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   12630篇
  免费   1303篇
  国内免费   190篇
耳鼻咽喉   99篇
儿科学   1096篇
妇产科学   946篇
基础医学   1214篇
口腔科学   302篇
临床医学   1063篇
内科学   1505篇
皮肤病学   183篇
神经病学   1149篇
特种医学   331篇
外国民族医学   2篇
外科学   970篇
综合类   1311篇
一般理论   2篇
预防医学   1804篇
眼科学   619篇
药学   611篇
  11篇
中国医学   243篇
肿瘤学   662篇
  2024年   18篇
  2023年   195篇
  2022年   283篇
  2021年   564篇
  2020年   540篇
  2019年   528篇
  2018年   465篇
  2017年   555篇
  2016年   556篇
  2015年   470篇
  2014年   810篇
  2013年   989篇
  2012年   681篇
  2011年   757篇
  2010年   645篇
  2009年   567篇
  2008年   549篇
  2007年   545篇
  2006年   519篇
  2005年   478篇
  2004年   357篇
  2003年   297篇
  2002年   287篇
  2001年   239篇
  2000年   193篇
  1999年   179篇
  1998年   150篇
  1997年   152篇
  1996年   142篇
  1995年   114篇
  1994年   136篇
  1993年   112篇
  1992年   120篇
  1991年   102篇
  1990年   92篇
  1989年   88篇
  1988年   74篇
  1987年   59篇
  1986年   58篇
  1985年   81篇
  1984年   52篇
  1983年   34篇
  1982年   44篇
  1981年   36篇
  1980年   50篇
  1979年   31篇
  1978年   24篇
  1977年   23篇
  1976年   21篇
  1975年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Background: Multiple factors related to specific dimensions of health – general, physical and mental – contribute to mortality in the elderly, but their relative contributions to mortality risk is not well‐known. The objectives of this prospective population‐based cohort study were to measure mortality rates and to identify predictors of mortality in community‐dwelling men and women aged 65 years or older in Korea by examining self assessments of general health, objective medical burden, and measurement of cognition, mood and function. Methods: A total of 1245 elderly (529 men; 716 women) were followed up longitudinally for 3.5 years. Fixed predictor variables observed at baseline examined in Cox proportional hazards models were age, sex, education, chronic medical illnesses, self‐rated health, basic activities of daily living, depression measured by the Geriatric Depression Scale, and cognition measured by the Mini‐Mental State Examination. Results: Mortality rates were similar to those of the 2001 Korean population. Older age, male sex, poor self‐rated health and presence of cerebrovascular disease were significant predictors of mortality. Presence of ischemic heart disease and cerebrovascular disease at baseline predicted mortality in men, but not in women. Depression predicted mortality only when chronic medical illnesses were excluded from the model. Conclusions: Subjective self‐rated health and objective medical burden are strong independent predictors of mortality in this elderly community population, in addition to age and sex.  相似文献   
62.
We investigated the age at onset distributions of schizophrenia in men and women and the relationship of age at onset and sex to the familial rates of schizophrenia and manic-depression in data from a Swedish family study of 270 schizophrenic probands. On the logarithmic scale, the age at onset distribution of schizophrenia in both male and female relatives was bimodal, suggesting that broadly defined schizophrenia may be a mixture of 2 (probably related) disorders. The risk of schizophrenia in relatives decreased as a function of the age at onset of the proband, irrespective of the sex of the proband or relative. In contrast, the risk of manic-depression was significantly higher in relatives of female probands with an age at onset in the twenties than in relatives of female probands with earlier or later onset, or in relatives of male probands. This suggests a third disorder related to affective psychosis, with an intermediate age at onset and female preponderance.  相似文献   
63.
We assessed the effect of long-term therapy with inhaled beclomethasone dipropionate (BDP) on the pituitary-adrenal axis, by measuring the integrated concentration (IC) of plasma cortisol in eight children with asthma (age, 6-16 years) who regularly used inhaled BDP in doses ranging from 8 to 26.5 micrograms/kg (200-450 micrograms/day) for 6 months to 4 years. The control group included six children (age, 6-16 years) who had the IC of plasma cortisol measured as part of an endocrinological evaluation and were found to be healthy. Cortisol concentration was measured in blood samples collected continuously over a 24-hr period. Mean IC of plasma cortisol in the study group was significantly lower than in the healthy controls (mean +/- SD, 4.9 +/- 3.3 vs 9.1 +/- 1.9 micrograms/mL; P less than 0.02). Cortisol response to 0.25 mg ACTH (iv) was abnormal in one of the eight BDP-treated patients. No correlation was found between IC of plasma cortisol and the BDP dose, severity of asthma, height percentile, or the Tanner stage. We conclude that long-term therapy, even with relatively conventional doses of inhaled BDP may cause reduction in the normal physiological secretion of cortisol. The clinical relevance of low IC of plasma cortisol is not clear, but it may reflect partial suppression of the pituitary-adrenal axis.  相似文献   
64.
Summary Recognition of adrenal atrophy during a review of autopsy findings in two sisters who died at 8 months and 3 1/2 years prompted estimation of very long chain fatty acids, phytanic acid and pristanic acid on wet liver fixed in formalin for 12 years. These were shown to be markedly increased and defects in multiple peroxisomal functions and decrease in particulate catalase were shown in cultured fibroblasts, confirming an abnormality of peroxisomal biogenesis. The patients had presented with failure to thrive, recurrent diarrohea and vomiting, poor mental development, retinal pigmentation, blindness and in the older patient deafness, with only mild dysmorphic features. Autopsy in the older patient showed adrenal atrophy, cirrhosis, and foamy histiocytes in multiple organs. The brain showed no demyelination, little cytoarchitectural abnormality, occasional perivascular histiocytes in the grey matter and meninges and prominent Purkinje cells in the molecular layer of the cerebellum. In the younger patient the changes were very subtle in spite of the marked clinical similarity. Despite the young age at death the clinicopathological features are most suggestive of infantile Refsum disease. In many situations anatomical pathology can be very useful in the recognition and study of peroxisomal disorders.  相似文献   
65.
目的:探讨避孕措施与细菌性阴道病(BV)的关系,为预防BV、指导选择避孕措施提供依据。方法:对某医院妇科门诊接受计划生育服务的育龄妇女非选择性地进行BV筛检。以筛检出的267例BV患者为病例组,其余478例未患BV且无BV史的妇女为对照组进行病例对照研究。结果:与未采用避孕措施者比较,单因素logistic回归分析显示:BV与IUD有正关联,而与避孕套、口服避孕药(OC)无关联。经婚姻状况、性卫生、性行为习惯调整后,BV与IUD的关联仍有统计学意义(OR=2.364,95%C1:1.216~3.620),但与OC及避孕套使用无关。同IUD使用者比较,BV与避孕套使用呈负关联,调整后的OR=0.299(95%C1:0.158~0.566);BV与OC使用间无关联。结论:使用IUD与未采用避孕措施者比较可能增加BV发生的危险,而避孕套使用者发生BV危险低于IUD使用者。无论从避孕还是预防BV角度,避孕套均是一种较好的选择。  相似文献   
66.
学龄儿童掌指骨发育某些正常变异的观察   总被引:1,自引:0,他引:1  
1980年和1990年对1259名城乡7~12岁学龄儿童掌指骨发育的正常变异进行了观察。结果证实,小指中节骨发育变异的检出率最高(总检出率14.7%),且男女儿童1990年此率均高于1980年(P<0.05),反映城市儿童该变异近10年有增高的趋势;1990年男女学龄儿童小指中节骨变异检出率城市明显高于农村(P<0.01);Ⅱ掌骨副骨骺总检出率3.8%,指骨骺核硬化总检出率2.2%,这两种变异男性明显高于女性.且无城乡差异。本观察各年龄组小指中节骨的变异同骨龄无规律性联系。  相似文献   
67.
Abstract Background: Aged Care Assessment Teams (ACATs) have been established throughout Australia during the past seven years. Early studies of their effect have concentrated on their impact on the rate of institutionalisation of disabled elderly, the clinical characteristics of referred cases and the relationship between disability and recommended care plan. Aims: The aim of this study was to explore the relationship between age, clinical features and social characteristics of AC AT subjects with outcomes at 12 months after assessment. Methods: The examination of an arbitrary sample of persons referred to ACATs over a year by one generalist geriatrician with follow-up of all cases by the three ACATs associated with the study was carried out. All analyses were performed on raw data presented as categorical variables in the form of contingency tables. Results: The sample included 324 subjects who suffered from 2030 clinical problems with a mean of 6.5 per person aged 75 or over and 5.5 for those under 75. Cardiovascular and neurological disease were the commonest source of problems. Study of accommodation outcome at 12 months, for those subjects who survived this period revealed that, in the older group, over 60% of subjects with neurological disease were resident in nursing homes while the majority of all other groups remained in the community, as did two-thirds of those aged under 75. Admission to a nursing home was independent of social support for older subjects with neurological disease, but it played a significant role in those with cardiopulmonary or musculoskeletal disease. Conclusions: The study demonstrates that for one-year survivors there is an increased likelihood of admission to a nursing home of people aged 75 or over with neurological disease, while those under 75 were more likely to remain at home. The association was independent of whether spouse, family or friends were living with the subject. (Aust NZ J Med 1994; 24: 378–385.)  相似文献   
68.
月经初潮与骨龄及发育指标研究   总被引:7,自引:0,他引:7  
本文研究了兰州市区6~17周岁女生360人的骨龄、身高、体重、胸围等项发育指标与月经初潮的关系,结果表明:已来潮女生各种发育指标均高于同龄未来潮者(P<0.01)。未来潮比已来潮者骨龄相差1.1岁,身高相差7.21cm,体重相差5.46kg,胸围相差3.65cm。平均初潮骨龄为13.45岁,初潮骨龄标准误差、最大-最小值及变异系数均小于生物年龄,说明初潮与骨龄关系最密切,用骨龄估计月经初潮最为准确可靠。初潮一般在拇籽骨出现15.7月内来潮。  相似文献   
69.
This study analyzed the effect of population aging on organ donation for transplants in 43 countries and on the effectiveness of the donation process by comparing the results between Spain and the United States. The percentage of the population aged 65 or over accounted for 33% of the difference in the donation rates between the countries and for 91% of the variation in the rates after age adjustment. However, the level of aging of the Spanish (16.5%) and American (12.3%) populations failed to account for the percentages of deceased donors 65 or over (28% vs. 10%), due to the different age-specific donation rates, much higher in Spain above 50 years. These differences lead to a higher effectiveness of the process in the United States (3.1 transplanted organs per donor vs. 2.5 in Spain), though at lower rates of transplant per million population (73 vs. 87). We conclude that older populations have a greater donation potential as donation rates are strongly associated with population aging. It should therefore be mandatory to adjust donation rates for age before making comparisons. Additionally, effectiveness decreases with older donors, so age should be considered when establishing standards relating to organ donation and effectiveness of the process.  相似文献   
70.
Many centers are reluctant to use older donors (>44 years) for adult right-lobe living donor liver transplantation (RLDLT) due to concerns about possible increased morbidity in donors and poorer outcomes in recipients. Since 2000, 130 adult RLDLTs have been performed at our institution. Recipients were divided into those who received a right lobe graft from a donor ≤age 44 (n = 89, 68%; median age 30) and those who received a liver graft from a donor age >44 (n = 41, 32%; mean age 52). The two donor and recipient populations had similar demographic and operative profiles. With a median follow-up of 29 months, the severity and number of complications in older donors were similar to those in younger donors. No living donor died. Older donor allografts had initial allograft dysfunction compared to younger donors. Complication rates were similar among recipients in both groups but there was a higher bile duct stricture rate with older donor grafts (27% vs. 12%; p = 0.04). One-year recipient graft survival was 86% for older donors and 85% for younger donors (p = 0.95). Early experience with the use of selected older adults (>44 years) for RLDLT is encouraging, but may be associated with a higher rate of biliary complications in the recipient.  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