, odds ratio [OR] 4.2, 95% confidence interval [CI] 2.27–7.85, P < 0.0001) and mental health disturbances (58% vs. 38%, OR 2.3, 95% CI 1.29–4.07, P = 0.006). Other features reported after benzofuran compound ingestion included gastrointestinal symptoms (16%), reduced level of consciousness (9%), chest pain (7%), and creatinine kinase elevation (5%). Conclusions. Reported ingestion of benzofuran compounds is associated with similar toxic effects to those of amphetamines and cathinones. Mental health disturbances and stimulant features were reported more frequently following reported ingestion of benzofuran compounds than after ingestion of mephedrone. 相似文献
72.
73.
Melatonin: Antioxidant and modulatory properties in age‐related changes during Trypanosoma cruzi infection 下载免费PDF全文
Vânia Brazão Fabricia H. Santello Rafaela P. Colato Tamires T. Mazotti Lucas F. Tazinafo Míriam Paula A. Toldo Gabriel T. do Vale Carlos R. Tirapelli José C. do Prado Jr. 《Journal of pineal research》2017,63(1)
The purpose of this study was to investigate the effects of melatonin on selected biomarkers of innate and humoral immune response as well as the antioxidant/oxidant status (superoxide dismutase—SOD and reduced glutathione levels (GSH) to understand whether age‐related changes would influence the development of acute Trypanosoma cruzi (T. cruzi) infection. Young‐ (5 weeks) and middle‐aged (18 months) Wistar rats were orally treated with melatonin (gavage) (05 mg/kg/day), 9 days after infection. A significant increase in both SOD activity and GSH levels was found in plasma from all middle‐aged melatonin‐treated animals. Melatonin triggered enhanced expression of major histocompatibility class II (MHC‐II) antigens on antigen‐presenting cell (APC) and peritoneal macrophages in all treated animals. High levels of CD4+CD28‐negative T cells (*P<.05) were detected in middle‐aged control animals. Melatonin induced a significant reduction (***P<.001) in CD28‐negative in CD4+ and CD8+ T cells in middle‐aged control animals. Contrarily, the same group displayed upregulated CD4+CD28+T and CD8+CD28+T cells. Melatonin also triggered an upregulation of CD80 and CD86 expression in all young‐treated groups. Significant percentages of B and spleen dendritic cells in middle‐aged infected and treated animals were observed. Our data reveal new features of melatonin action in inhibiting membrane lipid peroxidation, through the reduction in 8‐isoprostane, upregulating the antioxidant defenses and triggering an effective balance in the antioxidant/oxidant status during acute infection. The ability of melatonin to counteract the immune alterations induced by aging added further support to its use as a potential therapeutic target not only for T. cruzi infection but also for other immunocompromised states. 相似文献
74.
Prevalence of Sjögren's syndrome in Brazilian patients infected with human T‐cell lymphotropic virus
75.
Paulo Roberto Lima Falco do Vale Sheila Cerqueira Hudson P. Santos Beth P. Black Evanilda Souza de Santana Carvalho 《Nursing inquiry》2019,26(1)
The rapidly increasing number of cases of Zika virus and limited understanding of its congenital sequelae (e.g., microcephaly) led to stories of fear and uncertainty across social media and other mass communication networks. In this study, we used techniques generic to netnography, a form of ethnography, using Internet‐based computer‐mediated communications as a source of data to understand the experience and perceptions of families with infants diagnosed with Zika‐related microcephaly. We screened 27 YouTube? videos published online between October 2015 and July 2016, during which the Zika epidemic started, peaked, and declined. We identified three themes: (a) experiencing the news of a diagnosis of Zika‐associated microcephaly; (b) experiencing feelings and expectations of the ‘imperfect’ child; and (c) seeking to understand microcephaly to care for the child. We found that families experienced distressing feelings of shock, sadness, hopelessness, and pain, while dealing with emerging and sometimes conflicting information being transmitted by news outlets, uncertainty about the child's health, and healthcare providers’ lack of clarity to guide the family members. The ‘unknown’ factor of ZIKA was an additional stressful factor in the experience of the families. 相似文献
76.
Natália A. Gonzaga Gabriel T. do Vale Juliana M. Parente Rodrigo Yokota Bruno S. De Martinis Dulce E. Casarini Michele M. Castro Carlos R. Tirapelli 《Journal of the American Society of Hypertension》2018,12(7):561-573
We evaluated the possible mechanisms underlying the oxidative stress induced by ethanol withdrawal. With this purpose, we verified the role of AT1 receptors in such response. Male Wistar rats were treated with ethanol 3%–9% (vol./vol.) for 21 days. Ethanol withdrawal was induced by abrupt discontinuation of the treatment. Experiments were performed 48 hours after ethanol discontinuation. Increased plasma levels of angiotensin II were detected after ethanol withdrawal. Losartan (10 mg/kg; p.o. gavage), a selective AT1 receptor antagonist, impeded the increase in blood pressure induced by ethanol withdrawal. Increased lipoperoxidation and superoxide anion (O2?) levels were detected in aortas after ethanol withdrawal, and losartan prevented these responses. Decreased hydrogen peroxide and nitrate/nitrite concentration were detected in aortas after ethanol withdrawal, and losartan prevented these effects. Nitrotyrosine immunostaining in the rat aorta was increased after ethanol withdrawal, and AT1 blockade impeded this response. Increased expression of PKCδ and p47phox was detected after ethanol withdrawal, and treatment with losartan prevented these responses. Our study provides novel evidence that ethanol withdrawal increases vascular oxidative stress and blood pressure through AT1-dependent mechanisms. These findings highlight the importance of angiotensin II in ethanol withdrawal–induced increase in blood pressure and vascular oxidative damage. 相似文献
77.
Frederico Figueiredo Amancio Maira Alves Pereira Felipe Campos de Melo Iani Lorena D'anuncia??o Jorge Luís Carvalho de Almeida Janer Aparecida Silveira Soares Marcela Lencine Ferraz Thiago Cardoso Vale José Roberto Lambertucci Mariangela Carneiro 《Revista do Instituto de Medicina Tropical de S?o Paulo》2014,56(3):267-270
Dengue is currently a major public-health problem. Dengue virus (DENV) is
classified into four distinct serotypes, DENV 1-4. After 28 years of absence, DENV-4
was again detected in Brazil in 2010 in Roraima State, and one year later, the virus
was identified in the northern Brazilian states of Amazonas and Pará, followed by Rio
de Janeiro and São Paulo. In Minas Gerais, the first confirmed case of DENV-4
occurred in the municipality of Frutal in 2011 and has now been isolated from a
growing number of patients. Although DENV-2 is associated with the highest risk of
severe forms of the disease and death due to the infection, DENV-4 has also been
associated with severe forms of the disease and an increasing risk of hemorrhagic
manifestations. Herein, the first fatal case of confirmed DENV-4 in Brazil is
reported. The patient was an 11-year-old girl from the municipality of Montes Claros
in northern Minas Gerais State, Brazil. She had idiopathic thrombocytopenic purpura
as a comorbid condition and presented with a fulminant course of infection, leading
to death due to hemorrhagic complications. Diagnosis was confirmed by detection of
Dengue-specific antibodies using IgM capture enzyme-linked immunosorbent assay and
semi-nested RT-PCR. Primary care physicians and other health-care
providers should bear in mind that DENV-4 can also result in severe forms of the
disease and lead to hemorrhagic complications and death, mainly when dengue infection
is associated with coexisting conditions. 相似文献
78.
79.
Familial protein S deficiency with a variant protein S molecule in plasma and platelets 总被引:3,自引:0,他引:3
A protein S deficient family presenting a variant protein S molecule in plasma and platelets is described. The propositus, age 20, and two brothers suffered from venous thrombotic disease. The propositus, the only family member studied while taking oral anticoagulants, had a protein S antigen (ag) level of 17% and undetectable activity. As demonstrated by immunoblotting both the propositus and one clinically affected brother (42% ag, 7% activity) presented variant protein S molecules of 65,000 molecular weight (mol wt) while the other clinically affected brother (64% ag, 11% activity) had only protein S with normal electrophoretic mobility of 70,000 mol wt. The mother had normal protein S levels (93% ag, 100% activity) but had both normal and variant protein S molecules and based on her functional protein S data a normal anticoagulant activity of the variant molecule is suggested. One asymptomatic but protein S deficient sister (68% ag, 9% activity) as well as the asymptomatic protein S deficient father (59% ag, 10% activity) had only protein S molecules of 70,000 mol wt. The variant protein S bound to C4b-binding protein in plasma, and differed from normal protein S in carbohydrate content. Platelets of each family member contained the same immunoblotting pattern of normal and variant protein S forms as found in plasma, consistent with the hypothesis that protein S gene expression involves codominant expression of two alleles that is similar in cells that control the synthesis of both platelet and plasma forms of protein S. 相似文献
80.
To evaluate whether the hypothalamus is the site of action of CRF in inhibiting LH levels in female rats, we measured hypophysial-portal blood concentrations of immunoreactive GnRH (irGnRH) after the central injection of CRF. Ovine CRF (0.1, 1.0, 2.0, and 5.0 nmol) was injected intracerebroventricularly to intact rats on the afternoon of proestrus and in long term ovariectomized (OVX) rats in the presence or in absence of estradiol benzoate (OVX + EB). CRF injection decreased the amplitude of the proestrous irGnRH surge without affecting presurge levels. CRF (0.1 nmol) attenuated the afternoon irGnRH surge in OVX + EB rats; higher doses of CRF blocked this surge and decreased nonsurge irGnRH levels. No dose-related alterations of irGnRH levels were observed in OVX rats; only the highest dose of CRF was active. For comparison, plasma LH concentrations were measured after a single dose of CRF (2 nmol) in rats under the same experimental conditions. While CRF decreased LH concentrations in anesthetized proestrous and OVX + EB rats, it was inactive in OVX rats. In contrast, CRF injection in awake rats did decrease LH concentrations in all experimental conditions, suggesting that in OVX rats, the anesthetic (Saffan) used during portal blood collection affected CRF action on LH secretion. Indeed, the observation that the LH response to opiate receptor blockade with naloxone (2.5 mg/kg) in anesthetized OVX rats was different compared to that in awake rats suggested that the ineffectiveness of CRF to decrease irGnRH and LH in OVX anesthetized rats was related to the action of the anesthetic on the opioid system. The existence of a putative CRF-opioid interaction in the inhibitory control of LH secretion was supported by the effectiveness of naloxone to reverse the CRF-induced decrease in LH levels in EB-treated and untreated OVX rats. These results indicate that CRF attenuates LH secretion by a central action to inhibit irGnRH release into the hypophysial-portal circulation and that this action is independent of basal concentrations of irGnRH and/or LH. Moreover, the present results support the involvement of endogenous opioids in mediating the effect of CRF on LH secretion. 相似文献