全文获取类型
收费全文 | 34432篇 |
免费 | 2150篇 |
国内免费 | 150篇 |
专业分类
耳鼻咽喉 | 508篇 |
儿科学 | 795篇 |
妇产科学 | 646篇 |
基础医学 | 5035篇 |
口腔科学 | 3356篇 |
临床医学 | 2597篇 |
内科学 | 7357篇 |
皮肤病学 | 834篇 |
神经病学 | 2696篇 |
特种医学 | 643篇 |
外科学 | 3710篇 |
综合类 | 100篇 |
一般理论 | 11篇 |
预防医学 | 3877篇 |
眼科学 | 490篇 |
药学 | 2441篇 |
中国医学 | 328篇 |
肿瘤学 | 1308篇 |
出版年
2023年 | 314篇 |
2022年 | 704篇 |
2021年 | 1374篇 |
2020年 | 880篇 |
2019年 | 1108篇 |
2018年 | 1415篇 |
2017年 | 1034篇 |
2016年 | 1087篇 |
2015年 | 1264篇 |
2014年 | 1616篇 |
2013年 | 1908篇 |
2012年 | 2912篇 |
2011年 | 3299篇 |
2010年 | 1664篇 |
2009年 | 1241篇 |
2008年 | 2111篇 |
2007年 | 2064篇 |
2006年 | 1725篇 |
2005年 | 1494篇 |
2004年 | 1294篇 |
2003年 | 1102篇 |
2002年 | 992篇 |
2001年 | 569篇 |
2000年 | 506篇 |
1999年 | 431篇 |
1998年 | 162篇 |
1997年 | 126篇 |
1996年 | 105篇 |
1995年 | 97篇 |
1994年 | 83篇 |
1993年 | 73篇 |
1992年 | 184篇 |
1991年 | 175篇 |
1990年 | 143篇 |
1989年 | 149篇 |
1988年 | 108篇 |
1987年 | 102篇 |
1986年 | 92篇 |
1985年 | 100篇 |
1984年 | 65篇 |
1983年 | 58篇 |
1982年 | 44篇 |
1980年 | 40篇 |
1979年 | 63篇 |
1978年 | 42篇 |
1977年 | 37篇 |
1973年 | 49篇 |
1969年 | 39篇 |
1968年 | 52篇 |
1966年 | 39篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
J Estev?o-Costa J Correia-Pinto A Fragoso M Soares-Oliveira J Luis Carvalho 《Zeitschrift für Kinderchirurgie》2003,13(5):344-346
Splenic necrosis is extremely rare in neonates, the cases recorded so far being secondary to torsion of wandering organs. A newborn with an abdominal mass who underwent exchange transfusions through an umbilical catheter is presented here. Comprehensive investigation led to the suspicion of enteric duplication, but a splenic necrosis with no features of wandering spleen was found at laparotomy. The pathogenesis and preoperative diagnostic work-up of splenic necrosis are emphasised. 相似文献
62.
Renal dysfunction after myocardial revascularization. 总被引:5,自引:0,他引:5
Pedro E Antunes David Prieto J Ferr?o de Oliveira Manuel J Antunes 《European journal of cardio-thoracic surgery》2004,25(4):597-604
OBJECTIVES: In this study, we evaluate the incidence of and analyse the pre and intraoperative risk factors for the development of postoperative renal dysfunction (PRD), and the impact of such an event on perioperative mortality and on hospital length of stay. In addition, we sought to investigate the influence of a mildly increased serum creatinine (1.3-2.0 mg/dl) on perioperative mortality and morbidity. METHODS: The study included 2445 consecutive patients who had no pre-existing renal disease (creatinine or=2.1 mg/dl with a preoperative-to-postoperative increase >or=0.9 mg/dl. Univariate and multivariate analyses were performed where appropriate. RESULTS: Global 30-day mortality was 0.7%. The incidence of PRD was 5.6% (136 patients). Mortality for patients who experienced PRD was 8.8 vs. 0.1% for patients who did not (P<0.001). PRD increased the length of hospital stay by 3.4 days (7.6 vs. 11.0 days; P<0.001), and patients who needed haemodialysis (11%) had a perioperative mortality of 33.3% and a mean hospital length of stay of 16 days. Multivariable logistic regression identified the following variables as independent predictors of PRD: age (P=0.017; odds ratio (OR) 1.3 per 10 years), angina class III/IV (P=0.003; OR 1.7); cardiopulmonary bypass time (P=0.007; OR 1.01 per minute); preoperative serum creatinine levels: group 1 (1.3-1.6 mg/dl (P<0.001; OR 5.5)) and group 2 (1.7-2.0 mg/dl (P<0.001; OR 14.2)). Finally, a mild elevation of the preoperative creatinine level (1.3-2.0 mg/dl) increased significantly the probability of perioperative mortality, low cardiac output, haemodialysis and prolonged hospital stay. CONCLUSIONS: Although the likelihood of PRD in patients without pre-existing renal dysfunction is relatively low, it dramatically increases mortality, morbidity and length of stay after CABG. Mildly elevated (>1.2 mg/dl) preoperative serum creatinine level significantly increases the perioperative mortality and morbidity. 相似文献
63.
Andreia Coroas José G G de Oliveira Susana Sampaio Cátia Borges Isabel Tavares Manuel Pestana Maria D V de Almeida 《Journal of renal nutrition》2004,14(3):157-163
OBJECTIVE: Kidney transplantation restores renal filtration, although it does not achieve the function of 2 native kidneys, and with time it may involute back to chronic renal failure. We hypothesized that bioelectrical impedance analysis (BIA) might highlight differences for body compartments among kidney transplants (Tx) with different filtration rates. METHODS: Thirty transplantation patients (19 male, 11 female) were studied at 62.4+/-26.6 months postsurgery and were divided into 3 groups: good creatinine clearance (crCl, mL/min/1.73 m2; >65.0), borderline (35.0相似文献
64.
65.
A Cadete-Leite M C Alves M M Paula-Barbosa H B Uylings M A Tavares 《Alcohol and alcoholism (Oxford, Oxfordshire)》1990,25(5):467-475
The effects of chronic alcohol consumption and withdrawal on the organization of the basal dendrites of layer III pyramidal cells of the prelimbic cortex were studied in groups of rats fed on alcohol for 6 or 18 months, and in a group fed for 12 months, then switched to water for a further 6 months (withdrawal group). Three-dimensional analysis of the dendritic arborizations showed an age-dependent increase in several dendritic parameters, but a net stability was found in the metrical parameters between alcohol-fed and respective control rats. Conversely, a dendritic impoverishment occurred in the withdrawal group. The linear density of dendritic spines remained stable in all groups studied. Together with the previously found marked loss of the neurons after alcohol consumption and withdrawal, these findings point to a decrease in the available targets for afferents and therefore to the presence of probable functional alterations as a consequence of those in the connectivity patterns of the prelimbic area occurring under these conditions. 相似文献
66.
Cellular mechanism of the conduction abnormalities induced by serum from anti-Ro/SSA-positive patients in rabbit hearts. 总被引:1,自引:1,他引:0 下载免费PDF全文
S Garcia J H Nascimento E Bonfa R Levy S F Oliveira A V Tavares A C de Carvalho 《The Journal of clinical investigation》1994,93(2):718-724
In this study, IgG fractions from sera of SLE patients with anti-Ro/SSA or anti-Ro/SSA and anti-La/SSB activity were tested in Langendorff preparations of adult rabbit hearts, aiming to reproduce the cardiac manifestations observed in neonatal lupus in an experimental model. The hearts were perfused with normal Tyrode's solution for 30 min, followed by perfusion with Tyrode's containing 0.3 mg/ml of anti-Ro/SSA- (or anti-Ro/La-) positive IgG (nine sera), anti-ribonucleoprotein (RNP)-positive IgG (five sera), or IgG fractions from normal donors (five sera). In one third of the experiments done with anti-Ro/La-positive IgG, heart block was observed. With the remaining fractions, a decrease in heart rate of 17.1% was observed, but normal sinus rhythm was maintained. The IgG fractions with anti-RNP activity (five experiments) and from normal sera (six experiments) reduced heart rates by 12.9 and 3.3%, respectively, but heart block was not observed. To further characterize the cellular mechanisms involved in the conduction disturbances observed in the whole rabbit hearts, we conducted experiments with ventricular myocytes isolated from young rabbit hearts, studied by whole cell patch-clamp technique. In these experiments, the slow inward currents were analyzed during the superfusion of the cell with normal Tyrode's solution and 5 min after superfusion with Tyrode's solution containing 0.3 mg/ml of anti-Ro/SSA- (or anti-Ro/La-) positive IgG (five sera), anti-RNP-positive IgG (three sera), or IgG from normal donors (four sera). Resting and action potential amplitudes were not affected by any of the sera used. The anti-Ro/SSA IgG fraction induced a mean reduction in the peak slow inward current of 31.6%. IgG fractions with anti-RNP activity reduced slow inward current by 4.4%, whereas IgG fractions from normal donors increased this current by 3.3%. IgG-free fractions from sera of patients with anti-Ro/SSA activity did not alter the peak slow inward current. These results show, for the first time, that the presence of anti-Ro/SSA or anti-Ro/SSA and anti-La/SSB antibody activity in IgG fractions from lupus patients' sera can induce cardiac conduction disorders similar to those observed in neonatal lupus. 相似文献
67.
68.
R C de Oliveira A Gon?alves 《Revista do Instituto de Medicina Tropical de S?o Paulo》1991,33(3):233-239
In Brazil, Public Health specialization courses with the characteristics presently adopted by the National School of Public Health, i.e., short duration and great amplitude, are relatively recent, having started approximately fifteen years ago. In Brasília, nine such courses have been already completed, having, six of them, directive and/or teaching involvement by the authors. Results on a final assessment of one the courses are herewith presented in order to introduce our experience as a contribution to future analogous initiatives. The assessment was applied to a random sample of students, teachers and coordinators, with the objective of identifying positive and negative appreciations about methodological, operational, administrative and institutional aspects. Answers were quite variable, with the highest frequencies scored to field work and to the apprehension on admitting graduates to the Health System. Such aspects deserve final differentiated discussion. 相似文献
69.
P. E. Marchiori M. dos Reis M. E. Quevedo M. Scaff W. Cossermelli J. L. Assis R. M. de Oliveira 《Acta neurologica Scandinavica》1989,80(5):387-389
Radioimmunoassay techniques were used to detect antibodies to the acetylcholine receptor (AAChR) in 164 patients with adult-onset myasthenia gravis. AAChR levels above 0.6 nM/l were considered pathological and were found in 67% of the patients with an average value of 58.99 +/- 125.02 nM/l (0.6-900.0). Correlation, with clinical functional status, the histopathological thymus alterations and the different therapeutics used did not disclose any statistically significant differences. 相似文献
70.
Luciana Butini Oliveira Wagner Marcenes Thiago Machado Ardenghi Aubrey Sheiham Marcelo Bönecker 《Dental traumatology》2007,23(2):76-81
Abstract – The main objective of this study was to assess the epidemiology of traumatic dental injuries (TDI) to the primary teeth of preschool children and second, to investigate whether TDI were related to anterior open bite and, third, whether TDI are related to socio-economic circumstances in an urban Brazilian population. A clinical examination was performed during the National Day of Children's Vaccination. TDI were classified according to the modified classification proposed by Ellis. In addition to those criteria the presence of tooth discoloration was recorded. An interview was carried out with mothers or guardians. The data collected included mother's level of education and living conditions. The prevalence of TDI was 9.4%. The maxillary central incisors were the most affected teeth. Most children with a TDI experienced traumatic injuries to one tooth (6.3%), while 2.8% had two and 0.4% had three traumatized teeth. The most common crown fracture was in enamel only (68.8%), followed by crown fracture of enamel and dentin (13.8%). Missing teeth following trauma occurred in 10.9% of those with TDI. The prevalence of tooth discoloration was 5.1%. Children with anterior open bite had twice the level the level of TDI compared to those with normal occlusions ( P = 0.001). Socio-economic factors were not statistically significantly associated with the occurrence of TDI. The prevalence of dental injuries in Brazilian preschool children was low. Children with anterior open bite experienced more dental injuries. Neither of the indicators of socio-economic status was related to the prevalence of TDI. 相似文献