全文获取类型
收费全文 | 16600篇 |
免费 | 1551篇 |
国内免费 | 235篇 |
专业分类
耳鼻咽喉 | 77篇 |
儿科学 | 665篇 |
妇产科学 | 233篇 |
基础医学 | 923篇 |
口腔科学 | 554篇 |
临床医学 | 1964篇 |
内科学 | 2064篇 |
皮肤病学 | 89篇 |
神经病学 | 1530篇 |
特种医学 | 194篇 |
外科学 | 1027篇 |
综合类 | 1729篇 |
现状与发展 | 1篇 |
预防医学 | 4889篇 |
眼科学 | 99篇 |
药学 | 835篇 |
30篇 | |
中国医学 | 371篇 |
肿瘤学 | 1112篇 |
出版年
2024年 | 49篇 |
2023年 | 347篇 |
2022年 | 624篇 |
2021年 | 884篇 |
2020年 | 799篇 |
2019年 | 720篇 |
2018年 | 674篇 |
2017年 | 681篇 |
2016年 | 638篇 |
2015年 | 605篇 |
2014年 | 1109篇 |
2013年 | 1312篇 |
2012年 | 993篇 |
2011年 | 1079篇 |
2010年 | 809篇 |
2009年 | 911篇 |
2008年 | 906篇 |
2007年 | 845篇 |
2006年 | 631篇 |
2005年 | 524篇 |
2004年 | 444篇 |
2003年 | 385篇 |
2002年 | 312篇 |
2001年 | 254篇 |
2000年 | 238篇 |
1999年 | 188篇 |
1998年 | 178篇 |
1997年 | 146篇 |
1996年 | 121篇 |
1995年 | 134篇 |
1994年 | 93篇 |
1993年 | 93篇 |
1992年 | 84篇 |
1991年 | 71篇 |
1990年 | 61篇 |
1989年 | 64篇 |
1988年 | 57篇 |
1987年 | 41篇 |
1986年 | 30篇 |
1985年 | 60篇 |
1984年 | 39篇 |
1983年 | 26篇 |
1982年 | 24篇 |
1981年 | 22篇 |
1980年 | 16篇 |
1979年 | 16篇 |
1978年 | 13篇 |
1977年 | 7篇 |
1976年 | 8篇 |
1972年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
This paper reports the prevalence of chronic esophagitis and nutritional status among 538 young persons aged 15 to 26 years from the high risk area for esophageal cancer. Of these subjects, 166 were from households with history of esophageal cancer and 372 were from households without history of esophageal cancer. The Incidences of chronic esophagltis among male and female adolescents were 37. 6% and 36% respectively, which was significantly higher than those in the low risk area (17%). The frequency of chronic esophagltis in the adolescents in the households with history of esophageal cancer was aiso higher than in those In the households without history of esophageal cancer. The deficiencies of vitamins, especially of riboflavin and ascorbate, are prevalent and severe among these adolescents. Ascorbate deficiency Is correlated with the severity of the chronic esophagltis. These results indicate that chronic esophagltis may be involved in the natural history of esophageal carclnogenesis. Nutrient defic 相似文献
52.
A significant minority of medical and dental students fail their undergraduate courses. Early warning systems (EWSs) have been developed in some areas of higher education to predict 'at-risk' students at an early remedial stage. An attempt is made to develop an EWS to predict failure in the bacteriology component of the Batchelor of Dental Surgery course at Manchester Dental School. A system based on class tests and previous end-of-year performance is derived which is used to predict those students likely to fail or fall in the bottom 20-25% in their finals examination. The predictors are combined by a simple equal weights method, which is found to have the same predictive power as using multiple regression. Failure was correctly predicted in 60% of cases, at the expense of 71% false alarms. The high number of false alarms reflects the low failure rate rather than the lack of predictive information. The need for effective cross-validation of EWSs is discussed; many previous studies have not been tested on independent data. 相似文献
53.
Linda S. Scheirton Ph.D. 《HEC forum》1992,4(6):342-359
In December 1990, an empirical study assessing hospital ethics committee (HEC) success was completed. Success was measured in terms of the number of interventions undertaken by the committees in four functional areas: education, guidelines development, prospective and retrospective case review. Some commonly quoted success determinants, such as multidisciplinarity, physician chairpersons, and a high institutional status of the chairperson were found not to foster success; the latter two, actually decreased committee success. 相似文献
54.
A. L. Dinzburg A. M. Chirkov S. K. Chirkova I. S. Voit 《Bulletin of experimental biology and medicine》1992,114(5):1579-1581
Research Institute of Experimental Pathology and Therapy, Sukhumi. (Presented by Academician of the Russian Academy of Medical Sciences B. A. Lapin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 114, No. 11, pp. 457–459, November, 1992. 相似文献
55.
对山东省荣成市石岛镇大渔岛村91户398名散居渔民膳食结构及营养状况调查的结果表明:①蛋白质和热能人均摄入量占平均供给量的115.4%和112.2%,其它营养素除维生素B2占83.3%以外均摄入较充足。蛋白质、脂肪、碳水化合物的热量构成比分别为11.3%、27.6%、61.1%。②查体中未发现严重的营养缺乏症。③体重指数超过正常者占13.2%。④体重指数与收缩压、舒张压经相关回归分析,呈显著相关。⑤大渔岛居民头发锌含量高于泰安农民,铜、铁含量低于泰安农民。 相似文献
56.
57.
Dietary intake in the elderly estimated by a 24 hour recall and a food frequency questionnaire 总被引:1,自引:0,他引:1
P. Caughey C. E. A. Seaman† D. A. Parry† D. L. Farquhar‡ W. J. MacLennan§ R. Prescott§ 《Journal of human nutrition and dietetics》1994,7(3):209-213
Two hundred and thirty-five tenants living in sheltered housing in Scotland were surveyed to identify the extent of under-nutrition and the social factors which contribute to its development. A validated 24 h recall and the nutrient checklist published by NAGE were used to evaluate patterns of dietary intake. A questionnaire was developed which included scales designed to measure depression, social engagement, cognitive function, mobility and functional ability. The results show considerable evidence of a number of major nutrients in which there were low intakes. In order to express the extent of poor nutrition, a nutrient score was developed where points are awarded based on the number of nutrients falling below the Lower Reference Nutrient Intake, the Estimated Average Requirement or below half the daily Estimated Average Requirement. 相似文献
58.
E. A. Mowat S. Thomas R. Hyatt J. D. Maxwell M. N. Whitelaw 《Journal of human nutrition and dietetics》1992,5(1):35-51
Two sample groups of elderly were compared from a population living in South London. One group attended a local day centre (a socially orientated establishment), and the other attended a local day hospital (a therapeutically orientated establishment).
The aim of the study was to compare nutritional intake, functional status and muscle strength between these two groups.
The mean nutritional intakes of the day hospital and day centre attenders were similar. Intake of macronutrients, with the exception of fibre, met Recommended Daily Allowances (RDAs) in both groups. In take of folic acid, vitamin D and zinc fell below recommendations in both groups.
Low intake of folic acid was improved by supplementation, and some individual blood levels of folate reflected this. Blood folate levels were generally within normal limits. Low intake of vitamin D was improved by supplementation, but blood levels were generally normal anyway. There was, however, a tendency for the more dependent day hospital patients to have lower vitamin D levels. This group also had less sunshine exposure.
Communal dining, whether in the setting of day hospital or day centre, may have been an essential means of bolstering nutritional intake for many 'at risk' elderly.
There were significant differences in functional status and muscle strength in favour of the day centre group and these indicate that anthropometric indices rather than nutritional or biochemical indices were the most reliable markers of disease and disability in this study.
The effect of fortifying local meals-on-wheels was also highlighted, and suggests that this may be one means of preventing nutritional deficiencies in the vulnerable, house-bound elderly.
Alcohol intake was reported as being modest. However, discrepancies were noted on review of biochemical indices known to be influenced by alcohol intake. 相似文献
The aim of the study was to compare nutritional intake, functional status and muscle strength between these two groups.
The mean nutritional intakes of the day hospital and day centre attenders were similar. Intake of macronutrients, with the exception of fibre, met Recommended Daily Allowances (RDAs) in both groups. In take of folic acid, vitamin D and zinc fell below recommendations in both groups.
Low intake of folic acid was improved by supplementation, and some individual blood levels of folate reflected this. Blood folate levels were generally within normal limits. Low intake of vitamin D was improved by supplementation, but blood levels were generally normal anyway. There was, however, a tendency for the more dependent day hospital patients to have lower vitamin D levels. This group also had less sunshine exposure.
Communal dining, whether in the setting of day hospital or day centre, may have been an essential means of bolstering nutritional intake for many 'at risk' elderly.
There were significant differences in functional status and muscle strength in favour of the day centre group and these indicate that anthropometric indices rather than nutritional or biochemical indices were the most reliable markers of disease and disability in this study.
The effect of fortifying local meals-on-wheels was also highlighted, and suggests that this may be one means of preventing nutritional deficiencies in the vulnerable, house-bound elderly.
Alcohol intake was reported as being modest. However, discrepancies were noted on review of biochemical indices known to be influenced by alcohol intake. 相似文献
59.
The Relative Contribution of Domains of Quality of Life to Overall Quality of Life for Different Chronic Diseases 总被引:3,自引:0,他引:3
R. Arnold A.V. Ranchor R. Sanderman G.I.J.M. Kempen J. Ormel T.P.B.M. Suurmeijer 《Quality of life research》2004,13(5):883-896
This study examined the contribution of the quality of life (QoL) domains physical, social and psychological functioning to the explanation of overall QoL. Various disorders may differentially affect QoL domains due to disease-specific factors and, consequently, the relationship between QoL domains and overall QoL may vary between diseases. We therefore studied this relationship for several diseases as well as the differential impact of these diseases on QoL. The present study had a cross-sectional design. We selected patients (aged 57 years and older) with one of the following eight chronic medical conditions: lung disorder, heart condition, hypertension, diabetes mellitus, back problems, rheumatoid arthritis, migraine, or dermatological disorders. The total group of respondents included 1457 patients and 1851 healthy subjects. Regression analyses showed that the domain of psychological functioning contributed to overall QoL for all disorders, whereas physical and social functioning contributed to overall QoL for some disorders. Differences were found between most patient groups and healthy subjects with respect to physical functioning; with respect to social and psychological functioning some groups differed from the healthy group. Explanations for the findings and implications for clinical practice are discussed. 相似文献
60.
Harun Ulger Nuri Erdogan Sadan Kumanlioglu Erdogan Unur 《Skin research and technology》2003,9(3):284-289
Background/purpose: The localized or generalized skin thickness detected on mammography may reflect an underlying pathology of breast or a systemic disease involving the skin. The aim of this report is to describe the range of normal breast skin thickness in women using a film-screen mammographic technique.
Methods: Measurement of the mammographic skin thickness over different parts of the breast was performed in 144 women who had normal findings in a combined mammographic and ultrasonographic examination. Patients were grouped as premenopause, postmenopause and surgical menopause who were under continuous oestrogen treatment. The skin thickness in four regions (superior, inferior, medial, lateral) of both breasts was compared, and their relations with age, breast size, menopausal and hormonal status were investigated. The interobserver reliability was tested in a small subgroup of patients.
Results: Interobserver agreement was good for all measurements. The range of normal breast skin thickness was between 0.50 and 3.10 mm. There were no differences in skin thickness between the corresponding regions of the breasts, with significant differences between the regions in the same breast. While breast size increased with age, skin thickness decreased in all regions.
Conclusion: The breast size, age, regional variations and hormonal status of the patients should be considered when defining the normal range of skin thickness in mammographic examinations. We assume that upper limit of mammographic skin thickness should be set as 3.0 mm, regardless of the focal spot size and film-focus distance. 相似文献
Methods: Measurement of the mammographic skin thickness over different parts of the breast was performed in 144 women who had normal findings in a combined mammographic and ultrasonographic examination. Patients were grouped as premenopause, postmenopause and surgical menopause who were under continuous oestrogen treatment. The skin thickness in four regions (superior, inferior, medial, lateral) of both breasts was compared, and their relations with age, breast size, menopausal and hormonal status were investigated. The interobserver reliability was tested in a small subgroup of patients.
Results: Interobserver agreement was good for all measurements. The range of normal breast skin thickness was between 0.50 and 3.10 mm. There were no differences in skin thickness between the corresponding regions of the breasts, with significant differences between the regions in the same breast. While breast size increased with age, skin thickness decreased in all regions.
Conclusion: The breast size, age, regional variations and hormonal status of the patients should be considered when defining the normal range of skin thickness in mammographic examinations. We assume that upper limit of mammographic skin thickness should be set as 3.0 mm, regardless of the focal spot size and film-focus distance. 相似文献