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   3640篇
  免费   258篇
  国内免费   21篇
耳鼻咽喉   8篇
儿科学   116篇
妇产科学   83篇
基础医学   383篇
口腔科学   136篇
临床医学   463篇
内科学   637篇
皮肤病学   126篇
神经病学   335篇
特种医学   282篇
外科学   498篇
综合类   127篇
一般理论   2篇
预防医学   280篇
眼科学   35篇
药学   212篇
中国医学   1篇
肿瘤学   195篇
  2021年   55篇
  2020年   34篇
  2019年   67篇
  2018年   60篇
  2017年   45篇
  2016年   51篇
  2015年   58篇
  2014年   67篇
  2013年   98篇
  2012年   163篇
  2011年   167篇
  2010年   121篇
  2009年   118篇
  2008年   159篇
  2007年   177篇
  2006年   186篇
  2005年   167篇
  2004年   150篇
  2003年   148篇
  2002年   140篇
  2001年   134篇
  2000年   161篇
  1999年   88篇
  1998年   59篇
  1997年   54篇
  1996年   61篇
  1995年   46篇
  1994年   37篇
  1993年   47篇
  1992年   65篇
  1991年   63篇
  1990年   56篇
  1989年   69篇
  1988年   56篇
  1987年   64篇
  1986年   51篇
  1985年   60篇
  1984年   43篇
  1983年   34篇
  1981年   26篇
  1979年   28篇
  1978年   30篇
  1977年   25篇
  1975年   20篇
  1972年   23篇
  1971年   24篇
  1970年   23篇
  1969年   21篇
  1968年   22篇
  1967年   24篇
排序方式: 共有3919条查询结果,搜索用时 312 毫秒
121.
Patients with type 2 diabetes mellitus exhibit considerable platelet dysfunction, though this is poorly characterized in patients with diabetes taking aspirin for the primary prevention of cardiovascular events. We sought to compare platelet function in this patient population with that of a high-risk group of non-diabetic subjects with a history of previous myocardial infarction (MI), and to assess whether glycaemic control impacts on platelet function. Methods: Platelet aggregation was measured in response to incremental concentrations of five platelet agonists using light transmission aggregometry. All patients were taking aspirin, and aspirin insensitivity was defined as ≥ 20% arachidonic acid (AA) mediated aggregation. Patients with diabetes were divided according to glycaemic control (HbA(1c)): optimal ≤ 6.5, good 6.6-7.4 and suboptimal ≥ 7.5%. Results: In total, 85 patients with type 2 diabetes and 35 non-diabetic patients with previous MI were recruited. Compared to MI patients, diabetes patients had increased aggregation in response to multiple concentrations of epinephrine, collagen, adenosine diphosphate and AA. Aspirin insensitivity was more common in type 2 diabetes (15% vs. 0%, p=0.037). Platelet aggregation was increased in response to several agonists patients with suboptimal glycaemic control compared to patients with optimal control. Aspirin insensitivity was also more common in patients with suboptimal glycaemic control compared to those with good or optimal control (26.0% vs. 8.3% vs. 4%, p=0.04). Conclusion: Patients with type 2 diabetes mellitus, without proven vascular disease, exhibit platelet dysfunction and have increased platelet aggregation and aspirin insensitivity compared to non-diabetic patients with previous MI. Platelet dysfunction in diabetes is more severe in patients with suboptimal glycaemic control.  相似文献   
122.
Regular physical activity and limiting extended periods of sitting are two behaviours critical for the prevention of obesity in young people. The purpose of the systematic review was to synthesize the psychometric evidence for self‐report use‐of‐time tools that assess these behaviours. Articles were retrieved that reported reliability and/or validity for use‐of‐time tools in participants aged 18 years or under. Outcome variables were physical activity, sedentary behaviour and energy expenditure. Study quality was appraised, and the results summarized narratively. Sixteen studies and six different tools were identified. The tools were the Previous Day Physical Activity Recall, the Three‐Day Physical Activity Recall, the Physical Activity Interview, the Computerized Activity Recall, the Activitygram, and the Multimedia Activity Recall for Children and Adolescents. Overall, tools indicated moderate validity compared with objective and criterion comparison methods. Generally, validity correlation coefficients were in the range of 0.30–0.40. Correlation coefficients for test–retest reliability ranged widely from 0.24 to 0.98. Conclusion: Use‐of‐time tools have indicated moderate reliability and validity for the assessment of physical activity and energy expenditure. Future research should focus on using criterion methods and on validating specifically for sedentary behaviour outcomes. Implementation of these tools for population surveillance should be considered.  相似文献   
123.
124.
125.
Journal of Autism and Developmental Disorders - Pathways to diagnosis in adulthood are poorly understood. Even less is known about undiagnosed adults who believe they may be autistic. This...  相似文献   
126.
127.
128.
The surgical management of early stage endometrial carcinoma is controversial. The benefits of pelvic lymphadenectomy and administration of radiotherapy in this group have been disputed. We aimed to document the experience of stage 1 endometrial carcinoma at the National Maternity Hospital during the 10 year period 1989-1998 and to evaluate and compare clinical outcomes between retrospectively-assigned low and high-risk tumour groups. Seventy seven women were diagnosed with Stage 1 endometrial carcinoma in this period. Thirty-nine women had low-risk and 38 had high-risk tumours. Women with high-risk tumours were older and had a higher rate of lymph-vascular space invasion by tumour on histological examination. Three women (3.9%) developed disease recurrence and died of their disease; one low-risk and two high-risk tumour patients. Survival without recurrence did not differ between the two risk groups. No consistent pattern existed in surgical staging between the two risk groups. A prospectively-assigned definition of risk would minimise variations in clinical practice by providing a basis for a more tailored approach to adjuvant treatments.  相似文献   
129.
Two species of Bartonella, a novel Bartonella clarridgeiae-like bacterium and B. vinsonii subsp. berkhoffii, were isolated from rural dogs and gray foxes in northern California. A novel B. clarridgeiae-like species was isolated from 3 (1.7%) of 182 dogs and 22 (42%) of 53 gray foxes, while B. vinsonii subsp. berkhoffii was isolated from 1 dog (0.5%) and 5 gray foxes (9.4%). PCR and DNA sequence analyses of the citrate synthase (gltA) gene and the 16S-23S intergenic spacer region suggested that strains infecting dogs and gray foxes were identical. Fifty-four dogs (29%) and 48 gray foxes (89%) had reciprocal titers of antibodies against Bartonella spp. of > or =64. The high prevalence of bacteremia and seroreactivity to Bartonella spp. in gray foxes suggests that they may act as a reservoir species for the B. clarridgeiae-like species in this region. Domestic dogs were also tested for other arthropod-borne infectious agents. Fifty-one dogs (28%) were positive for Dirofilaria immitis antigen, seventy-four (40%) were seroreactive to Anaplasma phagocytophilum, and five (2.7%) were seropositive for Yersinia pestis. Fourteen dogs (7.6%) were PCR positive for A. phagocytophilum. Polytomous logistic regression models were used to assess the association of Bartonella antibody titer categories with potential risk factors and the presence of other vector-borne agents in domestic dogs. Older dogs were more likely to be seroreactive to Bartonella spp. There was no association between the exposure of dogs to Bartonella and the exposure of dogs to A. phagocytophilum in this study.  相似文献   
130.
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