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   47242篇
  免费   6172篇
  国内免费   906篇
耳鼻咽喉   167篇
儿科学   1477篇
妇产科学   1186篇
基础医学   3151篇
口腔科学   1319篇
临床医学   5843篇
内科学   10252篇
皮肤病学   454篇
神经病学   3445篇
特种医学   944篇
外国民族医学   2篇
外科学   4718篇
综合类   4381篇
现状与发展   9篇
一般理论   9篇
预防医学   8219篇
眼科学   698篇
药学   3670篇
  27篇
中国医学   417篇
肿瘤学   3932篇
  2024年   141篇
  2023年   1337篇
  2022年   1577篇
  2021年   3157篇
  2020年   2837篇
  2019年   2608篇
  2018年   2520篇
  2017年   2364篇
  2016年   2354篇
  2015年   2150篇
  2014年   3628篇
  2013年   4492篇
  2012年   2627篇
  2011年   2840篇
  2010年   2143篇
  2009年   2125篇
  2008年   2140篇
  2007年   1918篇
  2006年   1716篇
  2005年   1508篇
  2004年   1211篇
  2003年   1005篇
  2002年   874篇
  2001年   789篇
  2000年   599篇
  1999年   490篇
  1998年   450篇
  1997年   367篇
  1996年   299篇
  1995年   286篇
  1994年   228篇
  1993年   263篇
  1992年   193篇
  1991年   173篇
  1990年   133篇
  1989年   124篇
  1988年   117篇
  1987年   84篇
  1986年   74篇
  1985年   91篇
  1984年   82篇
  1983年   31篇
  1982年   57篇
  1981年   30篇
  1980年   33篇
  1979年   19篇
  1978年   8篇
  1977年   12篇
  1974年   4篇
  1972年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
目的探讨高血压病患者心肌灌注断层显像的结果和多种临床因素的关系.方法将97例高血压病患者的心肌灌注断层显像结果同患者的年龄、性别、体重指数、患高血压病的时间、有无抗高血压治疗,有无高血压家族史,患者的血清葡萄糖、肌酐、尿素氮、甘油三酯、胆固醇、脉搏、收缩压、舒张压、脉压差、平均动脉压、患者是否吸烟、饮酒进行非条件Logistic回归分析.结果患高血压病的时间(βi=0.4914,P=0.0017)、吸烟(βi=3.5022,P=0.0176)、高胆固醇血症(βi=1.6147,P=0.0194)是高血压病患者并发心肌缺血的危险因素.结论高血压痛患者戒烟、治疗高胆固醇血症,可降低其并发心肌缺血的风险.  相似文献   
103.
104.
BACKGROUND AND PURPOSE: Dotlike hemosiderin spots ongradient-echo T2(*)-weighted magnetic resonance imaging of the brain have been histologically diagnosed as old microbleeds associated with small vessel disease (SVD). The authors hypothesize that the presence of many dotHSs may be correlated with the fragility of small vessels and the recurrence of SVD, including lacunar infarction and deep intracerebral hemorrhage (ICH). METHODS: To investigate how dotHSs are related to past history of SVD, the number of subcortical or deep dotHSs was investigated in 146 patients with lacunar infarctions (95 men, 51 women, age 38 to 90 [66.6+/-9.4] years). They were divided into 2 subgroups according to history of deep ICHs or lacunar infarctions. The odds ratio (OR) for past history was estimated from logistic regression analyses with the number of subcortical or deep dotHSs as well as other factors. RESULTS: Of 146 patients with lacunar infarctions, 11 had past symptomatic ICHs and 19 had past symptomatic lacunar infarctions. An elevated rate of history of ICH was found for lacunar infarction patients with many deep dotHSs (>or=3; OR, 9.1; 95% confidence interval, 1.6-51, P=.015). However, history of lacunar infarction was not significantly associated with the number of subcortical or deep dotHSs. CONCLUSIONS: Our findings suggest that many deep dotHSs on T2(*)-weighted magnetic resonance imaging may be correlated with deep ICH-lacunar infarction type of SVD recurrence but not lacunar infarction-lacunar infarction type.  相似文献   
105.
The retinae of 137 patients were examined ophthalmologically and for visual acuity at diagnosis of noninsulin dependent diabetes and again in 1982 and 1983, approximately 7 and 8 years later, when colour photographs were also taken. In 1983, 46% were without detectable retinopathy, 32% had haemorrhages (including microaneurysms) only, 4% exudates alone and 18% both lesions. Those with haemorrhages were more hyperglycaemic than those without retinopathy and those with exudates only. Indeed, those with exudates alone had lower mean glucose levels than those without retinopathy (p<0.05). Patients with exudates (± haemorrhages) had a lower percentage of the fatty acids of plasma cholesterol esters as linoleate than those without (p<0.05) but this did not hold for those developing haemorrhages. Different risk factors appear to operate in different features of diabetic retinophathy. In some respects exudate formation may be more akin to macro than to micro angiopathy.  相似文献   
106.
S P Caudill  S J Smith  G R Cooper 《Statistics in medicine》1989,8(3):295-309; discussion 331-2
Using data from the National Health and Nutrition Examination Survey (NHANES II) 1976-1980, we demonstrate how cross-sectional total serum cholesterol surveillance data can be used by an individual to assess current and future personal cholesterol risk status. We propose statistical models, based on a person's current measured cholesterol level and the relationship between cross-sectional age and cholesterol percentile estimates, that will allow prediction of future cholesterol levels or the age at which specified cholesterol risk levels will be reached if no cholesterol-altering intervention is taken. These models incorporate the observed variation in the NHANES II data and expected intraperson biological variation and intralaboratory analytical variation. We illustrate the adequacy of the models using data from the longitudinal Framingham Study.  相似文献   
107.
AIM: The aim of this study was to explore a birthweight prediction model using ultrasound determined tissue thickness (SCTT) parameters. METHODS: We measured routine ultrasonographic biometric parameters and in addition, fetal SCTT in 201 healthy singleton pregnancies. Mid-arm fat and lean mass, mid-thigh fat and lean mass, subscapular fat mass and abdominal fat mass (AFM) were measured in order to calculate a birthweight prediction model. Ultrasound measurements were analyzed using an 'anovarepeated measures model'. The growth rate (beta-slope) of the selected parameters was computed and the correlation coefficient with the birthweight and the Kendall rank correlation tau, were calculated. RESULTS: From the ultrasound determined SCTT parameters, only abdominal circumference (AC), AFM, and MTLM showed a statistically significant trend. The beta-slope of mid-thigh lean mass was excluded since it exhibited significant correlation with the beta-slope of AFM. The final regression model could be calculated as: birthweight (gr.) = intercept +alpha(1)(AFM beta-slope) + alpha(2)(AC beta-slope), where alpha(1), alpha(2) represent regression coefficients. CONCLUSIONS: We provide a graphical birthweight prediction model for clinical practice using conventional and specific ultrasound measurements of fetal subcutaneous tissue thickness. This model is based upon an overall analysis of the ultrasound estimated body components.  相似文献   
108.
目的探讨骨科住院患者下肢深静脉血栓形成(lower extremity deep vein thrombosis,LD-VT)的危险因素。方法2003年8月~2006年8月收治的350例骨科住院患者中,确诊为LDVT者38例,对其相关因素进行回顾性分析。结果27项单因素相关分析中有9项有显著性意义,经Logis-tic回归分析显示,危险因素为:血浆D-二聚体、纤维蛋白原、血管性血友病因子阳性,4周内有手术史以及有外伤史。结论对上述危险因素存在的骨科住院患者,应警惕LDVT发生,如有D-二聚体测定阳性等危险因素应予预防性治疗。  相似文献   
109.
BACKGROUND: Optimal feeding practice in the first year of life is crucial for the survival and health of infants, and has long-term consequences in later life. However, non-optimal feeding practices exist widely. The present study aims to explore various constraints to optimal feeding practices in the first year of life of infants in urban areas of Beijing, China. METHODS: A cross-sectional study was conducted in urban areas of Beijing from 4 July to 20 August, 1998. Two hundred and fifty-one mothers of infants aged 6-12 months were chosen from six child health centers in three different urban districts in Beijing. A self-administered structured questionnaire was used to collect data regarding feeding practices and potentially related factors. RESULTS: Feeding practice for most of the infants was in accordance with the national and international recommendations. However, the rate of incidence of exclusive breast-feeding at 3 months of age was lower than that recommended by the World Health Organisation (WHO) (55.8%), and the introduction of solid/semisolid food before 4 months of age was found in approximately 19.3% of the infants. Cow's milk was given to 21.2% of infants from 6 months of age as the sole source of milk or as a supplement. Maternal education level (OR = 2.44, 95% CI: 1.42-4.19, P < 0.05), employment (OR = 2.05, 95% CI: 1.13-3.74, P < 0.05) and antenatal nonexclusive breast-feeding plans (OR = 4.10, 95% CI: 2.24-7.50, P < 0.001) were found to be correlated to inappropriate feeding practices. CONCLUSIONS: The feeding practices for most of the urban infants was found to be in accordance with the Chinese government and WHO recommendations; however, non-optimal feeding practices presenting as the early cessation of breast-feeding and the introduction of solid/semisolid foods existed. Information regarding optimal feeding practices should be disseminated to mothers and medical professionals in China, to ensure optimal infant health.  相似文献   
110.
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