全文获取类型
收费全文 | 5142篇 |
免费 | 336篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 37篇 |
儿科学 | 172篇 |
妇产科学 | 100篇 |
基础医学 | 664篇 |
口腔科学 | 399篇 |
临床医学 | 501篇 |
内科学 | 1226篇 |
皮肤病学 | 192篇 |
神经病学 | 323篇 |
特种医学 | 330篇 |
外国民族医学 | 4篇 |
外科学 | 458篇 |
综合类 | 54篇 |
一般理论 | 1篇 |
预防医学 | 371篇 |
眼科学 | 53篇 |
药学 | 318篇 |
中国医学 | 23篇 |
肿瘤学 | 272篇 |
出版年
2023年 | 50篇 |
2022年 | 96篇 |
2021年 | 185篇 |
2020年 | 90篇 |
2019年 | 139篇 |
2018年 | 175篇 |
2017年 | 121篇 |
2016年 | 124篇 |
2015年 | 143篇 |
2014年 | 204篇 |
2013年 | 224篇 |
2012年 | 313篇 |
2011年 | 362篇 |
2010年 | 217篇 |
2009年 | 203篇 |
2008年 | 277篇 |
2007年 | 266篇 |
2006年 | 219篇 |
2005年 | 216篇 |
2004年 | 201篇 |
2003年 | 166篇 |
2002年 | 138篇 |
2001年 | 124篇 |
2000年 | 106篇 |
1999年 | 92篇 |
1998年 | 72篇 |
1997年 | 75篇 |
1996年 | 82篇 |
1995年 | 62篇 |
1994年 | 51篇 |
1993年 | 65篇 |
1992年 | 50篇 |
1991年 | 48篇 |
1990年 | 33篇 |
1989年 | 52篇 |
1988年 | 58篇 |
1987年 | 56篇 |
1986年 | 52篇 |
1985年 | 43篇 |
1984年 | 22篇 |
1983年 | 18篇 |
1982年 | 32篇 |
1981年 | 19篇 |
1980年 | 16篇 |
1979年 | 11篇 |
1978年 | 13篇 |
1977年 | 19篇 |
1976年 | 14篇 |
1975年 | 20篇 |
1969年 | 15篇 |
排序方式: 共有5498条查询结果,搜索用时 15 毫秒
51.
Elma Izze da Silva Magalhes Bianca Rodrigues de Oliveira Lívia Carolina Sobrinho Rudakoff Vitria Abreu de Carvalho Poliana Cristina de Almeida Fonseca Viola Soraia Pinheiro Machado Arruda Carolina Abreu de Carvalho Carla Cristine Nascimento da Silva Coelho Maylla Luanna Barbosa Martins Bragana Heloisa Bettiol Marco Antnio Barbieri Viviane Cunha Cardoso Alcione Miranda dos Santos Renata Bertazzi Levy Antnio Augusto Moura da Silva 《Nutrients》2022,14(15)
Longitudinal studies evaluating the relationship between UPF consumption and the incidence of Metabolic Syndrome (MetS) and its components are still scarce. This study aimed to evaluate the effect of UPF consumption on the incidence of MetS and its components in adults. A prospective study was conducted with 896 participants from the 1978/79 Ribeirão Preto cohort, São Paulo, Brazil. UPF consumption was evaluated in %kcal and %g at ages 23–25 years. Incidence of MetS and its components were estimated at ages 37–39 years, according to the Joint Interim Statement criteria. Poisson regression was used to assess associations, and interactions with sex were investigated. UPF consumption had no association with MetS (%kcal Adjusted PR: 1.00; 95% CI: 0.99–1.01; %g Adjusted PR: 1.00; 95% CI: 0.99–1.01). However, women with higher UPF consumption, in %kcal and %g, had a higher risk of abdominal obesity (%kcal: p = 0.030; %g: p = 0.003); and women with higher UPF consumption, in %g, had a higher risk of low HDL-cholesterol (p = 0.041). For the other components of MetS, no significant associations were observed in either sex. These findings suggest evidence of no association between UPF consumption and MetS; however, consumption of UPF was associated with increased WC and low HDL-c, but only in women. 相似文献
52.
53.
Castillo Medina NM Velázquez Fonseca J Hernández Pacheco JA Acevedo Tacuba JL 《Ginecología y obstetricia de México》2008,76(5):287-291
Malaria is one of the most important parasitic infections in Mexico and Latin America. Here we report a case of a 21 year-old female with 38.4 weeks of pregnancy and previous hospitalization due to malaria. Showing a thick drop negative test she was referred to Mexico City Hospital de la Mujer with presumptive diagnosis of preeclampsia and HELLP syndrome. During her stay in ICU she developed malarial paroxysm and Plasmodium vivax was identified, conducting to specific therapy. 相似文献
54.
Michael Nazarkovsky Albina Mikhraliieva Carlos A. Achete Luiz Anastacio Alves Joyce Araujo Brulio S. Archanjo Jos Júnior Frana de Barros Liana Monteiro da Fonseca Cardoso Jos Nelson S. S. Couceiro Fernanda Davi Marques Bruno S. Oliveira Rafael Nascimento Dias de Souza Ayla Josma Teixeira Thiago L. Vasconcelos Vladimir Zaitsev 《RSC advances》2022,12(23):14342
Rational synthesis and simple methodology for the purification of large (35–45 nm in lateral size) and flat (1.0–1.5 nm of height) nitrogen-doped graphene oxide quantum dots (GOQDs) are presented. The methodology allows robust metal-free and acid-free preparation of N-GOQDs with a yield of about 100% and includes hydrothermal treatment of graphene oxide with hydrogen peroxide and ammonia. It was demonstrated that macroscopic impurities can be separated from N-GOQD suspension by their coagulation with 0.9% NaCl solution. Redispersible in water and saline solutions, particles of N-GOQDs were characterized using tip-enhanced Raman spectroscopy (TERS), photoluminescent, XPS, and UV-VIS spectroscopies. The size and morphology of N-GOQDs were studied by dynamic light scattering, AFM, SEM, and TEM. The procedure proposed allows nitrogen-doped GOQDs to be obtained, having 60–51% of carbon, 34–45% of oxygen, and up to 7.2% of nitrogen. The N-GOQD particles obtained in two hours of synthesis contain only pyrrolic defects of the graphene core. The fraction of pyridine moieties grows with the time of synthesis, while the fraction of quaternary nitrogen declines. Application of TERS allows demonstration that the N-GOQDs consist of a graphene core with an average crystallite size of 9 nm and an average distance between nearest defects smaller than 3 nm. The cytotoxicity tests reveal high viability of the monkey epithelial kidney cells Vero in the presence of N-GOQDs in a concentration below 60 mg L−1. The N-GOQDs demonstrate green luminescence with an emission maximum at 505 nm and sedimentation stability in the cell culture medium.This paper reveals the methodology for robust preparation of purified nitrogen-doped graphene oxide quantum dots with non-cytotoxic activity against monkey epithelial kidney cells (Vero ATCC® CCL-81™). 相似文献
55.
56.
Coexistence of benign phyllodes tumor and invasive ductal carcinoma in distinct breasts: case report
Guerino Barbalaco Neto Claudia Rossetti Natalia A Souza Fernando LA Fonseca Ligia Ajaime Azzalis Virginia Berlanga Campos Junqueira Vitor E Valenti Luiz Carlos de Abreu 《European journal of medical research》2012,17(1):8
This report describes a rare case of coexistence of benign phyllodes tumor, which measured 9 cm in the right breast, and invasive ductal carcinoma of 6 cm in the left breast, synchronous and independent, in a 66-year-old patient. The patient underwent a bilateral mastectomy due to the size of both lesions. Such situations are rare and usually refer to the occurrence of ductal or lobular carcinoma in situ when associated with malignant phyllodes tumors, and more often in ipsilateral breast or intra-lesional. 相似文献
57.
David E. Barroso Terezinha M.P.P. Casti?eiras Fernanda S. Freitas Jane W. Marsh Mary G. Krauland Mary M. Tulenko érica L. Fonseca Ana C.P. Vicente Maria C. Rebelo Elaine O. Cerqueira Adriano C. Xavier Ana P.C.M. Cardozo Simone E.M. da Silva Lee H. Harrison 《Emerging infectious diseases》2013,19(11):1847-1850
During 2003–2012, 8 clusters of meningococcal disease were identified in Rio de Janeiro State, Brazil, all caused by serogroup C Neisseria meningitidis. The isolates were assigned to 3 clonal complexes (cc): cc11, cc32, and cc103. These hyperinvasive disease lineages were associated with endemic disease, outbreaks, and high case-fatality rates. 相似文献
58.
Tatiana L. Fonseca Mayrin Correa-Medina Maira P.O. Campos Gabor Wittmann Joao P. Werneck-de-Castro Rafael Arrojo e Drigo Magda Mora-Garzon Cintia Bagne Ueta Alejandro Caicedo Csaba Fekete Balazs Gereben Ronald M. Lechan Antonio C. Bianco 《The Journal of clinical investigation》2013,123(4):1492-1500
Type II deiodinase (D2) activates thyroid hormone by converting thyroxine (T4) to 3,5,3′-triiodothyronine (T3). This allows plasma T4 to signal a negative feedback loop that inhibits production of thyrotropin-releasing hormone (TRH) in the mediobasal hypothalamus (MBH) and thyroid-stimulating hormone (TSH) in the pituitary. To determine the relative contributions of these D2 pathways in the feedback loop, we developed 2 mouse strains with pituitary- and astrocyte-specific D2 knockdown (pit-D2 KO and astro-D2 KO mice, respectively). The pit-D2 KO mice had normal serum T3 and were systemically euthyroid, but exhibited an approximately 3-fold elevation in serum TSH levels and a 40% reduction in biological activity. This was the result of elevated serum T4 that increased D2-mediated T3 production in the MBH, thus decreasing Trh mRNA. That tanycytes, not astrocytes, are the cells within the MBH that mediate T4-to-T3 conversion was defined by studies using the astro-D2 KO mice. Despite near-complete loss of brain D2, tanycyte D2 was preserved in astro-D2 KO mice at levels that were sufficient to maintain both the T4-dependent negative feedback loop and thyroid economy. Taken together, these data demonstrated that the hypothalamic-thyroid axis is wired to maintain normal plasma T3 levels, which is achieved through coordination of T4-to-T3 conversion between thyrotrophs and tanycytes. 相似文献
59.
F reticulocyte response in sickle cell anemia treated with recombinant human erythropoietin: a double-blind study 总被引:1,自引:0,他引:1
Nagel RL; Vichinsky E; Shah M; Johnson R; Spadacino E; Fabry ME; Mangahas L; Abel R; Stamatoyannopoulos G 《Blood》1993,81(1):9-14
Studies on baboons and preliminary observations in three patients with sickle cell anemia (SS) suggested that high doses of pulse administered recombinant human erythropoietin (rHuEPO) stimulate F-reticulocyte production. We now report on the administration of rHuEPO in a double- blind format to ascertain frequency of response and potential precipitation of side effects. Ten patients were enrolled, but one was discontinued due to the indication of a blood transfusion. Of the other nine, five received rHuEPO in escalating doses (from 400 to 1,500 U per kg twice daily [BID] per week), alternating with a placebo, in blinded fashion. The second group, consisting of four patients, followed an identical protocol (except starting dose was 1,000 U/Kg, BID per week) and were iron supplemented during treatment. The criterion of response was a transient doubling (as a minimum) of the steady-state F- reticulocyte level. We found that none of the five patients in the first group responded to rHuEPO, and two of them became iron deficient, as judged by a significant decrease in ferritin. Of the second group, four patients responded with F-reticulocyte increases. In three patients, open label administration of rHuEPO confirmed the effect. We observed seven painful episodes during this study, two during the EPO administration and five during the placebo arm. Three patients were phlebotomized because the hemoglobin level increased 1.5 g/dL more than steady-state levels. Of the six patients followed-up by percent dense cell determinations, one exhibited increased levels during periods of the treatment, whereas the other five showed no change. No anti-rHuEPO antibodies were detected. We conclude that rHuEPO can stimulate F- reticulocyte response in some patients with sickle cell anemia, without apparent negative clinical side effects. The state of iron stores may be critical. Whether higher doses of rHuEPO and/or a different regimen might induce sustained F cells and fetal hemoglobin increases remains to be determined. 相似文献
60.
Identification of the molecular defect in the erythrocyte membrane skeleton of some kindreds with hereditary spherocytosis 总被引:12,自引:0,他引:12
We have localized the molecular alteration in the membrane skeleton of two of four kindreds with hereditary spherocytosis (HS) to an alteration in the spectrin-protein-4.1 interaction due to a defective spectrin molecule. The defective spectrin-protein-4.1 interaction in these kindreds (referred to as type I HS) leads to a weakened spectrin- protein-4.1-actin ternary complex, which in turn may lead to the friable membrane skeleton and suggested membrane instability related to this disorder. Type I HS spectrin binds approximately 63% as much protein-4.1 as normal spectrin (with equal affinity). This defect does not correlate with splenic function or erythrocyte age in the circulation. However, the approximately 37% reduction in binding of protein-4.1 to HS spectrin approaches the theoretical value of 50% expected in this autosomal dominant disorder. All other type I membrane skeletal interactions (spectrin-syndein, spectrin heterodimer- heterodimer, syndein-band-3) were found to be normal. It would appear therefore that the defective HS spectrin-protein-4.1 interaction in type I hereditary spherocytosis may be the primary molecular defect rather than a secondary phenomena. 相似文献