全文获取类型
收费全文 | 1515篇 |
免费 | 101篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 27篇 |
儿科学 | 61篇 |
妇产科学 | 24篇 |
基础医学 | 146篇 |
口腔科学 | 211篇 |
临床医学 | 144篇 |
内科学 | 327篇 |
皮肤病学 | 26篇 |
神经病学 | 75篇 |
特种医学 | 94篇 |
外科学 | 110篇 |
综合类 | 17篇 |
预防医学 | 163篇 |
眼科学 | 28篇 |
药学 | 116篇 |
中国医学 | 25篇 |
肿瘤学 | 48篇 |
出版年
2023年 | 10篇 |
2022年 | 43篇 |
2021年 | 62篇 |
2020年 | 46篇 |
2019年 | 57篇 |
2018年 | 63篇 |
2017年 | 41篇 |
2016年 | 50篇 |
2015年 | 55篇 |
2014年 | 71篇 |
2013年 | 80篇 |
2012年 | 122篇 |
2011年 | 132篇 |
2010年 | 60篇 |
2009年 | 58篇 |
2008年 | 83篇 |
2007年 | 72篇 |
2006年 | 60篇 |
2005年 | 66篇 |
2004年 | 54篇 |
2003年 | 30篇 |
2002年 | 37篇 |
2001年 | 20篇 |
2000年 | 25篇 |
1999年 | 22篇 |
1998年 | 21篇 |
1997年 | 24篇 |
1996年 | 15篇 |
1995年 | 14篇 |
1994年 | 10篇 |
1993年 | 13篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 10篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 9篇 |
1986年 | 21篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1977年 | 9篇 |
1976年 | 4篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1961年 | 1篇 |
1940年 | 1篇 |
排序方式: 共有1642条查询结果,搜索用时 16 毫秒
71.
Luciano C. Brando-Lima Fabrícia C. Silva Paulo V. C. G. Costa Edgar A. Alves-Júnior Csar Viseras Josy A. Osajima Leilson R. Bezerra Jose F. P. de Moura Aline G. de A. Silva Maria G. Fonseca Edson C. Silva-Filho 《Materials》2022,15(1)
The potential use of amino acids by ruminal microorganisms converting them into microbial protein for ruminants makes it challenging to supplement these nutrients in an accessible form in animals’ diets. Several strategies to protect amino acids from ruminal degradation were reported, producing amino acids available for the protein used in the intestine called “bypass.” The intercalation of biomolecules in clay mineral minerals has gained notoriety due to its ability to support, protect, transport, physicochemical properties and non-toxicity. This study aimed to investigate the incorporation of L-lysine (Lys), L-methionine (Met), and L-tryptophan (Trp) amino acids in the clay minerals sepiolite (Sep) and Veegum® (Veg) using the adsorption method. The characterization techniques of X-ray diffraction and infrared spectroscopy indicated the presence of biomolecules in the inorganic matrices. Elemental and thermal analyzes monitored the percentages of incorporated amino acids. They showed better incorporation capacities for Veg, such as Met-Veg < Lys-Veg < Trp-Veg and Lys-Sep < Met-Sep < Trp-Sep for sepiolite, except for the incorporation of Met. Matrices provide a promising alternative for planning the administration of biomolecules, using essential amino acids as models, and may offer an alternative to improve functional diet strategies. 相似文献
72.
Luiz Guilherme Salvino da Silva Ana Paula Morelli Isadora Carolina Betim Pavan Mariana Rosolen Tavares Nathalie Fortes Pestana Mauricio Ariel Rostagno Fernando Moreira Simabuco Rosngela Maria Neves Bezerra 《Phytotherapy research : PTR》2020,34(6):1385-1396
Beetroot is an herb used worldwide as a food product, raw material for food industry, ethanol production and source of food coloring. Beet leaves are an unconventional food with antioxidant properties, which might neutralize reactive oxygen species (ROS) induced by oxidized Low‐Density Lipoprotein (LDL) present in dyslipidemias. This study aimed to elucidate the effects of beet leaves on the suppression of LDL oxidative processes. Beet leaves extract was produced, characterized, and tested for its antioxidant capacity using endothelial cells in vitro. A model of human umbilical vein endothelial cells was used in various tests, including viability assay, molecular analysis of antioxidant genes, ROS labeling, and macrophage adhesion assay. The extract improved the antioxidative protection of endothelial cells against different agents including oxidized LDL‐cholesterol and H2O2. It acted on ROS directly due to its high content of natural antioxidants, but also due to the activation and improvement of cellular defenses such as Superoxide dismutase 1, Superoxide dismutase 2, and catalase. The inhibition of LDL‐mediated oxidative effects on endothelial cells may turn this unconventional food a functional food with great potential for phytotherapy of atherosclerosis as an adjuvant for medicinal treatments. 相似文献
73.
Itamar S. Santos Márcio S. Bittencourt Ilka R.S. Oliveira Angelita G. Souza Danilo P. Meireles Tatjana Rundek Murilo Foppa Daniel C. Bezerra Cláudia M.V. Freire Leonard H. Roelke Sayonara Carrilho Isabela M. Benseñor Paulo A. Lotufo 《Atherosclerosis》2014
Objective
Carotid intima–media thickness (IMT) is a noninvasive measurement of early atherosclerosis. Most IMT studies have involved populations with low rates of racial blending. The aim of the present article is to describe IMT value distributions and analyze the influence of sex and race on IMT values in a large Brazilian sample, a setting with a high rate of racial admixture.Methods
The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) is a multicenter cohort of 15,105 adult (aged 35–74 years) civil servants in six Brazilian cities. Baseline assessment included IMT measurements in both common carotid arteries. Race was self-reported. We studied the association between sex and race with IMT values using multiple linear regression models. We conducted analyses in all and low-risk individuals, defined as those without classical cardiovascular risk factors.Results
We analyzed complete IMT data from 10,405 ELSA-Brasil participants. We present nomograms by age for all and low-risk individuals, stratified by sex and race. We found that men had significantly higher maximal IMT values compared with women (β = 0.058; P < 0.001). This association remained for low-risk individuals (β = 0.027; P = 0.001). In addition, Brown and White individuals had lower maximal IMT values compared with Black individuals for all (β = −0.034 and β = −0.054, respectively; P < 0.001) and low-risk individuals (β = −0.027; P = 0.013 and β = −0.035; P < 0.001, respectively).Conclusion
We found significantly higher IMT values in men. We found significantly higher IMT values in Black individuals than White and Brown individuals. These results persisted when analyses were restricted to low-risk individuals. 相似文献74.
Gomes PB Noronha EC de Melo CT Bezerra JN Neto MA Lino CS Vasconcelos SM Viana GS de Sousa FC 《Journal of ethnopharmacology》2008,120(2):209-214
Ethnopharmacological relevance
Petiveria alliacea L. (tipi) a shrub from Phytolaccaceae family is popularly used in folk medicine for treating a wide variety of disorders in South and Central America.Aim of the study
To investigate the neuropharmacological properties on experimental animals.Materials and methods
The acetate (FA), hexanic (FH), hydroalcoholic (FHA) and precipitated hydroalcoholic (FHAppt) fractions from the root of tipi were studied to investigate its pharmacological properties in the classical behavioral models (open-field, elevated plus maze-EPM, rotarod, barbiturate-induced sleeping time, forced swimming and pentylenetetrazole (PTZ)-induced convulsions tests) using mice. These fractions were administered intraperitoneally and orally to female mice at single doses of 100 and 200 mg/kg.Results
All these fractions decreased the locomotor activity, rearing and grooming in the open-field test, suggesting a possible central depressant action. No significant effect was evident on motor coordination of the animals in the rotarod test. On EPM, all the fractions of tipi presented a significant reduction on the time of permanence in the open arms, indicating an absence of anxiolytic-like effect. In addition, the fractions increased the immobility time in the forced swimming test and potentiated pentobarbital-induced sleeping time in mice, confirmed a probable sedative and central depressant effect. Furthermore, the fractions increased the latency to the first convulsion and the lethal time of the PTZ-induced convulsions test in the animals, confirmed its popular use as anticonvulsant.Conclusion
Our results suggest that the fractions of P. alliacea L. contains biologically active substance(s) that might be acting in the CNS and have significant depressant and anticonvulsant potentials, supporting folk medicine use of this plant. 相似文献75.
Marcos André C. Bezerra Magnun N.N. Santos Aderson S. Araújo Yara M. Gomes Frederico G.C. Abath 《Hemoglobin》2013,37(1):83-88
Various factors have been described as phenotypic modulators of sickle cell disease, such as levels of fetal hemoglobin (Hb F), presence of α-thalassemia (thal), and haplotypes of the β-globin genes. In order to characterize and determine the frequency of the βS and βC mutations and the prevalence of ?α3.7-thal, 74 patients with sickle cell disease detected during neonatal screening in the State of Pernambuco, Brazil, were studied. The haplotypes of the β gene and ?α3.7-thal were determined using polymerase chain reaction (PCR), and specific restriction endonucleases were used to establish the polymorphic sites of the haplotypes. The results showed the high frequency of the Central African Republic (CAR) or Bantu haplotype in the State of Pernambuco, Brazil. The low frequency of the Benin haplotype recorded in this study, in comparison with other states in northeast Brazil, suggests the diversity of origins of Afro-Brazilians in this region. 相似文献
76.
77.
78.
79.
We analyzed differences in infant mortality between areas of Recife, a city in the North East of Brazil, analyzing the relationship between living conditions and the risk of death. We compared infant mortality coefficients for 1995 with indicators of living conditions and collected data for the 770 infant deaths and the 27,965 live births. Neighborhoods were ranked according to the quality of living conditions and were grouped into four clusters. The infant, neonatal and postneonatal mortality coefficients were 27.53, 18.84 and 8.69 per 1,000 live births respectively. Lower quality living conditions were associated with higher coefficients. The main causes of infant deaths were perinatal disorders, the coefficient of which was 14.95 per 1,000 live births, followed by congenital malformations, gastroenteritis and bronchopneumonia. With the exception of congenital malformations, the coefficients of all these causes of death increased as living conditions worsened. These inequalities are generally obscured by the presentation of means for the city as a whole. 相似文献
80.
JN HANNA WL SEXTON JL FAOAGALI PJ BUDA ML KENNETT KA BRUSSEN 《Journal of paediatrics and child health》1995,31(4):345-349
Objective: To determine the immunity to hepatitis B, poliomyelitis and measles in fully vaccinated Aboriginal and Torres Strait Island children in north Queensland.
Methodology: A cross-sectional survey of immunity in a sample of children; 101 fully vaccinated Aboriginal and Torres Strait Island children, with a median age of 24.5 months, from 10 communities in North Queensland participated in this study. The main outcome measures were the prevalence of adequate antibody levels against hepatitis B, poliomyelitis and measles.
Results: Only 54% (95% Cl 44–63%) of the children had adequate immunity (10 m iu/mL) to hepatitis B, and one child had been infected despite vaccination. Although all the children (95% Cl 96–100%) had adequate immunity (i.e. neutralizing antibodies at a dilution of 1:8) to poliovirus 2, only 93% (95% Cl 86–96%) and 60% (95% Cl 50–69%) had adequate immunity to polioviruses 1 and 3, respectively. Nearly all (96%; 95% Cl 90–98%) of the children had adequate immunity (i.e. detectable IgG antibody) to measles.
Conclusions: Although a relatively low proportion of the children had adequate antibody levels against hepatitis B the clinical significance of this observation is uncertain. Further studies are needed to determine whether fully vaccinated Torres Strait Island children have been adequately protected and whether they require a booster dose of hepatitis B vaccine. A substantial proportion of fully vaccinated Aboriginal and Torres Strait Island children are inadequately protected against poliomyelitis, and therefore any such child with acute flaccid paralysis should be investigated fully for poliomyelitis. Vaccinated Aboriginal and Torres Strait Island children are well protected against measles, as are other Australian children. 相似文献
Methodology: A cross-sectional survey of immunity in a sample of children; 101 fully vaccinated Aboriginal and Torres Strait Island children, with a median age of 24.5 months, from 10 communities in North Queensland participated in this study. The main outcome measures were the prevalence of adequate antibody levels against hepatitis B, poliomyelitis and measles.
Results: Only 54% (95% Cl 44–63%) of the children had adequate immunity (10 m iu/mL) to hepatitis B, and one child had been infected despite vaccination. Although all the children (95% Cl 96–100%) had adequate immunity (i.e. neutralizing antibodies at a dilution of 1:8) to poliovirus 2, only 93% (95% Cl 86–96%) and 60% (95% Cl 50–69%) had adequate immunity to polioviruses 1 and 3, respectively. Nearly all (96%; 95% Cl 90–98%) of the children had adequate immunity (i.e. detectable IgG antibody) to measles.
Conclusions: Although a relatively low proportion of the children had adequate antibody levels against hepatitis B the clinical significance of this observation is uncertain. Further studies are needed to determine whether fully vaccinated Torres Strait Island children have been adequately protected and whether they require a booster dose of hepatitis B vaccine. A substantial proportion of fully vaccinated Aboriginal and Torres Strait Island children are inadequately protected against poliomyelitis, and therefore any such child with acute flaccid paralysis should be investigated fully for poliomyelitis. Vaccinated Aboriginal and Torres Strait Island children are well protected against measles, as are other Australian children. 相似文献