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   4469篇
  免费   263篇
  国内免费   12篇
耳鼻咽喉   11篇
儿科学   194篇
妇产科学   202篇
基础医学   503篇
口腔科学   84篇
临床医学   353篇
内科学   1042篇
皮肤病学   34篇
神经病学   621篇
特种医学   358篇
外科学   329篇
综合类   29篇
一般理论   4篇
预防医学   454篇
眼科学   36篇
药学   255篇
中国医学   1篇
肿瘤学   234篇
  2021年   43篇
  2020年   31篇
  2019年   60篇
  2018年   94篇
  2017年   82篇
  2016年   81篇
  2015年   92篇
  2014年   109篇
  2013年   186篇
  2012年   226篇
  2011年   232篇
  2010年   134篇
  2009年   149篇
  2008年   227篇
  2007年   201篇
  2006年   205篇
  2005年   218篇
  2004年   196篇
  2003年   199篇
  2002年   139篇
  2001年   150篇
  2000年   147篇
  1999年   113篇
  1998年   62篇
  1997年   70篇
  1996年   82篇
  1995年   67篇
  1994年   52篇
  1993年   76篇
  1992年   88篇
  1991年   77篇
  1990年   85篇
  1989年   87篇
  1988年   86篇
  1987年   78篇
  1986年   74篇
  1985年   69篇
  1984年   52篇
  1983年   31篇
  1982年   38篇
  1981年   24篇
  1980年   20篇
  1979年   27篇
  1978年   12篇
  1977年   20篇
  1976年   19篇
  1975年   32篇
  1974年   15篇
  1971年   9篇
  1970年   9篇
排序方式: 共有4744条查询结果,搜索用时 31 毫秒
1.
BackgroundA pancreatoduodenectomy (PD) is a highly advanced procedure associated with considerable post-operative complications and substantial costs. In this study the hospital costs associated with complications after PD were assessed.MethodsA retrospective cohort study was conducted on 100 consecutive patients who underwent a pylorus-preserving (PP)PD between January 2012 and July 2013. Per patient, all complications occurring during admission or in the 30-day period after discharge were documented. All hospital costs related to the (PP)PD were defined as the costs of all medical interventions and resources during the hospitalisation period as recorded by the electronic supply tracking system.ResultsThe median hospital costs ranged from €17 482 for a patient without complications to €55 623 for a patient with a post-operative haemorrhage. A post-operative haemorrhage was associated with a 39.6% increase in total hospital costs after adjusting for patient characteristics. Other factors significantly associated with an increase in total hospital costs were: the presence of a malignancy other than a pancreatic adenocarcinoma (29.4% cost increase), the severity grade of a complication (34.3–70.6% increase) and the presence of a post-operative infection (32.4% increase).ConclusionsThis study provides an in-depth analysis of hospital costs and identifies factors that are associated with substantial cost consequences of specific complications occurring after a PD.  相似文献   
2.
3.
The aim of this study was to investigate the test–retest (TRT) repeatability of various parametric quantification methods for [18F]Flortaucipir positron emission tomography (PET). We included eight subjects with dementia or mild cognitive impairment due to Alzheimer’s disease and six cognitively normal subjects. All underwent two 130-min dynamic [18F]Flortaucipir PET scans within 3 ± 1 weeks. Data were analyzed using reference region models receptor parametric mapping (RPM), simplified reference tissue method 2 (SRTM2) and reference logan (RLogan), as well as standardized uptake value ratios (SUVr, time intervals 40–60, 80–100 and 110–130 min post-injection) with cerebellar gray matter as reference region. We obtained distribution volume ratio or SUVr, first for all brain regions and then in three tau-specific regions-of-interest (ROIs). TRT repeatability (%) was defined as |retest–test|/(average (test + retest)) × 100. For all methods and across ROIs, TRT repeatability ranged from (median (IQR)) 0.84% (0.68–2.15) to 6.84% (2.99–11.50). TRT repeatability was good for all reference methods used, although semi-quantitative models (i.e. SUVr) performed marginally worse than quantitative models, for instance TRT repeatability of RPM: 1.98% (0.78–3.58) vs. SUVr80–100: 3.05% (1.28–5.52), p < 0.001. Furthermore, for SUVr80–100 and SUVr110–130, with higher average SUVr, more variation was observed. In conclusion, while TRT repeatability was good for all models used, quantitative methods performed slightly better than semi-quantitative methods.  相似文献   
4.
In this article the results are presented of the reconstruction of the alveolar process with iliac crest bone grafts in 14 patients. In all cases in a second operation a vestibuloplasty and a floor-of-mouth plasty was done. After an average follow-up period of 39 months, almost complete resorption of the bone grafts was observed. The clinical results varied. To obtain better results and avoid complications like pain at the donor and graft sites, mental nerve disturbances and other major problems associated with bone grafting, we prefer to perform the visor osteotomy in the future.  相似文献   
5.
Oral lichenoid drug eruptions   总被引:1,自引:0,他引:1  
OBJECTIVES: To identify, from amongst drugs reported as causing lichenoid drug eruptions, those affecting the oral mucous membranes and to review the clinical, histo-logical and immunological features of such oral lichenoid drug eruptions in comparison to oral lichen planus, amalgam contact lesions and lichen planus-like eruption in graft-versus-host disease (GVHD).
DATA SOURCES: Ovid® Medline data searches on CD-Rom were carried out for the years 1966–1996 to identify reports of oral lichenoid drug eruptions and their clinical, histological and immunological featureS. Articles retrieved were examined for further appropriate references in the period 1940–1996.
DATA EXTRACTION AND SYNTHESIS: Each paper was critically examined for evidence of a clinically verifiable lichenoid drug eruption affecting the oral mucous membranes and the effects of subsequent drug withdrawal. Available clinical, histological and immunological features were recorded. The papers examined were too diverse in nature to permit a structured criticism. The extracted data have been tabulated where appropriate.
CONCLUSIONS: The reports of oral lichenoid drug eruptions are considerably fewer than those of cutaneous eruptions and fewer drugs have been reported as causing oral rather than cutaneous lichenoid eruptionS. Histology and immunology cannot be used reliably to differentiate lichenoid drug eruptions from idiopathic lichen planus, amalgam contact lesions and lichen planus-like eruption in GVHD. Lichenoid drug eruptions may also show some histological characteristics of oral discoid lupus erythematosuS. An accepted protocol agreed by a number of international centres would permit the gathering of substantial information on LDE and could lead to a greater understanding of the mechanisms involved.  相似文献   
6.
7.
The relationship between microflora, eruption status and caries status in the first permanent molar of young children was investigated in 177 children aged 6-7 years. A significantly greater proportion of fully erupted teeth were classified as sound and plaque-free compared to partially erupted teeth. Fully erupted teeth yielded greater numbers and proportions of mutans streptococci compared with significantly greater numbers and proportions of Actinomyces israelii in partially erupted teeth. Logistical regression analysis showed significant associations between white spot lesions in partially erupted teeth and increased numbers of Streptococcus oralis, mutans streptococci and Streptococcus salivarius whereas the presence of Actinomyces naeslundii was associated with health. Significantly greater numbers and proportions of S. oralis and S. salivarius were isolated from partially erupted teeth with white spot lesions whereas Streptococcus mutans was isolated in significantly greater numbers and proportions from fully erupted molars with white spots. This study suggests that organisms other than mutans streptococci are associated with caries development in erupting permanent molar teeth.  相似文献   
8.
Nine Friesian sheep (age 1.5-2 years) were used to evaluate the quality of bone repair in artificial cleft-like maxillary defects repaired with autologous bone grafts of embryologically different origin. After bilateral extraction of the upper first deciduous molar the tooth socket was enlarged resulting in an open connection between the oral and nasal cavities. In the same session a graft, obtained from the iliac crest, was implanted in one of the two bilateral maxillary defects and on the opposite side a graft, obtained from the mandible, was inserted. During the experiment, serial radiographs were taken. After six months the sheep were sacrificed and the bone of the grafted areas was submitted to histological and histomorphometric investigation. Comparing both areas, it appeared that the quality of bone remodelling and alveolar reconstruction was independent of the origin of the grafts.  相似文献   
9.
10.
A cyst in the floor of the mouth of a 2-yr-old boy was characterized by smooth muscle tissue with an overlying epithelial lining of varying morphology including gastric mucosa. The combination of smooth muscle with a variety of epithelial linings argues against the "misplaced anlage" histogenesis.  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