全文获取类型
收费全文 | 1265篇 |
免费 | 94篇 |
国内免费 | 17篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 115篇 |
妇产科学 | 8篇 |
基础医学 | 96篇 |
口腔科学 | 29篇 |
临床医学 | 87篇 |
内科学 | 187篇 |
皮肤病学 | 27篇 |
神经病学 | 81篇 |
特种医学 | 137篇 |
外科学 | 115篇 |
综合类 | 134篇 |
预防医学 | 149篇 |
眼科学 | 4篇 |
药学 | 59篇 |
中国医学 | 39篇 |
肿瘤学 | 106篇 |
出版年
2023年 | 7篇 |
2022年 | 17篇 |
2021年 | 30篇 |
2020年 | 24篇 |
2019年 | 21篇 |
2018年 | 28篇 |
2017年 | 24篇 |
2016年 | 27篇 |
2015年 | 41篇 |
2014年 | 59篇 |
2013年 | 58篇 |
2012年 | 65篇 |
2011年 | 70篇 |
2010年 | 90篇 |
2009年 | 76篇 |
2008年 | 38篇 |
2007年 | 37篇 |
2006年 | 52篇 |
2005年 | 37篇 |
2004年 | 20篇 |
2003年 | 32篇 |
2002年 | 18篇 |
2001年 | 22篇 |
2000年 | 16篇 |
1999年 | 21篇 |
1998年 | 47篇 |
1997年 | 60篇 |
1996年 | 52篇 |
1995年 | 39篇 |
1994年 | 33篇 |
1993年 | 32篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 23篇 |
1988年 | 19篇 |
1987年 | 17篇 |
1986年 | 16篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 2篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1979年 | 3篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1958年 | 4篇 |
1957年 | 2篇 |
排序方式: 共有1376条查询结果,搜索用时 15 毫秒
71.
丁香水溶性化学成分的研究 总被引:2,自引:0,他引:2
目的:研究丁香水溶性化学成分。方法:利用HP-20大孔吸附树脂、反相硅胶柱色谱、反相制备薄层色谱、制备型反相高效液相色谱进行分离,NMR和MS等方法进行结构鉴定。结果:从丁香干燥花蕾的水提物中分离鉴定了5个化合物,分别为槲皮素-3-O-葡萄糖醛酸苷(1),槲皮素-3-O-葡萄糖醛酸苷6″-甲酯(2),槲皮素-3-O-葡萄糖苷(3),丁香酚-β-芸香糖苷(4),杨梅酮(5)。结论:化合物1~4为首次从丁香属植物中分离得到。 相似文献
72.
ER Brown KA Charles SA Hoare RL Rye DI Jodrell RE Aird R Vora U Prabhakar M Nakada RE Corringham M DeWitte C Sturgeon D Propper FR Balkwill JF Smyth 《Annals of oncology》2008,19(7):1340-1346
BACKGROUND: Tumour necrosis factor-alpha (TNF-alpha) is an important regulator of the chronic inflammation contributing to tumour progression. Infliximab, an anti-TNF-alpha monoclonal antibody was investigated in this trial of patients with advanced cancer. The primary objectives were to determine the safety profile and biological response of infliximab in a cancer population. Clinical response was a secondary objective. PATIENTS AND METHODS: Forty-one patients received infliximab at 5 mg/kg (n = 21) or 10 mg/kg (n = 20) i.v. at 0 and 2 weeks and then every 4 weeks. Post-treatment samples were measured for changes in plasma and serum TNF-alpha, CCL2, IL-6 and C-reactive protein (CRP). RESULTS: Infliximab was well tolerated with no dose-limiting toxic effects. At both doses of infliximab, neutralisation of serum TNF-alpha was observed after 1 h while plasma CCL2, IL-6 and serum CRP were decreased 24 and 48 h following infliximab administration. Seven patients experienced disease stablisation (range 10-50+ weeks). There was no evidence of disease acceleration in any patient. CONCLUSIONS: Infliximab treatment was safe and well tolerated in patients with advanced cancer. There was evidence of biological activity with baseline TNF-alpha and CCL2 being correlated with infliximab response. 相似文献
73.
实验动物资源是国家生命科学研究的重要科技资源。实验动物资源的共享和充分利用是生物科技创新的基础和保障。有效的共享机制和合理的共享方式是实现实验动物资源共享和充分利用的重要保障,是规范实验动物资源共享行为和确保共享安全的迫切需要。 相似文献
74.
A Ohlsson SA Calvert M Hosking AT Shennan 《Acta paediatrica (Oslo, Norway : 1992)》1992,81(10):751-756
This randomized controlled trial was designed to answer the question: does administration of dexamethasone to neonates with bronchopulmonary dysplasia decrease the need for assisted ventilation? Twenty-five infants with a birth weight < 1501 g, requiring mechanical ventilation and FiO2 of ± 0.30 at 21-35 days of age, were randomized to treatment with iv dexamethasone or to sham injections for 12 days. The primary outcome criterion was extubation within seven days after study entry. Treatment (n= 12) and control (n= 13) groups were well matched at entry. Dexamethasone facilitated weaning from assisted ventilation (p= 0.0154). There was no increased incidence of infection. Dexamethasone treatment resulted in a significant increase in glucosuria (p= 0.0002) and in systolic blood pressure (p= 0.0034). There was a significant decrease in heart rate (p= 0.0001) and a significant weight loss (p= 0.0002) following dexamethasone treatment. Dexamethasone treatment facilitated weaning from assisted ventilation but several systemic effects were noted that deserve further evaluation before dexamethasone becomes routine treatment. 相似文献
75.
Effects of positive and negative pressure ventilation on cerebral blood volume of newborn infants 总被引:3,自引:0,他引:3
KS Palmer SA Spencer YABD Wickramasinghe T Wright DP Southall P Rolfe 《Acta paediatrica (Oslo, Norway : 1992)》1995,84(2):132-139
The effects of intermittent positive airway and continuous negative extrathoracic pressure ventilation on cerebral blood volume in preterm infants were studied using near infrared spectroscopy. In 12 infants continuous negative extrathoracic pressure caused a median decrease in cerebral blood volume of 0.14ml/100ml brain (95% confidence intervals (CI) 0.035–0.280) compared with no respiratory support. Oxygenated and deoxygenated haemoglobin also decreased, implying increased venous drainage as the main effect. In 17 infants intermittent positive pressure ventilation also caused a median reduction in cerebral blood volume of 0.06 ml/100 ml brain (95% CI 0.010–0.115) compared with endotracheal positive airway pressure. Deoxygenated haemoglobin increased by 0.07 ml/100 ml brain (95% CI 0.010–0.100) while oxygenated haemoglobin decreased by O.lOml/lOOml brain (95% CI 0.005–0.175). The increase in deoxygenated haemoglobin implies decreased venous drainage and the decrease in oxygenated haemoglobin implies that other factors may also be significant. Heart rate, blood pressure and oxygen saturation were monitored continuously and remained stable. 相似文献
76.
Neighbourhood socioeconomic context and self reported health and smoking: a secondary analysis of data on seven cities 总被引:5,自引:4,他引:1
下载免费PDF全文
![点击此处可从《Journal of epidemiology and community health》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Reijneveld SA 《Journal of epidemiology and community health》2002,56(12):935-942
OBJECTIVE: Many studies have shown that poor health status and harmful health behaviour occur more frequently in deprived neighbourhoods. Most studies show modest associations between area level socioeconomic factors, the neighbourhood context, and health outcomes. However, estimates for the contextual effects vary. It is unclear if this variation is attributable to differences in methodology. This study examines whether contextual neighbourhood differences in health outcomes really vary between cities or that differences in methodology may account for these differences. DESIGN: Secondary analysis of data from health interview surveys in seven large Dutch cities in the 1990s comprising 23 269 residents of 484 neighbourhoods, using multilevel logistic models. SETTING: General population aged 16 and over. MAIN OUTCOME MEASURES: Self reported health, smoking of cigarettes. MAIN RESULTS: The socioeconomic context of neighbourhoods is associated with health outcomes in all large Dutch cities. The strength of the association varies between cities, but variation is much smaller in the age group 25-64. Furthermore, neighbourhood differences vary in size between native and other residents. Contextual neighbourhood differences are about two times larger for self reported health than for the smoking of cigarettes, but for native Dutch people they are of similar size. CONCLUSIONS: A comparatively large improvement in health may be gained in deprived neighbourhoods, because of the poorer health status to which the context of these neighbourhoods also contributes. Health promoting interventions should be aimed at the residents and at the context of deprived neighbourhoods, taking differences between ethnic groups and age groups into account. 相似文献
77.
Family factors and life events as risk factors for behavioural and emotional problems in children 总被引:2,自引:0,他引:2
Harland P Reijneveld SA Brugman E Verloove-Vanhorick SP Verhulst FC 《European child & adolescent psychiatry》2002,11(4):176-184
The aim of this study was to identify groups of children at increased risk of behavioural or emotional problems on the basis of socio-demographic characteristics, family characteristics, and recent life events with a focus on unemployment and divorce or separation. We obtained data on the Child Behavior Checklist (CBCL) from a community-based national sample of 4480 parents of school-aged children and interviewed them about their demographic and family characteristics and about the child's recent life events. Results showed that family characteristics and recent life events were more strongly associated with children's risks of behavioural and emotional problems as measured by the CBCL than other demographic characteristics. Risks were somewhat higher for children who had experienced parental unemployment and divorce or separation recently, as compared to those who had experienced these events in the more distant past. We conclude that children with recent experience of parental unemployment or parental divorce or separation are at a relatively high risk of behavioural and emotional problems as reported by parents. Although relatively high, the risks that were found do not justify restriction of screening for behavioural and emotional problems to these children. 相似文献
78.
目的:通过对突发性聋病人血中一氧化氮(NO)、丙二醛(MDA)、超氧化物歧化酶(SOD)含量的检洲,探讨突聋与血氧自由基和自由基的清除剂SOD之间的关系。方法:采用硝酸还原酶法测定了30例突聋病人血中NO含量,并以25例同期体检正常的健康人为对照组;同时还用硫代巴比妥酸比色法测定MDA含量,用黄嘌呤氧化酶法测定SOD含量。砖呆;应用金纳多、能量合剂、克林臭(即马来酸桂哌齐特,钙通道阻滞药)联合静脉输入,突聋各组的听力均有不同程度提高,有效率在78.57%以上。治疗后同对照组相比,血清NO、MDA水平明显低于患病之初,而SOD活性明显高于治疗之前,P〈0.01。结论;检测突聋病人血中N0、MDA、SOD的含量,能帮助我们探讨突聋的发病机理,估计预后。血氧自由基的升高可能是突聋发病因素之一,而SOD的含量可以帮助我们估计预后。 相似文献
79.
F Haque ST Fazal SA Ahmad SZ Abbas S Naseem 《Journal of Medical Imaging and Radiation Oncology》2006,50(1):63-65
Primary osteogenic sarcoma of the skull is an exceedingly rare condition. An adult male patient is described, who had a painless swelling in the right forehead that had rapidly enlarged in the previous 6 months. Radiological investigations showed a large destructive mass lesion involving the right side of the frontal bone with extension into the frontal sinus, causing marked extradural compression of brain parenchyma. Histopathological examination confirmed the lesion to be primary osteogenic sarcoma. 相似文献
80.
维甲酸和联合应用神经营养因子对新生大鼠神经干细胞分化的影响 总被引:1,自引:0,他引:1
目的研究全反式维甲酸(ATRA)及联合应用神经营养因子(BDNF,GDNF)对体外培养的神经干细胞(NSCs)分化的影响。方法取新生SD大鼠的前脑室下带(SVZ)区,按NSCs的常规培养方法分离、培养。用免疫细胞化学法鉴定巢蛋白(nestin)、微管相关蛋白-2(MAP-2)、胶质原纤维酸性蛋白(GFAP)的表达,以此来观察ATRA、BDNF、GDNF单独或联合应用对次代神经球细胞分化的作用。结果原代及次代神经球均显示nestin阳性,并可分化为MAP-2阳性神经元样细胞及GFAP阳性胶质细胞样细胞。1μmol/LATRA可促进NSCs分化为MAP-2阳性细胞的比例达(29.14±5.00)%,显著高于对照组的(7.19±1.21)%,差异有高度统计学意义(P〈0.001)。ATRA联合应用10ng/ml的BDNF或GDNF,与单独使用ATRA比较,并不显著提高NSCs分化为MAP-2阳性细胞的比例。结论ATRA可促进神经干细胞向神经元方向分化,ATRA联合应用BDNF或GDNF无明显的协同作用。 相似文献