首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1859篇
  免费   116篇
  国内免费   22篇
耳鼻咽喉   12篇
儿科学   109篇
妇产科学   32篇
基础医学   177篇
口腔科学   32篇
临床医学   117篇
内科学   317篇
皮肤病学   39篇
神经病学   66篇
特种医学   156篇
外科学   313篇
综合类   149篇
一般理论   1篇
预防医学   110篇
眼科学   17篇
药学   124篇
中国医学   44篇
肿瘤学   182篇
  2023年   13篇
  2022年   23篇
  2021年   42篇
  2020年   39篇
  2019年   40篇
  2018年   43篇
  2017年   32篇
  2016年   40篇
  2015年   54篇
  2014年   68篇
  2013年   75篇
  2012年   97篇
  2011年   121篇
  2010年   111篇
  2009年   86篇
  2008年   85篇
  2007年   74篇
  2006年   84篇
  2005年   66篇
  2004年   45篇
  2003年   51篇
  2002年   47篇
  2001年   41篇
  2000年   31篇
  1999年   45篇
  1998年   58篇
  1997年   60篇
  1996年   55篇
  1995年   40篇
  1994年   36篇
  1993年   34篇
  1992年   16篇
  1991年   14篇
  1990年   13篇
  1989年   29篇
  1988年   23篇
  1987年   22篇
  1986年   18篇
  1985年   13篇
  1984年   13篇
  1982年   9篇
  1981年   8篇
  1980年   15篇
  1979年   7篇
  1977年   10篇
  1976年   8篇
  1975年   5篇
  1972年   5篇
  1971年   4篇
  1958年   4篇
排序方式: 共有1997条查询结果,搜索用时 15 毫秒
81.
刘蕤  陈紫雯  华桂丰  王立强  萨翼  刘昶 《中草药》2020,51(18):4829-4836
目的建立保健食品原料评价体系(Functional Food Crude Materials Evaluation System,FUFMES),为保健食品原料目录排名提供科学依据与技术保障。方法首先,利用文献调研和多轮专家访谈方法筛选FUFMES的指标并确定其层级关系;第二,使用层次分析法(Analytic Hierarchy Process,AHP)计算指标权重,具体方法是依据专家打分构建判断矩阵,利用R语言进行一致性检验与最大特征根检验,得出各级指标权重;第三,使用极值法计算原料的单个指标值;第四,利用线性加权综合法得到每种原料的评价指数并据此进行排名;最后,将获得的分析结果与专家评价结果进行比较。结果 FUFMES包括6个一级指标、39个二级指标、11个三级指标。利用FUFMES对9种保健食品原料进行评价,获得的评价指数依次是:西洋参(0.49)、人参(0.48)、银杏叶(0.21)、灵芝孢子粉(0.08)、鱼油(0.06)、螺旋藻(0.03)、辅酶Q10(0.02)、褪黑素(0.01)、大蒜油(-0.03)。基于该评价指数的排名结果与专家评价结果显示了较高一致性。结论构建了科学、完整的FUFMES,FUFMES将成为保健食品原料目录评价与排名的有力工具,为推进保健食品原料备案制提供科学依据与技术保障。  相似文献   
82.
83.
Aim: To describe cardiorespiratory fitness and body mass index (BMI) values in a representative population of 9-year-old Norwegian children in two rural communities and compare present values with previous findings.
Methods: Two hundred and fifty-nine 9-year-old children were invited, and 256 participated in this study. Maximal oxygen uptake was directly measured during a continuous progressive treadmill protocol. Body mass and height were also measured.
Results: The mean ± SD relative maximal oxygen uptake was 52.8 ± 6.5 for boys and 46.9 ± 7.2 mL/kg/min for girls. Eight percent of the boys and 16.8% of the girls were classified as overweight, and 1.6% of the boys and 6.9% of the girls as obese. Mean age, body mass, height and Ponderal index were not significantly different between sexes. Girls had a higher BMI than boys (p = 0.05).
Conclusion: Compared to earlier Norwegian studies, children's BMI values seem to have increased substantially. This increase is most pronounced in girls. When assessing these differences using the PI, this increase is less marked. Comparing maximal oxygen uptake data with that in earlier Nordic studies, there is no evidence that fitness has declined among 9-year olds. However, the limitations of the few earlier studies make reliable comparisons difficult.  相似文献   
84.
85.
Peripheral nerve disorders may be classified into compressive or entrapment neuropathies and non‐compressive neuropathies. Muscle denervation recognized on MRI may be a useful sign in the diagnosis of peripheral nerve disorders. Acute or subacute denervation results in prolonged T2 relaxation time, producing increased signal in skeletal muscle on short tau inversion‐recovery and fat‐suppressed T2‐weighted images. Chronic denervation produces fatty atrophy of skeletal muscles, resulting in increased muscle signal on T1‐weighted images. This review will outline and illustrate the various ways that muscle denervation as seen on MRI may assist in the diagnosis and localization of peripheral nerve disorders.  相似文献   
86.
87.
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   
88.
The effects of dexamethasone therapy on the hypothalamic-pituitary-adrenal axis were tested in 10 premature infants with bronchopulmonary dysplasia by means of the corticotropin-releasing hormone stimulation test before therapy and on the seventh day of therapy. Adrenocorticotropic hormone and cortisol levels were determined by radioimmunoassay. There was significant suppression of the hypothalamic-pituitary-adrenal axis after 7 days of a currently used dexamethasone treatment regimen. A site of suppression was located at the level of the pituitary gland.  相似文献   
89.
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   
90.
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   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号