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   5261篇
  免费   385篇
  国内免费   14篇
耳鼻咽喉   70篇
儿科学   204篇
妇产科学   130篇
基础医学   779篇
口腔科学   49篇
临床医学   734篇
内科学   917篇
皮肤病学   88篇
神经病学   473篇
特种医学   210篇
外科学   668篇
综合类   65篇
一般理论   3篇
预防医学   438篇
眼科学   129篇
药学   342篇
中国医学   4篇
肿瘤学   357篇
  2021年   79篇
  2020年   49篇
  2019年   87篇
  2018年   81篇
  2017年   67篇
  2016年   67篇
  2015年   101篇
  2014年   98篇
  2013年   175篇
  2012年   226篇
  2011年   236篇
  2010年   139篇
  2009年   126篇
  2008年   198篇
  2007年   212篇
  2006年   224篇
  2005年   201篇
  2004年   231篇
  2003年   194篇
  2002年   192篇
  2001年   163篇
  2000年   157篇
  1999年   180篇
  1998年   62篇
  1997年   47篇
  1996年   51篇
  1995年   48篇
  1994年   43篇
  1992年   110篇
  1991年   100篇
  1990年   115篇
  1989年   101篇
  1988年   90篇
  1987年   86篇
  1986年   100篇
  1985年   85篇
  1984年   64篇
  1983年   49篇
  1982年   40篇
  1981年   41篇
  1979年   83篇
  1978年   58篇
  1977年   54篇
  1976年   49篇
  1974年   47篇
  1973年   55篇
  1972年   49篇
  1969年   38篇
  1968年   36篇
  1967年   36篇
排序方式: 共有5660条查询结果,搜索用时 15 毫秒
51.
This article observes changes during the first 5 years of Resource Utilization Group, Version II (RUG-II) system utilization by the New York State Department of Health (NYDOH) for Medicaid program reimbursement. Findings include a dramatic increase in the number of residents scoring in the highest intensity resident-care categories, a substantial increase in staffing and expenditures for rehabilitation therapies, and a possible negative impact on the financial performance of New York long-term care (LTC) facilities. RUG-II appears to have been successful in improving access to nursing homes for individuals with heavy-care needs and in encouraging the appropriate utilization of institutionalized skilled nursing care.  相似文献   
52.
53.
54.
OBJECTIVE: The role of social support as a predictor of long-term survival among patients with schizophrenia was examined. METHODS: Social histories were abstracted from the medical records of a cohort of 133 deceased schizophrenic patients admitted for inpatient treatment between 1934 and 1944. Two independent raters assessed the quantity and quality of support available in each patient's social environment. RESULTS: Cox regression analysis revealed that higher quantity of social support was significantly related to survival time (p<.05) after controlling for marital status and quality of support. The Cox model indicated that a 1-point increase in the support quantity rating was associated with a proportional 25% decrease in the hazard rate. CONCLUSIONS: The present findings suggest that social environment, specifically the quantity of social support available to the patient, may impact longevity in psychiatric populations.  相似文献   
55.
The distribution of pathology related to Alzheimer's disease (AD) is not uniform throughout the brain. Sites which have a predilection for the development of Alzheimer-type pathology are the limbic regions and neocortical association areas. The changes in these areas of the brain develop gradually, following a well-determined sequence that allows a pathological staging of the disease process. According to the staging hypothesis, the first pathological alterations develop in the transentorhinal and entorhinal regions. The neurofibrillary pathology then spreads into the hippocampus, but not until the final stages does it affect the neocortex. In this study we analyse the relationship between the pathological stages of AD, according ot the staging hypothesis, and the clinical diagnosis in a prospectively assessed patient group. Prediction of any given pathological stage from the clinical diagnosis was found to be poor. This may be partly due to the fact that additional pathologies can alter the clinical picture and severity of dementia in patients who are only in the initial stages of AD. Nevertheless, the NINCDS-ADRDA clinical criteria had a high sensitivity for detection of AD-related pathology: the 'probable AD' category included 22/38 (57.9%) of those in the late isocortical stage, while the 'possible AD' category included 19/23 (82.6%) of those in the limbic stage. Using proposed neuro-imaging protocols for improved identification of patients with AD-related pathology, we largely identified subjects in whom the extent of pathology had spread to the neocortex.  相似文献   
56.
Micturating cystourethrography (MCU) examinations of paediatric patients in a major Dutch children's hospital (JKZ) were evaluated to generate quantitative information on effective dose (E). A standard examination involves three radiographs plus fluoroscopy. Observed total dose-area product (DAP) for 84 children increased, on average, with increasing age class from 0.2 to 2.2 Gy cm2. In 11 cases, separate DAP per view was measured; enabling determination, per view, of organ (CF) and effective (CE) dose conversion factors, i.e. dose per unit of DAP. Monte Carlo simulation of photon transport in male and female mathematical phantoms was applied for newborn, 1 year, 5 year, 10 year and 15-year-old patients, and interpolated for other ages. CE per view decreases with increasing age class, yielding about a factor of 10 difference between the extremes of the range. Female values are usually some 20-30% above male ones. CE for one of the views appeared to be representative for the complete examination and was used to estimate total E for each patient. Averaged per age class, E remains approximately constant at 0.3-0.4 mSv, although a tendency to increase with increasing age exists, for females in particular. Within an age class, individual patients may differ in E by a factor of two up to six. Stomach, lower large intestine, bladder wall, liver and ovaries receive relatively high doses. Compared with published data and DAP measured in a few other Dutch hospitals, the radiation burden of MCU is low at the JKZ. This indicates a good degree of optimization with respect to radiation protection (e.g. modern equipment, increased tube voltage, fast film-screen combination).  相似文献   
57.
PURPOSE: To present the imaging findings and treatment options for incomplete intertrochanteric fractures. MATERIALS AND METHODS: Among 31 patients with the magnetic resonance (MR) imaging diagnosis of incomplete intertrochanteric fracture, 30 also underwent radiography. MR and radiographic findings were compared. Note was made of fracture length and extent as depicted on the coronal and axial MR images, treatment (surgical vs conservative), and follow-up. RESULTS: Correlation between radiographic and MR findings was poor. Incomplete intertrochanteric fracture was the prospective radiographic diagnosis in only one case. Fracture in 18 patients was treated surgically and in 13 was managed conservatively. In both groups, the average age of the patients and length of the fractures and the percentage of separate fractures involving the greater trochanter and crossing the midline of the femur in the axial plane were the same. Fractures crossed the midline in the coronal plane in 50% of the surgical group but in only 23% of the nonsurgical group. Average time from injury to ambulation was 2 days less in the surgical group, but no difference in functional status was found subjectively between the two groups at clinical follow-up. CONCLUSION: Incomplete intertrochanteric fractures are a previously unrecognized subset of intertrochanteric fractures that are diagnosed unequivocally only with MR imaging.  相似文献   
58.
59.
60.
The linguistic and cognitive development of 26 premature and 27 full-term infants was studied longitudinally over the first 3 years of life. Infants in the premature population included 12 who were below 1500 g in birthweight and an even larger number with "at risk" signs. Language samples were collected in the home approximately every other month, the children were given experimenter-designed tests periodically, and mothers were asked to keep diaries of their children's lexical development. The children were given standardized tests as they exited the study. Cognitive development was also measured periodically. The patterns of lexical and cognitive development of the prematures did not differ markedly from those of full-term infants. There were no significant differences between the prematures as a whole and the full-term infants on standard language test measures as they exited from the study. There were significant differences between the very low birthweight and full-term infants on two of the exit measures. However, the performance of the very low birthweight infants was well within the range of normal on these two measures. The nature of the study and the factors that might have led to lack of differences between the two groups are discussed.  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