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   849篇
  免费   63篇
  国内免费   49篇
耳鼻咽喉   5篇
儿科学   27篇
妇产科学   33篇
基础医学   91篇
口腔科学   17篇
临床医学   132篇
内科学   133篇
皮肤病学   19篇
神经病学   67篇
特种医学   159篇
外国民族医学   3篇
外科学   66篇
综合类   13篇
预防医学   55篇
眼科学   15篇
药学   51篇
中国医学   1篇
肿瘤学   74篇
  2021年   14篇
  2019年   11篇
  2018年   10篇
  2017年   6篇
  2016年   12篇
  2015年   24篇
  2014年   19篇
  2013年   34篇
  2012年   26篇
  2011年   31篇
  2010年   16篇
  2009年   19篇
  2008年   23篇
  2007年   50篇
  2006年   18篇
  2005年   17篇
  2004年   9篇
  2003年   14篇
  2002年   10篇
  2001年   9篇
  2000年   18篇
  1999年   22篇
  1998年   30篇
  1997年   35篇
  1996年   29篇
  1995年   28篇
  1994年   22篇
  1993年   23篇
  1992年   22篇
  1991年   15篇
  1990年   19篇
  1989年   31篇
  1988年   24篇
  1987年   19篇
  1986年   24篇
  1985年   19篇
  1984年   9篇
  1983年   21篇
  1982年   12篇
  1981年   13篇
  1980年   10篇
  1979年   6篇
  1978年   13篇
  1977年   19篇
  1976年   15篇
  1975年   9篇
  1974年   10篇
  1973年   7篇
  1971年   8篇
  1967年   8篇
排序方式: 共有961条查询结果,搜索用时 0 毫秒
1.
2.
A diary method using household measures was employed to obtain dietary records in a large national prospective survey and a computer program, DIDO (Diet In Data Out), was designed for direct entry of the diaries. The accuracy of this computerized coding system was examined alongside that of the manual coding used for a similar diary in a previous wave, 7 years earlier, of the same survey. Accuracy was assessed by analysis of the errors in the coded and checked records by stringent re-checking of nominal 2% random subsamples of the diet diaries coded by each method. The mean time to code and check each of the 2086 7-day records in the whole survey using DIDO was 58 minutes (SD 30) compared with reported results of 1–4 hours for manual methods. The mean error rate of computerized coding and checking with DIDO was 2.3% (SD 2.1; range 0–8.9) per diary in the subsample. Correcting these mistakes made insignificant changes to the calculated mean energy and nutrient intakes for the subsample. The percentage of individuals changing to an adjacent third of nutrient distribution after correcting unambiguous errors ranged from none (for alcohol) to 11% (for carbohydrate and calcium intake). The mean error rate on a similar subsample of diaries from the earlier survey which had been coded manually was significantly higher at 5.9% (SD 4.1; range 0–17) per diary. Emphasis is laid on the importance, in coding, of dealing with ambiguities in the subjects' records, since this can affect the accuracy and the precision of the nutrient results obtained. We conclude that the DIDO coding method has the advantages of greater accuracy, speed, consistency and efficient data handling, and affords greater data accessibility for checking, compared with manual systems.  相似文献   
3.
This report describes the postcontrast MR findings of Wernicke encephalopathy seen in a malnourished 11-year-old boy. The examination showed increased signal on T2-weighted images in the periaqueductal gray matter and medial thalami. On T1-weighted acquisition, these areas showed decreased signal intensity, but on postcontrast T1-weighted examination, they showed moderately intense enhancement. Also noted on the postcontrast examination was mamillary body enhancement.  相似文献   
4.
Neurofibromatosis 2 (NF2) is an inherited cancer syndrome resulting from mutations in the NF2 tumor suppressor gene. Analysis of NF2 mutations has revealed some general genotype-phenotype correlations. Severe disease has been associated with mutations that produce a premature termination while more mild disease has been associated with missense mutations. Here, we provide experimental proof for these genotype-phenotype correlations by demonstrating that nonsense mutations fail to produce stable merlin protein while missense mutations result in the generation of merlin proteins defective in negative growth regulation. This inability to suppress cell growth may result from defects in the function of merlin at several levels, including failure to form an intramolecular complex. Based on these findings, we propose a model for merlin growth suppression that provides a framework for analyzing NF2 patient mutations and merlin function.   相似文献   
5.
We randomly assigned 65 women who had been sexually abused by a father, stepfather, or other close relative to 1 of 3 treatment conditions: a 10-week interpersonal transaction (IT) group, a 10-week process group, or a wait list condition. Subjects were evaluated at pretreatment, posttreatment, and (if assigned to a group) a 6-month follow-up on measures of social adjustment, depression, fearfulness, and general distress. Results suggested that both the IT and process group formats were more effective than the wait list condition in reducing depression and in alleviating distress; changes were maintained at follow-up. Subjects in the process group format exhibited improvement in social adjustment, whereas subjects in the wait list condition actually deteriorated.  相似文献   
6.
Breast cancer detection: one versus two views   总被引:2,自引:0,他引:2  
Mammographic examinations of 169 patients with 172 biopsy-proved carcinomas, and of 194 healthy subjects, were interpreted independently and retrospectively by three experienced mammographers, initially as single-view oblique examinations and 6 months later as two-view oblique-cephalocaudal examinations. For the single-view examinations of the cancer patients, 67% of the cancers were correctly recommended for biopsy, additional views were requested for 23%, and a "negative" interpretation was made for 10%. For the single-view examinations of healthy subjects, biopsy was recommended for 7% and additional views were recommended for 32%. For the two-view examinations of women with cancer, 80% of the cancers were correctly recommended for biopsy, additional views were requested for 4%, and a "negative" interpretation was made for 16%. For two-view examinations of healthy subjects, biopsy was recommended for 7% and additional views were requested for only 5%. The authors conclude that single-view screening should not be performed, because it would lead to an excessive number of "call-back" examinations of healthy patients, producing additional cost and anxiety that would outweigh any theoretical benefit.  相似文献   
7.
BackgroundHypertension is a major risk factor for cardiovascular morbidity and mortality in post-menopausal women. Although menopausal hormone therapy (MHT) is a very effective treatment for vasomotor symptoms during this period, the influence of this therapy on blood pressure is not yet clear.ObjectiveTo evaluate the relationship between the use of MHT and hypertension in participants of the ELSA-Brasil.MethodsA cross-sectional study using the baseline ELSA-Brasil data in a cohort of 2,138 women who had experienced natural menopause. This study analyzed hypertension, defined as arterial pressure ≥140/90 mmHg or previous antihypertensive use, and use of MHT, with participants being classified into never, past, and current users. Associations were assessed using an adjusted logistic regression model, with statistical significance set at p<0.05.ResultsOverall, 1,492 women (69.8%) had never used MHT, 457 (21.4%) had used it in the past, and 189 (8.8%) were current users. The use of MHT was more common in women who had a body mass index (BMI) <25 kg/m2and triglyceride levels <150 mg/dl, and who were physically less inactive, non-smokers, and non-diabetics. Current MHT users were less likely to have hypertension (OR=0.59; 95% CI: 0.41-0.85) compared to those who had never used MHT. In most cases, MHT was started at or before 59 years of age, within 10 years of becoming menopausal, and its use lasted for up to five years.ConclusionCurrent MHT use was not related to hypertension, particularly in healthy women and in those under 60 years of age.  相似文献   
8.
Diarrhea is a common complaint—unpleasant at best, life-threatening at worst Much has been learned recently about its pathophysiology and etiology, with important implications for management Dr Farmer reviews the major causes of infectious diarrhea for us in the following pages.  相似文献   
9.
[Purpose] The purpose of this study was to investigate the use of smartphones by university students in selected areas, their musculoskeletal symptoms, and the associated hazard ratio. [Subjects and Methods] This involved the completion of a self-administered questionnaire by dental hygiene students in Seoul, Gyeonggido, and Gyeongsangbukdo. The 292 completed copies of the questionnaire were then analyzed. [Results] The most painful body regions after the use of smartphones were found to be the shoulders and neck. In the musculoskeletal system, back pain was found to have a positive correlation with the size of the smartphone’s liquid crystal display (LCD) screen, and pain in legs and feet were found to have a negative correlation with the length of time that the smartphone was used. As a result, it was revealed that the use of a smartphone was correlated with musculoskeletal symptoms. [Conclusion] Therefore, in today’s environment, where the use of smartphones is on the rise, it is necessary to improve the ways that they are used and to develop a preventive program to alleviate the symptoms of musculoskeletal damage.Key words: Smartphone, Musculoskeletal symptoms, Prevent  相似文献   
10.
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